No Evidence That Islands Are Sinking Due to Rising Seas

According to the climate-change narrative, island nations such as the Maldives in the Indian Ocean and Tuvalu in the Pacific face the specter of rising seas, fleeing residents and vanishing villages. But recent research belies the claim that such tropical paradises are about to disappear beneath the waves, revealing that most of the hundreds of atolls studied actually grew in size from 2000 to 2017.

Low-lying atoll islands consist of a ring-shaped coral reef partly or completely encircling a shallow green lagoon in the midst of a deep blue sea. Perched just a few meters above sea level, these coral-reef islands are susceptible to rising waters that can cause flooding, damage to infrastructure and the intrusion of saltwater into groundwater. Such concerns are behind the grim prognosis that islanders will become “climate refugees,” forced to leave their homes as the oceans rise.

However, two recent studies conclude that this threat is unfounded. A 2021 study analyzed changes in land area on 221 atolls in the Indian and Pacific Oceans, utilizing cloud-free imagery from Landsat satellites. The atolls studied are shown in red in the following figure. Apart from the Maldives and Tuvalu, the dataset included islands in the South China Sea, the Marshall Islands and French Polynesia.

The study found that the total land area of the atolls increased by 6.1% between 2000 and 2017, from 1,008 to 1,069 square kilometers (389 to 413 square miles). Most of the gain was from the Maldives and South China Sea atolls, which together accounted for 88% of the total increase, and came from artificial building of islands within those areas for development of infrastructure, extra land and resorts.

As shown in the next figure, the areas of two island groups – French Polynesia and Palau – did diminish over the study period. Although these two groups accounted for 68 of the 221 atolls studied, the combined decrease represents only 0.15% of the global total area. The Republic of the Marshall Islands is designated as RMI; the percentages at the bottom of the figure are the increases or decreases of the individual island groups.

An earlier study by the same researchers analyzed shoreline changes in the 101 reef islands of the Pacific nation of Tuvalu between 1971 and 2014; this excluded the 9 atolls forming part of the subsequent study. During these 43 years the local sea level rose at twice the global average, at a rate of 3.9 mm (about 1/8 of an inch) per year. But despite surging seas, the total land area of the 101 islands expanded by 2.9% over the slightly more than four decades. The changes are illustrated in the figure below, where the areas on the horizontal axis and the changes on the vertical axis are measured in hectares (ha).

Altogether, 73 reef islands grew in size – some by more than 100% – and the other 28 shrank, though by a smaller average amount. Light blue circles enclosing symbols in the figure denote populated islands. Tuvalau is home to 10,600 people, half of whom live on the urban island of Fogafale in Funafuti atoll. Fogafale expanded by 3% or 4.6 hectares (11.4 acres) over the 43-year study period.

Concerns about rising seas in the Maldives, the world’s lowest country, gained worldwide attention in 2009 when the Maldivian president and cabinet held an underwater meeting at the bottom of a turquoise lagoon. But the theatrics of ministers clad in black diving suits and goggles, signing a document asking all countries to reduce their CO₂ emissions, were unnecessary. A research paper published subsequently in 2018 by Northumbria University scientists found that the Maldives actually formed when sea levels were even higher than they are today.

The researchers studied the formation of five atoll rim islands in the southern Maldives, by drilling cores in sand- and gravel-based reefs. A timeline was established by radiocarbon dating. What they found was that the islands formed approximately three to four thousand years ago, through the pounding on the reefs of large waves caused by distant storms off the coast of South Africa.

These large waves, known as high-energy wave events, broke coral debris off the reefs and transported it onto reef platforms, initiating reef island growth. Sea levels at that time were at least 0.5 meters (1.6 feet) higher than they are today, so the waves had more energy than current ocean swells. Further vertical reef growth is possible in the future, the study authors say, as sea levels continue to rise and large wave events increase, accompanied by sedimentation.

Next: Little Evidence That Global Warming Is Causing Extinction of Coral Reefs

No Evidence That Thwaites Glacier in Antarctica Is about to Collapse

Contrary to recent widespread media reports and dire predictions by a team of earth scientists, Antarctica’s Thwaites Glacier – the second fastest melting glacier on the continent – is not on the brink of collapse. The notion that catastrophe is imminent stems from a basic misunderstanding of ice sheet dynamics in West Antarctica.

The hoopla began with publication of a research study in November 2021 and a subsequent invited presentation to the AGU (American Geophysical Union). Both postulated that giant cracks recently observed in the Thwaites Eastern Ice Shelf (pictured to the left) may cause the whole ice shelf to shatter within as little as five years. The cracks result from detachment of the ice shelf’s seaward edge from an underwater mountain about 40 kilometers (25 miles) offshore that pins the shelf in place like a cork in a bottle.

Because the ice shelf already floats on the ocean, collapse of the shelf itself and release of a flotilla of icebergs wouldn’t cause global sea levels to rise. But the researchers argue that loss of the ice shelf would speed up glacier flow, increasing the contribution to sea level rise of the Thwaites Glacier – often dubbed the “doomsday glacier” – from 4% to 25%. A sudden increase of this magnitude would have a devastating impact on coastal communities worldwide. The glacier’s location is indicated by the lower red dot in the figure below.  

But such a drastic scenario is highly unlikely, says geologist and UN IPCC expert reviewer Don Easterbrook. The misconception is about the submarine “grounding” of the glacier terminus, the boundary between the glacier and its ice shelf extending out over the surrounding ocean, as illustrated in the next figure.

The grounding line of the Thwaites Glacier, shown in red in the left figure below, has been retreating since 2000. According to the study authors, this spells future disaster: the retreat, they say, will lead to dynamic instability and greatly accelerated discharge of glacier ice into the ocean, by as much as three times.

As evidence, the researchers point to propagating rifts on the top of the ice shelf and basal crevasses beneath it, both of which are visible in the satellite image above, the rifts as diagonal lines and the crevasses as nearly vertical ones. The crevasses arise from basal melting produced by active volcanoes underneath West Antarctica combined with so-called circumpolar deep water warmed by climate change.

However, as Easterbrook explained in response to a 2014 scare about the adjacent Pine Island glacier, this reasoning is badly flawed since a glacier is not restrained by ice at its terminus. Rather, the terminus is established by a balance between ice gains from snow accumulation and losses from melting and iceberg calving. The removal of ice beyond the terminus will not cause unstoppable collapse of either the glacier or the ice sheet behind it.

Other factors are important too, one of which is the source area of Antarctic glaciers. Ice draining into the Thwaites Glacier is shown in the right figure above in dark green, while ice draining into the Pine Island glacier is shown in light green; light and dark blue represent ice draining into the Ross Sea to the south of the two glaciers. The two glaciers between them drain only a relatively small portion of the West Antarctic ice sheet, and the total width of the Thwaites and Pine Island glaciers constitutes only about 170 kilometers (100 miles) of the 4,000 kilometers (2,500) miles of West Antarctic coastline.

Of more importance are possible grounding lines for the glacier terminus. The retreat of the present grounding line doesn’t mean an impending calamity because, as Easterbrook points out, multiple other grounding lines exist. Although the base of much of the West Antarctic ice sheet, including the Thwaites glacier, lies below sea level, there are at least six potential grounding lines above sea level, as depicted in the following figure showing the ice sheet profile. A receding glacier could stabilize at any of these lines, contrary to the claims of the recent research study.

As can be seen, the deepest parts of the subglacial basin lie beneath the central portion of the ice sheet where the ice is thickest. What is significant is the ice thickness relative to its depth below sea level. While the subglacial floor at its deepest is 2,000 meters (6,600 feet) below sea level, almost all the subglacial floor in the above profile is less than 1,000 meters (3,300 feet) below the sea. Since the ice is mostly more than 2,500 meters (8,200 ft) thick, it couldn’t float in 1,000 meters (3,300 feet) of water anyway.

Next: Science Under Renewed Attack: New Zealand Proposal to Equate Maori Mythology with Science

Sudden Changes in Ocean Currents Warmed Arctic, Cooled Antarctic in Past

Abrupt changes in ocean currents – and not greenhouse gases – were responsible for sudden warming of the Arctic and for sudden cooling in the Antarctic at different times in the past, according to two recent research studies. The Antarctic cooling marked the genesis of the now massive Antarctic ice sheet.

The first study, by a team of European scientists, discovered that the expansion of warm Atlantic Ocean water flowing into the Arctic caused sea surface temperatures in the Fram Strait east of Greenland to rise by about 2 degrees Celsius (3.6 degrees Fahrenheit) as early as 1900. The phenomenon, known as “Atlantification” of the Arctic, is important because it precedes instrumental measurements of the effect by several decades and is not simulated by computer climate models.

The conclusion is based on an 800-year reconstruction of Atlantification along the Fram Strait, which separates Atlantic waters from the Arctic Ocean. The researchers used marine sediment cores as what they call a “natural archive” of past climate variability, deriving the chronological record from radionuclide dating.

Shown in the figure below is the sea surface temperature and Arctic sea ice extent from 1200 to 2000. The blue curve represents the reconstructed mean summer temperature (in degrees Celsius) of Atlantic waters in the eastern Fram strait, while the red curve indicates the April retreat (in kilometers) of the sea ice edge toward the Arctic. You can see clearly that the seawater temperature increased abruptly around 1900, after centuries of remaining constant, and that sea ice began to retreat at the same time, after at least a century of extending about 200 kilometers farther into the strait.

Along with temperature, the salinity of Atlantic waters in the strait suddenly increased also. The researchers suggest that this Atlantification phenomenon could have been due to weakening of two ocean currents – the AMOC (Atlantic Meridional Overturning Circulation) and the SPG (Subpolar Gyre), a circular current south of Greenland – at the end of the Little Ice Age. The AMOC forms part of the ocean conveyor belt that redistributes seawater and heat around the globe.

This abrupt change in ocean currents is thought to have redistributed nutrients, heat and salt in the northeast Atlantic, say the study authors, but is unlikely to be associated with greenhouse gases. The change caused subtropical Atlantic waters to flow northward through the Fram Strait, as illustrated schematically in the figure below; the halocline is the subsurface layer in which salinity changes sharply from low (at the surface) to high. The WSC (West Spitsbergen Current) carries heat and salt to the Arctic and keeps the eastern Fram Strait ice-free.

Sudden cooling occurred in the Antarctic but millions of years earlier, a second study has found. Approximately 34 million years ago, a major reorganization of ocean currents in the Southern Ocean resulted in Antarctic seawater temperatures abruptly falling by as much as 5 degrees Celsius (9 degrees Fahrenheit). The temperature drop initiated growth of the Antarctic ice sheet, at the same time that the earth underwent a drastic transition from warm Greenhouse to cold Icehouse conditions.

This dramatic cooling was caused by tectonic events that opened up two underwater gateways around Antarctica, the international team of researchers says. The gateways are the Tasmanian Gateway, formerly a land bridge between Antarctica and Tasmania, and Drake Passage, once a land bridge from Antarctica to South America. The scientists studied the effect of tectonics using a high-resolution ocean model that includes details such as ocean eddies and small-scale seafloor roughness.

After tectonic forces caused the two land bridges to submerge, the present-day ACC (Antarctic Circumpolar Current) began to flow. This circumpolar current, although initially less strong than today, acted to weaken the flow of warm waters to the Antarctic coast. As the two gateways slowly deepened, the warm-water flow weakened even further, causing the relatively sudden cooling event.

Little cooling occurred before one or both gateways subsided to a depth of more than 300 meters (1,000 feet). After the second gateway had subsided from 300 meters (1,000 feet) to 600 meters (2,000 feet), surface waters along the entire Antarctic coast cooled by 2 to 3.5 degrees Celsius (3.6 to 6.3 degrees Fahrenheit). And once the second gateway had subsided below 600 meters (2,000 feet), the temperature of Antarctic coastal waters decreased another 0.5 to 2 degrees Celsius (0.9 to 3.6 degrees Fahrenheit). The next figure depicts the gradual opening of the two gateways.

Although declining CO₂ levels in the atmosphere may have played a minor role, the study authors conclude that undersea tectonic changes were the key factor in altering Southern Ocean currents and in creating our modern-day Icehouse world.

Next: No Evidence That Thwaites Glacier in Antarctica Is about to Collapse

El Niño and La Niña May Influence the Climate More than Greenhouse Gases

The familiar El Niño and La Niña cycles are known to cause drastic fluctuations in global temperature, along with often catastrophic climatic effects in tropical regions of the Pacific Ocean. What is less well known is that the powerful ocean oscillations have been a feature of our climate for at least 20,000 years – that is, since before the most recent ice age ended.

A 2005 study established a complete record of El Niño events in the southeastern Pacific, by examining marine sediment cores drilled off the coast of Peru. The cores contain an El Niño signature in the form of tiny, fine-grained stone fragments, washed into the sea by multiple Peruvian rivers following floods on the continent caused by heavy El Niño rainfall. As indicated in the adjacent figure, the study site was approximately 80 kilometers (50 miles) from Lima at a depth of 184 meters (604 feet).

Northern Peru sees the heaviest El Niño rainfall, generating floods capable of dispersing large amounts of fine-grained river sediments. Smaller amounts of rainfall in central and southern Peru, which are not caused by El Niño, don’t result in flooding with the same dispersal capability.

The study authors classified the flood event signal as very strong when the concentration of stone fragments, known as lithics, was more than two standard deviations above the centennial mean. The frequency of these very strong events over the last 12,000 years is illustrated in the next figure; the black and gray bars show the frequency as the number of 500- and 1,000-year floods, respectively. Radiocarbon dating of the sediment cores was used to establish the timeline.

It can be seen that the number of very strong Peruvian flood events peaked around 9,500 years ago and again about 2,500 years ago, since when the number has been decreasing. No extreme floods occurred at all from about 5,500 to 7,500 years in the past.

A more detailed record is presented in the following figure, showing the variation over 20,000 years of the sea surface temperature off Peru (top), the lithic concentration (bottom) and a proxy for lithic concentration (middle). Sea surface temperatures were derived from chemical analysis of the marine sediment cores.

As indicated in this figure, the lithic concentration and therefore El Niño strength were high around 2,000 and 10,000 years ago – approximately the same periods when the most devastating floods occurred. The figure also reveals the absence of strong El Niño activity from 5,500 to 7,500 years ago, a dry interval without any major Peruvian floods.

But it’s seen that El Niños were strong in other eras too. During this 20,000-year span, El Niños first became prominent between 17,000 and 16,000 years before now, at the same time that sea surface temperatures jumped several degrees. The initial rise in both El Niños and ocean temperature was followed by roughly centennial fluctuations, alternating between weaker and stronger El Niño activity. After the gap from 7,500 to 5,500 years ago, El Niños surged again, as did sea surface temperatures.

On a finer scale, El Niños during the last two millennia were distinctly stronger than their modern counterparts between 2,000 and 1,300 years ago, then relatively weak during the MWP (Medieval Warm Period) from about 800 (1,300 years ago) to 1300. During the LIA (Little Ice Age) from about 1500 to 1850, El Niños strengthened once more before falling back to their present-day levels.

It may seem counterintuitive that El Niños, which release vast amounts of heat from the Pacific Ocean into the atmosphere and often raise the global temperature by several tenths of a degree for a year or so, are associated historically with prolonged periods of cooling such as the LIA. But ecologist Jim Steele has explained this phenomenon as arising from the absence of La Niña conditions during an El Niño. La Niña is the cool phase of the so-called ENSO (El Niño–Southern Oscillation), El Niño being the warm phase.

In a La Niña event, east to west trade winds cause warm water heated by the sun to pile up in the western tropical Pacific. This removes solar‑heated water from the eastern Pacific, resulting in upwelling of cooler subsurface waters there that replace the surface waters transported to the west and cause a temporary decline in global temperatures. But at the same time, the ocean gains heat at greater depths.

With the absence of this recharging of ocean heat during an El Niño, global cooling sets in for an extended period. Such cooling is usually associated with lower heat output from the sun, characterized by a falloff in the average monthly number of sunspots. Conversely, La Niñas usually accompany periods of higher solar output and result in extended global warming, as occurred during the MWP.

El Niño and La Niña have been major influences on our climate for many millennia and will continue to be. Until they are better understood, we can’t be sure they play less of a role in global warming than greenhouse gases.

Next: Sudden Changes in Ocean Currents Warmed Arctic, Cooled Antarctic in Past

The Crucial Role of Water Feedbacks in Global Warming

One of the most important features of our climate system, and the computer models developed to represent it, is feedbacks. Most people don’t know that without positive feedbacks, the climate would be so insensitive to CO₂ and other greenhouse gases that global warming wouldn’t be a concern. Positive feedbacks amplify global warming, while negative feedbacks tamp it down.

A doubling of CO₂, acting entirely on its own, would raise global temperatures only by a modest 1.1 degrees Celsius (2.0 degrees Fahrenheit). In climate models, it’s positive feedback from water vapor – by far the most abundant greenhouse gas – and, to a lesser extent, feedback from clouds, snow and ice, that boosts the warming effect of doubled CO₂ alone to the predicted very likely range of 2 degrees Celsius (3.6 degrees Fahrenheit) to 5 degrees Celsius (9 degrees Fahrenheit).

Contributions of the various greenhouse gases to global warming can be surmised from the figure below, which depicts the wavelength spectrum of thermal radiation transmitted through the atmosphere, where wavelength is measured in micrometers. Greenhouse gases cause warming by absorbing a substantial portion of the cooling longwave radiation emitted upwards by the earth. The lower panels of the figure show how water vapor absorbs strongly in several wavelength bands that don’t overlap CO₂.

The assumption that water vapor feedback is positive and not negative was originally made by the Swedish chemist Svante Arrhenius over a century ago. The feedback arises when slight CO₂-induced warming of the earth causes more water to evaporate from oceans and lakes, and the extra moisture then adds to the heat-trapping water vapor already in the atmosphere. This amplifies the warming even more.

The magnitude of the feedback is critically dependent on how much of the extra water vapor ends up in the upper atmosphere as the planet warms, because that’s where heat escapes to outer space. An increase in moisture there means stronger, more positive water vapor feedback and thus more heat trapping.

The concentration of water vapor in the atmosphere declines steeply with altitude, more than 95% of it being within 5 kilometers of the earth’s surface. Limited data do show that upper atmosphere humidity strengthened slightly in the tropics during the 30-year period from 1979 to 2009, during which the globe warmed by about 0.5 degrees Celsius (0.9 degrees Fahrenheit). However, the humidity diminished in the subtropics and possibly at higher latitudes also during this time.

But the predicted warming of 2 degrees Celsius (3.6 degrees Fahrenheit) to 5 degrees Celsius (9 degrees Fahrenheit) for doubled CO₂ assumes that the water vapor concentration in the upper atmosphere increases at all latitudes as it heats up. In the absence of observational evidence for this assumption, we can’t be at all sure that the water vapor feedback is strong enough to produce temperatures in the predicted range.

The uncertainty over CO₂ warming is exacerbated by lack of knowledge about another water feedback, from clouds. As I’ve discussed in another post, cloud feedback can be either positive or negative.

Positive cloud feedback is normally associated with an increase in high-level clouds such as cirrus clouds, which allow most of the sun’s incoming shortwave radiation to penetrate, but also act as a blanket inhibiting the escape of longwave heat radiation to space. More high-level clouds amplify warming that in turn evaporates more water and produces yet more clouds.

Negative cloud feedback can arise from a warming-induced increase in low-level clouds such as cumulus and stratus clouds. These clouds reflect 30-60% of the sun’s radiation back into space, acting like a parasol and thus cooling the earth’s surface. The cooling results in less evaporation that then reduces new cloud formation.

Conversely, a decrease in high-level clouds would imply negative cloud feedback, while a decrease in low-level clouds would imply positive feedback. Because of all these possibilities, together with the paucity of empirical data, it’s simply not known whether net cloud feedback in the earth’s climate system is one or the other – positive or negative.

If overall cloud feedback is negative, rather than positive as the computer models suggest, it’s possible that negative feedbacks in the climate system from the lapse rate (the rate of temperature decrease with altitude in the lower atmosphere) and clouds dominate the positive feedbacks from water vapor, and from snow and ice. This would mean that the response of the climate to added CO₂ in the atmosphere is to lessen, rather than magnify, the temperature increase from CO₂ acting alone, the opposite of what climate models tell us. Most feedbacks in nature are negative, keeping the natural world stable.

So until water feedbacks are better understood, there’s little scientific justification for any political action on CO₂ emissions.

Next: El Niño and La Niña May Influence the Climate More than Greenhouse Gases

Challenges to the CO2 Global Warming Hypothesis: (5) Peer Review Abused to Axe Skeptical Paper

A climate research paper featured in a previous post of mine has recently been removed by the publisher, following a post-publication review by seven new reviewers who all recommended rejection of the paper. This drastic action represents an abuse of the peer review process in my opinion, as the reviews are based on dubious science.

The paper in question was a challenge to the CO₂ global warming hypothesis by French geologist Pascal Richet. From analysis of an Antarctic ice core, Richet postulates that greenhouse gases such as CO₂ had only a minor effect on the earth’s climate over the past 423,000 years, and that any assumed forcing of climate by CO₂ is incompatible with ice-core data.

Past atmospheric CO₂ levels and surface temperatures are calculated from ice cores by measuring the air composition and the oxygen ¹⁸O to ¹⁶O isotopic ratio, respectively, in air bubbles trapped by the ice. Data from the core, drilled at the Russian Vostok station in East Antarctica, is depicted in the figure below. The CO₂ level is represented by the upper graphs (below the insolation data) that show the substantial drop in CO₂ during an ice age; the associated drop in temperature ΔT is represented by the lower graphs.

It’s well known that the CO₂ level during the ice ages closely mimicked changes in temperature, but the CO₂ concentration lagged behind. What Richet observed is that the temperature peaks in the Vostok record are much narrower than the corresponding CO₂ peaks. From this observation, he argued that CO₂ can’t drive temperature since an effect can’t last for a shorter period than its cause.

The seven negative reviews focused on two main criticisms. The first is that Richet supposedly fails to understand that CO₂ can act both as a temperature driver, when CO₂ leads, and as an amplifying feedback, when CO₂ lags.

At the end of ice ages, it’s thought that a subtle change in the earth’s orbit around the sun initiated a sudden upward turn of the temperature. This slight warming was then amplified by feedbacks, including CO₂ feedback triggered by a surge in atmospheric CO₂ as it escaped from the oceans; CO₂ is less soluble in warmer water. A similar but opposite chain of events is believed to have enhanced global cooling as the temperature fell at the beginning of an ice age. In both cases – deglaciation and glaciation – CO₂ as a feedback lagged temperature.

However, several of Richet’s reviewers base their criticism on a 2012 paper, by paleoclimatologist Jeremy Shakun and coauthors, which proposes the somewhat preposterous notion that CO₂ lagged temperature during the most recent glaciation, all through the subsequent ice age, and during 0.3 degrees Celsius (0.5 degrees Fahrenheit) of the initial warming as the ice age ended – but then switched roles from feedback to driver and led temperature during the remaining deglaciation.

Shakun’s proposal is illustrated in the left graph below, in which the blue curve shows the mean global temperature during deglaciation, the red curve represents the temperature in Antarctica and the yellow dots are the atmospheric CO₂ concentration. The CO₂ levels and Antarctic temperatures are derived from an ice core, as in Richet’s paper but using the so-called Dome C core, while global temperatures are calculated from proxy data obtained from ocean and lake sediments.

The apparent switch of CO₂ from feedback to driver is clearly visible in the figure above about 17,500 years ago, when the temperature escalated sharply. Although the authors attempt to explain the sudden change as resulting from variability of the AMOC (Atlantic Meridional Overturning Circulation), their argument is only hand-waving at best and does nothing to bolster their postulated dual role for CO₂.

In any case, a detailed, independent analysis of the same proxy data has found there is so much data scatter that whether CO₂ leads or lags the warming can’t even be established. This analysis is shown in the right graph above, where the green dots represent the temperature data and the black circles are the CO₂ level.

All this invalidates the reviewers’ first main criticism of Richet’s paper. The second criticism is that Richet dismisses computer climate models as an unreliable tool for studying the effect of CO₂ on climate, past or present. But, as frequently pointed out in these pages, climate models indeed have many weaknesses. These include the omission of many types of natural variability, exaggeration of predicted temperatures and the inability to reproduce the past climate accurately. Repudiation of climate models is therefore no reason to reject a paper.

Some of the reviewers’ lesser criticisms of Richet’s paper are justified, such as his analysis of only one Antarctic ice core when several are available, and his inappropriate philosophical and political comments in a scientific paper. But outright rejection of the paper smacks of bias against climate change skeptics and is an abuse of the time-honored tradition of peer review.

Next: The Crucial Role of Water Feedbacks in Global Warming

Ice Sheet Update (2): Greenland Ice Sheet Melting No Faster than Last Century

The climate doomsday machine makes much more noise about warming-induced melting of Greenland’s ice sheet than Antarctica’s, even though the Greenland sheet holds only about 10% as much ice. That’s because the smaller Greenland ice sheet is melting at a faster rate and contributes more to sea level rise. But the melt rate is no faster today than it was 90 years ago and appears to have slowed over the last few years.

The ice sheet, 2-3 km (6,600-9,800 feet) thick, consists of layers of compressed snow built up over at least hundreds of thousands of years. Melting takes place only during Greenland’s late spring and summer, the meltwater running over the ice sheet surface into the ocean, as well as funneling its way down through thick glaciers, helping speed up their flow toward the sea.

In addition to summer melting, the sheet loses ice at its edges from calving or breaking off of icebergs, and from submarine melting by warm seawater. Apart from these losses, a small amount of ice is gained over the long winter from the accumulation of compacted snow at high altitudes in the island’s interior. The net result of all these processes at the end of summer melt in August is illustrated in the adjacent figure, based on NASA satellite data.

The following figure depicts the daily variation, over the past year, of the estimated surface mass balance of the Greenland ice sheet – which includes gains from snowfall and losses from melt runoff, but not sheet edge losses – as well as the mean daily variation for the period from 1981 to 2010. The loss of ice during the summer months of June, July and August is clearly visible, though the summer loss was smaller in 2021 than in many years. An unusual, record-setting gain can also be seen in May 2021.

The next figure shows the average annual gain or loss of both the surface mass balance (in blue) and a measure of the total mass balance (in black), going all the way back to 1840. Most of the data comes from meteorological stations across Greenland. The total mass balance in this graph includes the surface mass balance, iceberg calving and submarine melting (combined in the gray dashed line), and melting from basal sources underneath the ice sheet, but not peripheral glaciers – glaciers that contribute 15 to 20% of Greenland’s total mass loss.

It can be seen that the rate of ice loss excluding glaciers has increased since about 2000. But it’s also clear from the graph that high short-term loss rates have occurred more than once in the past, notably in the 1930s and the 1950s – so the current shrinking of the Greenland ice sheet is nothing remarkable. There’s no obvious correlation with global temperatures, since the planet warmed from 1910 to 1940 but cooled from 1940 to 1970.

The total ice loss (not its rate) since 1972 is displayed in more detail in the final figure below. The slightly different estimates of the total mass are because some estimates include losses from peripheral glaciers and basal melting, while others don’t. Nevertheless, the insert showing mass loss from 2010 to 2020 reveals clearly that the rate of loss may have slowed down since about 2015.

The 2020 loss was 152 gigatonnes (168 gigatons), much lower than the average annual losses of 258 gigatonnes (284 gigatons) and 247 gigatonnes (272 gigatons) from 2002 to 2016 and 2012 through 2016, respectively. The 2020 loss also pales in comparison with the record high losses of 458 gigatonnes (505 gigatons) in 2012 and 329 gigatonnes (363 gigatons) in 2019. The 2021 loss is on track to be similar to 2020, according to estimates at the end of the summer melt season.

The Sixth Assessment Report of the UN’s IPCC (Intergovernmental Panel on Climate Change) maintains with high confidence that, between 2006 and 2018, melting of the Greenland ice sheet and peripheral glaciers was causing sea levels to rise by 0.63 mm (25 thousandths of an inch) per year. This can be compared with a rise of 0.37 mm (15 thousandths of an inch) per year from melting of Antarctic ice. However, the rate of rise from Greenland ice losses may be falling, as discussed above.

If the rate of Greenland ice loss were to remain at its 2012 to 2016 average of 247 gigatonnes (272 gigatons) per year, which is an annual loss of about 0.01% of the total mass of the ice sheet, it would take another 10,000 years for all Greenland’s ice to melt. If the rate stays at the 2020 value of 152 gigatonnes (168 gigatons) per year, the ice sheet would last another 17,000 years.

Next: Challenges to the CO2 Global Warming Hypothesis: (5) Peer Review Abused to Axe Skeptical Paper

Ice Sheet Update (1): Evidence That Antarctica Is Cooling, Not Warming

Melting due to climate change of the Antarctic and Greenland ice sheets has led to widespread panic about the future impact of global warming. But, as we’ll see in this and a subsequent post, Antarctica may not be warming overall, while the rate of ice loss in Greenland has slowed recently.

The kilometers-thick Antarctic ice sheet contains about 90% of the world’s freshwater ice and would raise global sea levels by about 60 meters (200 feet) were it to melt completely. The Sixth Assessment Report of the UN’s IPCC (Intergovernmental Panel on Climate Change) maintains with high confidence that, between 2006 and 2018, melting of the Antarctic ice sheet was causing sea levels to rise by 0.37 mm (15 thousandths of an inch) per year, contributing about 10% of the global total.

By far the largest region is East Antarctica, which covers two thirds of the continent as seen in the figure below and holds nine times as much ice by volume as West Antarctica. The hype about imminent collapse of the Antarctic ice sheet is based on rapid melting of the glaciers in West Antarctica; the glaciers contribute an estimated 63% (see here) to 73% (here) of the annual Antarctic ice loss. East Antarctica, on the other hand, may not have shed any mass at all – and may even have gained slightly – over the last three decades, due to the formation of new ice resulting from enhanced snowfall.  

The influence of global warming on Antarctica is uncertain. In an earlier post, I reported the results of a 2014 research study that concluded West Antarctica and the small Antarctic Peninsula, which points toward Argentina, had warmed appreciably from 1958 to 2012, but East Antarctica had barely heated up at all over the same period. The warming rates were 0.22 degrees Celsius (0.40 degrees Fahrenheit) and 0.33 degrees Celsius (0.59 degrees Fahrenheit) per decade, for West Antarctica and the Antarctic Peninsula respectively – both faster than the global average.

But a 2021 study reaches very different conclusions, namely that both West Antarctica and East Antarctica cooled between 1979 and 2018, while the Antarctic Peninsula warmed but at a much lower rate than found in the 2014 study. Both studies are based on reanalyses of limited Antarctic temperature data from mostly coastal meteorological stations, in an attempt to interpolate temperatures in the more inaccessible interior regions of the continent.

This later study appears to carry more weight as it incorporates data from 41 stations, whereas the 2014 study includes only 15 stations. The 2021 study concludes that East Antarctica and West Antarctica have cooled since 1979 at rates of 0.70 degrees Celsius (1.3 degrees Fahrenheit) per decade and 0.42 degrees Celsius (0.76 degrees Fahrenheit) per decade, respectively, with the Antarctic Peninsula having warmed at 0.18 degrees Celsius (0.32 degrees Fahrenheit) per decade.

It’s the possible cooling of West Antarctica that’s most significant, because of ice loss from thinning glaciers. Ice loss and gain rates from Antarctica since 2003, measured by NASA’s ICESat satellite, are illustrated in the next figure, in which dark reds and purples show ice loss and blues show gain.

The high loss rates along the coast of West Antarctica have been linked to thinning of the floating ice shelves that terminate glaciers, by so-called circumpolar deep water warmed by climate change. Although disintegration of an ice shelf already floating on the ocean doesn’t raise sea levels, a retreating ice shelf can accelerate the downhill flow of glaciers that feed the shelf. It’s thought this can destabilize the glaciers and the ice sheets behind them.

However, not all the melting of West Antarctic glaciers is due to global warming and the erosion of ice shelves by circumpolar deep water. As I’ve discussed in a previous post, active volcanoes underneath West Antarctica are melting the ice sheet from below. One of these volcanoes is making a major contribution to melting of the Pine Island Glacier, which is adjacent to the Thwaites Glacier in the first figure above and is responsible for about 25% of the continent’s ice loss.

If the Antarctic Peninsula were to cool along with East Antarctica and West Antarctica, the naturally occurring SAM (Southern Annular Mode) – the north-south movement of a belt of strong southern westerly winds surrounding Antarctica – could switch from its present positive phase to negative. A negative SAM would result in less upwelling of circumpolar deep water, thus reducing ice shelf thinning and the associated melting of glaciers.

As seen in the following figure, the 2021 study’s reanalysis of Antarctic temperatures shows an essentially flat trend for the Antarctic Peninsula since the late 1990s (red curve); warming occurred only before that time. The same behavior is even evident in the earlier 2014 study, which goes back to 1958. So future cooling of the Antarctic Peninsula is not out of the question. The South Pole in East Antarctica this year experienced its coldest winter on record.

Next: Ice Sheet Update (2): Evidence That Greenland Melting May Have Slowed Down

Sea Ice Update: No Evidence for Recent Ice Loss

Climate activists have long lamented the supposedly impending demise of Arctic sea ice due to global warming. But, despite the constant drumbeat of apocalyptic predictions, the recently reached minimum extent of Arctic ice in 2021 is no smaller than it was back in 2008.  And at the other end of the globe, the sea ice around Antarctica has been expanding for at least 42 years.

Scientific observations of sea ice in the Arctic and Antarctic have only been possible since satellite measurements began in 1979. The figure below shows satellite-derived images of Arctic sea ice extent in the summer of 1979 (left image), and the summer (September) and winter (March) of 2021 (right image, with September on the left). Sea ice shrinks during summer months and expands to its maximum extent during the winter.

Over the interval from 1979 to 2021, Arctic summer ice extent decreased by approximately 30%; while it still embraces northern Greenland, it no longer reaches the Russian coast. The left graph in the next figure compares the monthly variation of Arctic ice extent from its March maximum to the September minimum, for the years 2021 (blue curve) and 2008 (green curve). The 2021 summer minimum is seen to be almost identical to that in 2008, with the black curve depicting the median extent over the period from 1981 to 2010.

The right graph in the figure shows the estimated month-by-month variation of Arctic ice volume in recent years. The volume depends on both ice extent and its thickness, which varies with location as well as season – the thickest, and oldest, winter ice currently lying along the northern coasts of the Canadian Arctic Archipelago and Greenland.

Arctic ice thickness is notoriously difficult to measure, the best data coming from limited submarine observations. According to one account based on satellite data, more than 75% of the Arctic winter ice pack today consists of thin ice just a few months old, whereas in the past it was only 50%. However, these estimates are unreliable and a trio of Danish research institutions that monitor the Arctic estimate that the ice volume has changed very little over the last 17 years, as seen in the figure above.

Another indication that Arctic ice is not melting as fast as climate activists claim is the state of the Northwest Passage – the waterway between the Atlantic and Pacific Oceans through the Arctic Ocean, along the coast of North America. Although both the southern and northern routes of the Northwest Passage have been open intermittently since 2007, ice conditions this year are relatively severe compared to the past two decades: thicker multiyear ice is the main hazard. The northern deep-water route is already choked with ice and will not open until at least next year.

In the Antarctic, sea ice almost disappears completely during the southern summer and reaches its maximum extent in September, at the end of winter. This is illustrated in the satellite-derived images below, showing the summer minimum (left image) and winter maximum extent (right image) in 2021. The Antarctic winter sea ice extent is presently well above its long-term average.

In fact, despite the long-term loss of ice in the Arctic, the sea ice around Antarctica has expanded slightly during the satellite era, as shown in the following figure up to 2020. Although the maximum Antarctic ice extent (shown in red) fluctuates greatly from year to year, and took a tumble in 2017, it has grown at an average rate between 1% and 2% per decade (dashed red line) since 1979.

Note that the ice losses shown in this figure are “anomalies,” or departures from the monthly mean ice extent for the period from 1981 to 2010, rather than the minimum extent of summer ice. So the Arctic data don’t reveal how the 2021 minimum was almost identical to 2008, as illustrated in the earlier figures.

Several possible reasons have been put forward for the greater fluctuations in Antarctic winter sea ice compared to that in the Arctic. One analysis links the Antarctic oscillations to ENSO (the El Niño – Southern Oscillation), a natural cycle that causes variations in mean temperature and other climatic effects in tropical regions of the Pacific Ocean. The Pacific impinges on a substantial portion of the Southern Ocean that surrounds Antarctica.

The analysis suggests that the very large winter ice extents of 2012, 2013 and 2014 were a consequence of the 2012 La Niña, which is the cool phase of ENSO. Reinforcing that idea is the fact that this year’s surge in ice extent follows another La Niña earlier in 2021; the big loss of sea ice in 2017 could be associated with 2016’s strong El Niño, the warm phase of ENSO. The natural Pacific Decadal Oscillation may also play a role.

Next: Ice Sheet Update (1): Evidence That Antarctica Is Cooling, Not Warming

Weather Extremes: Hurricanes and Tornadoes Likely to Diminish in 2021

Despite the brouhaha over the recent record-breaking heat wave in the Pacific northwest and disastrous floods in Europe and China, windy weather extremes – hurricanes and tornadoes – are attracting little media attention because they’re both on track for a relatively quiet season.

Scientists at the Climate Prediction Center of NOAA (the U.S. National Oceanic and Atmospheric Administration) don’t anticipate that 2021 will see the record-breaking 30 named storms of 2020, even though they think the total may still be above average. However, of last year’s 30 storms, only 13 became actual hurricanes, including 6 major hurricanes. The record annual highs are 15 hurricanes recorded in 2005 and 8 major hurricanes in 1950.

Hurricanes are classified by their sustained wind speeds on the Saffir-Simpson scale, ranging from Category 1, the weakest, to Category 5, the strongest. A major hurricane is defined as one in Category 3, 4 or 5, corresponding to a top wind speed of 178 km per hour (111 mph) or greater. NOAA predicts just 6 to 10 hurricanes this year, with 3 to 5 of those being in the major hurricane categories.

Hurricanes in the Atlantic basin, which has the best quality data available in the world, do show heightened ac­tivity over the last 20 years, particularly in 2005 and 2020. This can be seen in the figure below, depicting the frequency of all Atlantic hurricanes from 1851 to 2020. But researchers have found that the apparent increase in recent times is not related to global warming.

Rather, say the scientists who work at NOAA and several universities, the increase reflects natural variability. Although enhanced evaporation from warming oceans pro­vides more fuel for hurricanes, recent numbers have been artificially boosted by a big improvement in our ability to detect hurricanes, especially since the advent of satellite coverage in the late 1960s. And global warming can’t be the explanation, as the earth was cooling during the previous period of increased activity in the 1950s and 1960s.

Prior to that time, most data on hurricane frequency were based on eyewitness accounts, thus excluding all the hurricanes that never made landfall. What the researchers did was examine the eyewitness records, preserved by NOAA workers, in order to calculate the ratio of Atlantic hurricanes that didn’t come ashore to those that did, both in the modern era and in the past. The observations of non-landfalling hurricanes before the early 1970s came primarily from ships at sea.

Then, using a model for the radius of hurricane or major hurricane winds, the researchers were able to estimate the number of hurricanes or major hurricanes going back to 1860 that were never recorded. Their analysis revealed that the recent hike in the hurricane count is nothing remarkable, being comparable to earlier surges in the early 1880s and late 1940s. In the U.S., the past decade was in fact the second quietest for landfalling hurricanes and landfalling major hurricanes since the 1850s. Hurricane Ida was the first major U.S. landfalling hurricane this year.

Tornadoes, which occur predominantly in the U.S., have been less violent and fewer in number than average so far in 2021. Like hurricanes, tornadoes are categorized according to wind speed, using the Fujita Scale going from EF0 to EF5; EF5 tornadoes attain wind speeds up to 480 km per hour (300 mph).

Up to the end of August, 958 tornadoes had been reported by NOAA’s Storm Prediction Center in 2021 – of which 740 had been confirmed, according to Wikipedia. These numbers can be compared with the January to August average of 1035 confirmed tornadoes; the yearly average is 1253.

The annual incidence of all tornadoes in the U.S. shows no meaningful trend from 1950 to 2020, a period that included both warming and cooling spells, with net global warming of approximately 1.1 degrees Celsius (2.0 degrees Fahrenheit) during that time. But the number of strong tornadoes (EF3 or greater) has declined dramatically over the last half century, as seen in the next figure illustrating the number observed each year from 1954 to 2017.

Clearly, the trend is downward instead of upward. Indeed, the average number of strong tornadoes annually from 1986 to 2017 was 40% less than from 1954 to 1985. In May this year, there wasn’t a single strong tornado for the first time since record-keeping began in 1950. Although there’s debate over whether the current system for rating tornadoes is flawed, 2021 looks like being another quiet year.

Next: What “The Science” Really Says about the Coronavirus Pandemic

Latest UN Climate Report Is More Hype than Science

In its latest climate report, the UN’s IPCC (Intergovernmental Panel on Climate Change) falls prey to the hype usually characteristic of alarmists who ignore the lack of empirical evidence for the climate change narrative of “unequivocal” human-caused global warming.

Past IPCC assessment reports have served as the voice of authority for climate science and, even among those who believe in man-made climate change, as a restraining influence – being hesitant in linking weather extremes to a warmer world, for instance. But all that has changed in its Sixth Assessment Report, which the UN Secretary-General has hysterically described as “code red for humanity.”

Among other claims trumpeted in the report is the statement that “Evidence of observed changes in extremes such as heat waves, heavy precipitation, droughts, and tropical cyclones, and, in particular, their attribution to human influence, has strengthened since [the previous report].” This is simply untrue and actually contrary to the evidence, with the exception of precipitation that tends to increase with global warming because of enhanced evap­oration from tropical oceans, resulting in more water vapor in the atmosphere.

In other blog posts and a recent report, I’ve shown how there’s no scientific evidence that global warm­ing triggers extreme weather, or even that weather extremes are becoming more frequent. Anomalous weather events, such as heat waves, hurricanes, floods, droughts and tornadoes, show no long-term trend over more than a century of reliable data.

As one example, the figure below shows how the average glob­al area and intensity of drought remained unchanged on aver­age from 1950 to 2019, even though the earth warmed by about 1.1 degrees Celsius (2.0 degrees Fahrenheit) over that interval. The drought area is the percentage of total global land area, excluding ice sheets and deserts, while the intensity is characterized by the self-calibrating Palmer Drought Severity Index, which measures both dryness and wetness and classifies events as “moderate,” “severe” or “extreme.”

Although the IPCC report claims, with high confidence, that “the frequency of concurrent heatwaves and droughts on the global scale” are increasing, the scientific evidence doesn’t sup­port such a bold assertion. An accompanying statement that cold extremes have become less frequent and less severe is also blatantly incorrect.

Cold extremes are in fact on the rise, as I’ve discussed in previous blog posts (here and here). The IPCC’s sister UN agency, the WMO (World Meteorological Organi­zation) does at least acknowledge the existence of cold weather extremes, but has no explanation for their origin nor their growing frequency. Cold extremes include prolonged cold spells, unusually heavy snowfalls and longer winter seasons. Why the IPCC should draw the wrong conclusion about them is puzzling.

In discussing the future climate, the IPCC makes use of five scenarios that project differing emissions of CO₂ and other greenhouse gases. The scenarios start in 2015 and range from one that assumes very high emissions, with atmospheric CO₂ doubling from its present level by 2050, to one assuming very low emissions, with CO₂ declining to “net zero” by mid-century.

But, as pointed out by the University of Colorado’s Roger Pielke Jr., the estimates in the IPCC report are dominated by the highest emissions scenario. Pielke finds that this super-high emissions scenario accounts for 41.5% of all scenario mentions in the report, whereas the scenarios judged to be the most likely under current trends account for only a scant 18.4% of all mentions. The hype inherent in the report is obvious by comparing these percentages with the corresponding ones in the Fifth Assessment Report, which were 31.4% and 44.5%, respectively. 

Not widely known is that the supposed linkage between climate change and human emissions of greenhouse gases, as well as the purported connection between global warming and weather extremes, both depend entirely on computer climate models. Only the models link climate change or extreme weather to human activity. The empirical evidence does not – it merely shows that the planet is warming, not what’s causing the warming.

A recent article in the mainstream scientific journal Science surprisingly drew attention to the shortcomings of climate models, weaknesses that have been emphasized for years by climate change skeptics. Apart from falsely linking global warming to CO₂ emissions – because the models don’t include many types of natural variability – the models greatly exaggerate predicted temperatures, and can’t even reproduce the past climate accurately. As leading climate scientist Gavin Schmidt says, “You end up with numbers for even the near-term that are insanely scary—and wrong.”

The new IPCC report, with its prognostications of gloom and doom, should have paid more attention to its modelers. In making wrong claims about the present climate, and relying too heavily on high-emissions scenarios for future projections, the IPCC has strayed from the path of science.

Next: Weather Extremes: Hurricanes and Tornadoes Likely to Diminish in 2021

Has the Sun’s Role in Climate Change Been Trivialized?

Central to the narrative that climate change comes largely from human emissions of greenhouse gases is the assertion that the sun plays almost no role at all. According to its Fifth Assessment Report, the IPCC (Intergovernmental Panel on Climate Change) attributes no more than a few percent of total global warming to the sun’s influence.

But the exact amount of the solar contribution to global warming is critically dependent on how much the sun’s heat and light output, known technically as the TSI (total solar irradiance), has varied since the 19th century. According to an international team of scientists in a recently published paper, different estimates of the TSI lead to different conclusions about global warming – ranging from the sun making a trivial contribution, which backs up the IPCC claim that recent warming is mostly human-caused, to the opposite conclusion that global warming is mostly natural and due to changes in solar activity.

How can there be such a wide discrepancy between these two positions? Over the approximately 11-year solar cycle, the TSI varies by only a tenth of one percent. However, long-term fluctuations in the sun’s internal magnetic field cause the baseline TSI to vary over decades and centuries.

This can be seen in the somewhat congested figure below, which depicts several reconstructions of the TSI since 1850 and shows variations in both the TSI baseline and its peak-to-peak amplitude. The curve plotted in black forms the basis for the current CMIP6 generation of computer climate models; the curve in yellow was the basis for the previous CMIP5 models featured in the IPCC’s Fifth Assessment Report.

A rather different reconstruction of the TSI since 1700 is shown in the next figure, based on an earlier solar irradiance model augmented with recent satellite data. You can see that in this reconstruction, the TSI since 1850 exhibits much larger fluctuations – from 1358 to 1362 watts per square meter – compared with the reconstruction above, in which the variation since 1850 is only from about 1360.5 to 1362 watts per square meter.

The dramatic difference between the two estimates of the TSI arises from rival sets of satellite data. Satellite measurements of TSI began in 1978, the two main sources of data being the Royal Meteorological Institute of Belgium’s so-called ACRIM (Active Cavity Radiometer Irradiance Monitor) composite, and the World Radiation Center’s PMOD (Physikalisch-Meteorologisches Observatorium Davos) composite.

The ACRIM composite implies that the TSI rose during the 1980s and 1990s but has fallen slightly since then, as seen in the second figure above. The PMOD composite implies that the TSI has been steadily dropping since the late 1970s, a trend just visible in the first figure. The PMOD composite, showing a decline in solar activity during the period after 1975 in which global temperatures went up, therefore downplays the sun’s role in global warming. On the other hand, the ACRIM composite indicates an increase in solar activity over the same period, so supports the notion that global temperatures are strongly linked to the TSI.

The ACRIM satellite data set and the PMOD data differ in the procedures used to bridge a two-year gap in ACRIM data around 1990. The gap in data gathering occurred after the launch of a new ACRIM satellite was delayed by the Challenger disaster. It’s these disparate gap-bridging procedures that result in the ACRIM and PMOD composite data showing such different behavior of the TSI during the most recent solar cycles 21 to 23.

The authors of the recent paper also discuss other TSI reconstructions, some of which support the ACRIM data and some of which back the rival PMOD data. Rather than passing judgment on which dataset is the better representation of reality, the authors urge the climate science community to consider all relevant estimates of the TSI and not just the one illustrated in the first figure above. But they conclude that, contrary to the current narrative, the question of how much the sun has influenced recent global temperatures – at least in the Northern Hemisphere – has not yet been answered satisfactorily.

The researchers go on to comment: “The PMOD dataset is more politically advantageous to justify the ongoing considerable political and social efforts to reduce greenhouse gas emissions under the assumption that the observed global warming since the late 19th century is mostly due to greenhouse gases.” They add that political considerations have been acknowledged as one of the motivations for the development of the PMOD composite as a rival dataset to the ACRIM measurements.

Next: Latest UN Climate Report Is More Hype than Science

New Doubts on Climatic Effects of Ocean Currents, Clouds

Recent research has cast doubt on the influence of two watery entities – ocean currents and clouds – on future global warming. But, unlike many climate studies, the two research papers are grounded in empirical observations rather than theoretical models.

The first study examined so-called deep water formation in the Labrador Sea, located between Greenland and Canada in the North Atlantic Ocean, and its connection to the strength of the AMOC (Atlantic Meridional Overturning Circulation). The AMOC forms part of the ocean conveyor belt that redistributes seawater and heat around the globe. Despite recent evidence to the contrary, computer climate models have predicted that climate change may weaken the AMOC or even shut it down altogether.  

Deep water formation, which occurs in a few localized areas across the world, refers to the sinking of cold, salty surface water to depths of several kilometers because it’s denser than warm, fresher water; winter winds in the Labrador Sea both cool the surface and increase salinity through evaporation. Most climate models link any decline in North Atlantic deep water formation, due to global warming, to decreases in the strength of the AMOC.

But the researchers found that winter convection in the Labrador Sea and the adjacent Irminger Sea (east of Greenland) had very little impact on deep ocean currents associated with the AMOC, over the period from 2014 to 2018. Their observational data came from a new array of seagoing instruments deployed in the North Atlantic, including moorings anchored on the sea floor, underwater gliders and submersible floats. The devices measure ocean current, temperature and salinity.

Results for the strength of the AMOC are illustrated in the figure below, in which “OSNAP West” includes the Labrador and Irminger Seas while the more variable “OSNAP East” is in the vicinity of Iceland. As can be seen, the AMOC in the Labrador Sea didn’t change on average during the whole period of observation. The study authors caution, however, that measurements over a longer time period are needed to confirm their conclusion that strong winter cooling in the Labrador Sea doesn’t contribute significantly to variability of the AMOC.

Understanding the behavior of the AMOC is important because its strength affects sea levels, as well as weather in Europe, North America and parts of Africa. Variability of the AMOC is thought to have caused multiple episodes of abrupt climate change, in a decade or less, during the last ice age.

The second study to question the effect of water on global warming involves clouds. As I described in an earlier post, the lack of detailed knowledge about clouds is one of the major limitations of computer climate models. One problem with the existing models is that they simulate too much rainfall from “warm” clouds and, therefore, underestimate their lifespan and cooling effect.

Warm clouds contain only liquid water, compared with “cool” clouds that consist of ice particles mixed with water droplets. Since the water droplets are usually smaller than the ice particles, they have a larger surface area to mass ratio which makes them reflect the sun’s radiation more readily. So warm clouds block more sunlight and produce more cooling than cool, icy clouds. At the same time, warm clouds survive longer because they don’t rain as much.

The research team used satellite data to ascertain how much precipitation from clouds occurs in our present climate. The results for warm clouds are illustrated in the following map showing the warm-rain fraction; red designates 100% warm rain, while various shades of blue indicate low fractions. As would be expected, most warm rain falls near the equator where temperatures are highest. It also falls predominantly over the oceans.

The researchers then employed the empirical satellite data for rainfall to modify the warm-rain processes in an existing CMIP6 climate model (the latest generation of models). The next figure, which shows the probability of rain from warm clouds at different latitudes, compares the satellite data (gray) to the model results before (maroon) and after (yellow) modification.

It’s seen that the modified climate model is in much better agreement with the satellite data, except for a latitude band just north of the equator, and is also a major improvement over the unmodified model. The scientists say that their correction to the model makes negative “cloud-lifetime feedback” – the process by which higher temperatures inhibit warm clouds from raining as much and increases their lifetime – almost three times larger than in the original model.

This larger cooling feedback is enough to account for the greater greenhouse warming predicted by CMIP6 models compared with earlier CMIP5 models. But, as the study tested only a single model, it needs to be extended to more models before that conclusion can be confirmed.

Next: Could Pacific Northwest Heat Wave, European Floods Have Been Caused by the Sun?

Fishy Business: Alleged Fraud over Ocean Acidification Research, Reversal on Coral Extinction

In the news recently have been two revelations about the sometimes controversial world of coral reef research. The first is fraud allegations against research claiming that ocean acidification from global warming impairs the behavior of coral reef fish. The second is an about-face on inflated estimates for the extinction risk of Pacific Ocean coral species due to climate change. 

The alleged fraud involves 22 research papers authored by Philip Munday, a marine ecologist at JCU (James Cook University) in Townsville, Australia and Danielle Dixson, a U.S. biologist who completed her PhD under Munday’s supervision in 2012. The fraud charges were made in August 2020 by three of an international group of mostly biological and environmental scientists, plus the group leader, fish physiologist Timothy Clark of Deakin University in Geelong, Australia. The Clark group says it will publicize the alleged data problems shortly.

The research in question studied the behavior of coral reef fish in slightly acidified seawater, in order to simulate the effect of ocean acidification caused by the absorption of up to 30% of humanity’s CO₂ emissions. The additional CO₂ has so far lowered the average pH – a measure of acidity – of ocean surface water from about 8.2 to 8.1 since industrialization began in the 18th century.

Munday and Dixson claim that the extra CO₂ causes reef fish to be attracted by chemical cues from predators, instead of avoiding them; to become hyperactive and disoriented; and to suffer loss of vision and hearing. But Clark and his fellow scientists, in their own paper published in January 2020, debunk all of these conclusions. Most damningly of all, the researchers find that the reported effects of ocean acidification on the behavior of coral reef fish are not reproducible – the basis for their fraud allegations against the JCU work.

In a published rebuttal, Munday and Dixson say that the Clark group’s replication study differed from the original research “in at least 16 crucial ways” and didn’t acknowledge other papers that support the JCU position.

Nevertheless, while the university has dismissed the allegations after a preliminary investigation, Science magazine points out that a 2016 paper by another former PhD student of Munday’s was subsequently deemed fraudulent and retracted. And Clark and his colleagues say they have evidence of manipulation in publicly available raw data files for two papers published by Munday’s research laboratory, as well as documentation of large and “statistically impossible” effects from CO₂ reported in many of the other 20 allegedly fraudulent papers.

CREDIT: ALEX MUSTARD/MINDEN PICTURES

The about-turn on coral extinction involves another JCU group, the university’s Centre of Excellence for Coral Reef Studies. Four Centre researchers published a paper in March 2021 that completely contradicts previous apocalyptic predictions of the imminent demise of coral reefs, predictions that include an earlier warning by three of the same authors of ongoing coral degradation from global warming.

As an example of past hype, the IUCN (International Union for Conservation of Nature) states on its website that 33% of all reef-building corals are at risk of extinction. The IUCN is highly regarded for its assessments of the world’s biodiversity, including evaluation of the extinction risk of thousands of species. An even more pessimistic environmental organization suggests that more than 90% of the planet’s coral reefs may be extinct by 2050.

The recent JCU paper turns all such alarming prophecies on their head. But the most astounding revelation is perhaps the sheer number of corals estimated to exist on reefs across the Pacific Ocean, from Indonesia to French Polynesia – approximately half a trillion, similar to the number of trees in the Amazon, or birds in the world. To estimate abundances, the JCU scientists used a combination of coral reef habitat maps and counts of coral colonies.

This colossal population is for a mere 300 species, a small fraction of the 2,175 coral species estimated to exist worldwide by the IUCN. And of the 80 species considered by the IUCN to be at an elevated risk of extinction, those in its “critically endangered” and “endangered” categories, 12 species have estimated Pacific populations of over a billion colonies. One of the study’s authors remarks that the eight most common coral species in the region each have a population size larger than the 7.8 billion people on Earth.

The implication of this stunning research is that the global extinction risk of most coral species is lower than previously estimated, even though a local loss can be ecologically devastating to coral reefs in the vicinity. So any future extinctions due to global warming are unlikely to unfold rapidly, if at all.

Next: New Doubts on the Climatic Effects of Ocean Currents, Clouds

Challenges to the CO2 Global Warming Hypothesis: (4) A Minimal Ice-Age Greenhouse Effect

As an addendum to my 2020 series of posts on the CO₂ global warming hypothesis (here, here and here), this post presents a further challenge to the hypothesis central to the belief that humans make a substantial contribution to climate change. The hypothesis is that observed global warming – currently about 1 degree Celsius (1.8 degrees Fahrenheit) since the preindustrial era – has been caused primarily by human emissions of CO₂ and other greenhouse gases into the atmosphere.

The new challenge to the CO₂ hypothesis is set out in a recent research paper by French geologist Pascal Richet. Richet claims, by reexamining previous analyses of an Antarctic ice core, that greenhouse gases such as CO₂ and methane had only a minor effect on the earth’s climate over the past 423,000 years, and that the assumed forcing of climate by CO₂ is incompatible with ice-core data. The paper is controversial, however, and the publisher has subjected it to a post-publication review, as a result of which the paper has since been removed.

The much-analyzed ice core in question was drilled at the Russian Vostok station in East Antarctica. Past atmospheric CO₂ levels and surface temperatures are calculated from ice cores by measuring the air composition and the oxygen ¹⁸O to ¹⁶O isotopic ratio, respectively, in air bubbles trapped by the ice. The Vostok record, which covers the four most recent ice ages or glaciations as well as the current interglacial (Holocene), is depicted in the figure below. The CO₂ level is represented by the upper set of graphs (below the insolation data), and shows the substantial drop in CO₂ during an ice age; the associated drop in temperature ΔT is represented by the lower set of graphs.

It is seen that transitions from glacial to interglacial conditions are relatively sharp, while the ice ages themselves are punctuated by smaller warming and cooling episodes. And, though it’s hardly visible in the figure, the ice-age CO₂ level closely mimics changes in temperature, but the CO₂ concentration lags behind – with CO₂ going up or down after the corresponding temperature shift occurs. The lag is more pronounced for temperature declines than increases.

The oceans, which are where the bulk of the CO₂ on our planet is stored, can hold much more CO₂ (and heat) than the atmosphere. Warm water holds less CO₂ than cooler water, so the oceans release CO₂ when the temperature rises, but take it in when the earth cools.

Richet noticed that the temperature peaks in the Vostok record are much narrower than the corresponding CO₂ peaks. The full widths at half maximum, marked by thick horizontal bars in the figure above, range from about 7,000 to 16,000 years for the initial temperature peak in cycles II, III and IV, but from 14,000 to 23,000 years for the initial CO₂ peak; cycle V can’t be analyzed because its start is missing from the data. All other peaks are also narrower for temperature than for CO₂.

The author argues that CO₂ can’t drive temperature since an effect can’t last for a shorter period of time than its cause. The fact that the peaks are systematically wider for CO₂ than for temperature implies that the CO₂ level responds to temperature changes, not the other way round. And for most of cycles II, III and IV, CO₂ increases correspond to temperature decreases and vice versa.

Richet’s conclusion, if correct, would deal a deathblow to the CO₂ global warming hypothesis. The reason has to do with the behavior of the temperature and CO₂ level at the commencement and termination of ice ages.

Ice ages are believed to have ended (and begun) because of changes in the Earth’s orbit around the sun. After tens of thousands of years of bitter cold, the temperature suddenly took an upward turn. But according to the CO₂ hypothesis, the melting of ice sheets and glaciers caused by the slight initial warming could not have continued, unless this temperature rise was amplified by positive feedbacks. These include CO₂ feedback, triggered by a surge in atmospheric CO₂ as it escaped from the oceans.

The problem with this explanation is that it requires a similar chain of events, based on CO₂ and other feedbacks, to have enhanced global cooling as the temperature fell at the beginning of an ice age. But, says Richet, “From the dual way in which feedback would work, temperature decreases and increases should be similar for the same concentrations of greenhouse gases, regardless of the residence times of these gases in the atmosphere.” The fact that temperature decreases don’t depend in any straightforward way on CO₂ concentration in the figure above demonstrates that the synchronicity required by the feedback mechanism is absent.

Next: Fishy Business: Alleged Fraud over Ocean Acidification Research, Reversal on Coral Extinction

New EPA Climate Change Indicator Is Deceptive

New climate change indicators on the U.S. EPA (Environmental Protection Agency) website are intended to inform science-based decision-making by presenting climate science transparently. But many of the indicators are misleading or deceptive, being based on incomplete evidence or selective data.

A typical example is the indicator for heat waves. This is illustrated in the left panel of the figure below, depicting the EPA’s representation of heat wave frequency in the U.S. from 1961 to 2019. The figure purports to show a steady increase in the occurrence of heat waves, which supposedly tripled from an average of two per year during the 1960s to six per year during the 2010s.

Unfortunately, the chart on the left is highly deceptive in several ways. First, the data is derived from minimum, not maximum, temperatures averaged across 50 American cities. The corresponding chart for maximum temperatures, shown in the right panel above, paints a rather different picture – one in which the heat wave frequency less than doubled from 2.5 per year in the 1960s to 4.5 per year in the 2010s, and actually declined from the 1980s to the 2000s.

This maximum-temperature graph revealing a much smaller increase in heat waves than the minimum-temperature graph displayed so boldly on the EPA website is dishonestly hidden away in its technical documentation.

A second deception is that the starting date of 1961 for both graphs is conveniently cherry-picked during a 30-year period of global cooling from 1940 to 1970. That in itself exaggerates the warming effect since then. Starting instead in 1980, after the current bout of global warming had begun, it can be seen that the heat wave frequency based on maximum temperatures (right panel) barely increased at all from 1981 to 2019. Similar exaggeration and sleight of hand can be seen in the EPA indicators for heat wave duration, season length and intensity.

A third deception is that the 1961 start date ignores the record U.S. heat of the 1930s, a decade characterized by persistent, searing heat waves across North America, especially in 1934 and 1936. The next figure shows the frequency and magnitude of U.S. heat waves from 1900 to 2018.

The frequency (top panel) is the annual number of calendar days the maximum temperature exceeded the 90th percentile for 1961–1990 for at least six consecutive days. The EPA’s data is calculated for a period of at least four days, while the heat wave index (lower panel) measures the annual magnitude of all heat waves of at least three days in that year combined.

Despite the differences in definition, it’s abundantly clear that heat waves over the last few decades – the ones publicized by the EPA – pale in comparison to those of the 1930s, and even those of other decades such as the 1910s and 1950s. The peak heat wave index in 1936 is a full three times higher than it was in 2012 and up to nine times higher than in many other years.

The heat wave index shown above actually appears on the same EPA website page as the mimimum-temperature chart. But it’s presented as a tiny Figure 3 that is only 20% as large as the much more prominent Figure 1 showing minimum temperatures. As pointed out recently by another writer, a full-size version of the index chart, from 1895 to 2015, was once featured on the website, before the site was updated this year with the new climate change indicators.

The EPA points out that the 1930s heat waves in North America, which were concentrated in the Great Plains states of the U.S. and southern Canada, were exacerbated by Dust Bowl drought that depleted soil moisture and reduced the moderating effects of evaporation. While this is undoubtedly true, it has been suggested by climate scientists that future droughts in a warming world could result in further record-breaking U.S. heat waves. The EPA has no justification for omitting 1930s heat waves from their data record, or for suppressing the heat wave index chart.

Although the Dust Bowl was unique to the U.S. and Canada, there are locations in other parts of North America and in other countries where substantial heat waves occurred before 1961 as well. In the summer of 1930 two record-setting, back-to-back scorchers, each lasting eight days, afflicted Washington, D.C.; while in 1936, the province of Ontario – also well removed from the Great Plains – experienced 44 degrees Celsius (111 degrees Fahrenheit) heat during the longest, deadliest Canadian heat wave on record. In Europe, France was baked during heat waves in both 1930 and 1947, and many eastern European countries suffered prolonged heat waves in 1946.   

What all this means is that the EPA’s heat-wave indicator grossly misrepresents the actual science and defeats its stated goal for the indicators of “informing our understanding of climate change.”

Next: Challenges to the CO2 Global Warming Hypothesis: (4) A Minimal Ice-Age Greenhouse Effect

Is Recent Record Cold Just La Niña, or the Onset of Global Cooling?

Little noticed by the mainstream media in their obsession with global warming is an exceptionally chilly 2020-21 winter in the Northern Hemisphere and an unusually early start to the Southern Hemisphere winter. Low temperature and snowfall records are tumbling all over the globe. The harsh cold has already crippled this year’s crops and vines in Europe, while the U.S. state of Texas was ravaged by the subfreezing polar vortex.

Is this the beginning of the predicted grand solar minimum, which was the subject of an earlier post – or simply a manifestation of the naturally occurring La Niña cycle? A grand solar minimum is signified by a steep decline in the maximum number of sunspots during the 11-year solar cycle, a decline that appears to be underway already.

The familiar El Niño and La Niña cycles arise from seesaw changes in surface temperatures in the tropical Pacific Ocean and last for periods of a year or more at a time. The persistent but irregular pattern is visible in the graph below, showing satellite measurements of the global temperature since 1979. Warm spikes such as those in 1998, 2010 and 2016 are due to El Niño; cool spikes like those in 2000 and 2008 are due to La Niña. The climatic effects of El Niño and La Niña include catastrophic flooding in the western Americas and flooding or severe drought in Australia; La Niña has also been tied to major landfalling hurricanes in both the U.S. and the western Pacific.

The zero baseline in the figure represents the average temperature in the tropical lower atmosphere or troposphere from 1991 to 2020 (though the satellite record began in 1979). Observations in the troposphere are a more reliable indicator of global warming than surface data, which are distorted by the urban heat island effect on land and by insufficient measurement stations across the oceans.

Right now, in May 2021, it’s clear that we’re experiencing another La Niña, with the mean April temperature having fallen back to the long-term average. This isn’t permanent of course, and the mercury will continue to rise and fall with future El Niño and La Niña fluctuations. But those fluctuations are superimposed on an overall warming trend of 0.14 degrees Celsius (0.25 degrees Fahrenheit) per decade at present – the familiar global warming.

Whether the present frigid and snowy conditions in much of the world are merely a result of La Niña, or the start of a longer cooling trend, we won’t know for several years yet. Climate, after all, is a long-term average of the weather over an extended period of time, up to decades.

Nonetheless, there’s ample evidence that the current cold snap is not about to let up. At the same time as the UK experienced its lowest average minimum temperature for April since 1922, and both Switzerland and Slovenia suffered record low temperatures for the month, bone-chilling cold struck Australia, New Zealand and even normally shivery Antarctica in the Southern Hemisphere. The next figure shows how the 2021 sea ice extent (in blue) around Antarctica is above or close to the 30-year average from 1981 to 2010 (in gray).

Snow records have continued to be broken around the world too. Belgrade, the capital of Serbia, registered its all-time high snowfall for April, in record books dating back to 1888; during April, both Finland and Russia reported their heaviest snow in decades; and the UK, Spain and several countries in the Middle East saw rare spring snowfalls from March to May. On the other side of the globe, up to 22 cm (9 inches) of snow fell on southeastern Australia mountain peaks a full two months before the start of the 2021 ski season; and southern Africa was also blanketed in early-season snow.

The figure below shows the  Northern Hemisphere snow mass (excluding mountains) for the current season, based on data from the Finnish Meteorological Institute. As can be seen, the snow mass for much of the season has tracked more than one standard deviation above the average for 1982-2012, and in March 2021 exceeded the average by two standard deviations. The mass is measured in billions of tonnes (Gigatonnes, Gt where 1 tonne = 1.102 U.S. tons).

As startling as all this unusual weather is, it should be noted that recent bursts of extreme cold have sometimes been interspersed with brief periods of unseasonal warmth. Such swings between extremes may result from jet stream blocking, a phenomenon that can arise from natural sources such as a downturn in UV from a quieter sun, which can in turn produce changes in upper atmosphere wind patterns.

Next: New EPA Climate Change Indicator Is Deceptive

Little Evidence for Link between Natural Disasters and Global Warming

A new report on extreme weather in 2020 shows how socio-economic studies of natural disasters have been used to buttress the popular but mistaken belief that global warming causes weather extremes. Two international agencies, UNDRR (the UN Office for Disaster Risk Reduction) – in conjunction with CRED (the Centre for Research on the Epidemiology of Disasters) – and IFRC (the International Red Cross), both issued reports in 2020 claiming that climate-related disasters are currently escalating.

However, as the two reports themselves reveal, such claims are manifestly wrong. This can be seen in the following figure, originally included in the UNDRR-CRED’s report but since withdrawn, showing the annual number of climate-related disasters from 2000 through 2020. The disasters are those in the yellow climatological (droughts, glacial lake outbursts and wildfires), green meteorological (storms, extreme temperatures and fog), and blue hydrological (floods, landslides and wave action) categories.

The UNDRR-CRED report draws a strong link between global warming and extreme weather events, citing a “staggering rise in climate-related disasters over the last twenty years.” But, as shown in the figure above, the total number of climate-related disasters in fact exhibits a distinctly declining trend (in red) since 2000, falling by 11% over the last 21 years. This completely contradicts the claims in two different sections of the report that the annual number of disasters since 2000 has either risen significantly from before or been “relatively stable.”

Another blatant inconsistency in the UNDRR-CRED report, an inconsistency that bolsters its false claim of a rising disaster rate, is a comparison between the period from 2000 to 2019 and the preceding 20 years from 1980 to 1999. The report contends that the earlier 20 years saw only 4,212 disasters, compared with 7,348 during the later period.       

However, the University of Colorado’s Roger Pielke Jr., who studies natural disasters, says that the report’s numbers are flawed. As CRED has repeatedly acknowledged, data from 20th-century disasters are unreliable because disasters were reported differently before the Internet existed. Climate writer Paul Homewood has noted a sudden jump in the annual number of disasters listed in CRED’s EM-DAT (Emergency Events Database) after 1998, which the agency itself attributes to increased disaster reporting in the Internet era. So its claim that the number of disasters over 20 years jumped from 4,212 to 7,348 is meaningless.

The IFRC report reaches the same erroneous conclusions as the CRED-UNDRR report – not surprisingly, since they are both based on CRED’s EM-DAT. As seen in the next figure, which is the same as the Red Cross report’s Figure 1.1, climate- and weather-related disasters since 2000 have declined by approximately the same 11% noted above. The report’s misleading assertion that such disasters have risen almost 35% since the 1990s relies on the same failure to account for a major increase in disaster reporting since 1998 due to the arrival of the Internet.

That natural disasters are in fact diminishing over time is reinforced by data on the associated loss of life. The figure below illustrates the annual global number of deaths from natural disasters, including weather extremes, corrected for population increase over time and averaged by decade from 1900 to 2015.

Because the data is compiled from the same EM-DAT database, the annual number of deaths shows an uptick from the 1990s to the 2000s. Yet it’s abundantly clear that disaster-related deaths have been dwindling since the 1920s. However, this is due as much to improvements in planning and engineering to safeguard structures, and to early warning systems that allow evacuation of threatened communities, as it is to diminishing numbers of natural disasters.

Economic loss studies of natural disasters have been quick to blame human-caused climate change for the apparently increasing frequency and intensity of weather-related events. But once the losses are corrected for population gain and the ever-increasing value of property in harm’s way, there’s very little evidence to support any connection between natural disasters and global warming.

According to numerous analyses by Pielke, the frequency and intensity of the phenomena causing financial losses show no detectable trend to date. Climate-related losses themselves are actually declining as a percentage of global gross domestic product. Another research study, based on the NatCatSERVICE database of reinsurance giant Munich Re, has concluded that both human and economic vulnerability to climate-related disasters exhibit a decreasing trend, and that average disaster mortality has dropped by a sizable 6.5 times from 1980–1989 to 2007–2016.

The IPCC (Intergovernmental Panel on Climate Change), whose assessment reports serve as the voice of authority for climate science, endorsed these findings in a 2014 report on the impacts of climate change. But most of the political world and the mainstream media cling to the erroneous notion that extreme weather is triggered by global warming and becoming more frequent, despite a lack of scientific evidence for either assertion.

Next: Is Recent Record Cold Just La Niña, or the Onset of Global Cooling?

Natural Sources of Global Warming and Cooling: (1) Solar Variability and La Niña

The role played by the sun in climate change has long been trivialized by advocates of the orthodoxy that links global warming almost entirely to our emissions of greenhouse gases. But recent research suggests that solar fluctuations, while small, may affect climate by driving the multidecadal switch from El Niño to La Niña conditions in the Pacific Ocean. Other research finds that our inability to correctly simulate the cooling La Niña cycle is a major reason that computer climate models run hot.     

La Niña is the cool phase of ENSO (the El Niño – Southern Oscillation), a natural cycle that causes temperature fluctuations and other climatic effects in tropical regions of the Pacific. The familiar El Niño and La Niña events, which last for a year or more at a time, recur at irregular intervals from two to seven years. Serious effects of ENSO range from catastrophic flooding in the U.S. and Peru to severe droughts in Australia. 

The sun has several natural cycles, the most well known of which is the 11-year sunspot cycle. During the sunspot cycle the sun’s heat and light output waxes and wanes by about 0.08%. Although this variation in itself is too small to have any appreciable direct effect on the earth’s climate, indirect solar effects can have an impact on the warming and cooling of our planet – indirect effects that are ignored in climate models.

Just such an indirect solar effect may have been discovered in a new study revealing a correlation between the end of sunspot cycles and the switch from El Niño to La Niña states of the tropical Pacific. The research was conducted by a team of scientists from NASA and the U.S. National Center for Atmospheric Research.

The researchers found that the termination of all five solar cycles between 1960 and 2010-11 coincided with a flip from a warmer El Niño to a cooler La Niña. And the end of the most recent solar cycle, which has just occurred, also coincides with the beginning of a new La Niña event. Because the end of the 11-year solar cycle is fuzzy, the research team relied for its “clock” on the sun’s more well-defined magnetic polarity cycle known as a Hale cycle, which is precisely 22 years in length.

The correspondence between the 11-year solar cycle and the onset of La Niña events is illustrated in the figure below, showing the six-month smoothed monthly sunspot number since 1950 in black and the Oceanic El Niño Index in color. The red and blue boxes mark El Niño and La Niña periods, respectively, in the repeating pattern. What stands out is that the end of each sunspot cycle is closely correlated with the switch from El Niño to La Niña. That the correlation is mere coincidence is statistically highly unlikely, say the study authors, although further research is needed to establish the physical connection between the sun and earth responsible for the correlation.

Another study, headed by climate scientists at the U.S. Lawrence Livermore National Laboratory, finds that multidecadal La Niña variability is why computer climate models overestimate sea surface temperatures in the Pacific by two to three times. The La Niña cycle results in atmospheric cooling and a distinct pattern of cooler-than-normal sea surface temperatures in the central and eastern tropical Pacific, with warmer waters to the north and south.

Many climate models produce ENSO variations, but are unable to predict either the timing of El Niño and La Niña events or temperatures measured by satellite in the tropical lower atmosphere (troposphere). However, the study authors found that approximately 13% of 482 simulations by 55 computer models do show tropospheric warming in the tropics that matches the satellite record. And, unexpectedly, those simulations reproduce all the characteristics of La Niña.

The next figure shows how well one of these particular simulations reproduces a La Niña temperature pattern, in both geographic extent (upper panel) and ocean depth (lower panel). The panels labeled B are the computer simulation and the panels labeled C are the satellite observations. Temperatures are depicted as an average warming (positive) or cooling (negative) rate, in degrees Celsius per decade, over the period from 1979 to 2018. La Niña cooling in the Pacific is clearly visible in both B and C.

The other 87% of the computer simulations overestimate tropical Pacific temperatures, which is why, the authors say, the multimodel mean warming rate is two to three times higher than observed. But their results show that natural climate variability, here in the form of La Niña, is large enough to explain the difference between reality and climate model predictions.

Next: Little Evidence for Link between Natural Disasters and Global Warming

How Near-Saturation of CO2 Limits Future Global Warming

The climate change narrative is based in part on the concept that adding more and more CO₂ to the atmosphere will cause the planet to become unbearably hot. But recent research refutes this notion by concluding that extra CO₂ quickly becomes less effective in raising global temperatures – a saturation effect, long disputed by believers in the narrative.

First reported in 2020, the new and highly detailed research is described in a preprint by physicists William Happer and William van Wijngaarden. Happer is an emeritus professor at Princeton University and prominent in optical and radiation physics. In their paper, the two authors examine the radiative forcings – disturbances that alter the earth’s climate – of the five most abundant greenhouse gases, including CO₂ and water vapor.

The researchers find that the current levels of atmospheric CO₂ and water vapor are close to saturation. Saturation is a technical term meaning that the greenhouse effect has already had its maximum impact and further increases in concentration will cause little additional warming. For CO₂, doubling its concentration from its 2015 level of 400 ppm (parts per million) to 800 ppm will increase its radiative forcing by just 1%. This increase in forcing will decrease the cooling radiation emitted to space by about 3 watts per square meter, out of a total of about 300 watts per square meter currently radiated to space.

The science behind greenhouse gas warming is illustrated in the figure below, depicting the wavelength spectrum of the intensity of thermal radiation transmitted through the atmosphere, where wavelength is measured in micrometers. Radiation is absorbed and radiated by the earth in two different wavelength regions: absorption of solar radiation takes place at short (ultraviolet and visible) wavelengths, shown in red in the top panel, while heat is radiated away at long (infrared) wavelengths, shown in blue.

Greenhouse gases in the atmosphere allow most of the downward shortwave radiation to pass through, but prevent a substantial portion of the upward longwave radiation from escaping – resulting in net warming, as suggested by the relative areas of red and blue in the figure above. The absorption by various greenhouse gases of upward (emitted) radiation at different wavelengths can be seen in the lower panels of the figure, water vapor and CO₂ being the most dominant gases.

The research of Happer and van Wijngaarden takes into account both absorption and emission, as well as atmospheric temperature variation with altitude. The next figure shows the authors’ calculated spectrum for cooling outgoing radiation at the top of the atmosphere, as a function of wavenumber or spatial frequency rather than wavelength, which is the inverse of spatial frequency. (The temporal frequency is the spatial frequency multiplied by the speed of light.)

The blue curve is the spectrum for an atmosphere without any greenhouse gases at all, while the green curve is the spectrum for all greenhouse gases except CO₂. Including CO₂ results in the black or red curve, for concentrations of 400 ppm or 800 ppm, respectively; the gap in the spectrum represents the absorption of radiation that would otherwise cool the earth. The small decrease in area underneath the curve, from black to red, corresponds to the forcing increase of 3 watts per square meter resulting from doubling the CO₂ level.

What matters for global warming is how much the additional forcing bumps up the temperature. This depends in part on the assumption made about climate feedback, since it’s the positive feedback from much more abundant water vapor in the atmosphere that is thought to amplify the modest temperature rise from CO₂ acting alone. The strength of the water vapor feedback is closely tied to relative humidity.

Assuming positive water vapor feedback and constant relative humidity with increasing altitude, the preprint authors find that the extra forcing from doubled CO₂ causes a temperature increase of 2.2 to 2.3 degrees Celsius (4.0 to 4.1 degrees Fahrenheit). If the water vapor feedback is set to zero, then the temperature increase is only 1.4 degrees Celsius (2.5 degrees Fahrenheit). These results can be compared with the prediction of 2.6 to 4.1 degrees Celsius (4.7 to 7.4 degrees Fahrenheit) in a recent study based on computer climate models and other evidence.

Although an assumption of zero water vapor feedback may seem unrealistic, Happer points out that something important is missing from their calculations, and that is feedback from clouds – an omission the authors are currently working on. Net cloud feedback, from both low and high clouds, is poorly understood currently but could be negative rather than positive.

If indeed overall cloud feedback is negative rather than positive, it’s possible that negative feedbacks in the climate system from the lapse rate (the rate of temperature decrease with altitude in the lower atmosphere) and clouds dominate the positive feedbacks from water vapor, and from snow and ice. In either case, this research demonstrates that future global warming won’t be nearly as troublesome as the climate change narrative insists.

Next: Natural Sources of Global Cooling: (1) Solar Variability and La Niña