Will Greenland Begin Accumulating Ice in 2015 and Beyond?

Based on NOAA’s 2014 Arctic Report Card, the past 2 decades of ice loss in Greenland has slowed dramatically in 2013-2014. In contrast toVelicogna’s (2014) previously published average mass loss of 280 +/-58 gigatons/year using GRACE satellite data, or the maximum loss of 570 gigatons in 2012-2013, there was only an insignificant loss of 6 gigatons from June 2013 to June 2014, or  mere 1% of the previous year’s loss. A loss of 360 gigatons translates into a 1 millimeter rise in sea level, therefore the 2013-2014 sea level rise should be 1.3 mm less than the year before. And based on historical analyses, Greenland will likely begin gaining mass in the coming years.

In Vanishing Ice Most Likely All Natural (transcipt here) I argued that Greenland’s glaciers would soon stabilize and sea ice in the Barents Sea would soon recover based on trends in the transport of warm Atlantic water into the Arctic. Although a one-year recovery is much too short a period from which to derive reliable projections, it is exactly what natural climate dynamics predict.

Based on GRACE satellite gravity estimates (illustrated in the graph below on the left) and hydrographic measurements (graph on right), Greenland’s lost ice has correlated best with the pulses of warm Atlantic water that entered into the Irminger Current that flows to the west around Greenland, delivering relatively warm water to the base of Greenland’s marine terminating glaciers. (Temperatures of  the Irminger warm pulse are represented by the numbers graph on the right.) Marked by the red arrow most of Greenland’s ice loss has happened in the southeast region, precisely where the brunt of warm subsurface waters entered the Irminger Current. Accordingly Kahn (2014) reported between 2003 -2006 that 50 % of the total ice loss of the Greenland Ice Sheet occurred in southeast Greenland, and thinning and calving of just 2 glaciers (marked HG) and (KG) accounted half of that loss. Thinning and calving are driven primarily by submarine melting. Although NOAA highlights Greenland’s surface melt rates, Rignot (2009) report that rates of iceberg discharge and rates of “submarine melting are two orders of magnitude larger than surface melt rates.”

 

Greenland ICe loss and the Warm Irminger Current

Researchers have measured the inflow of warm Atlantic waters along a line between Scotland and the Irminger Sea (A. below) and have determined how that water was partitioned between flows entering the Irminger Current and the flows entering the basins that feed the Barents Sea. Using satellite altimetry to measure changes in sea level, Chafik (2014) reported the flow of warm Atlantic waters into the Irminger Current had increased significantly between 1992-1998 (B. below), but over the past 18 years the volume of warm water has been declining. Accordingly researchers had reported that large glaciers, like the Jakobshavn with submarine grounding points, had been stable or advancing between the 1960s and early 1990s. Then coincident with the arrival of a warmer water via the Irminger Current, the glaciers abruptly began retreating. Since 1997 the loss of Greenland ice accelerated culminating in the widely trumpeted loss of 570 gigatons in 2012-2013, which was opportunistically portrayed as evidence of CO2 warming.

Trends in Inflow of Warm Atlantic Water

 

Because the inflow of warm water has been waning since the late 1990s, it suggested that accelerated loss of ice would soon wane as well. Based on the drop in sea level (B. above) the volume of intruding warm Atlantic water has decreased by 10%. If the previous pulse of warm water has been the driving force for retreating Greenland glaciers and melting Barents Sea ice, then that reduced inflow predicts Greenland’s glaciers should soon stabilize while Barents Sea ice begins to recover. Indeed 2014 also witnessed an increase in Barents Sea ice. Likewise NOAA’s 2014 Arctic Report card also stated the “coverage of multiyear ice in March 2014increased to 31% of the ice cover from the previous year's value of 22%.” Suggesting more ice is surviving the melt season. In addition the mean sea-ice thickness in multiyear ice zone along northwest Greenland has increased by 0.38 m.

But why did the loss of Greenland ice continue to accelerate after the initial 90s pulse of warm water intrusions? The warm intruding Atlantic water is saltier and denser and flows between 100 and 900 meters below the surface.  The weight of the glaciers have depressed the continental shelf so it slopes towards the shore (similar to the condition illustrated below for Antarctica’s Amundsen Sea glaciers.). When pulses of warm water are strong enough to rise over the shelf’s outer ridge, that warm dense water then flows downward to the grounding point of the glacier and remains there until a new equilibrium is established via basal melting and a retreating grounding point. Increased basal melting also increases calving of the floating ice shelf  and the loss of buttressing power that inhibits the glaciers’ seaward flow. The end result is the glaciers accelerate seaward, causing dynamic thinning, increased calving, and a large loss of ice mass that continues until a new equilibrium is established. The continued reduction of warm water inflows and the dramatic reduction of lost ice mass in 2014, now suggest the glaciers are no longer adjusting to the previous warm water intrusions. 

Glacier Basal Melt due to Warm Water Intrusions

Before the Little Ice Age (LIA), Greenland’s glaciers, like the Jakobshavn, were smaller than seen in the present day (Young 2011). During the Little Ice Age between ~1400 and 1850, glaciers grew to their maximum Holocene extent. That LIA advance correlates with 1)  lower solar flux, 2) decreased inflows of warm Atlantic water, and 3) a more persistent negative North Atlantic Oscillation. Although topographical features of Greenland’s glaciers will cause each glacier to adjust in a unique manner, overall the recent decrease in solar flux approaching LIA levels, the current decline in warm water inflows, and the current trend to a more persistent negative North Atlantic Oscillation all suggest that Greenland will begin accumulating ice mass over the next decade.

In Ocean Gyre Circulation Changes Associated with the North Atlantic Oscillation (NAO) Curry (2001) created a Transport Index illustrating the correlation between the pole-ward transport of warm tropical water and the North Atlantic Oscillation. As seen in their illustration, there was a rapid increase in the pole-ward transport during the 80s and 90s when the NAO was in an increasingly positive phase. In general agreement but supplemented by other atmospheric dynamics, Barrier (2014) suggest increased transport is due to the spin-up of the subtropical gyre during the persistent positive NAO and reduced transport follows a spin-down during persistent NAO- conditions. 

Transport Index of  Warm Atlantic Water and North Atlantic Oscillation

So why didn’t Greenland’s glaciers begin retreating earlier during the 1980s and 90s? When the NAO is positive, both the sub-Tropical gyre (STG in the illustration below) and the sub-Polar gyre (SPG) speed up and expand. While the spin-up of the sub-Tropical gyre transports more tropical water pole-ward, in contrast the expanded sub-Polar gyre limits how much warm water will enter the Arctic seas. This quasi-blocking effect causes more warm water to be re-circulated equator-ward and stored in the sub-Tropical gyre. The amount of warm water entering the Irminger Current is particularly limited because the sub-Polar gyre also shunts the pole-ward transport to the east towards the Barents Sea.  When the NAO first enters a negative phase the sub-Polar gyre contracts towards the west, allowing more warm water to enter the Irminger Sea.

Statistical studies have debated the correlation between retreating Arctic ice and the negative NAO because it generates a confounding short term warming trend that is contradicted by the longer cooling trend suggested for the LIA as well as observed during the 1960s and 70s.  But that contradiction is easily explained by the effects of an expanding and contracting sub-Polar gyre (SPG). The initial contraction of the SPG during the early negative NAO allows more warm water to enter the Arctic. However the negative NAO also implies a spin-down of the subtropical gyre and therefore a drop in the pole-ward transport of warm tropical waters. Thus as the negative NAO persists, the initial warm pulse into the Arctic is exhausted and followed by cooling trend decades later. A similar scenario was reported byBengtsson (2004) in The Early Twentieth-Century Warming in the Arctic—A Possible Mechanism to explain the rapid 1930s and 40s warming of the Arctic and retreat of Greenland glaciers that persisted into the early phase of the negative NAO.

Subpolar Gyre and Arctic Currents 

With all things considered, the evidence strongly suggests we will soon witness a similar natural cycle and a rebound in the Greenland’s ice.

Why Vanishing Ice Is Likely All Natural?

 (transcript for  video: Vanishing Ice Most Likely All Natural)

A list of reviewed papers used for this presentation available at http://landscapesandcycles.net/shrinkingice.html

Mount Kilimanjaro

If we are to truly prepare for the dangers of climate change and build more resilient environments, we must first understand natural climate change. Unfortunately due to the narrow focus on rising CO2, the public remains ill-informed and fearful about the causes retreating ice. Africa’s Mount Kilimanjaro and America’s Glacier National Park are 2 iconic examples of failed climate interpretations. For example, Al Gore’s “Inconvenient Truth” suggested warmth from rising CO2 had been melting Kilmanjaro’s glaciers. In truth, instrumental data revealed local temperatures have never risen above the freezing point. In 2004, Dr. Geoff Jenkins, Head of the Climate Prediction Programme at England’s Hadley Centre, was prompted by the evidence of no warming, to email the IPCC’s Phil Jones and ask and I quote “would you agree that there is no convincing evidence for Kilimanjaro glacier melt being due to recent warming (let alone man-made warming)?” Yet due to the politicization of climate science, Al Gore shared the Nobel Prize despite perpetuating the global warming myth of Kilimanjaro.

Glacier experts from the University of Innsbruk published and I quote, “The near extinction of the plateau ice in modern times is controlled by the absence of sustained regional wet periods rather than changes in local air temperature on the peak of Kilimanjaro.” Changing patterns of precipitation were recorded in the water level of nearby Lake Naivasha. As researchers documented in this graph, the region had experienced increasing precipitation during the Little Ice Age, followed by a sharp drying trend that began in the late 1700s, which triggered Kilimanjaro’s retreat long before CO2 ever reached significant concentrations. 

Ice structures such as these penitentes, are commonly seen in many high elevation glaciers, and help scientists determine if retreating ice was caused by below freezing sublimation, or melting from warmer air. Over decades, sublimation creates sharp features at the border between sunlight and shade. In contrast, any melting from warm air temperatures oozes across the icy surface destroying those sharp features in a matter of days. So the presence of sharp-angled features like these penitentes, are excellent long term indicators of dry and below freezing temperatures.

Penitentes 

Over 30 years ago I visited Glacier National Park, home of the 2nd iconic example of misrepresented glacier retreat. After thousands of years with less ice, the park’s glaciers grew to their maximum extent during the Little Ice Age. Then they began retreating around 1850. Although the media now hypes the park’s disappearing glaciers as evidence of CO2 warming, the greatest retreats happened long before CO2 could exert any possible effect. In 1913 the park’s largest glacier, the Sperry Glacier was nearly 500 feet thick at a point that would soon become its 1946 terminal edge. By 1936 that thickness had dwindled by 80%. That rapid retreat prompted scientists 70 years ago to predict a natural disappearance of the park’s glaciers. 

As seen here, the contrast between the early and late 20th century retreat is striking. Between 1913 and 1945 the rate of retreat for the Sperry glacier was 10 times faster [due to drought] than rate of retreat since 1979. If rising CO2 has been the driver of recent melting, we would expect an increasingly faster rate of retreat, not slower!  If we are to prepare for changes caused by melting ice, we must view our vanishing ice from a perspective of centuries and millennia, and tht perspective insists that we understand natural climate change.

 There is an abundance of evidence demonstrating that relative to today, far less ice covered the globe during the last 10,000 years, a period known as theHolocene.[i.e. here and here) Far less ice despite much lower CO2 concentrations.

Likewise, although most of today’s average global temperature has been driven by heat ventilating from the Arctic Ocean, as visualized in this NASA graphic, Arctic temperatures were also far warmer during most of the Holocene. Based on changes in tree line, pollen samples and ocean sediments, scientists estimate Arctic air temperatures during the mid Holocene averaged 2 to 7°C higher than today. 

This ice core data from Greenland, exemplifies the Holocene’s changing temperature patterns common for most of the Arctic. But it is a pattern that also corresponds to climate change in many other regions across the globe. After the last Ice Age ended, the period of warmer temperatures between 9,000 and 4,000 years ago has been dubbed the Holocene Optimum. During that time, remnant glaciers from the Ice Age retreated and shrank to sizes far smaller than we witness today. All of Norway’s glaciers completely disappeared at least once, and Greenland’s greatest glaciers, like the Jakobshavn, remained much further inland than now observed. Like many northern glaciers, Jakobshavn had only recently advanced past its present terminus during the unprecedented cold of the Little Ice Age.  

  

Greenland GISP2 Holocene Temperature data vs CO2 trend 

From whale bones, Arctic driftwood, and patterns of Arctic shoreline erosion,we also know that during the Holocene, Arctic summer sea ice retreated 1000 kilometers further north than seen today. Treelines advanced to their greatest northern limits, reaching Arctic Ocean shores 9000 years ago, hundreds of kilometers further north than their current limits.

The paleo-eskimos, or Tuniit, colonized the Arctic’s shoreline about 5000 years ago. They hunted Musk Ox and Caribou with bow and arrow. They lived in tents and heated those tents with Wood. Archaeologists studying Tuniit colonization of Arctic shores, reported periodic abandonment and occupation that corresponded with periods when summer sea surface temperatures bounced between 2–4° cooler and 6°C Warmer than present. Likewise, concentrations of Arctic summer sea ice ranged from 2 months more sea ice to 4 months more open water.

Changes in insolation due to the sun’s orbital cycles, or Milankovitch cycles, correspond with the recent 100,000-year cycles of past major ice ages. We are currently in another warm peak. The Milankovitch orbital cycles also predicted the current cooling trend that began about 4000 years ago. However warm spikes due to high solar output punctuated this cooling trend roughly every thousand years.  The unprecedented Holocene glacier growth during the Little Ice Age occurred when solar output was extremely low.

Past 300 years of solar flux 

In this graph depicting 300+ years of solar flux, the earth warmed as we ascended from the Little Ice Age. Our recent warm spike coincides with high solar flux. However, recently solar output has again retreated, approaching Little Ice Age levels, and correlates with the increasing frequency of cold winters. The next two decades will allows us to evaluate more accurately the effect of these solar changes on climate and glaciers.

The correlation between Greenland ice core data and solar flux, is also seen inScandinavian tree ring data. Tree rings suggest the warmest decade in the past 2000 years, happened during the warm spike of the Roman Warm Periodbetween 27 and 56 AD. After a period of resumed cooling a new warm spike occurred 1000 years ago during the Medieval Warm Period.  After more extreme cooling during the Little Ice Age, a third warm spike peaked around the 1940s.  Most interesting, the consensus from multiple tree ring data sets around the world, also suggest natural habitats were warmer during the 1940s than they are now. Likewise, the greatest rates of retreat for glaciers from Glacier National Park to the European Alps also happened during the 1940s.

The Great Aletsch, the largest and best studied of all the Swiss Alp’s glaciers beautifully illustrates the 3000-year cooling trend punctuated with periodic warm spikes that caused rapid glacier retreats. The Great Aletsch’s maximum length during the Holocene was also reached during the Little Ice age. About 1850 it began retreating to its current position, represented by this baseline. 

However during the warmth of the Bronze Age 3000 years ago, the glacier was Much smaller than today. During the cooler Iron Age the glacier began to grow, but rapidly retreated during the warm spike of the Roman Warm Period. The glacier advanced again almost reaching its Little Ice Age maximum, but retreated rapidly during the warm spike during the Medieval Warm Period.

Great Aletsch: 3000 years of advances and retreats

  During the Little Ice Age, the Great Aletsch advanced to its greatest length of the Holocene, in rhythm with a series of 4 documented solar minimums. Each advance was followed by a rapid retreat, similar to what we observe today,  when solar flux increased.

The glaciers recent retreat does not appear any different from retreats in past. So what does that tell us? To be clear the skeptic argument is not “because it was natural before then CO2 can not possibly contribute today”.

The skeptic argument is simply, we can not determine the sensitivity of our climate and glaciers to rising CO2, until we have fully accounted for past and present natural dynamics. Far too often the media, and a few invested atmospheric scientists, simply assert that retreating glaciers were all natural in the past, but since 1950 the retreat is suddenly due to CO2. But past natural climate dynamics did not suddenly stop operating in 1950. To what degree are natural climate dynamics contributing today? Well, more recent patterns of advancing and retreating ice suggest natural dynamics are the main drivers of today’s retreating ice

A century of mass change measurements for several Swiss glaciers allow us to more finely resolve changes between decades. Again the greatest rate of 20thcentury retreat occurred during the 1930 and 40s, and once again, before CO2 concentration had any significant impact. The rapid 1940s retreat is linked to unusually high solar insolation and patterns of precipitation governed by theAtlantic Multidecadal and North Atlantic Oscillation. 

Swiss Alp glacier advances and retreats

Furthermore when solar flux dipped between the 1960s and 80s, a high proportion of Alpine glaciers, as well as glaciers around the world, stopped retreating and many began to advance as seen here in the Alps.

Changes in solar insolation affect oceans in two critical ways. During high solar output of the Medieval Warm Period, tropical waters in both the Atlantic and Pacific increased by as much as 1°C warmer than today. During the solar minimums of the Little Ice Age, tropical oceans dropped by as much as 1°C degree cooler than today. But equally important changes in insolation affected the volume of warmer tropical waters that were transported toward the poles.

Multiple lines of evidence correlate higher solar activity during the Roman and Medieval Warm Periods, with an increased flow of warm Atlantic water into the Arctic, resulting in reduced sea ice. Conversely, during low solar activity during the Little Ice Age, transport of warm water was reduced by 10% and Arctic sea ice increased. Although it is not a situation I would ever hope for, if history repeats itself, then natural climate dynamics of the past suggest, the current drop in the sun’s output will produce a similar cooler climate, and it will likely be detected first as a slow down in the poleward transport of ocean heat. Should we prepare for this possibility?

Water heated in the tropics is saltier and denser, and when transported into theArctic lurks 100 to 900 meters below the surface. That warm subsurface water can melt sea ice and undermine grounding points of submerged glaciers causing an acceleration of ice discharge. Intruding warm deep water also melts the underside of floating ice shelves, which also accelerates calving and ice discharge.

Instrumental records of Greenland’s air temperatures, also recorded the fastest rate of warming during the 1930s and 40s coinciding with increased inflows of warm Atlantic water. Accordingly intruding warm waters alsotransported more southerly fish species, prompting the birth of Greenland’s Cod fishery. CO2 driven models have completely failed to simulate this Arctic warming.

Simultaneously the best studied Greenland glacier, the Jakobshavn, began retreating from its Little Ice Age maximum with it fastest observed retreat of 500 meters per year between 1929 and 1942. The rapid retreat was amplified when the glacier’s terminal front became ungrounded from the ridge. That earlier grounding point had previously prevented warm subsurface waters from entering its fjord. With more warm water entering the fjord, the grounding point rapidly retreated.

When warm water intrusions subsided, the glacier stabilized, and even began advancing between 1985–2002. Although the recent retreat of Greenland’s glaciers is reported as an acceleration relative to the 70s, the rate of retreat is now much slower than the 30s and 40s. And again the 20th century pattern of retreat does not correlate with rising CO2 concentrations.

Warm Water Flow into the Irminger Current

The 20th century pattern of Greenland’s melting glaciers correlates best with the timing and distribution of intruding warm Atlantic water. As seen in these illustrations, due to changes in the North Atlantic Oscillation in the 1990s, a sudden influx of warm Atlantic water entered the Irminger Current. The numbers here indicate that the current’s temperature cooled from 10°C to 1.5°C above freezing as it traveled along Greenland’s coast.

Lost Ice Mass from Grace satellite data

As seen here from recent satellite estimates, the amount of Greenland’s lost continental ice, coincides with the warmth of the Irminger Current, with pinker areas representing the highest rates of lost ice.

Warm Atlantic waters that don’t enter the Irminger Current, continue deeper into the Arctic, mostly via the Barents Sea.  Greater volumes of intruding warm water cause greater reductions of ice in the Barents and Kara Seas, deep inside the Arctic Circle. Danish Sea Ice records reveal a similar loss of sea ice during the 1930s rivaling the recent decline.

Coinciding with cycles of reduced sea ice, glaciers on the island Novaya Zemlyain the Barents Sea, also underwent their greatest retreat around 1920 to 1940.  After several decades of stability, its tidewater glaciers began retreating again around the year 2000, but at a rate five times slower than the 1930s. The recent cycle of intruding warm Atlantic water is now waning and if solar flux remains low, we should expect Arctic sea ice in the Barents and Kara seas to begin a recovery and Arctic glaciers to stabilize within the next 15 years.

The contrasting behavior of Antarctic Ice is further confirmation that intruding warm water is a natural driver of melting polar ice. Unlike ice that melted deep inside the Arctic Circle, Antarctic Sea Ice has increased to record extent and expands far outside the Antarctic Circle. Why such polar opposites? Because Antarctica is shielded from intruding warm waters by a Circumpolar Current.

Antarctica’s Circumpolar Current consists of warm subtropical waters driven eastward by westerly winds. Because there are no continents to block its path or deflect those warm waters poleward, the Circumpolar Current simply encircles the continent. The one place where Antarctic sea ice has retreated slightly, only occurs along the western side of the Antarctic Peninsula where the Circumpolar Current makes its closest approach.

Likewise without intruding warm waters, Antarctica has lost far less continental ice than Greenland. Although Antarctica contains 14 times more ice than Greenland, Greenland has lost between 2 and 5 times more ice than Antarctica. Based on changes in gravity, most areas of Antarctica have slightly gained ice designated by greenish tones. However where warm waters and winds of the Circumpolar current approach the Peninsula, there has been moderate ice loss designated by bluish tones. And despite being Antarctica’s most poleward coastline, there has been a great loss of glacier ice around the Amundsen Sea, illustrated by redder tones, causing a net loss of ice for the continent.

Antarctic Basal Melt Hot Spots 

The reason for this concentrated melting is due to the upwelling of relatively warm Circumpolar Deep Water that lurks 300 feet below the surface. Glaciers along the Amundsen Sea terminate in deep water, and are most susceptible to periodic upwelling of that warmer deep water, which causes basal melting.

Maps pinpointing regions with the greatest basal melt, highlighted here by red dots, coincide with the greatest loss of glacier ice along the Amundsen Sea hot spot. Amundsen glaciers are grounded along the coastal shelf where ancient channels can direct warm, upwelled deep water directly to the base of the glaciers. Early explorers reported excessive crevasses and concave surfaces on these glaciers suggesting extreme basal melting was happening in 1950s, and was likely a process that has been ongoing on for millennia. Much like Greenland’s  Jakobshavn glacier, once Amundsen’s glaciers retreated from their Highest ridge on the continental shelves, upwelled warm water could overflow the ridge and melt an increasingly larger cavity near the glaciers grounding points. In turn, a larger cavity allows even more warm water to enter. In contrast, the few Amundsen Sea glaciers with grounding points located beyond the reach of upwelled waters, those glaciers have not lost any ice.

Like the rhythm of retreating and advancing glaciers, rates of sea level rise have ebbed and flowed as seen in this graph from the IPCC. Again it is the 30s and 40s that experienced both the greatest retreat of glaciers and the fastest rise in global sea level. With the recent decline in solar flux and the shift to cool phases of ocean oscillations, natural climate change suggests that although glacier retreat and sea level rise will likely continue over the next few decades, the rates of sea level rise and glacier retreats will slow down.The next decade will provide the natural experiment to test the validity of competing hypotheses. Are changes in the earth’s ice  driven by natural or CO2 driven climate change. I am betting on natural climate change.   

Rates of Change in Sea Level 

Read more about natural climate change In Landscapes and Cycles: An Environmentalist’s Journey to Climate Skeptisicsm!  

Fabricating Climate Doom: Hijacking Conservation Success in the UK to Build Consensus!

Adapted from the chapter  Deceptive Extremes in Landscapes & Cycles: An Environmentalist’s Journey to Climate Skepticism by Jim Steele 

Reposted from August 2013

What Good Conservation Science Reported

Good stewards of the environment are compelled to engage in good science. In 1980, butterfly experts in the United Kingdom predicted that both the Silver-spotted Skipper and the Large Blue butterfly were doomed to extinction. The widespread Silver-spotted Skipper was gradually restricted to just 46 locations. The more rare Large Blue had been declining from over 90 estimated colonies supporting tens of thousands in the 1800s to just two colonies and about 325 individuals by 1972. The question that had continuously eluded conservationists was why? Disturbed by repeated failures to correctly identify the causes of the decline, Dr. Jeremy Thomas embarked upon extensive research that ultimately unraveled the mystery. It is a model of superb scientific research and demonstrates why good environmental stewards must employ carefully detailed studies. For those of you who enjoy bizarre nature stories, the life of the Large Blue is a fascinating tale of deception and betrayal in which plump, seemingly helpless caterpillars turn the tables on voracious ants. And oddly enough, despite global warming, the Large Blue went extinct in England because its microclimate had cooled.

In earlier attempts to stave off the Large Blue’s extirpation, UK conservationists had protected nine areas in order to minimize any human impact on the remaining populations. However this habitat protection uncharacteristically failed to slow the species’ decline, so conservationists inferred that the most likely culprits must be unscrupulous butterfly collectors who were trying to cash in on the value of its increasing rarity. So conservationists hurriedly erected protective fences, only to watch hopelessly as the last population continued to decline. Ironically, the fence itself, not greedy collectors, was the final nail in the Large Blue’s coffin.¹

Europe’s Large Blue belongs to a group of butterflies whose survival has been eternally entwined with the fate of local ants. In a process that sounds lifted from a Disney or Pixar screenplay, Large Blue caterpillars summon ant bodyguards with special calls and scents. The discovery of talking caterpillars is a fascinating story in itself, but the story gets better. Upon arriving, the summoned ants are fed with a sugary reward oozed from special pores in the caterpillar’s bodies. The caterpillars also exude intoxicating chemicals that make their new ant bodyguards more aggressive against other less friendly ant species.

One species of the Blues not only beckons the ants to come to its protection, but then seduces the ants to carry it into the ant colony. Once inside, the caterpillar then mimics the sounds of the queen ant, demanding to be fed in royal ant fashion. This is not quite the royal treatment imagined by humans: the caterpillar’s instinctual impersonation induces the worker ants to approach and regurgitate their stomach contents, upon which the caterpillar gratefully dines.

The Large Blue’s relationship with ants has an added twist more reminiscent of a grade B movie depicting the horrors of adopting a mysterious orphan. After hatching, Large Blue caterpillars feed on their host plant just as all other caterpillars do. And like other species of Blues, they soon drop to the ground to summon and then mesmerize a local ant species. Because the ants’ worm-like larvae resemble the size and shape of the early stage of these caterpillars, the intoxicating charade is sufficiently convincing, and the ants quickly carry the caterpillar into their nest.

Once the caterpillar is safely nestled into the ant’s nursery, the hideous betrayal commences. One by one the ungrateful adoptee devours the ant’s larvae. The Large Blue’s very existence has evolved to become completely dependent on eating “baby ants.” And only this one species of ant will do. Ironically, these butterflies often cause the extirpation of the adopting ant colony, which in turn limits the butterfly’s population.

Large Blue Caterpillar Feeding on Ant Larvae

Earlier conservation solutions had been simply based on the prevailing biases that failed to prevent extinction. Thomas lamented, “every hypothesis [collectors, insecticides, fragmentation, inbreeding, climate, pollution] on which the conservation measures of the previous 50 years had been based was untenable.” 

To be kind to those earlier researchers, the critical changes in the Large Blue’s protected habitat were barely perceptible. These changes created a baffling illusion that something was oozing across the boundaries of their protected conservation areas and decimating the species. So blaming collectors, pollution, climate change, or disease made sense simply because those phenomena readily cross artificial boundaries. But further observations never supported these suspicions. To unravel the Large Blue’s extinction mystery, Jeremy Thomas painstakingly identified and measured every possible confounding factor that might affect not only the butterfly directly, but also its host plants and the host ants. In addition to general weather variables, he tallied the various local ant species, measured temperatures above and below ground, differences in turf height, plant species composition, and the amounts of bare ground available.

It was laborious and detailed work, but exactly what good science dictates. Why the real agent of extinction had gone unnoticed finally became clear. Thomas discovered that just a few millimeters of change in the height of the grass, during the spring and autumn, could lead to the butterflies’ local extinction. The species of ants that the Large Blue plundered requires a very short grass habitat, which allowed the sun to warm the soil and their underground colony. When the grass grew from 1 to 2 centimeters, the temperatures just below the surface in the ants’ brood chamber dropped by 3–5°F. When the turf exceeded 3 cm, the microclimate below the grass cooled enough that competing ant species overran the Large Blue’s host ants. Three centimeters is less than your little finger, so such a small change in the height of the grass had been understandably overlooked.

Over the years, as more efficient animal husbandry reduced sheep and cattle grazing, pastures were increasingly abandoned. Biologists assumed that as more pastures returned to their natural state, wildlife biodiversity and abundance would also increase. That assumption is often true, but without human management, not only did the grass grow taller, but shady trees and shrubs soon invaded. The increasing shade was killing not only the Large Blue but was also endangering a diverse array of the United Kingdom’s other warmth-requiring butterflies like the Silver-spotted Skipper.

In addition to reduced grazing, earlier attempts to control UK rabbit populations added to the demise of these warmth-loving butterflies. Rabbits are not native to the British Isles, or to Australia, but had been introduced long ago as a source of meat. As growing populations of escaped rabbits competed for grasslands with the sheep and cattle (also nonnative), people attempted various forms of pest control. In Australia, humans erected the “great rabbit fence” to separate western and eastern Australia. Eventually, they turned to germ warfare, employing a newly discovered myxomatosis virus, which decimated the Australian rabbit population. In France a bacteriologist introduced the disease to rid his estate of rabbits. It then quickly spread, killing 90% of France’s native rabbit population. The virus then spread, either naturally or intentionally, into Great Britain. By the mid 1950s it had devastated the rabbit populations there. With fewer cattle, fewer sheep, and fewer rabbits grazing, the grasslands became increasingly overgrown, and warmth-loving butterflies became increasingly scarce. Not realizing the importance of grazers, the well-intentioned conservationists who had erected the protective fence unwittingly destroyed that which they sought to protect.

Once informed by the detailed work of Jeremy Thomas and his colleagues, by 1980 conservationists had begun efforts to successfully reintroduce the extinct Large Blue. Government subsidies and environmental schemes were enacted to encourage grazing, while conservationists mowed abandoned pastures to the optimum turf height. Individuals from Large Blue populations that still survived in Sweden were shuttled to England’s “terra nova” for a second chance. Under careful management, the reintroduced Large Blue is slowly rebounding.

But why should people need to intervene so directly and so intensively? Why couldn’t the Large Blue and other butterflies just exist “naturally”? Another ironic twist to this story is that humans actively created much of England’s grasslands, starting between four and six thousand years ago when new colonists introduced farming and grazing to England. To feed their sheep and cattle, early Britons increasingly cut down the natural forests that had once covered most of Great Britain. These human-generated grasslands were then maintained by grazing sheep and cattle that ate the sprouts of any trees that dared to recolonize. Similarly, the Victorians set fires to clear much of Scotland’s forest to encourage heather for grouse hunting. Much of Great Britain’s “natural” habitat is actually the product of millennia of human design. To maintain human-made biodiversity requires human stewardship.

Metamorphosing Conservation Success into Climate Alarm

“We search for a climate fingerprint in the overall patterns, rather than critiquing each study individually” ³

Dr. Camille Parmesan, University of Texas

While serving on the Intergovernmental Panel on Climate Change (IPCC), Dr. Camille Parmesan (whose work was introduced here Fabricating Climate Doom – Part 1: Parmesan’s Butterfly Effect) issued the paper “A Globally Coherent Fingerprint of Climate Change Impacts Across Natural Systems.” In contrast to Jeremy Thomas’s detailed investigations, Parmesan again advocated that biologists should ignore local details. She wrote, “Here we present quantitative estimates of the global biological impacts of climate change. We search for a climate fingerprint in the overall patterns, rather than critiquing each study individually.” However, critiquing individual studies is always the essential first step. Otherwise the overall pattern will be distilled from faulty information. And in order to support her supposed pattern of global warming disruption, she again omitted crucial contradictory details.

Parmesan tactfully offered lip service to altered landscapes, but stated that her “probabilistic model” accurately separated the effects of land use from climate change. To demonstrate her model’s power, she wrote, “Consider the case of the silver-spotted skipper butterfly (Hesperia comma) that has expanded its distribution close to its northern boundary in England over the past 20 years. Possible ecological explanations for this expansion are regional warming and changes in land use. Comparing the magnitudes and directions of these two factors suggests that climate change is more likely than land-use change to be the cause of expansion.” That was a very odd claim.

This was the very same Silver-spotted Skipper that Jeremy Thomas’ detailed studies and subsequent conservation prescriptions had saved from extinction along with the Large Blue. Parmesan was hijacking a conservation success story to spin a tale of climate disruption. Her “proof” that climate change was driving the Silver-spotted Skipper northward came from the work of her old friend C.D. Thomas, known for predicting that rising CO₂ levels had committed 60% of the world’s species to extinction.⁵ Using a mesmerizing statistical model, C.D. Thomas argued that because the Silver-spotted Skipper “needs warmth,” only global warming could account for its recent colonization of a few cooler north-facing slopes of England’s southern hills.

The Skipper is indeed fond of hotter south-facing slopes. However, the butterfly had historically inhabited cooler northern slopes if those slopes had been grazed. Like the Large Blue, the Skipper had disappeared from both cool north-facing slopes and warm south-facing slopes whenever the turf grew too high.^6,7 C.D. Thomas’ model was statistically significant only if he ignored recent conservation efforts to promote warmer, short-turf habitat. At the end of his paper, relegated to his methods sections, he quietly stated, “we assumed that grazing patterns were the same in 1982 as in 2000.”⁴Parmesan and C.D. were guilty of grave sins of omission.

I emailed Dr. Jeremy Thomas regarding the study by C.D. Thomas and asked, “I assume due to earlier collaboration, you are aware of the habitat his study referenced? If so, is his implied assumption of no changes to turf height valid?” He replied, “No, it's not valid.There was a massive change in turf height and vegetation structure …between 1980 and the 1990s onwards for 2 reasons. (emphasis added)” First, since the 1986 paper, several of the key surviving sites were grazed more appropriately by conservationists and most of them, and many neighbors, are today in “agri-environmental schemes” to maintain optimum grass heights. Second, from 1990 onwards the rabbits had gradually returned and did the same job on several abandoned former sites.

Although he did not have local climate data for the Silver-spotted Skipper’s recovery, Jeremy Thomas suggested that at least two thirds of the Skippers’ recovery and their subsequent recolonization had resulted from both the increased grazing and the rabbits’ recovery. He was willing to attribute as much as a third of the butterflies’ recovery to climate warming between the 1970s and the present.

If, for argument’s sake, we accept that one-third of the recovery was due solely to CO₂warming and ignore published arguments that the warming in England have been caused by the warm mode of the North Atlantic Oscillation⁹ (and recent cooling by the cool mode), habitat improvements still account for at least two-thirds of the skippers’ expansion. Furthermore, the Silver-spotted Skipper had yet to expand further northward than its previous 1920s boundary. Yet that was Parmesan’s best example of a “coherent fingerprint of global warming” disruption! It was bad science, but the consensus flocked to it in agreement.

To date more than 3500 papers have referenced her interpretation as evidence of climate disruption. It is a consensus built on misleading results that hijacked legitimate conservation science. In contrast, Jeremy Thomas’ successful preservation of two species on the brink of regional extinction had unequivocally demonstrated that the long-term changes were due to the quality of the caterpillar’s habitat. Although weather change causes short-term fluctuations in butterfly populations, a change in habitat quality affects populations 100 times more powerfully than weather.⁸ But such successful conservation efforts do not get funded in the same way as global warming horror stories do, and Jeremy Thomas’ “Evidence Based Conservation of Butterflies” has been cited by just 17 papers. Such a gross imbalance is a sad testimony to how the politics of climate change has corrupted the environmental sciences. I fear it is a hijacking that will only breed distrust for our legitimate green concerns in the future.The misguided obsession with CO₂ and Parmesan’s faulty probabilistic model has supported equally bad analyses regards the fate of polar bears, penguins, frogs, pika and marine ecosystems, but that takes a whole book to document.

Why have so few scientists celebrated the good science like Jeremy Thomas’ when it empowers us with the critical understanding that allows us to locally build a more resilient environment? Why instead have thousands of scientists uncritically pushed false scenarios of catastrophic climate change? Although some skeptics have suggested a nefarious scientific conspiracy, I believe it demonstrates the ease with which the human mind embraces illusions. Once those scientists accepted CO₂ warming as a reasonable explanation for ecological disruptions, despite never thoroughly examining the issue, they embraced whatever supported their choice. Their intellectual identity became intimately entwined with any validation of their chosen hypothesis. Like an avid sports fan, they feel great when their team is “winning” and distraught when their team is “wrong”. They brand anyone who challenges their hypothesis as a denier, stupid, traitor or infidel, and do not hesitate to brutalize anyone on the wrong team.

Robert Bolton wrote, "A belief is not merely an idea the mind possesses; it is an idea that possesses the mind." Once we make a choice, that choice possesses us. One of the more active areas of psychological research deals with “change blindness” and “choice blindness”. An international team from Harvard, the University of Tokyo, and Lund University in Sweden cleverly demonstrated how humans are hardwired to defend their choices despite contrary evidence. Test subjects were asked to choose who was the most attractive person in a set of two pictures displayed on the other side of the table. The researchers would then retrieve the pictures and ask the subjects to explain why they made their choice. However the lighting in the room was designed to allow the researchers to switch pictures and the test subjects were handed the picture they did notchoose. Most subjects never noticed the switch, and believing it was their choice proceeded to explain in great detail how the picture they never chose was the most attractive.¹⁰ A National Geographic series called Brain Games modified that experiment on a recent segment called “You Decide” and I urge you to watch it. Once you believeCO₂ is destroying the world, any “search for a climate fingerprint” will always be “found” even when it is not there. Whether you are a CO₂ advocate or skeptic, we are all victims to “choice blindness.” More critical analyses and respectful debate are the only paths to follow if we are ever to free ourselves from the shackles of our own illusions.

Literature Cited

1. Thomas, J., et al., (2005) Successful Conservation of a Threatened Maculinea Butterfly. Science, vol. 325, p.80-83.

2. Thomas, J., et al. (1986) Ecology and Declining Status of the Silver-spotted Skipper Butterfly (Hesperia Comma) in Britain. Journal o Applied Ecology. Vol. 23, p. 365-380.  

3. Parmesan, C. and Yohe, G. (2003) A globally coherent fingerprint of climate change impacts across natural systems. Nature, vol. 142, p.37-42

4. Thomas, C.D, et al., (2000) Ecological and evolutionary processes at expanding range margins. Nature, vol. 411, p. 577?581.

5. Thomas, C.D, et al., (2004) Extinction risk from climate change. Nature , vol. 427.

6. Thomas, C. D.  and Jones, T. M., (1993) Partial recovery of a Skipper Butterfly (Hesperia comma) from Population Refuges: Lessons for Conservation in a Fragmented Landscape. Journal of Animal Ecology, vol. 62, p. 472-481.

7. Thomas, J., et al. (1986) Ecology and Declining Status of the Silver-spotted Skipper Butterfly (Hesperia Comma) in Britain. Journal o Applied Ecology. Vol. 23, p. 365-380.  

8. Thomas, J et al. (2011) Evidence based Conservation of butterflies. J. Insect Cons., vol. 15, p. 241?258.

9.Hurrell, J. and Deser, C. (2009) North Atlantic climate variability: The role of the North Atlantic Oscillation.Journal of Marine Systems, vo. 78, p. 28–41.

10. Johansson, P., et al. (2008) From Change Blindness to Choice Blindness. Psychologia, vol. 51, p. 142-155

Adapted from the chapter Deceptive Extremes in Landscapes & Cycles: An Environmentalist’s Journey to Climate Skepticism by Jim Steele

Essay first posted to Watts Up With That as

Fabricating Climate Doom - Part 2: Hijacking Conservation Success in the UK to Build Consensus!