|Current Issues in Climate Science: Focus on the Poles|
|Written by Robert Ferguson|
|Friday, 13 July 2007 10:28|
> Let me give you just one fact. Al Gore says the Antarctic and Greenland ice sheets will melt and cause sea level to rise 20 feet, putting the present-day populations of Manhattan, Shanghai, Bangladesh and other coastal regions at risk. The official scientific consensus, represented by the UN Intergovernmental Panel on Climate Change, says that over the coming century the contribution of these two ice sheets to sea-level rise will be not 20 feet but 2 inches; that in each of the past four interglacial warm periods sea level rose to a height five metres above its present level, and did so without any influence from humankind; that sea level will do the same in the present interglacial period; but that it will not rise by 20 feet for several millennia. Indeed, the UN says the probability that our activities make any difference to sea level is little better than 50:50. So, on the scariest of all the "global warming" scares - sea-level rising and displacing hundreds of millions - Al Gore is exaggerating 120-fold, or almost 12,000 per cent. He does not represent the scientific mainstream consensus, but instead speaks for a small, fringe group of politically-motivated scientists. - Lord Christopher Monckton.
In 2007, the heat has been turned up at the Poles. Not by climate change, but by climate alarmists: “Greenland is melting into the sea, Antarctica is soon to follow, sea level will rise by several meters this century. Polar bears will become extinct. Permafrost will melt. Methane will be released. Warming will accelerate.” So the litany goes.
But are things really so? Should school children fear a devastating rise in global sea levels? Will we soon mourn the passing of the polar bears? Will changes in the climate of the Polar Regions lead to ecological and biological devastation? The answer is resoundingly, No! Not according to current observations. Not according to our knowledge of the past. Not according to our best understanding of the future.
Polar bears, as a species, have survived through periods in the past lasting several thousands of years in which Arctic temperatures were significantly higher and Arctic sea ice was significantly less than conditions currently. Their existence today is the strongest testament to their ability to adapt to a changing climate.
The Intergovernmental Panel on Climate Change (IPCC) projects, in its just-released Fourth Assessment Report, a median sea level rise throughout the 21st century of just 14 inches. If the current inputs from Greenland and Antarctica simply reflect natural variability (there is evidence to support this possibility) and/or short-term accelerations, then future sea level rise may even be less.
This paper examines the evidence supporting a non-alarmist view of climate change science, with special emphasis on the polar regions, both the Arctic and the Antarctic. Evidence is presented suggesting that the near term impact of future climate change on the polar regions of the earth, and the rest of the Earth at large - although detectable - will be modest. While this evidence may not be the type that is splashed across the evening news, it is nevertheless a more realistic assessment of the of the Earth’s ever dynamic and variable climate.
II. Greenland Ice Sheets: Yesterday, Today, and Tomorrow
Greenland’s glaciers and ice fields respond to climate changes by advancing and retreating. During rapid warm-up in the early 20th century, Greenland’s glaciers recessed significantly from their extended locations at the end of the Little Ice Age. Currently, many of Greenland’s glaciers are no shorter than the limits established during the mid-20th century.
The existence of the Greenland ice cap is actually a geographical and climatological anomaly, as Greenland sits too far south to have as much snow and ice as it does (about 5% of the world’s ice, enough to raise sea level about 23 feet, lies atop Greenland). Compare the southern portions of Greenland, which lies beneath nearly a mile of ice, with say the European capital cities of Oslo, Stockholm, and Helsinki, which lie roughly along the same line of latitude.
The reason that Greenland currently has so much ice and snow is the altitude and geological formation of the central plateau. More than a mile thickness of ice sits atop all but the coastal portions of Greenland and this enormous mountain of ice serves to make its own climate. Due to its elevation, the surface of Greenland’s central ice cap is some 20 to 30ºF colder than it would be if there was no ice at all. And further, this mountain of ice perturbs the atmospheric circulation and spins up weather systems producing ample precipitation from the moisture supplied to it by the warm Gulf Stream waters. Together, the enhanced precipitation and increased elevation maintain Greenland’s ice cap—a remnant of the last ice age.
But this does not imply that Greenland’s ice cap and glaciers are immune to climate changes. Greenland ice sheets respond to temperature (and precipitation) changes, just like ice everywhere else. When the temperatures local to Greenland warm, the ice load on Greenland generally shrinks, and vice versa for periods of cooling. A complicating factor to the ice/temperature relationship is precipitation change. Warming temperatures also tend to lead to increased precipitation, which, over the inland of Greenland, usually means more snow (and thus ice accumulation and lower sea levels). On the other hand, more precipitation falling as rain along the continental margins enhances melting (and ice loss).
The behavior of Greenland ice sheets to climate changes appears to be well-established in the scientific literature, dating back to the mid-1940s and even earlier—before climate changes potentially induced by anthropogenic activities were possibilities. Prominent climatologists of the time had clearly documented a series of glacial advances and retreats in Greenland since the end of the last ice age, some 12,000 years ago. The most readily detectable of which was the rapid and large-scale pullback associated with a warming climate after the end of the Little Ice Age in the mid-19th century. Earlier 20th century warming was well documented, as was the accompanying glacial retreat, sea ice melting, permafrost recession, and shifts in biology (including the northward expansion of the ranges of plants and animal species). It is interesting to note that back then the warm-up was termed a “climate improvement.”
Here is how the noted Arctic climatologist H. W. Ahlmann described his research in an article titled “Researches on Snow and Ice, 1918-1940” written more than 60 years ago in 1946 for the scientific journal The Geographical Journal:
Like the Fröya glacier, all the other glaciers in north-east Greenland have terminal moraines marking their maximum extension in post-glacial times. There is reason to presume that in Greenland, as in Norway and Iceland, this maximum extension occurred in the latter half of the eighteenth [1700s] and beginning of the nineteenth [1800s] centuries. In north-east Greenland, as elsewhere round the northernmost Atlantic, a post-glacial warm period occurred [the Climate Optimum, ~9,000 to 5,000 years ago], during which time the local glaciers disappeared completely or became much reduced in size. The outlet glaciers of the inland ice receded considerably, and the peripheral parts of the inland ice itself grew thinner. After this postglacial warm period, glaciation again increased and, after alternating advance and regression, culminated in the maximum extension of the eighteenth and nineteenth centuries [maximum extent of the Little Ice Age]. This was followed by a slow regression, which was interrupted by minor advances, but has increased rapidly during the last decades [1918-1940]. The present extensive regression is due to the recent climatic improvement.
Apart from the proofs of climatic improvement given by these investigations, the following facts may also be mentioned. The experiences of the Russian scientists along the North-East Passage are especially noteworthy. In 1930 the Leningrad Arctic Institute was established, and in 1933 became responsible for the scientific work of the Central Northern Sea Route Administration in Moscow. Throughout the 1939 war the Arctic Institute has maintained seventy-seven scientific stations in the Russian sector of the Arctic. The regular air surveys of the extent of the drift-ice, which are carried out during the summer months, have shown that between 1924 and 1942 the drift-ice was reduced by about 1 million square kilometres. The average thickness of the sea-ice in the Polar Sea has diminished from 365 centimetres at the time of the Nansen Fram expedition of 1893-95, to the 218 centimetres found by the ice-breaker Sedov, which in 1937-40 drifted along a route similar to that followed by the Fram. Two fossil-ice islands in the Laptev Sea have completely melted in recent years, leaving only submarine banks. And finally, the temperature has increased in the so-called Atlantic waters of the Polar Sea as well as in the Kara Sea…
On the basis of the known extension of the drift-ice it is possible to calculate the general distribution of atmospheric pressure. The direction of the ice-drift is parallel to the isobars, and the speed of the ice-drift is inversely proportional to the distances between the isobars. The Arctic fauna has followed the climatic change, and both fishes and fowl are now found much farther north than formerly. The southern limit of permanently frozen ground in Asia has moved many kilometres farther north, and the Spitsbergen period of navigation has lengthened considerably. From 1909 to 1912 it lasted ninety-five days, but in 1930-38 it had increased to one hundred and seventy-five days, and in 1939 to as many as two hundred and three days (from April 29 to November 17). This part of the Arctic may, without exaggeration, be said to have experienced a climatic revolution.
Again, the above passage was written in 1946, describing the events associated with a warming climate that had little if anything to do with human activities in that it occurred during a period prior to a significant atmospheric build-up of carbon dioxide from the combustion of fossil fuels. It demonstrates that rapid and significant climate swings can and do occur naturally and that elements of the earth’s natural systems react accordingly.
Thus, changes in both the cryosphere and the biosphere that have been associated with the current warming period (beginning in the early-1990s in Greenland) are neither extraordinary, unprecedented, nor unanticipated, despite often vocal claims, by scientists, environmentalists, politicians, and the media, to the contrary.
Temperature history (and location) of various temperature stations established along the margin of Greenland, including the more than century-long histories from the stations of Godthab (Nuuk) and Ammassalik. Recent temperatures are only starting to approach those of the extended warm period from the 1920s through the 1940s (from Chylek et al., 2006).
Currently, in 2007, some glaciers along the periphery of Greenland are shrinking, but it has only been within the last couple of years that they have begun to approach, or in some cases, exceeded their recessed locations during the late-1940s and early 1950s (most Greenland glaciers advanced to a limited degree during the late-1950s through the early-1990s, during a period of cooling there).
On some glaciers, the recent recession as been dramatic, but despite the attention that these rapid changes garner in the media, they are the exception rather than the rule. For instance, the glacier that empties into the bay near Jakobshavn, on Greenland’s western coast, has been called the fastest moving glacier in the world. In recent years, it is reported to have speed up to nearly twice its previous speed and rapidly retreated. This glacier is the one that House Speaker Nancy Pelosi just visited (http://apnews.myway.com/article/20070528/D8PDMFK80.html), and it has scheduled visits by a string of global dignitaries who want to see the effects of “climate change” for themselves.
Interestingly, had Speaker Pelosi gone astray and stumbled upon the Store Glacier, a large outlet glacier lying just 100km to the north of Jakobshavn, she would have witnessed much of the same thing—a big glacier flowing off the central Greenland ice cap into a large bay, dramatically calving off large icebergs in the process. If fact, here is how a trip to Greenland’s Store glacier, via kayak, is described on a travelogue website (http://www.ushuaia.com/anglais_version/emission3/groenland/c1.htm):
On the western coast of Greenland is the Store glacier. Its source is in the very heart of the icecap and emerges in a funnel: the fjord of Uumannaq, in the bay of Disko. The icebergs and growlers pile up at the bottom of the fjord, floating slowly along with the current. Traveling through the bay in a kayak is chancy; it is necessary to push back the pieces of ice to make progress. In the midst of this distressed world, the various sculptures of striated ice, whose colors develop from dark blue to azure blue, make navigation seem surreal. Approaching the glacier, a big cracking noise is heard; it is the ice decompressing. During the Arctic summer, the Store glacier cracks and breaks apart. The sight is impressive, but it can also become dangerous: the more the icebergs melt, the greater the risk of falling pieces of ice.
This is precisely the scene that Pelosi and her entourage encountered at the end of Jakobshavn’s glacier. But there would be one major difference—the calving front of the Store glacier, instead of recessing some tens of kilometers like Jakobshavn glacier has done in recent years, has remained in virtually the same location for the past 35 or more years. Obviously, Store glacier would not well serve in the role of climate change icon, and thus receives little attention.
This same thing is true for scores of other glaciers along coastal Greenland. The full picture is that aside from a few headlining grabbing glacial recessions in recent years, a large number of Greenland’s glacier have not recessed beyond their positions established in the 1940s-1970s.
For example, there is a new and comprehensive study on the natural fluctuations of glacier activity around Disko Island, central West Greenland - not far away from Jakobshavn's glacier - that appeared to be missed by Speaker Pelosi and her science advisors. The University of Aarhus scientists, Jacob Yde and Tvis Knudesen, described the results of their study as follows:
This study assesses glacier fluctuations on Disko Island, central West Greenland, during the 20th century. 247 glaciers of which 75 are classified as surge-type glaciers are included, representing about 95% of the glacierized area. ... [G]laciers on Disko Island have undergone a sustained period of recession throughout the 20th century, although the MAAT [Mean Annual Air Temperature] and MSAT [Mean Summer Air Temperature] has shown no long-term trends between 1930 and 1990. ... In the 1900, many glaciers were under recession after the last advance period during the LIA (Steenstrup, 1901). Field observations in 1913 and comparison with the 1931-1933 map indicated that glacier recession continued during the first half of the 20th century (Jost, 1940). From the early descriptions of glacier terminus positions and calculated recession rates, it seems that glacier recession rates have been higher during the first half of the 20th century than during the second half. This supports the findings of Weidick (1968) that accelerated recession occurred between 1920 and 1940. During the period from 1953 to 1964 the majority of glacier termini remained stationary followed by a period (1964-1985) with more glaciers under recession. Towards the end of the 20th century (1985-2005) most glaciers showed little change in length, although many still receded.
And in some cases, even the fast recessing glaciers have slowed back down. Consider this BBC story from December 2005, reporting on two rapidly retreating glaciers along Greenland’s central eastern coast (http://news.bbc.co.uk/2/hi/science/nature/4508964.stm):
Greenland glacier races to ocean
Kangerdlugssuaq Glacier on the east coast of Greenland has been clocked using GPS equipment and satellites to be flowing at a rate of 14km per year.
It is also losing mass extremely fast, with its front end retreating 5km back up its fjord this year alone. The glacier “drains” about 4% of the ice sheet, dumping tens of cubic km of fresh water in the North Atlantic. This gives it significant influence not just on global sea level rise but on the system of ocean circulation which drives through the Arctic.
“We've seen a 5km retreat of the terminus, we've see an almost 300% acceleration in the flow speed and we've seen about a 100m thinning of the glacier - all occurring in the last one or so years,” said Dr Gordon Hamilton, of the Climate Change Institute at the University of Maine.
“These are very dramatic changes.” And they are not confined to Kangerdlugssuaq. He was speaking here at the American Geophysical Union Fall Meeting. Helheim Glacier, just to the south of Kangerdlugssuaq, is exhibiting similar changed behaviour. It is flowing only slightly slower at 12km per year - the equivalent of half a football field a day.
Hamilton thinks a couple of factors may be triggering the quick melt. The observed recent increase in summer surface melting on the Greenland Ice Sheet is producing large quantities of liquid water which, if it percolates down to the base of the glacier, can lubricate its flow over rocks towards the ocean.
And if that same warming is bringing higher-temperature sea waters into contact with the front of Kangerdlugssuaq and Helheim, this could explain their rapid retreat. If other large glaciers in the region are seen to go the same way, it could begin to “pull the plug” on Greenland, said Dr Hamilton.
“The model predictions for sea level rise do not include the effects of rapid changes in ice dynamics” he added. “We're seeing now that this component might be extremely important. And what it suggests is that the predictions for both the rate and the timing for sea level rise in the next few decades will be largely underestimated.”
But, during the year and a half since the BBC ran its story, both the Helheim glacier as well as the Kangerdlugssuaq glacier have slowed down and stopped recessing. In fact, Helheim glacier has advanced in the past year such that it is currently within observed, documented, historical limits. Ian Howat and colleagues published an article in Science magazine in the spring of 2007 describing this turn of events:
The calving fronts of both glaciers appeared relatively stable from the mid-20th century until 2002, when [Helheim glacier] retreated over 7 km in 3 years. This was followed by a 5-km retreat of [Kangerdlugssuaq glacier] during the winter of 2004-5. These retreats are much greater than the 1 to 2-km seasonal fluctuations previously observed and followed a sustained period of low-elevation ice thinning. Retreats were concurrent with accelerated ice flow. This acceleration increased rates of mass loss by 28 and 15 Gt/yr at [Kangerdlugssuaq glacier] and [Helheim glacier], respectively, between 2000 and 2005, representing >40% of the ice sheet’s increase in mass loss…
[On the Kangerdlugssuaq glacier] [t]hinning moved inland between 2005 and 2006, with a peak thinning of 68 m at about 26 km, but with virtually no thinning at the front. Average thinning over the glacier during the summer of 2006 declined to near zero, with some apparent thickening in areas on the main trunk [emphasis added]…
[On the Helheim glacier] [b]etween the summers of 2005 and 2006, the rate of thinning decreased within 20 km of the front, reaching zero at the front and increasing to 50 m/year 25 km from the front. During this period, the glacier advanced 4 km as a floating or near-floating tongue to near the 2003–2004 front position. It appears that the front of this floating tongue may have regrounded in summer 2006, contributing to the deceleration and the region of compression [emphasis added].
Helheim glacier, central eastern Greenland coast. Recent and historical terminations are indicated. From September 1999 (peach line) to May 2001 (orange line) the Helheim glacier advanced slightly, pushing its calving front beyond its location in 1972 (green line). A slow retreat that began in 2001 was followed by a rapid, headline-grabbing retreat from 2004 to August 2005 (black line). Thereafter, the glacier stopped receding and began advancing again. By August 2006, the calving front had advanced beyond its location in 1933 (blue line) and is again approaching its summer 2004 location.
Ultimately, Howat et al. caution:
The highly variable dynamics of outlet glaciers suggest that special care must be taken in how mass-balance estimates are evaluated, particularly when extrapolating into the future, because short-term spikes could yield erroneous long-term trends.
A bit further to the north of Helheim and Kangerdlugssuaq glaciers, Britannia glacier—carefully mapped out in the early 1950s by a Great Britain expedition, is shown, in recent satellite photographs to currently be larger and further reaching that when it was first visited.
Left: the current position of the Britannia glacier as captured from a satellite photo available from Yahoo Maps. Right: A detailed map of the position of the Britannia glacier produced from photographs and ground survey done in 1954 (Hamilton et al., 1956). Currently, the Britannia glacier, as well as a smaller side glacier, is advanced beyond its 1954 terminus (red circles)
The recent warm temperatures in the regions surrounding Greenland has led to a general pull back of the peripheral glaciers there. But the pullback is from the advanced positions established in the early 1990s after a 40-year period of cooling in Greenland. Previous to that, from the late 19th to the mid-20th century, a rapid and prolonged warming occurred over Greenland during which time a significant glacial recession occurred when most of Greenland’s outlet glaciers rapidly retreated from the Little Ice Age maxima. The glacial recession associated with the warming observed in Greenland over the past 10 to 20 years is returning the glaciers to their mid-20th century positions. This recession is neither unusual nor unprecedented when viewed outside the context of the past 10 years and instead, within the context of the past 100 years—most of which was dominated by natural variability.
Ahlmann, H. W., 1946. Researches on snow and ice, 1918-1940. The Geographical Journal, 107, 11-25.
Chylek, P., et al., 2006. Greenland warming of 1920-1930 and 1995-2005. Geophysical Research Letters, 33, L11707, doi:10.1029/2006GL026510.
Hamilton, R. A., et al., 1956. British North Greenland Expedition 1952-4: Scientific Results. The Geographical Journal, 122, 203-237.
Howat, I. M., et al., 2007. Rapid changes in ice discharge from Greenland outlet glaciers. Science, 315, 1559-1561.
Yde, J. C. And Knutsen, N. T., 2007. 20th century glacier fluctuations on Disko Island, Greenland. Annals of Glaciology, 46, in press.
It is a little known fact that the Arctic habitat of the polar bear has been as warm as or warmer than present for the better part of the last 9,000 years. And the polar bears survived.
Polar bears, Ursus maritimus, inhabit much of the Northern Hemisphere’s arctic regions. They evolved into a separate species about 200,000 years ago. According to the website polarbearsinternational.org (http://www.polarbearsinternational.org/bear-facts/polar-bear-evolution/:
Scientists believe that the polar bear is a descendant of the brown bear. It is thought to be the most recent of the eight bear species.
The polar bear probably first appeared roughly 200,000 years ago, during the Pleistocene. The polar bears of that time period were much larger than they are today, as were many other species.
Scientists believe that the polar bear evolved from a group of brown bears that became isolated by glaciers in an area near Siberia. The stranded bears underwent a rapid series of evolutionary changes in order to survive on the ice. Today's polar bear is superbly adapted to life in the Arctic… [A]daptations include a longer neck, useful in keeping the polar bear's head above water when swimming; warm, thick fur; and huge paws, which help spread the bear's weight on thin ice and are useful in swimming.
While brown bears hibernate in winter, polar bears do not. During an Arctic winter, there is no shortage of food, as seals are still available.
Since becoming a separate species 200,000 years ago, polar bears have survived large climate changes from ice age cold to interglacial warmth, including two lengthy periods (lasting several thousands of years each) when Arctic temperatures were significantly warmer than today. The fact that polar bear’s exist as a species today is the strongest evidence available that warming temperatures will not lead to their ultimate demise.
But these facts don’t dissuade global warming alarmists who cry that anthropogenic climate change will push the polar bear to extinction. In fact the (fictitious) plight of a lone polar bear is featured in Al Gore’s “documentary” An Inconvenient Truth. In an animated sequence, a presumably tired-of-swimming polar bear struggles to pull himself out the water onto a small chuck of ice, which subsequently breaks apart beneath him. The scene then widens to show the poor bear in the middle of a vast iceless sea, with no land in sight, left to swim on or drown trying.
In another apparent effort to alarm the public, Gore adviser, Dr. James Hansen, incorrectly implied coming extinction of polar bears in context of the mid Pliocene warm period of about 3 million years ago in an interview for a newspaper article (March 19, 2006 ). Such claims are highly problematic because the polar bear is a fairly recent species evolving from brown bears only some 250,000-200,000 years ago.
Polar bear expert, Dr. Mitch Taylor of Canada, confirms the robust resiliency of polar bears under the wide range of climatic and ice conditions having occurred in the past 250,000 years.
“Polar bears are believed to have evolved from grizzly bears during the Pleistocene era some 200-250,000 years ago. Polar bears are well developed as a separate species by the Eemian interglacial approximately 125,000 years ago. This period was characterized by temperature fluctuations caused by entirely natural events ... Polar bears obviously adapted to the changing environment, as evidenced by their presence today. ... This fact alone is sufficient grounds to reject the petition. Clearly polar bears can adapt to climate change. They have evolved and persisted for thousands of years in a period characterized by fluctuating climate. No rational person could review this information and conclude that climate change pre-destined polar bears to extinction.”
Furthermore, alarming claims by Gore and Hansen about species extinctions in general are clearly unsupported according to a new paper by Professor Daniel Botkin and 18 colleagues in the prestigious BioScience (March 2007 issue, vol. 57, 227-236) finding that "Current projections of extinction rates are overestimate[d]".
Even further alarmism has been brought to bear on the U.S. Fish and Wildlife Service who, despite its initial hesitation, is now considering listing the polar bear as an endangered species under the guise that global warming is going to wipe-out their sea ice habitat and thus potentially push the polar bear to the verge of extinction. While this scenario stands against historical evidence, it nevertheless plays in the hearts of sentimentalists worldwide making it a perfect climate alarmist’s tool for spreading disinformation about the impacts of anthropogenic fossil fuel use.
Here is how the Center for Biological Diversity (http://www.biologicaldiversity.org/swcbd/species/polarbear/index.html) describes their efforts at forcing action at the U.S. Fish and Wildlife Service:
On February 16, 2005 — the same day the Kyoto Protocol entered into force without the participation of the United States — the Center for Biological Diversity filed a scientific petition with the U.S. Fish and Wildlife Service to list the polar bear as a threatened species under the Endangered Species Act. Polar bears are at risk of extinction because global warming is causing catastrophic environmental change in the Arctic, including the rapid melting of sea ice. Because the bears are deeply dependent on the sea ice for their survival, they stand to become the first mammals in the world to lose 100 percent of their habitat to global warming.
On December 15, 2005, the Center and our partners NRDC and Greenpeace sued the Bush administration for ignoring our petition. In response, on February 9, 2006, the U.S. Fish and Wildlife Service issued a positive 90-day petition finding for polar bears, opened a 60-day comment period, and initiated a status review of the species. Finally, on December 27, 2006, the administration announced a proposed rule to list the polar bear as threatened. Comments will be accepted on the proposal until April 9, 2007, and the administration must make a final listing determination by January 9, 2008.
Because all listing decisions under the Endangered Species Act must be made on the basis of the best available science, the current rulemaking for polar bears would have to concede the severity of the global warming crisis, acknowledging the fact that a rapid, dramatic reduction in greenhouse gas emissions is necessary to prevent the extinction of the species.
Protection under the Endangered Species Act will provide concrete help to polar bears and could revolutionize American climate policy. Since U.S. resistance to curbing greenhouse gases has allowed other countries to shirk their responsibilities as well, major changes in American policy are likely to have a powerful domino effect, catalyzing change in climate policy worldwide. The polar bear’s protected status will require a new level of environmental review before oil and gas development continue in polar bear habitat in the American Arctic. Even more critically, because it is illegal to harm threatened species or jeopardize their survival, the polar bear listing could mean that all U.S. industries emitting large quantities of greenhouse gases — and requiring a federal permit to do so — will come under the purview of the Endangered Species Act. From polluting power plants in the Midwest to auto manufacturers, a vast array of industries may have to clean up their acts to give the polar bear a chance to survive.
The Center for Biological Diversity makes their ultimate goal clear, it is not about saving the polar bear, but wanting to “revolutionize American climate policy,” which is to say gain control of energy policy and choices.
Other scientists and groups are just as eager to ignore climate history and jump aboard the polar-bears-are-doomed express.
New York University’s Scienceline, a blog site written by grad students in NYU’s Science, Health and Environmental Reporting Program (http://scienceline.org/2007/02/05/health_driscoll_polarbears/), quotes Deborah Williams, president of Alaska Conservation Solutions, an environmental organization devoted to fighting global warming, as stating “There is no evidence [polar bears] can survive on land without sea ice.” (Williams even goes as far as to suggest that global warming is leading to previously undocumented cases of cannibalism among polar bears—anything, it seems for attention)
Obviously, these individuals and organizations are willfully ignorant of what paleoclimatologists overwhelmingly tell us about the past climate of the Arctic and its polar bear denizens.
A. Early Holocene
There is a plethora of scientific evidence that demonstrates that for a multi-thousand year period lasting from about 9,000 to 4,000 years ago, the Arctic was much warmer than present day temperatures.
The Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change includes this graphic from its paleoclimate chapter (Chapter 6). It depicts the extent and magnitude of the temperatures since the end of the last ice age, about 12,000 years ago. The y-axis of the chart is latitude (north is upwards) and the x-axis is time before present (in thousands of years, going backwards to the left). The colored lines and rectangles indicate spatial and temporal extent of temperature anomalies, yellows and reds are periods that were warmer than the pre-industrial period (which itself was about 0.5ºC-0.8ºC cooler than present), and blue shading represents periods cooler than the pre-industrial. Notice that north of about 30ºN, that there were many places and periods lasting many thousands of years, that were likely as warm or warmer than present—including vast areas of the far north (Arctic), including Greenland and North Eurasia.
Timing and intensity of temperature deviation from pre-industrial levels. (source: IPCC, AR4, Chapter 6, p. 462)
The North Eurasia data comes from a paper by UCLA’s Glen MacDonald published back in 2000. Here is how the abstract of that paper reads:
Radiocarbon-dated macrofossils are used to document Holocene tree line history across northern Russia (including Siberia). Boreal forest development in this region commenced by 10,000 yr B.P. Over most of Russia, forest advanced to or near the current arctic coastline between 9000 and 7000 yr B.P. and retreated to its present position by between 4000 and 3000 yr B.P. Forest establishment and retreat was roughly synchronous across most of northern Russia. Tree line advance on the Kola Peninsula, however, appears to have occurred later than in other regions. During the period of maximum forest extension, the mean July temperatures along the northern coastline of Russia may have been 2.5° to 7.0°C warmer than modern. The development of forest and expansion of tree line likely reflects a number of complementary environmental conditions, including heightened summer insolation, the demise of Eurasian ice sheets, reduced sea-ice cover, greater continentality with eustatically lower sea level, and extreme Arctic penetration of warm North Atlantic waters. The late Holocene retreat of Eurasian tree line coincides with declining summer insolation, cooling arctic waters, and neoglaciation.
To summarize MacDonald’s results, he finds that for a period lasting somewhere around 5,000 years, the summer temperatures along the northern coastline of Russia may have been 2.5 to 7.0ºC warmer than present, and such a warming was associated with reduced sea ice, among other things.
If today’s level of Arctic warming, which has only lasted for about a decade or so, is pushing sea ice to shrink rapidly, then it would seem reasonable to think that a much warmer period lasting several thousands of years certainly did the same and even more so.
While MacDonald’s work is fairly recent, the idea that Arctic temperatures during the mid-Holocene were much warmer than our current era, and that this warming was accompanied by significant ice retreat is anything but new.
style="line-height: 150%;"> Noted early-20th century British meteorologist and climate historian Dr. C.E.P. Brooks, wrote an article in 1949 for the Swedish scientific journal Geografiska Annaler entitled “Post-Glacial Climatic Changes in the Light of Recent Glaciological Research.” Dr. Brooks describes the early 20th century glacial recession in an historical context:
style="margin: 0in 0.25in 0.0001pt; text-align: justify;"> We now [in 1949] seem to have entered this stage of unstable ice-sheet and glaciers. We know little about the extent of the floating ice-cap before the 19th Century, but the voyages of the Norsemen to Greenland in the early Middle Ages are strong evidence that up to about 1300 there was much less ice than at present in the East Greenland Current. The glaciological evidence shows that regions in Iceland and Norway are being laid bare which have been ice-covered for more than 600 years, but which were at one time cultivated. The retreat has evidently not yet reached the stage which it formerly maintained for several centuries, and it may be expected to continue until either the reduced polar ice-cap reaches a new position of stability, or until some meteorological “accident” reverses the trend and ushers in a new period of re-advance.
style="margin: 0in 0.25in 0.0001pt; text-align: justify;">
style="margin: 0in 0.25in 0.0001pt; text-align: justify;"> A still more advanced stage in the process of retreat was reached in the Post-glacial “Climatic Optimum” [~9,000 to 4,000 years ago], when the Arctic was so warm that peat-bogs could grow in Spitsbergen. It is not unlikely that during this period there was no permanent ice-cap in the Arctic; merely a winter ice-cap which largely disintegrated each summer [emphasis added].
And what effect did this multi-millennial warming have on the polar bears? Well, one thing is for sure, their existence today proves that they didn’t go extinct!
The most likely explanation is that they modified their behavior to adapt to the changing conditions, probably by spending more time on land foraging, hunting, and denning than they would during cooler, icier periods. There is evidence that these are precisely the kinds of adaptations that the bears are making to best cope with today’s warming climate. For instance, In May 2007, an AP article (http://www.tahoebonanza.com/article/20070502/Environment/105020027) reported that “More pregnant polar bears in Alaska are digging snow dens on land instead of sea ice, according to a federal study, and researchers say deteriorating sea ice due to climate warming is the likely reason.” So instead of perishing, the polar bears will adapt as best they can, as they always have.
style="line-height: 150%;"> The early Holocene wasn’t the only period of extended warmth and greatly reduced sea ice that the polar bears managed to survive through. Another long much-warmer-than-present period occurred during the warm period in between the last two ice ages (known as the last interglacial).
A recent project was created to pull together available data on past environments in the Arctic. The Circum-Arctic Paleo Environments (CAPE) is an activity within the International Geosphere-Biosphere Program that aims to facilitate international syntheses of Arctic records. The 25-member CAPE-Last Interglacial Project Members team recently published an article characterizing the Arctic warmth during the time of the last interglacial (LIG). The work “Last interglacial Arctic warmth confirms polar amplification of climate change” was published early in 2007 in the scientific journal Quaternary Science Reviews. Many previous works indicate that Earth was warmer during the LIG than for any other period within the past 250,000 years. However, few detailed quantitative reconstructions of the period exist. The CAPE research group quantitatively estimated circum-Arctic summer air and sea surface temperatures for the LIG as reconstructed from terrestrial- and marine-based proxy records detailed in previous research conducted by a large body of scientists. The group emphasized temperatures in summer because they “exert the dominant control on glacier mass balance” and summer temperature is “the most effective predictor for most biological processes.”
The group found evidence that the LIG persisted for 10,000 to 12,000 years and that Arctic summer air temperatures during the LIG were 4 to 5ºC above present for much of the region. The warming seems to have occurred rapidly, peaking in the early portion of the LIG. The group contends that Arctic summer temperatures were warm enough “to melt all glaciers below 5 km elevation, except the Greenland ice sheet, which was reduced by ca 20-50%.” In regard to Arctic Ocean sea ice, the group states that the margins of the permanent ice “retracted well into the Arctic Ocean basin” and the ice was of an extent that was smaller than during the highly publicized ice retreat of the Holocene. When examining evidence of vegetation changes, the group concluded that “boreal forests advanced to the Arctic Ocean Coast across vast regions of the Arctic currently occupied by tundra.” In fact, across most of northern Russia, they report that forests were displaced northward by as much as 400 to 1000 km.
Regional maximum LIG summer Arctic temperature anomalies (ºC) relative to present. (taken from Cape Project Members report, 2006). Temperature across large portions of the Arctic were several degrees above present day values.
The CAPE’s review of the evidence clearly shows an extended Arctic warm period lasting at least 2,000 years during which time glacier and sea ice was much reduced and the limits of the great boreal forests were pushed much further northward, to the shores of the Arctic Ocean. The Arctic environment was a substantially different place than we know it today. Yet, despite these major environmental changes, polar bears managed to adapt and survive.
C. Polar Bears Today
style="line-height: 150%;"> Despite claims by activists, it is generally believed that the global population of polar bears is increasing, from 5,000 in the 1940s via 10,000 to 15,000 in the mid-1970s to 20,000 to 25,000 today. Much of this increase has been credited to stricter hunting regulations. However, it is critical to note that the increase also occurred during a time of warming temperatures in the Arctic—proof that polar bears can flourish in a changing (warming) environment. A recent survey of polar bear populations across Canada (home to about 2/3rds of the world’s polar bears) found that of the 13 distinct populations there, only two are documented to be in decline while some others are strongly increasing. For instance, polar bear biologist Mitch Taylor has documented an increase in the population of bears that are found in the Davis straight region of eastern Canada from approximately 850 individuals in the mid-1980s to about 2,100 now. “There aren’t just a few more bears. There are a ... lot more bears,” Dr. Taylor told the Christian Science monitor in a May 2007 article (http://www.csmonitor.com/2007/0503/p13s01-wogi.html?page=1). University of Alberta scientist Andrew Derocher counters that the population of bears in the western Hudson’s Bay region has at the same time dropped by 22%, falling from 1,194 in 1987 to 935 in 2004. “They are declining due to global warming and changes in when the ice freezes and melts in Hudson Bay,” said Derocher. But this conclusion was recently challenged in the scientific literature by a team led by Nunavat government scientist M.G. Dyck. In a viewpoint article published in the journal Ecological Complexities entitled “Polar bears of western Hudson Bay and climate change: Are warming spring air temperatures the ‘ultimate’ survival control factor?” Dyck and colleagues summarize:
style="margin: 0in 0.25in 0.0001pt; text-align: justify;"> Long-term warming of late spring (April–June) air temperatures has been proposed by Stirling et al. (1999) as the ‘‘ultimate’’ factor causing earlier sea-ice break-up around western Hudson Bay (WH) that has, in turn, led to the poorer physical and reproductive characteristics of polar bears occupying this region. Derocher et al. (2004) expanded the discussion to the whole circumpolar Arctic and concluded that polar bears will unlikely survive as a species should the computer-predicted scenarios for total disappearance of sea-ice in the Arctic come true. We found that spring air te