Timing and intensity of temperature deviation from pre-industrial levels. (source: IPCC, AR4, Chapter 6, p. 462)

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-20^th 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 20^th 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.

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 temperatures around the Hudson Bay basin for the past 70 years (1932–2002) show no significant warming trend and are more likely identified with the large-amplitude, natural climatic variability that is characteristic of the Arctic. Any role of external forcing by anthropogenic greenhouse gases remains difficult to identify. We argue, therefore, that the extrapolation of polar bear disappearance is highly premature. Climate models are simply not skilful for the projection of regional sea-ice changes in Hudson Bay or the whole Arctic. Alternative factors, such as increased human–bear interaction, must be taken into account in a more realistic study and explanation of the population ecology of WH polar bears. Both scientific papers and public discussion that continue to fail to recognize the inherent complexity in the adaptive interaction of polar bears with both human and nature will not likely offer any useful, science-based, preservation and management strategies for the species.

D. Summary

So, the next time that you see Al Gore’s photo collection of decaying glaciers and animations of polar bears drowning as the distance between icebergs and the shore is too far to swim, or desperate pleas from environmental organizations with ulterior motives to declare the polar bear as “threatened” under the Endangered Species Act, think of the conditions during the early Holocene and during the last interglacial period—natural periods in Earth’s history when the conditions in the Arctic were much milder than those of today. In fact, during the majority of the past 9,000 years, the climate of large portions of the Arctic was likely warmer and less icy than it is currently. Further, consider that during the last several decades of Arctic warming, worldwide polar bear numbers have increase by some 50% or more. And finally, remember that today’s very existence of the polar bear is the strongest evidence available that these creatures are extremely adaptable to large-scale variations in their natural climate and habitat. These are facts that climate alarmists don’t want you know.

References:

CAPE Project Members, 2006. Last interglacial Arctic warmth confirms polar
amplification of climate change. Quaternary Science Reviews, 25, 1383-1400.

Dyck, M. G. et al., 2007. Polar bears of western Hudson Bay and climate change: Are warming spring air temperatures the “ultimate” survival control factor? Ecological Complexities, in press.

style="line-height: 150%;"> Intergovernmental Panel on Climate Change, 2007. Fourth Assessment Report. Chapter 6, Paleoclimate.

style="line-height: 150%;"> IV. Arctic Permafrost and Methane

style="line-height: 150%;"> Another scare story coming out of the Arctic is that Arctic warming will release untold amounts of the potent greenhouse gas methane into the atmosphere from widespread melting of the Arctic permafrost. However, a douse of cold water was recently thrown to this alarmist scenario.

style="line-height: 150%;"> The alarmist theory of Arctic permafrost goes something like this.

Permafrost is a sink for carbon dioxide and other greenhouse gases such as methane. Basically, the soils of the high latitudes froze at the beginning of the last ice age, and when they froze, they entrapped very large amounts of organic material (carbon rich grasses, animal remains, soil material) in the frozen permafrost. As the permafrost thaws, carbon trapped within the once-frozen soils is released largely as methane, and as this methane is mixed into the global atmosphere it will cause even more warming which feeds back onto itself and causes more permafrost melting and more methane release and more warming.

The entire process is described by many as a time bomb that is going off before our very eyes. The bomb is not just causing the world to warm at a more rapid pace, but the melting permafrost is also routinely connected to the destruction of forests (recall Gore’s pictures of “drunken forests” in An Inconvenient Truth), collapse of homes and other structures (e.g., pipelines), erosion of coastal areas and hillsides, disruption of animal habitats, etc.

On this particular point, observations by Professor Syun-Ichi Akasofu, founding director of the International Arctic Research Center of the University of Alaska Fairbanks, are noteworthy:

[People] say permafrost is melting, and houses are collapsing. What happens is that, when permafrost is in the area, housing is cheap and the land is cheap. When people build a house directly over the permafrost, and then warm the house in the wintertime, and the ice underneath melts and the house collapses, that's a man-made effect! [sic.]

In addition, Gore’s methane bomb was recently factually defused in an article appearing in Geophysical Research Letters entitled “Near-surface permafrost degradation: How severe during the 21st century?” by Georg Delisle, a scientist from Germany’s Federal Institute for Geosciences and Natural Resources (the central geoscientific authority providing advice to the German Federal Government in all geo-relevant questions).

The final sentence of the abstract states “Based on paleoclimatic data and in consequence of this study, it is suggested that scenarios calling for massive release of methane in the near future from degrading permafrost are questionable.”

Delisle acknowledges that warming is occurring in the Arctic regions and that the warming will undoubtedly impact the permafrost of the high latitudes. The author notes, however, that many numerical models used to simulate the impact of warming on permafrost deal only with the upper 10 feet of the earth’s surface. The previously-used models do not take into account the cooling effect of deeper and colder zones that interact thermodynamically with the active layer near the surface. Delisle also exposes other assumptions of previous models that are “in clear conflict with field evidence.” In other words, the models driving lurid headlines and political anxiety get it wrong, again.

Delisle instead presents “a unidimensional long term permafrost temperature model of general application” “which is fully capable of incorporating all relevant thermal processes within the active layer and the permafrost, and between the permafrost and the non frozen ground below. The model space is made up of 600 layers with a minimum spacing of 10 cm within the active layer and the uppermost ‘permafrost zone’.” Rather than look at only 10 feet into the surface as was done by previous models, the new model goes 100 yards into the surface, and is deemed as more realistic.

With the improved model, Delisle reports that continuous permafrost in Alaska and Siberia will survive over the next 100 years, even if a significant warming takes place. Further, he states that “Based on this result and on the presented analysis, it appears that all areas north of 60°N will maintain permafrost at least at depth. North of 70°N, surface temperature values today are in general below -11°C. These areas should maintain their active layer. It appears unlikely that almost all areas with near-surface permafrost today will lose their active layer within the next 100 years” as concluded by others. Delisle claims that the new model is far more consistent with field measurements and far more realistic in terms of including the energy flux component from the deeper and colder core.

Delisle adds a zinger at the end of his article stating:

A second, rarely touched upon question is associated with the apparently limited amount of organic carbon that had been released from permafrost terrain in previous periods of climatic warming such as e.g. the Medieval Warm Period or during the Holocene Climatic Optimum. There appear to be no significant CH4-excursions in ice core records of Antarctica or Greenland during these time periods which otherwise might serve as evidence for a massive release of methane into the atmosphere from degrading permafrost terrains.

In other words, the ice cores that have long been relied upon to show the chemical fluctuations in the atmosphere over many tens of thousands of years into the past—the ones that are used to related changes in atmospheric greenhouse gases such as carbon dioxide and methane to changes in global temperatures—fail to capture a large methane release during previous warm periods during the Holocene. This finding suggests that warmer temperatures in the Arctic—recall that Arctic temperatures were as warm as or warmer than present for several thousand years during the Climatic Optimum lasting from approximately 9,000 to 4,000 years ago—did not prompt a massive release of methane from permafrost melting.

The recent paper by Schaefer and colleagues in Science, also reported lack of evidence supporting the “catastrophic methane emissions from melting permafrost” scenario:

[O]ur δ¹³CH₄ record support neither catastrophic nor gradual clathrate emissions at the YD-PB [roughly 12.2 to 11.2 thousand years ago] transition." And this transition period has been estimated to have undergone perhaps as large as 28˚C (!) changes in winter temperatures or about 16˚C in annual-mean temperatures by Broecker in a 2006 paper in Global and Planetary Change. Such a large change in temperatures around the Greenland and Arctic region will not likely to be soon surpassed under any future man-made emission scenarios.

style="line-height: 150%;"> In fact, there is no evidence in the atmospheric record of methane concentrations to indicate that the current warm-up is causing a significant methane release from melting permafrost. In fact, the build-up of methane in the atmosphere has been dramatically slowing since the early 1980s, and is now quite close to zero on a year-over-year basis. This behavior of methane is documented (among other places) in a recent paper by Khalil and colleagues from Oregon Graduate Institute entitled “Atmospheric Methane: Trends and Cycles of Sources and Sinks” appearing in the journal Environmental Science and Technology.

style="line-height: 150%;"> Khalil et al. start their article noting “Methane concentrations in the atmosphere have more than doubled over the last century, raising concerns that it is contributing to global warming and will continue to do so in the future,” but then continue “Although these past increases were alarmingly rapid, subsequent measurements showed a persistent slowdown in the trends to nearly zero at present.”

They continue:

It is apparent that there are ups and downs, but these are superimposed on a systematically declining rate of accumulation. The slowdown of methane trends has been known and discussed for a long time; however, it is particularly noteworthy that the decrease of the methane trend is not a new phenomenon, but rather it has occurred from the time that systematic measurements were first taken. Most probably it started even before then. Since fluctuations are superimposed on a generally decreasing trend, there have been years in recent times when methane has not increased at all or has even fallen slightly relative to the previous year. This has attracted more interest than in the past when there were similar short-term down turns but on the whole methane still increased over previous years. The recent incursions of the trend into negative territory are therefore part of a much longer term process.

style="margin: 0in 0.5in 0.0001pt;"> The annual trend in atmospheric methane concentration as compiled by Khlail et al. (2007). The trend has been declining since the early 1980s and currently approaches zero.

style="line-height: 150%;"> Khalil and colleagues summarize their findings thus:

style="margin: 0in 0.25in 0.0001pt; text-align: justify;"> The present data set spans more than two decades. It shows that both methane emissions and its lifetime may have been constant over this period. To quantitatively explain the decreasing trends of methane it is not necessary to look for decreasing sources or increasing OH [hydroxyl radical]. During the time of the measurements if either has changed the other must also have changed by a proportionate amount to account for the observed trends. Moreover, while such circumstances may have occurred, if the sources have increased in the past they would have no environmental consequences such as increased global warming, because the extra amounts put into the atmosphere would be the same amounts that would have to be taken out by the increased OH to be consistent with the observed concentrations of methane during the last two decades. The concentrations behave exactly as if the sources and sinks had been constant. A confirming aspect of this apparent constancy of sources and sinks is that the trend has been decreasing for the last two decades until the present when it has reached near zero, thus attracting renewed attention. The major agricultural sources such as rice agriculture and cattle have little or no potential for large increases in the future and have already shown reduction in emissions from some regions. Seeing that the total source has remained constant for at least the last two decades, it is questionable whether human activities can cause methane concentrations to increase greatly in the future. This prediction is within the lower range of the IPCC SRES scenarios. [emphasis added]

style="line-height: 150%;"> The great majority of projections of future methane concentrations as put forth by the Intergovernmental Panel on Climate Change (IPCC) likely err on the high side as the build-up rate of atmospheric methane concentration has slowed for the past 30 years and now is near zero.

style="line-height: 150%;"> Secondly, there is absolutely no indication at all that global methane emissions have increased (from sources such as permafrost melting) during the past 30 years despite the global warming that has taken place. This finding, coupled with the results from Delisle that a massive methane release from future permafrost melting is not anticipated, is strong indication that alarmist scare stories about Arctic warming leading to a runaway greenhouse effect are simply ungrounded in the best available science.

References:

Broecker, W. S., 2006. Abrupt climate change revisited. Global and Planetary Change, 54, 211-215.

Delisle, G. 2007. Near-surface permafrost degradation: How severe during the 21st century? Geophysical Research Letters, 34, L09503, doi:10.1029/2007GL029323.

Khalil, M.A.K., C.L. Butenhoff, and R.A. Rasmussen, 2007. Atmospheric Methane: Trends and Cycles of Sources and Sinks. Environmental Science and Technology, available on-line (10.1021/es061791t).

Schaefer, H., et al., 2006. Ice record of δ¹³C for atmospheric CH₄ across the younger-dryas-preboreal transition. Science, 313, 1109-1112.

{mospagebreak}

V. Antarctica Ice Mass: Growing into the Future

style="line-height: 150%;"> Both models and observations indicate that the mass of Antarctica’s ice sheets should continue to increase into the future as warming temperatures lead to enhanced atmospheric moisture and increased snowfall. The net result is a negative contribution to future global sea level.

style="line-height: 150%;"> It has been long held that a warming climate in the regions surrounding Antarctica would enhance snowfall there, lead to snow and ice accumulation, and ultimately result in a negative contribution to sea level rise (in other words, continued snow and ice build up on the Antarctic continent would result in a lowering of sea levels). This idea has been reflected in each and every report of the Intergovernmental Panel on Climate Change (IPCC). For instance, in the IPCC’s First Assessment Report, published in 1995, they summarize the expectations from Antarctica in a warming climate as “On the whole, the sensitivity of Antarctica to climate change is such that a future warming should lead to increased accumulation and thus a negative contribution to sea level change.” In the IPCC’s Fourth Assessment Report, released in 2007, 12 years after their initial report, they state that “General Circulation Models indicate that the Antarctic Ice Sheet will receive increased snowfall without experiencing substantial surface melting, thus gaining mass and contributing negatively to sea level.” In fact, under every IPCC future emissions scenario, the expected Antarctic contribution to sea level rise in the 21^st century is negative.

style="line-height: 150%;"> However, with the March 2006 Science article by researchers Isabella Velicogna and John Wahl, this idea was (purportedly) turned on its head.

style="margin: 0in 0.25in 0.0001pt; text-align: justify;"> The [IPCC] report predicted that the Antarctic ice sheet will probably gain mass during the 21^st century because of increased precipitation in a warming global climate. Recent radar altimeter measurements have shown an increase in the overall thickness of the East Antarctic Ice Sheet’s (EAIS’s) interior during 1992–2003. However, the IPCC prediction does not consider possible dynamic changes in coastal regions, and radar altimetry provides only sparse coverage of those areas. Detailed interferometric synthetic-aperture radar and airborne laser altimeter surveys of glaciers along the edge of the West Antarctic Ice Sheet (WAIS) show rapid increases in near-coastal discharge during the past few years. The overall contribution of the Antarctic ice sheet to global sea-level change thus depends on the balance between mass changes in the interior and those in coastal areas. The gravitational survey of Antarctica provided by the Gravity Recovery and Climate Experiment (GRACE) satellites and discussed in this paper is a comprehensive survey of the entire ice sheet and is thus able to overcome the issue of limited sampling….

style="margin: 0in 0.25in 0.0001pt; text-align: justify;">

style="margin: 0in 0.25in 0.0001pt; text-align: justify;"> Using measurements of time-variable gravity from the [GRACE] satellites, we determined mass variations of the Antarctic ice sheet during 2002–2005. We found that the mass of the ice sheet decreased significantly, at a rate of 152 ± 80 cubic kilometers of ice per year, which is equivalent to 0.4 ± 0.2 millimeters of global sea-level rise per year. Most of this mass loss came from the West Antarctic Ice Sheet.

style="line-height: 150%;"> This result, reported by Velicogna and Wahl, indicated that instead of gaining ice, Antarctic was instead rapidly losing ice and contributing to sea level rise. However, while big attention was being paid to its suggested implications (a future warming would lead to a sea level rise much greater than expected), little attention was being paid to the fact that the study only covered a period of three years (2002-2005)—a period far too short to reliably determine long-term tendency or behavior of the balance of Antarctica’s mass of snow and ice.

style="line-height: 150%;"> In fact, longer-term studies that better illustrate the trend and variability of Antarctica’s amount of snow and ice, find overall increases in ice mass as well as multi-year variations in ice accumulation that could explain Velicogna and Wahl’s results.

style="line-height: 150%;"> For instance, over the short term, variations in snowfall amounts from year-to-year can explain the reported mass loss from 2002-2005. Andrew Monaghan and colleagues, made this point abundantly clear in a paper they published in Science less than six months after the Velicogna and Wahl study was published. Monaghan et al. investigated the behavior of snowfall over the Antarctic continent and examined both its long-term and short-term variability. They found that a short-term decrease in snowfall during the time period examined by Velicogna and Wahl could explain their results. Monaghan et al. wrote:

style="margin: 0in 0.25in 0.0001pt; text-align: justify;"> Interannual and interdecadal snowfall variability must be more seriously considered when assessing the rapid ice volume changes that are occurring over Antarctica. With regard to interannual variability, consider a recent estimate of Antarctic ice sheet mass loss that is the equivalent of 0.4 ± 0.2 mm year^-1 GSL [global sea level rise] rise for 3 years (2002–2005) from satellite-derived time-variable gravity measurements [made by Velicogna and Wahl]. Antarctic-wide annual snowfall accumulation decreased by about 25 mm y^-1 WEQ [water equivalent], or about 0.86 mm year^-1 GSL rise, between calendar year 2002 and 2003, suggesting that the gravity fluctuations could be heavily influenced by interannual snowfall variations.

style="line-height: 150%;"> Over the longer term, recent papers continue to show overall snow and ice mass gain in Antarctica. Davis et al., 2005 reported that ice mass gain over the East Antarctic Ice Sheet likely exceeded ice mass loss from the West Antarctic Ice Sheet, indicating a net gain in mass over the entire Antarctic continent. Wingham et al. reported an overall increase of 27 ± 29 Gt per year during the same time period. Wingham et al. explained “Mass gains from accumulating snow, particularly on the Antarctic Peninsula and within East Antarctica, exceed the ice dynamic mass loss from West Antarctica.”

style="margin: 0in 0.5in 0.0001pt; line-height: 150%;"> Elevation change in the Antarctic Ice Sheet, 1992-2003, as derived by Wingham et al., 2006.

style="line-height: 150%;"> Finally, in a recent careful study of geological evidence around the George VI Ice Shelf by the Antarctic Peninsular, James Smith and colleagues from British Antarctic Survey and elsewhere confirmed that "The absence of a currently extant ice shelf during this time interval [i.e., early Holocene around 9600 to 7730 years BP] suggests that early Holocene ocean-atmosphere variability in the AP [Antarctic Peninsula] was greater than that measured in recent decades."

style="line-height: 150%;"> The bottom line for the Antarctic ice sheet is that over the long term, increased precipitation in the form of snow should accompany warming temperatures. There may be shorter term variability that will be overlaid on this long-term trend, but, currently, our best scientific understanding is that the long-term ice accumulation will dominate shorter-term loss variations, with the net result being a small sea level drawdown resulting from climate processes taking place over Antarctic during the course of the 21^st century.

style="line-height: 150%;"> References:

style="line-height: 150%;"> Davis, C. H., et al., 2005. Snowfall-driven growth in East Antarctic Ice Sheet mitigates recent sea-level rise. Science, 308, 1898-1901.

style="line-height: 150%;"> Monaghan, A. J., et al., 2006. Insignificant change in Antarctic snowfall since the International Geophysical Year. Science, 313, 827-831.

style="line-height: 150%;"> Smith, J. A., et al., 2007. Oceanic and atmospheric forcing of early Holocene ice shelf retreat, George VI Ice Shelf, Antarctica Peninsula. Quaternary Science Reviews, 26, 500-516.

style="line-height: 150%;"> Velicogna, I., and J. Wahl, 2006. Measurements of time-variable gravity show mass loss in Antarctica. Science, 311, 1754-1756.

style="line-height: 150%;"> Wingham, D. J., et al., 2006. Mass balance of the Antarctic ice sheet. Philosophical Transactions of the Royal Society A, 364, 1627-1635.

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style="line-height: 150%;"> VI. Sea Level Rise

style="line-height: 150%;"> Scare stories of rapidly rising sea levels, with a magnitude exceeding many feet per century, inundating coastlines and forcing the redistribution of coastal communities as a result of increasing atmospheric levels of carbon dioxide are exaggerations of our best scientific knowledge.

style="line-height: 150%;"> The Intergovernmental Panel on Climate Change (IPCC) in its Fourth Assessment Report (AR4), projects a median sea level rise of 14 inches from its middle-of-the-road future emissions scenario (A1B). The full range of IPCC AR4 sea level rise projections, encompassing all of its various SRES emissions scenarios is 7.1 to 23.2 inches.