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Ice Sheets (Antarctica) -- Summary
To get right to the heart of the matter, in a satellite radar study of West Antarctica's Pine Island Glacier, Rignot (1998) determined the glacier's grounding line had retreated inland at a rate of 1.2 0.3 km per year between 1992 and 1996, feeding speculation the glacier's retreat could ultimately lead to a collapse of the West Antarctic Ice Sheet.  In a Reuters news report of 24 July 1998, for example, glaciologist Richard Alley of Penn State University was quoted as saying that if the glacier retreated too far, "it would make a hole in the side of the ice sheet and the remaining ice would drain through that hole," causing a collapse of the West Antarctic Ice Sheet that he called "the disaster scenario."  Even Rignot helped the hype along, saying "we are seeing a glacier melt in the heart of Antarctica."  Because of the many complexities associated with the catastrophic consequences they were discussing, however, Rignot had to admit in his Science paper that questions about the ice sheet's long-term stability "cannot be answered at present."

Earlier that year, Bindschadler and Vornberger (1998) had also published a paper in Science in which they used recently-declassified satellite imagery to study an ice stream that flows into the Ross Ice Shelf, finding that since 1963 its width had increased by about 5%, but that its flow speed had decreased by close to 50%.  Although their findings clearly indicated that large dynamic changes can occur in regions of the West Antarctic Ice Sheet over relatively short time periods (implying that trends opposite to the ones they observed could also occur), they too were constrained to state that such observations "do not resolve the overriding question of the stability of the West Antarctic Ice Sheet."  Indeed, the two 1998 studies, taken together, clearly demonstrated that in terms of ice delivered to the ocean, what one ice stream giveth, another taketh away.

Three years later, Shepherd et al. (2001) reported once again on the Pine Island Glacier.  On the basis of satellite altimetry and interferometry measurements, they determined that the thickness of the entire glacial drainage basin had thinned by up to 1.6 meters per year between 1992 and 1999.  Media reports suggested these changes at the edge of the continent could be transmitted swiftly inland, leading to faster sea level rise, with one of them noting that "melting all the Antarctica ice would cause a global sea level rise of about 240 feet" that "would flood virtually all the world's coastal areas and drown many islands."

The scientists, fortunately, were more circumspect in their comments, stating in their paper that "the thinning cannot be explained by short-term variability in accumulation and must result from glacier dynamics," which typically operate on much longer time scales.  They also wrote that if the Pine Island Glacier "continues to lose mass at the present rate it will be entirely afloat within 600 years," which they estimated would raise world sea level by a grand total of about 6 mm or as we put it in our Journal Review of their paper, by about the thickness of one paper clip per century.

Less than two months after Shepherd et al.'s paper appeared in print, however, satellite imagery revealed the development of a huge crack across the Pine Island Glacier.  Glaciologist Robert Bindschadler predicted this event would likely result in the calving of a major iceberg in less than 18 months.  And he was right.  In just under half that time the new berg was born, measuring a respectable 233 square miles in area and providing substantial new grist for the climate alarmists' CO2 catastrophe-theory mill.

So what's new?  Nothing, really.  The Antarctic coastline has been calving icebergs for millennia.  In the area of the Antarctic Peninsula, for example, Vaughan et al. (2001) report the loss of seven ice shelves during just the past 50 years.  Yet even this is nothing new, as Pudsey and Evans (2001) have determined that the Prince Gustav Channel Ice Shelf - which collapsed in 1995 - had also disappeared in mid-Holocene time, when Vaughan et al. note the climate there "was as warm as it has been recently."  As Pudsey and Evans remind us, however, "colder conditions after about 1.9 ka allowed the shelf to reform," which subsequently allowed it to disintegrate again in response to the localized warming experienced in that part of the continent over the past half-century or so.

There is no compelling reason to believe that any of these cyclical changes in coastal ice dynamics has been forced by human-induced changes in atmospheric CO2 concentration.  Vaughan et al. remark that "it may be tempting to cite anthropogenic greenhouse gases as the culprit, but to do so without offering a mechanism is superficial."  Likewise, Pudsey and Evans warn that "we should not view the recent [ice] decay as an unequivocal indicator of anthropogenic climate change."

We agree.  The most recent disappearance of the ice shelves is not unique; it's happened before - clearly without our help - and it appears to be doing so again.  At least five of the seven Antarctic Peninsula ice shelves that recently collapsed, for example, had been retreating throughout the entire period of historical observation, i.e., since at least 1843, and possibly even earlier.  Hence, the beginning of their end commenced well before mankind started to have a serious impact on the atmosphere's supply of CO2 and other greenhouse gases.

Expanding our perspective somewhat, we proceed to the study of Anderson and Andrews (1999), who analyzed sediment cores from both the east and west sides of the Weddell Sea in an attempt to better understand the dynamics of East and West Antarctic ice sheet behavior.  What they found led them to conclude "that the current interglacial setting is characterized by a more extensive ice margin and larger ice shelves than existed during the last glacial minimum, and that the modern West and East Antarctic ice sheets have not yet shrunk to their minimum."  Hence, it is to be expected, independent of what global air temperature may currently be doing, that because of the great inertial forces at work over much longer time scales, the East and West Antarctic ice sheets will continue to shrink and release many more huge icebergs into the Southern Ocean over the coming years, decades and even centuries, thereby raising global sea level.  And there is nothing man can do - no matter how many Kyoto Protocols he might implement - that will impact this scenario in the least degree.

The insignificance of man is also evident in the results of the study of Wingham et al. (1998), who used satellite radar altimeter measurements from 1992 to 1996 to estimate the rate of change of the thickness of nearly two thirds of the grounded portion of the Antarctic Ice Sheet.  Based on the data they collected, the scientists determined that "a large century-scale imbalance for the Antarctic interior is unlikely," noting that their conclusion is in harmony with a large body of relative sea level and geodetic evidence "supporting the notion that the grounded ice has been in balance at the millennial scale."  Truly, the great ice mass is totally oblivious to the climate alarmists' "unprecedented" warming of the past century, as it will also be to whatever puny climatic impact man might possibly produce in the future.

Reeh (1999) comes to much the same conclusion, indicating there is a broad consensus that a 1C warming of the globe would actually add to Antarctica's burden of ice, leading to a sea level fall of 0.2 to 0.7 mm per year.  As for what's happening currently with both Antarctica and Greenland, Reeh notes that we simply do not know "whether the ice sheets are currently in balance; neither do we know if their volume or mass has increased or decreased during the last 100 years."  These conclusions are also those of Vaughn et al. (1999), who after analyzing over 1800 published and unpublished in situ measurements of the surface mass balance of Antarctica conclude "we are still unable to determine even the sign of the contribution of the Antarctic Ice Sheet to recent sea level change."  Yet proponents of CO2 emission regulations will look you square in the eye and swear that unless the evil gas is brought under control, we can say goodbye to Tuvalu ... and a whole lot more.

What makes the climate alarmists' less-than-rational behavior (their ignoring the testimony of real-world measurements) even more curious is the fact that even ice sheet and climate models do not support their contentions.  Naslund et al. (2000), for example, used data on ice sheet bed and surface topography for western Dronning Maud Land in East Antarctica to calculate volume changes for this portion of the East Antarctic Ice Sheet for scenarios of as much as 10C warming, finding that it took the ice sheet some 20,000 years to stabilize, and at a volume not much different from its original size.  Also when Wild and Ohmura (2000) used the Max Plank Institute for Meteorology's ECHAM3 and ECHAM4 GCMs to calculate the mass balance of the Antarctic ice sheet for present-day and doubled atmospheric CO2 concentrations, they found that both models projected net increases in ice sheet growth as the air's CO2 content rose.

In light of these several observations, it is difficult to believe that science is behind the anti-CO2 juggernaut that is sweeping the world; logic will just not allow that conclusion.  So what is behind the campaign to vilify fossil fuels?  That's the real question we should be asking ourselves ... and attempting to answer.

Reference
Anderson, J.B. and Andrews, J.T.  1999.  Radiocarbon constraints on ice sheet advance and retreat in the Weddell Sea, Antarctica.  Geology 27: 179-182.

Bindschadler, R. and Vornberger, P.  1998.  Changes in the West Antarctic Ice Sheet since 1963 from declassified satellite photography.  Science 279: 689-692.

Naslund, J.O., Fastook, J.L. and Holmlund, P.  2000.  Numerical modeling of the ice sheet in western Dronning Maud Land, East Antarctica: impacts of present, past and future climates.  Journal of Glaciology 46: 54-66.

Pudsey, C.J. and Evans, J.  2001.  First survey of Antarctic sub-ice shelf sediments reveals mid-Holocene ice shelf retreat.  Geology 29: 787-790.

Reeh, N.  1999.  Mass balance of the Greenland ice sheet: Can modern observation methods reduce the uncertainty?  Geografiska Annaler 81A: 735-742.

Rignot, E.J.  1998.  Fast recession of a West Antarctic glacier.  Science 281: 549-550.

Shepherd, A., Wingham, D.J., Mansley, J.A.D. and Corr, H.F.J.  2001.  Inland thinning of Pine Island Glacier, West Antarctica.  Science 291: 862-864.

Vaughan, D.G., Bamber, J.L., Giovinetto, M., Russell, J. and Cooper, A.P.R.  1999.  Reassessment of net surface mass balance in Antarctica.  Journal of Climate 12: 933-946.

Vaughan, D.G., Marshall, G.J., Connolley, W.M., King J.C. and Mulvaney, R.  2001.  Devil in the detail.  Science 293: 177-179.

Wild, M. and Ohmura, A.  2000.  Change in mass balance of polar ice sheets and sea level from high-resolution GCM simulations of greenhouse warming.  Annals of Glaciology 30: 197-203.

Wingham, D.J., Ridout, A.J., Scharroo, R., Arthern, R.J. and Shum, C.K.  1998.  Antarctic elevation change from 1992 to 1996.  Science 282: 456-458.