"And the polar bears of the Artic, who are supposed to be so threatened by global warming have increased their numbers 5 fold in the last 40 years."
I'll bet you're only saying that cuz you like to be wrong a lot, and you rely on Faux and Lomborg.
Lomborg even thinks the polar bears can evolve backwards. At least he is aware of evolution.
Some recent media reports have cited inaccurate data concerning polar bears. For clarification on polar bear numbers, we turned to Dr. Andrew Derocher, Chair of the IUCN/SSC Polar Bear Specialist Group.
polarbearsinternational.org
"Ignorant people write ignorant things."
thestar.com
gristmill.grist.org
theregister.co.uk
Message 23884407
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"The Antarctic ice as a whole is getting thicker, not thinner."
Antarctic ice is growing
Posted by Coby Beck at 9:28 AM on 06 Nov 2006
Objection: The Antarctic ice sheets are actually growing, which wouldn't be happening if global warming were real.
Answer: There are two distinct problems with this argument.
First, any argument that tries to use a regional phenomenon to disprove a global trend is dead in the water. Anthropogenic global warming theory does not predict uniform warming throughout the globe. We need to assess the balance of the evidence.
In the case of this particular region, there is actually very little data about the changes in the ice sheets. The growth in the East Antarctic ice sheet indicated by some evidence is so small, and the evidence itself so uncertain, the sheet may well be shrinking.
But even this weak piece of evidence may no longer be current. Some recent results from NASA's GRACE experiment, measuring the gravitational pull of the massive Antarctic ice sheets, have indicated that on the whole, ice mass is being lost.
Second, ice-sheet thickening is not inconsistent with warming! Warmer climates tend toward more precipitation. The Antarctic is one of the most extreme deserts on the planet. As it warms, we would expect it to receive more snow. (As the air warms, it hold more moisture, increasing snowfall in the center of the continent). But even a whopping warming of 20 degrees -- say, from -50 degrees C to -30 degrees C -- would still leave it below freezing, so the snow wouldn't melt. Thus, an increase in ice mass.
While on the subject of ice sheets: Greenland is also growing ice in the center, for the same reasons described above. But it is melting on the exterior regions, on the whole losing approximately 200 km3 of ice annually, doubled from just a decade ago. This is a huge amount compared to changes in the Antarctic -- around three orders of magnitude larger. So in terms of sea-level rise, any potential mitigation due to East Antarctic Ice Sheet growth is wiped out many times over by Greenland's melting.
gristmill.grist.org
But this theory is under challenge...
However, with the March 2006 Science article by researchers Isabella Velicogna and John Wahl, this idea was (purportedly) turned on its head.
The [IPCC] report predicted that the Antarctic ice sheet will probably gain mass during the 21st 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….
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.
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.
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.
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:
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.
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.”
scienceandpublicpolicy.org |
