Bear Facts
Polar Bear Numbers & Climate Change
Map caption: The IUCN Polar Bear Specialist Group reclassified the polar bear as a vulnerable species at their 2005 meeting in Seattle. At their 2009 meeting in Copenhagen, they reported that of the 19 subpopulations of polar bears, eight are declining, three are stable, one is increasing, and seven have insufficient data on which to base a decision. Click image to enlarge.
Media reports and letters to the editor can be confusing. Scientists clearly state that polar bears are in trouble. Yet a small group of naysayers maintain that the bears are fine: they claim that polar bear numbers have doubled since the 1960s.
The same holds true for climate change. While all sides now agree that the planet is warming, the current debate centers around the cause: Is it part of a natural cycle, as the minority opinion argues? Or are greenhouse gases to blame?
Polar Bear Numbers
Let's start with polar bear numbers. First, it's important to note that scientists lack historical data on polar bear numbers—they only have rough estimates. What we do know, though, is that in the 1960s, polar bear populations dropped precipitously due to over-hunting. When restrictions on polar bear harvests were put in place in the early 1970s, populations rebounded. That situation was a conservation success story ... but the current threat to polar bears is entirely different, and more dire.
Today's polar bears are facing the rapid loss of the sea-ice habitat that they rely on to hunt, breed, and, in some cases, to den. Last summer alone, the melt-off in the Arctic was equal to the size of Alaska, Texas, and the state of Washington combined—a shrinkage that was not predicted to happen until 2040. The loss of Arctic sea ice has resulted in a shorter hunting season for the bears, which has led to a scientifically documented decline in the best-studied population, Western Hudson Bay, and predictions of decline in the second best-studied population, the Southern Beaufort Sea.
The Western Hudson Bay population has dropped by 22% since 1987. The Southern Beaufort Sea bears are showing the same signs of stress the Western Hudson Bay bears did before they crashed, including smaller adults and fewer yearling bears.
At the most recent meeting of the IUCN Polar Bear Specialist Group (Copenhagen, 2009), scientists reported that of the 19 subpopulations of polar bears, eight are declining, three are stable, one is increasing, and seven have insufficient data on which to base a decision. (The number of declining populations has increased from five at the group's 2005 meeting.)
Some members of the press take advantage of the complexity by stating that "polar bears are not in trouble—their numbers have doubled since the 1960s." That's a disingenuous statement, of course. It is true that polar bear populations rebounded after over-hunting was restricted, but that situation has nothing to do with the threat polar bears now face: the loss of the sea ice habitat essential to their survival.
Climate Change
The current warming trend in the Arctic is taking place at a much faster pace than computer models had previously projected, with large expanses of darker, open water absorbing more heat and accelerating the process. Over the past 30 years, the Arctic sea ice has retreated dramatically, with the most extreme decline seen in the summer melt season.
No one disputes the fact that the Arctic sea ice is undergoing a rapid melt-down, but reports continue to circulate that the warming trend is part of a natural cycle and that scientists do not yet agree that a build-up of CO2 has caused the earth's climate to warm.
The truth of the matter is that the debate has ended: in peer-reviewed papers, the vast majority of climatologists have concluded that the warming taking place in the Arctic can be linked to human activities that have caused a build-up of greenhouse gases. Natural forces from ocean currents to sunspots may be adding to the trend as well, but scientists no longer doubt that carbon emissions have had a significant impact on the global climate.
While it is true that the planet has undergone warming and cooling cycles throughout its history, the current trend of global warming is taking place at a faster clip than most previous warming cycles. Most important, the only warming events in the last several hundred thousand years that may have matched the current pace were regional and episodic—not global in scope. At the same time, a graph showing the build-up of carbon emissions over the past century correlates precisely with the rise in the planet's temperature.
The hundreds of climate scientists who participate in the Intergovernmental Panel on Climate Change have concluded with at least 90% certainty that the current high levels of CO2 are driving the melt-down in the Arctic—a melt-down that will eventually affect the entire planet unless steps are taken to the reverse the trend. Given the risks involved in not taking action—from droughts to floods to rising sea levels and more intense storms—a reduction in carbon emissions is the only sensible course.
“Conserving energy and finding new energy sources are good insurance policies for the health of the planet,” says Leeann Myers, who serves on PBI's board of directors. “And although high gas prices are painful, they have a positive side in motivating people to conserve—something we should be doing anyway. Dwindling oil supplies have also prompted a renewed interest in alternative energy sources.”
“Humans have solved major problems before,” she adds, “including the threat to the ozone layer. We're confident that, given the will, we can reduce carbon emissions and restore the bears' habitat.”
The same holds true for climate change. While all sides now agree that the planet is warming, the current debate centers around the cause: Is it part of a natural cycle, as the minority opinion argues? Or are greenhouse gases to blame?
Polar Bear Numbers
Let's start with polar bear numbers. First, it's important to note that scientists lack historical data on polar bear numbers—they only have rough estimates. What we do know, though, is that in the 1960s, polar bear populations dropped precipitously due to over-hunting. When restrictions on polar bear harvests were put in place in the early 1970s, populations rebounded. That situation was a conservation success story ... but the current threat to polar bears is entirely different, and more dire.
Today's polar bears are facing the rapid loss of the sea-ice habitat that they rely on to hunt, breed, and, in some cases, to den. Last summer alone, the melt-off in the Arctic was equal to the size of Alaska, Texas, and the state of Washington combined—a shrinkage that was not predicted to happen until 2040. The loss of Arctic sea ice has resulted in a shorter hunting season for the bears, which has led to a scientifically documented decline in the best-studied population, Western Hudson Bay, and predictions of decline in the second best-studied population, the Southern Beaufort Sea.
The Western Hudson Bay population has dropped by 22% since 1987. The Southern Beaufort Sea bears are showing the same signs of stress the Western Hudson Bay bears did before they crashed, including smaller adults and fewer yearling bears.
At the most recent meeting of the IUCN Polar Bear Specialist Group (Copenhagen, 2009), scientists reported that of the 19 subpopulations of polar bears, eight are declining, three are stable, one is increasing, and seven have insufficient data on which to base a decision. (The number of declining populations has increased from five at the group's 2005 meeting.)
Some members of the press take advantage of the complexity by stating that "polar bears are not in trouble—their numbers have doubled since the 1960s." That's a disingenuous statement, of course. It is true that polar bear populations rebounded after over-hunting was restricted, but that situation has nothing to do with the threat polar bears now face: the loss of the sea ice habitat essential to their survival.
Climate Change
The current warming trend in the Arctic is taking place at a much faster pace than computer models had previously projected, with large expanses of darker, open water absorbing more heat and accelerating the process. Over the past 30 years, the Arctic sea ice has retreated dramatically, with the most extreme decline seen in the summer melt season.
No one disputes the fact that the Arctic sea ice is undergoing a rapid melt-down, but reports continue to circulate that the warming trend is part of a natural cycle and that scientists do not yet agree that a build-up of CO2 has caused the earth's climate to warm.
The truth of the matter is that the debate has ended: in peer-reviewed papers, the vast majority of climatologists have concluded that the warming taking place in the Arctic can be linked to human activities that have caused a build-up of greenhouse gases. Natural forces from ocean currents to sunspots may be adding to the trend as well, but scientists no longer doubt that carbon emissions have had a significant impact on the global climate.
While it is true that the planet has undergone warming and cooling cycles throughout its history, the current trend of global warming is taking place at a faster clip than most previous warming cycles. Most important, the only warming events in the last several hundred thousand years that may have matched the current pace were regional and episodic—not global in scope. At the same time, a graph showing the build-up of carbon emissions over the past century correlates precisely with the rise in the planet's temperature.
The hundreds of climate scientists who participate in the Intergovernmental Panel on Climate Change have concluded with at least 90% certainty that the current high levels of CO2 are driving the melt-down in the Arctic—a melt-down that will eventually affect the entire planet unless steps are taken to the reverse the trend. Given the risks involved in not taking action—from droughts to floods to rising sea levels and more intense storms—a reduction in carbon emissions is the only sensible course.
“Conserving energy and finding new energy sources are good insurance policies for the health of the planet,” says Leeann Myers, who serves on PBI's board of directors. “And although high gas prices are painful, they have a positive side in motivating people to conserve—something we should be doing anyway. Dwindling oil supplies have also prompted a renewed interest in alternative energy sources.”
“Humans have solved major problems before,” she adds, “including the threat to the ozone layer. We're confident that, given the will, we can reduce carbon emissions and restore the bears' habitat.”
Polar Bear Numbers & Climate Change - Related Topics
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