A link between CO2 emissions and the decline of polar bears has been established
A study published Thursday quantifies a direct link between greenhouse gas emissions and the number of snow-free days in bear habitat.
Polar bears need sea ice to hunt seals, move around, or breed.
AFP
Polar bears have long symbolized the damage caused by climate change, which is melting the sea ice on which their survival depends. But measuring the impact of a coal-fired power plant on these iconic mammals has never been done.
A new study published Thursday in the journal “Science” shows that bears can now calculate a direct link between a certain amount of greenhouse gas emissions and the number of snow-free days in populated areas. This in turn affects the percentage of mature bears.
Threatened species since 2008
With this level of precision, the authors of this study hope to be able to fix what is perceived as a loophole in US law. Polar bears have been listed as an endangered species under the US Endangered Species Act since 2008.
But a legal argument published the same year prevented the law from being used to assess new permits for fossil fuel projects with climate considerations and their impact on these species.
Republican Party leader George W. The argument, written by David Bernhardt, a lawyer for the Bush administration, argued that science could not distinguish the impact of a specific source of greenhouse gases from the impact of emissions as a whole. “We have presented the necessary information to break down this argument,” Steven Amstrup, one of the study’s authors, told AFP.
little life
Polar bears need sea ice to hunt seals, move around, or breed. When it melts in the summer, they retreat inland or onto the ice far from the coast, where they can go without food for long periods of time. These fasting periods are getting longer as global warming intensifies.
A large study published in 2020 was the first to quantify the link between observed changes in sea ice due to climate change and the number of polar bears. Based on this work, the two authors of this new study established a relationship between greenhouse gas emissions, the number of fasting days and the survival rate of young.
They did this calculation for 15 of 19 subpopulations of polar bears between 1979 and 2020. And we were able to draw several conclusions. For example, the world currently emits 50 billion tons of CO2 or its equivalent into the atmosphere annually, which reduces the survival rate of cubs in the population of polar bears by 3% per year, according to the study.
“The Undeniable Link”
In healthy populations, the survival rate of cubs in their first years of life is about 65%. “You don’t need huge downward variation to not have enough young for the next generation,” argues Steven Amstrup. The study also gives U.S. officials tools to measure the impact of new fossil fuel projects, such as new power plants, on polar bears.
This technique can be used prospectively to understand the past impact of a particular project. For Joel Berger, a researcher specializing in wildlife conservation at Colorado State University, this new study “establishes an indisputable quantitative link between emissions (greenhouse gases, editor’s note), the loss of sea ice, the rapid period (…) and emissions. Polar bear populations” .
AFP
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