Greenhouse Gas Emissions Imperil Polar Bear Survival, Study Confirms

greenhouse gas emissions imperil polar bear survival study confirms.jpg Science

In a breakthrough for conservation efforts, a recent study has made significant strides towards incorporating the impact of climate change into the evaluation of projects such as oil and gas drilling, a consideration that was previously obstructed by the Endangered Species Act. This study, published in Science’s Policy Forum, comes fifteen years after polar bears were listed as threatened species, and it marks the first time scientists have been able to directly quantify the impact of human-caused greenhouse gas emissions from specific sources on polar bear cub survival.

The Endangered Species Act necessitates that agencies ensure their approved projects do not inflict additional harm on listed species. However, a 2008 Department of Interior legal opinion claimed greenhouse gas emissions did not require consideration because the impact from specific projects could not be distinguished from that of all historic global emissions. This study challenges that perspective, providing a new lens to understand and measure the specific implications of greenhouse gas emissions on the survival of polar bear cubs.

A Breakthrough for Polar Bear Conservation: Climate Change Impacts Can Now Be Evaluated

Overcoming Legal Obstacles

Fifteen years following the classification of polar bears as a threatened species, a recent study has broken down a major hurdle in the Endangered Species Act. This milestone allows the federal government to contemplate the effects of climate change while assessing the impacts of projects such as oil and gas drilling. The act ensures that agencies do not approve projects that can potentially harm listed species. However, a 2008 legal opinion from the Department of Interior stated that greenhouse gas emissions need not be considered, as the impact from specific projects could not be differentiated from all historical global emissions.

New Study Breaks Ground

In a study published by Science’s Policy Forum, researchers for the first time have managed to directly quantify the effect of greenhouse gas emissions from certain sources on the survival of polar bear cubs. Lead author Steven C. Amstrup, chief scientist emeritus at Polar Bears International and a professor at the University of Wyoming, noted the oddity of listing polar bears as threatened due to loss of sea ice from global warming, but not considering emissions.

The Plight of Polar Bears

Polar bears, spread across 19 subpopulations in the Arctic, depend on sea ice for seal hunting. As ice melts due to global warming, bears either end up on land or are left swimming further from shore to find ice, affecting their ability to find food and leading to fasting periods that deplete fat reserves. A 2020 study found that the number of fasting days, dictated by the number of ice-free days every summer, directly influenced cub survival. The new study took this further by quantifying the number of ice-free, fasting days caused by a certain amount of human-caused greenhouse gas emissions.

Implications of the Study

The study presents a method of connecting emissions to ice-free days and their impacts on polar bears. This method could potentially be applied to many other species, such as sea turtles or coral reefs. According to Amstrup, the study makes a case for rescinding the 2008 opinion that barred climate considerations, as the Endangered Species Act requires agencies to use the best available scientific data.

However, the study also faced some critique, with some experts stating that it shows a correlation between emissions and polar bear cub survival, but not a direct cause and effect.

Closing Thoughts

While the study is a significant leap forward in understanding the effects of cumulative emissions on polar bears, it also highlights the need for change in policy and the way federal actions that increase greenhouse gas emissions are handled. The fight for the survival of polar bears, and indeed all species threatened by climate change, necessitates not only scientific advancements but also the political will to make hard decisions. This study is a step in the right direction, but there is still a long journey ahead.

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