Melting Survival: How Pollution Threatens Polar Bear Reproduction

melting survival how pollution threatens polar bear reproduction.jpg Science

The survival and reproduction of polar bears, an iconic symbol of the Arctic’s biodiversity, are now directly linked to human-induced greenhouse gas emissions, according to a groundbreaking study. Researchers from Polar Bears International, the University of Washington, and the University of Wyoming have quantified the correlation between the number of ice-free days endured by a polar bear population, the volume of pollution released into the atmosphere, and survival rates of the species. This compelling discovery provides a crucial piece in the puzzle of understanding how anthropogenic climate change is impacting Arctic wildlife, potentially paving the way for stronger protective measures for the species.

Polar bears, spread across 19 distinct populations in the Arctic regions of Canada, the United States, Russia, Greenland, and Norway, are critically dependent on ice sheets to hunt their main prey, two species of seal. However, the rapid melting of sea ice due to climate change is disrupting their feeding patterns, forcing them onto land where they must rely on previously accumulated fat reserves for survival. The new study, published in the journal Science, offers evidence of how increasing greenhouse gas emissions are directly contributing to longer periods of forced fasting for polar bears, leading to a decline in their population. This research could potentially challenge previous assertions by the US Department of Interior, which stated that specific sources of greenhouse gases could not be directly linked to threats to a particular species.

Polar Bears’ Survival Linked to Human-Caused Emissions for the First Time

In a groundbreaking new study, scientists have found a direct link between human-related emissions and the reproduction and survival of polar bears. This discovery could potentially pave the way for better conservation efforts to protect this endangered species.

The Polar Bear Plight

Polar bears, residing in 19 distinct populations across the Arctic, depend heavily on ice sheets to hunt their primary prey, two species of seals. However, with accelerated sea ice loss due to human-induced climate change, these majestic creatures are facing an increasing number of ice-free days. This leaves them stranded on land, forced to survive on their stored fat reserves and leading to a decline in their population.

The Direct Link to Emissions

The study, published in the journal Science, was conducted by researchers from Polar Bears International, the University of Washington, and the University of Wyoming. The team quantified the correlation between the number of ice-free days endured by the polar bear population and the amount of greenhouse gas emissions. They found that as emissions increased, so too did the number of days polar bears went without food.

For instance, polar bears in the Arctic Ocean’s Chukchi Sea had to fast for about 12 days in 1979. By 2020, this period had risen to roughly 137 days, with an additional fasting day for every 14 gigatons of emissions released into the atmosphere.

Impact of Emissions on Polar Bear Survival

This research builds on a 2020 study that found the number of days a bear can survive without food varies by region and condition. However, the more ice-free days experienced, the steeper the decline in reproduction and survival. By combining these findings, the researchers were able to calculate the impact of cumulative emissions on the rate of polar bear survival.

Each power plant in the US, though individually contributing minimally to emissions, collectively emits nearly 2 gigatons of greenhouse gases each year. Over a polar bear’s lifespan in the southern Beaufort Sea, this translates to an extra fasting day for every 23 gigatons of emissions, reducing their survival rate by about 4% over that period.

Implications for Other Species

This research signifies a paradigm shift in demonstrating the effects of climate change on ecosystems. Not only does it prove a direct link between carbon emissions and climate change, but it also shows the impact on polar bear populations. The findings enable us to connect the decline in polar bear populations to individual sources of carbon emissions.

The researchers hope that the study can serve as a template for protecting other species affected by human-caused climate change.


This research underscores the urgent need for collective action to curb greenhouse gas emissions. It serves as a stark reminder of the real-world consequences of climate change, not just for polar bears, but potentially for a wide range of species. The direct link established between emissions and polar bear survival rates provides a tangible measure of the impact of human activities on wildlife, making it a powerful tool for conservation advocacy.

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