Arctic warming’s $70 trillion bill

The release of greenhouse gases from thawing permafrost in the Arctic will accelerate global warming and add up to $70 trillion to the cost of climate change. That’s the conclusion of the most comprehensive study yet into the ramifications of permafrost melt in the world’s high north, reports NationalGeographic​.com. As the region’s icy ground thaws, soil microbes start to digest the gigatons of organic carbon—the remains of plants and animals—that have been buried in the permafrost for thousands of years. Those microbes exhale climate-warming carbon dioxide and methane. To calculate the impact of those emissions, researchers measured how much frozen organic matter was in the ground at multiple points across the permafrost zone—which covers a quarter of the land in the northern hemisphere—then ran the data through climate simulation software. They found that, even if the world meets the Paris Agreement climate targets, the released gases and the retreat of sunlight-reflecting ice will hike climate change’s price tag—the cost of rising seas, longer droughts, and so on—by up to 5 percent, or $70 trillion. That’s 10 times higher than the projected benefits of a melting Arctic, such as shorter shipping routes. The study’s key takeaway, said co-author Kevin Schaefer of the National Snow and Ice Data Center in Boulder, “is the greater the warming, the stronger the feedbacks and the higher the costs to society.” ■