Two centuries of burning fossil fuels has put more carbon dioxide, a powerful greenhouse gas, into the atmosphere than nature can remove. As that CO2 builds up, it traps excess heat near Earth’s surface, causing global warming. There is so much CO2 in the atmosphere now that most scenarios show ending emissions alone won’t be enough to stabilize the climate – humanity will also have to remove CO2 from the air.
The U.S. Department of Energy has a new goal to scale up direct air capture, a technology that uses chemical reactions to capture CO2 from air. While federal funding for carbon capture often draws criticism because some people see it as an excuse for fossil fuel use to continue, carbon removal in some form will likely still be necessary, IPCC reports show. Technology to remove carbon mechanically is in development and operating at a very small scale, in part because current methods are prohibitively expensive and energy intensive. But new techniques are being tested this year that could help lower the energy demand and cost.