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Scrubbing Carbon from the Sky

Can we remove enough CO2 from the atmosphere to slow or even reverse climate change?

By Richard Conniff | Scientific American January 2019 Issue Download PDF

Scrubbing Carbon from the Sky

The Hellisheiði Power Station, in Hengill, southwest Iceland. Credit: Liz Tormes


To limit global warming to 1.5 degrees Celsius, nations will have to remove one trillion tons of carbon dioxide emissions from the planet's atmosphere this century.

Finding the optimal mix of carbon capture methods will be critical. Machines that pull CO2 from the air could remove 250 billion tons by 2100. Replanting clear-cut forests could achieve 180 billion tons. Net costs range from $0 to $300 per ton. Unless big markets are developed to use the captured CO2, a carbon tax may provide the best support for the techniques.

Not long ago it seemed as if reducing greenhouse gas emissions would be enough to save the world from climate change. Replace fossil-fuel power plants with clean energy sources, make cars and buildings more efficient, switch to LED lights, eat less meat, and so on. Slashing emissions and boosting renewables looked like the answer even to the Intergovernmental Panel on Climate Change as recently as 2005. But the strategy has not worked out as planned. Global emissions have gone up instead of down. It now appears that even cutting annual net emissions worldwide to zero by 2050 will not be enough.

To prevent economic and environmental devastation, climate experts maintain that we will now also have to achieve negative emissions. Doing so means removing billions of tons of carbon dioxide from the atmosphere every year. That is like saying we can no longer put out the garbage—and we need to steadily take back the garbage we put out in the past.

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