This Is Why the Atmosphere Isn't Absorbing More Carbon Right Now

Over the past 10 years, the atmosphere is not absorbing as much carbon as it was before.

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Nov 8 2016, 4:00pm

Image: Pexels

Ever since the industrial revolution unleashed the technologies that sustain modern societies—cars, power plants, computers and refrigerators—we've been turning up the heat on our climate.

By burning fossil fuels and discharging an increasing amount of carbon dioxide or CO2 we fuel global climate change. Last year was the hottest year on record, 2016 is on track to be just as hot, and by 2025 this will likely be our new normal.

But here's some unexpected news that could make the future less bleak. Typically the more CO2 we release, the more that ends up in the atmosphere. But over the past ten years that hasn't been the case, according to a new study lead by Trevor Keenan of the Lawrence Berkeley National Lab.

Keenan and his colleagues analyzed more than 50 years of atmospheric CO2 data to see how much carbon the atmosphere absorbed over time. "For most of that time period the growth rate in CO2 has been increasing because we've been increasing the CO2 we release into the atmosphere," Keenan told Motherboard. "In the recent decade though there seems to be a divergence; even though we're emitting more CO2 the growth rate wasn't increasing."

Image: Nature

It's not the first time there's been a pause—emissions flat lined in 2009—but according to Keenan, this pause is different. In 2009 the global recession meant that we were driving less, shipping less, doing less, and thus emitting less CO2. In this case, the amount of CO2 that we're emitting is still going up—it's the rate at which CO2 is entering the atmosphere that's holding steady.

To understand, it helps to think of carbon emissions entering the atmosphere like filling a kiddie pool with a hose. The more you push on the spray handle, the faster the water comes out of the hose, and the faster the pool fills up. But Keenan's research found that even though we're pushing harder on the spray handle—emitting more CO2—the water isn't coming out any faster, though the pool is still filling.

Kennan thinks a process called global greening might be holding atmospheric carbon absorption rates steady. The increase in CO2 and the warming temperatures have made it easier for plants to grow, and satellite footage has revealed that the earth is getting greener. Plants absorb carbon from the atmosphere becoming essentially, a piggy bank for carbon known as a carbon land sink.

This doesn't, however, mean that we can, or should, do nothing about our CO2 emissions. We don't really know how these ecosystems will behave in the future. If it gets too hot the plants might begin releasing some of the carbon that they've absorbed. We also don't actually know which greenspaces have begun absorbing more of our carbon—it's possible that we can accidentally destroy them, unleashing more carbon into the atmosphere.

It is difficult to pinpoint if you were using this as a conservation tool that says let's only protect the forest in Maine or the forest in Minnesota," said Mary Heskel a plant ecophysiologist at the ecosystem center at the Marine Biological Laboratory in Woods Hole, who did not contribute this study.

And, there's probably a lot of variation year to year. New England had a huge drought this year so it's not going to be as effective [as a carbon sink]. It's a fact that's all the more frightening given that two-thirds of the countries that have signed onto the Paris Agreement on Climate Change plan on using land sinks as a main part of their mitigation standards.

"This is not a climate change is good story," says Keenan, "We're very lucky that plants are taking about a third of our emissions, but that doesn't save us from climate change."

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