Hide and Seek: Where is all the CO2 going?

Earth has absorbed a large portion of our CO2 emissions.Big news: Earth has been absorbing approximately half of the carbon dioxide emissions we have been pumping into the atmosphere. A recent article by Climate Central’s Michael D. Lemonick, citing a study by Ashley Ballantyne at the University of Colorado, says that plants and oceans have been absorbing carbon dioxide, removing it from the atmosphere where it would drive up global temperatures.

Impressive, right? Scientists know that this phenomenon cannot continue forever (especially at our current rate of emissions), but Ballantyne’s study indicates that we don’t have to worry about reaching a tipping point just yet. In fact, as we have quadrupled our emissions over the last 50 years, the planet has doubled its CO2 absorption.

How do we know how much CO2 has been absorbed? Scientists used an incredibly straightforward approach:

Total human CO2 emissions from the last 50 years – Amount of CO2 still in the atmosphere = Amount of CO2 absorbed by the planet over the last 50 years

That almost seems too easy, doesn’t it? Scientists caution that total emissions figures aren’t always precise, so there is some level of estimation there. But, determining atmospheric CO2 levels has only become more precise with time.

What’s missing? One major gap in the available research is that scientists don’t know with certainty where the CO2 is going. They postulate it is being absorbed by vegetation in the tropics or by the deep ocean – both areas where very little scientific data has been gathered. However, knowing where the CO2 goes is an important piece of the puzzle. This knowledge would give us the ability to judge the planet’s remaining CO2 capacity. It would also give us insight into potential mitigating actions we could take. For example, if vegetation absorbs a majority of CO2, reforestation would likely become a priority.

What does this mean? For me, the most important takeaway from this study is that even with the planet absorbing such a large amount of our CO2 emissions, atmospheric carbon has still been rising steadily (Take a look at this video from NOAA to see how current CO2 levels compare with those from the last 800,000 years). As soon as we reach the planet’s absorption capacity, CO2 levels will rise at a much more dramatic pace, quickening the onslaught of the effects of climate change. This study ably demonstrates that Earth has many mechanisms to protect itself and remain in balance, but human activity has increased to such a level that the planet truly cannot keep up.

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