Four Degree Rise in Global Warming Could End Vegetation Carbon Sink

It turns out that plant life may not be as good of a carbon sink as scientists once thought. New research reveals that the length of time that carbon remains in vegetation will change as CO2 levels rise. This could have major implications for the entire carbon load in the atmosphere in addition to the carbon cycle as a whole.

Carbon sinks are natural systems that drain and store CO2 from the atmosphere. As human activities continue to raise carbon dioxide levels, these sinks are more important than ever to help stabilize the climate. Vegetation in particular picks up and stores carbon, and places like the Amazon rainforest and the vast, circumpolar Boreal forest have played huge roles in helping mitigate climate change.

Yet now, it seems that these regions may be in trouble. Scientists have used climate modeling to show that while initially the higher CO2 will encourage plant growth, these trends will eventually reverse. A warmer world through drought will start to negate this natural balance until it reaches a saturation point. In fact, a global warming of just four degrees will result in Earth's vegetation becoming "dominated" by negative impacts, such as moisture stress, on a global scale.

In order to make these findings, the researchers used seven global vegetation models. These models were run exhaustively using supercomputers to create simulations of future scenarios. In the end, the scientists discovered that the future may not be all that bright for vegetation's ability to store carbon.

"Global vegetation contains large carbon reserves that are vulnerable to climate change, and so will determine future atmospheric CO2," said Andrew Friend, one of the researchers, in a news release. "The impacts of climate on vegetation will affect biodiversity and ecosystem status around the world. This work pulls together all the latest understanding of climate change and its impacts on global vegetation--it really captures our understanding at the global level."

The findings are important for understanding how carbon dioxide levels will change in the future and how that will impact our climate. If vegetation can't keep up with excess carbon dioxide, then it's likely that we may just see a warmer future.

The findings are published in the journal Proceedings of the National Academy of Sciences.