From: Allison Winter, ENN
Published October 18, 2013 08:59 AM

Plants Absorb Carbon, Reduce Historical Warming

From providing habitat to food sources, to regulating water cycles, plants are the backbone of all life on Earth. What often goes unrecognized, but is equally as important are plants' roles as climate controllers.

According to a new study conducted by researchers at Princeton University, Earth's leafy greens have significantly slowed the planet's warming by absorbing carbon in the form of CO2, a popular greenhouse gas, especially during the past 60 years.

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How much carbon are we talking about? Approximately 186 billion to 192 billion tons of carbon have been taken out of the atmosphere since the mid-20th century!

Ironically, as carbon dioxide (along with other pollutants) was emitted into the atmosphere from industrial development, plants thrived because CO2 is also a plant nutrient. Carbon dioxide is absorbed through small pores in plant leaves where it is then synthesized with water using light energy and produced into sugar and oxygen. Without these benefits of CO2 fertilization, the atmospheric CO2 concentration would have risen and the global climate would have warmed by an additional 0.31 degrees Celcius, the study finds.

Those "carbon savings" amount to a current average global temperature that is cooler by one-third of a degree Celsius (or a half-degree Fahrenheit).

Since the early 1900s, the planet has warmed by only 0.74 degrees Celsius (1.3 degrees Fahrenheit). The point at which scientists calculate a “dangerous” global temperature would be 2 degrees Celsius (3.6 degrees Fahrenheit) more than pre-industrial levels.

The study is the most comprehensive look at the historical role of terrestrial ecosystems in controlling atmospheric carbon, explained first author Elena Shevliakova, a senior climate modeler in Princeton's Department of Ecology and Evolutionary Biology. Previous research has focused on how plants might offset carbon in the future, but overlooked the importance of increased vegetation uptake in the past, she said.

"People always say we know carbon sinks are important for the climate," Shevliakova said. "We actually for the first time have a number and we can say what that sink means for us now in terms of carbon savings."

"Changes in carbon dioxide emissions from land-use activities need to be carefully considered. Until recently, most studies would just take fossil-fuel emissions and land-use emissions from simple models, plug them in and not consider how managed lands such as recovering forests take up carbon," she said. "It's not just climate — it's people. On land, people are major drivers of changes in land carbon. They're not just taking carbon out of the land, they're actually changing the land's capacity to take up carbon."

The study can be found in the Proceedings of the National Academy of Sciences.

Read more at Princeton University.

CO2 and tree image via Shutterstock.

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