NASA repored that the increasing level of CO2 in the atmosphere is making the planet greener. The new vegetation could mitigate some global warming, but scientists warn it won’t be enough to offset the negative effects of climate change.
The new study looks at the planet’s leaf area index, or amount of vegetation cover across the planet. The researchers found that in the past 35 years, an area of the planet twice the size of the continental United States became greener with vegetation. The main cause is CO2, the principal gas causing climate change.
Plants use carbon dioxide, along with water and sunlight, to produce their food, sugar. Scientists have found that an increase in CO2 increases photosynthesis and spurring greater plant growth.
NASA said in a press release that this effect explains 70 percent of the new plant growth, with the second most important component being nitrogen.
This is good news for people, since the plant growth slows the rate of global warming according to NASA simulations. Plants are already taking in huge amounts of carbon, but not enough to keep up with industrialization.
Every year, civilization puts about 10 billion tonnes of CO2 into the atmosphere, plants take in about half of it – and as the vegetation expands the benefits expand as well.
Co-author Shilong Piao of the College of Urban and Environmental Sciences at Peking University explained.
“While our study did not address the connection between greening and carbon storage in plants, other studies have reported an increasing carbon sink on land since the 1980s, which is entirely consistent with the idea of a greening Earth.”
Despite the obvious positives for mitigating global warming, climate scientists have struggled to incorporate a greener planet into their models. Increased vegetation has a downside too.
Plant growth into areas of the tundra, for example, would increase the canopy over lighter colored areas. The darker colors absorb more solar radiation than snow cover, heating the planet even further.
As a result, according to NASA models that incorporate a greener planet show little change from those without, unless they include what’s called “down regulation,” which is the ability of planets to conserve more water and nutrients if the atmosphere has more CO2.
Lahouari Bounoua of Goddard Space Flight Center in Greenbelt, Md, explained that putting in the process had an important effect on the models.
“What we did is improve plants’ physiological response in the model by including down-regulation. The end result is a stronger feedback than previously thought.”