December 8, 2010

NASA Predicts Plants Could Slow Global Warming

NASA said on Tuesday that plants could grow larger and create a cooling effect on a warming globe due to more carbon dioxide in the atmosphere.

One of the mysteries scientists face with climate change is how to predict it over time, or more specifically how to account for Earth's reaction to warmer temperatures.

It has long been known that plants are able to adapt to higher carbon dioxide levels by using nutrients more efficiently and growing bigger leaves.

"The process is called 'down-regulation.' This more efficient use of water and nutrients has been observed in experimental studies and can ultimately lead to increased leaf growth," NASA said in a statement.

However, that effect on increased plant growth is difficult to predict.

NASA's new computer modeling effort calculated the plants' cooling effect to be -0.5 degrees Fahrenheit globally.

However, that number falls short of the temperature increase of 3.5 to 8.0 degrees Fahrenheit that is the standard basis for many global warming modeling simulations.

"This feedback slows but does not alleviate the projected warming," said Lahouari Bounoua, lead author of the paper and expert at the Goddard Space Flight Center outside Washington.

Bounoua's model found that warming was on the lower scale of the widely accepted range when carbon dioxide was doubled.

NASA said that previous climate models have not included the larger leaf growth that would come from "down-regulation" and have projected little to no cooling from vegetation growth.

"This is what is completely new," Bounoua, referring to how the model was adapted to include changed leaf growth, said in a press release.

"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."

NASA said that the latest research shows "how, over time, scientists will create more sophisticated models that will chip away at the uncertainty range of climate change and allow more accurate projections of future climate."

Study co-author Forrest Hall of the University of Maryland-Baltimore County and Goddard Space Flight Center said in a statement that having more precise projections will help in the search for solutions.

"As we learn more about how these systems react, we can learn more about how the climate will change," said Hall.

"Each year we get better and better. It's important to get these things right just as it's important to get the track of a hurricane right. We've got to get these models right, and improve our projections, so we'll know where to most effectively concentrate mitigation efforts."


Image Caption: A new NASA modeling effort found that in a doubled-carbon dioxide world plant growth could lessen global warming by about 0.3 degrees C globally. The same model found that the world would warm by 1.94 degrees C without this cooling feedback factored in. Image: Great Smoky Mountains National Park; Credit: National Park Service


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