Earlier Springs, Later Autumns Sprout from Climate Change

Every year, as temperatures warm and the winter snows melt away, forests on the East Coast become a sea of green, just to morph into a display of reds, oranges and greens the following autumn. Over the last two decades, this cycle has gone slightly askew, as a result of climate change, cultivating earlier springs and later autumns.

Using a combination of satellite imagery, tower-mounted instruments and on-the-ground observations, researchers found that forests throughout the eastern United States are showing signs of spring growth earlier than ever, and the growing season in some areas extends further into the fall.

Other than the fact that some get to enjoy a much-welcomed prolonged spring, the expanded growing season has also allowed forests to store as much as 26 million metric tons more carbon dioxide (CO2) than before.

Yet, researchers remind us that this is just one small upside to climate change, and does in no way outweigh its many negative affects.

"This has been beneficial for forests in the past, but we do not expect the response to continue unchecked in the future. It must also be kept in mind that this positive effect of warming is but one amid a barrage of detrimental impacts of climate change on the Earth's ecosystems," research associate Trevor Keenan noted in a press release.

Keenan, Andrew Richardson and fellow colleagues were able to paint a region-wide picture of the eastern forest - which stretches along the eastern seaboard from Maine to Georgia, and as far inland as Wisconsin - displaying when forests turn green in the spring, and when leaves began to turn in the fall. It clearly showed that spring started earlier, and the growing season lasted longer than at any point in the last two decades.

However, researchers stress that we should not rely on this prolonged period of carbon uptake to take care of the millions of tons of fossil fuel emissions in the atmosphere.

"If forests weren't storing additional carbon in this manner, we would be even worse off in terms of atmospheric CO2 levels, so at the moment, it's a good thing...but this is not going to solve the CO2 problem," Richardson said.

Moreover, "climate change isn't just about warmer temperatures," he continued. "It's also about changes in precipitation patterns...so in the future, an earlier spring might not help forests take up more carbon, if they end up running out of water in mid-summer."

The findings are described in a June 1 paper published in Nature Climate Change.