Tropical Forests May Inhale Third of Fossil Fuel Emissions

Plant a tree.  Preserve a forest.  Save the Earth from climate change?

It’s of course much more complicated than that, and slowing the tide of climate change will take a lot more than saving trees from chainsaws.  But a new study highlights how critical forests may be, especially in the tropics, in absorbing human-caused carbon dioxide (CO2) emissions and mitigating climate change.

Tropical forests are so critical to fighting climate change that they may absorb up to one-third of all of humans’ fossil fuel emissions and may become more effective at doing so as atmospheric CO2 concentrations increase, according to a new study published in the Proceedings of the National Academy of Sciences.

“While forests cannot solve the CO2 and climate change problem, without them the problem would be even harder,” said the study’s lead author David Schimel, a research scientist at NASA’s Jet Propulsion Laboratory at the California Institute of Technology.

All forests, especially dense tropical forests, are excellent at capturing carbon and storing it.  Scientists call them “carbon sinks” because they absorb CO2 from the atmosphere, storing it in tree bark, wood and roots.  Logging a forest has the opposite effect, as the felled wood burns or decomposes and releases stored CO2 back into the atmosphere.

Research suggests that higher CO2 concentrations in the atmosphere may make trees more efficient at storing carbon and force them to grow faster, a phenomenon called the “fertilization effect.”

Roughly half of all of humans’ fossil fuel emissions are absorbed by the land and the oceans, but scientists don’t fully understand why it happens and why forests have been absorbing more CO2 as atmospheric concentrations rise, Schimel said.

“This study provides strong evidence that as CO2 in the atmosphere increases, ecosystems are able to take up more carbon, keeping the ratio between how much CO2 we release from fossil fuels and how much accumulates in the atmosphere,” he said.

The findings build upon 2007 research led by study co-author Britton Stephens, an atmospheric scientist at the National Center for Atmospheric Research in Boulder, Colo., suggesting that tropical forests are more effective at absorbing CO2 than those in the Northern Hemisphere.

The new research evaluates the various ways scientists study how forests may absorb CO2, including research methods using measurements taken on the ground and others using measurements of atmospheric CO2 concentrations.

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