Carbon Source or Carbon Sink: Greenhouse Gases in the Tropics

The lush vegetation wrapping the center of the globe is one of the most important features for regulating a stable climate in the world. Much excess CO2 emissions from industrialized regions find their way to the equator to be absorbed by abundant CO2-consuming plant life. However, as large tracts of tropical rainforest are cut down in the Amazon, Congo, and Southeast Asia, worries have grown that this vital region may turn from a carbon sink to a carbon source. Those worries can be put at ease somewhat thanks to a recent study from the Woods Hole Research Center (WHRC). Their report suggests that carbon storage of forests, shrublands, and savannas in the tropics are 21 percent higher than previously believed.

Larger carbon storage equates to a larger capacity to absorb and retain greenhouse gasses from the atmosphere. The loss of carbon storage due to deforestation is still a concern, but has been overestimated. In fact, the net flux of carbon into the atmosphere from tropical vegetation loss is overestimated by up to 12 percent.

The researcher group, led by Alessandro Baccini, assistant scientist at WHRC, estimated carbon densities in the tropics around the world using the LiDAR satellite. The LiDAR satellite is a NASA project which uses "laser radar" that can determine the heights of tree canopies. It's accurate sensing capabilities gave the researchers a consistent measure of carbon densities around the world. Other satellites, such as NASA's Aqua and Terra, were used, as well as field observations.

Their finding is very important in order for tropical countries to meet greenhouse gas reporting requirements under the United Nations Framework Convention on Climate Change (UNFCCC). It will also impact REDD+, the international system for reducing emissions from deforestation. For many of the developing nations in the tropics, deforestation is the largest source of GHG emissions. This report will allow these countries to more accurately track their carbon storage capacity (i.e. deforestation and reforestation), which will allow them to measure their net GHG emissions.

The WHRC study also produced a high resolution map of carbon density for tropical regions around the world. This map will be a helpful tool for governments as they calculate their carbon storage and devise strategies for preserving vegetation cover.

"The study represents a major step forward in the effort to map the current state of global tropical biomass stocks," commented Greg Asner, an ecologist at the Carnegie Institution for Science. "The 500m resolution of the map will help countries implement activities to improve forest management and to help fight climate change through reduced carbon emissions from deforestation."

"For the first time we were able to derive accurate estimates of carbon densities using satellite LiDAR observations in places that have never been measured," said lead author, Alessandro Baccini. "This is like having a consistent, very dense pantropical forest inventory."

The study has been published in the journal, Nature Climate Change.

Link to published article: http://eorder.sheridan.com/3_0/display/index.php?flashprint=1608