Understanding responses of the Amazon rainforest to climate and land-use change

photo by Chris Linder

Scientists have for years been working to understand what is causing the observed increase in carbon sequestration by rainforests of the Amazon and what that means for future global climate change. A new paper published by a scientific team led by WHRC visiting scientist Dr. Andrea Castanho used a suite of computer models of vegetation dynamics and long-term forest observations to take a closer look at tropical forest growth and its response to changing climate and atmospheric CO2 content.

The computer model results suggest that since the 1970s increased atmospheric CO2, via its affect on photosynthetic efficiency, has been the greatest contributor to the observed increase in forest carbon sequestration. However, the team also found that deforestation in the eastern and southern Amazon caused a reduction in forest biomass of comparable scale. According to Dr. Castanho, “future climate, the amount of CO2 in the atmosphere, and rates of deforestation will all be key factors in determining the contribution of the Amazonian forest to the global carbon balance.”

While some studies have shown an overall resilience of the forests in the Amazon to climate change, in large part because of the predicted increase in photosynthetic efficiency, they have not necessarily accounted for widespread forest degradation from fire as well as forest clearing for agriculture. As a result, co-author and WHRC Senior Scientist Michael Coe stated, “persistent even relatively small scale future deforestation may effectively cancel or reverse the significant carbon sink that tropical forests are providing and may severely impact national goals for reducing greenhouse gas emissions in the tropics.”

Link to the abstract »

WHRC is an independent research institute where scientists investigate the causes and effects of climate change to identify and implement opportunities for conservation, restoration and economic development around the world.