Carbon Cycle Regulated by Tropical Ecosystems

RedOrbit reports on a new study by the National Academy of Sciences that links rising temperatures to the release of carbon dioxide from tropical ecosystems:

Rising temperatures, influenced by natural events such as El Nino, have a corresponding increase in the release of carbon dioxide from tropical forest ecosystems, according to a new study out today. 

The study, published in the journal Proceedings of the National Academy of Sciences, found that a temperature anomaly of just 1 degree C (in near surface air temperatures in the tropics) leads to a 3.5-Petagram (billion tonnes of carbon) anomaly in the annual CO2 growth rate, on average. This is the equivalent of 1/3 of the annual global emissions from the combustion of fossil fuels and deforestation together. 

Importantly, the NASA Earth Exchange (NEX) study results provide scientists with a new diagnostic tool to understand the global carbon cycle as it undergoes major changes due to the influences of human activities. 

NASA study co-author, CSIRO’s Dr Pep Canadell, said that the study’s 50-year analysis centered on temperature and rainfall patterns during El Nino years, when temperatures increase in tropical regions and rainfall decreases. An accompanying analysis assessed the effects of volcanic eruptions, which lead to decreased temperatures due to volcanic aerosols in the atmosphere. 

“Our study indicates that carbon exchanges in tropical ecosystems are extremely sensitive to temperature, and they respond with the release of emissions when warmer temperatures occur”. 

“Many processes involved in this response are the same as what is known as the carbon-climate feedback, which it is thought will lead to an acceleration of carbon emissions from vegetation and soils and into the atmosphere under future climate change. 

“The observed temperature changes are more important than changes in rainfall in influencing concentration of atmospheric CO2.”