A recent NASA study has found that tropical rainforests are increasingly absorbing more carbon dioxide in response to rising levels of greenhouse gases in the environment. These forests are acting as a sink for 1.4 billion metric tons, a little more than half of the 2.5 billion metric tons absorbed worldwide. This NASA study also revealed that these estimates of carbon dioxide absorption are not only high in comparison to previous calculations, but also the amount of carbon absorbed in tropical rainforests far exceeds amounts absorption rates by boreal forests in northern regions like Canada and Siberia.
Increased absorption by tropical rainforests is positive due to the increase of greenhouse gases being put into the environment and in light of the declining rates of absorption by boreal forests. Trees remove carbon dioxide from the air and use it for their photosynthetic process, forests and other vegetation are currently remove up to 30% of carbon dioxide emissions during photosynthesis. This NASA study, led by David Schimmel of the Jet Propulsion Laboratory in Pasadena, CA was published in the Journal Proceedings of the National Academy of Sciences is the first of its kind to develop an “apples-to-apples” comparison of carbon dioxide estimates on various scales. Researchers analyzed computer models of ecosystem processes, atmospheric models run backward in time to deduce the sources of today’s concentrations (called inverse models), satellite images, data from experimental forest plots and more to assess the accuracy of results based on whether or not they produced independent, ground-based measurements. The new estimate of carbon absorption is based on models verified to be the most trustworthy and reliable.
Co-author of the study, Joshua Fisher states, “Until our analysis, no one had successfully completed a global reconciliation of information about carbon dioxide effects from the atmospheric, forestry and modeling communities. It is incredible that all these different types of independent data sources start to converge on an answer.” Another co-author from the National Center for Atmospheric Research, Boulder, CO, Britton Stephens emphasizes the criticality of understanding which forest types are the greatest absorbers, “It has big implications for our understanding of whether global terrestrial ecosystems might continue to offset our carbon dioxide emissions or might begin to exacerbate climate change.”
Until the mid-2000s the most commonly used computer models showed that mid-latitude forests in the Northern Hemisphere were the largest and most active carbon sink. This was based on the then-current understanding of global air currents and limited data showing that deforestation was causing tropical forests to release more carbon than they were absorbing. More recently, Stephens was able to use measurements of carbon collected via aircraft to illustrate that many climate models were incorrectly representing carbon flows above the ground level. There was still too little data to validate global-scale rainforest absorption, so Schimel says that their new study was able to integrate large amounts of data collected and analyzed by other scientist to develop their paper pulling together national and regional data of various kinds into robust, global data sets.
NASA is able to monitor the planet’s vital signs from land, air and space with a fleet of satellites as well as airborne and ground-based observation campaigns. They develop new ways to observe and study Earth’s interconnected natural systems and compile long-term data records and computer analysis tools to better view and track how the planet is changing. For an informative and interesting visualization of carbon dioxide levels and movements in the earth’s atmosphere and how it changes over the course of a year visit: http://news.nationalgeographic.com/news/2014/11/141118-nasa-video-carbon-dioxide-global-warming-climate-environment/.