London: Using a combination of remote sensing and field data, researchers have produced the first-of-its kind wall-to-wall map that can give accurate estimates of carbon storage of forests, shrublands, and savannas in the tropics of Africa, Asia, and South America.
The study by scientists from Woods Hole Research Center (WHRC), Boston University, and the University of Maryland revealed that tropical vegetation contains 21 percent more carbon than previous studies had suggested.
The colour of the map - with a spatial resolution of 500 m x 500 m- represent the amount of carbon density stored in the vegetation in a continuum fashion, which can help in understanding the amount of carbon released into the atmosphere by changes in land cover and land use.
Based on new data in this study, researchers believe that current models may overestimate the net flux of carbon into the atmosphere due to tropical vegetation loss by 11 to 12 percent.
For countries trying to meet their greenhouse gases reporting requirements under the United Nations Framework Convention on Climate Change (UNFCCC), these new data are particularly important.
Lead author Alessandro Baccini, an assistant scientist at WHRC, explained that the new data set provides a spatially and temporally consistent estimate of carbon stock and a stronger foundation for estimating carbon emissions by better characterizing the carbon density of the forest that has been lost.
“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 Baccini.
“This is like having a consistent, very dense pantropical forest inventory.”
In many developing nations, deforestation is the largest source of emissions of greenhouse gases.
In order to reliably report emissions to the UNFCCC, and to participate in international schemes such as Reducing Emissions from Deforestation and Forest Degradation (REDD+), which provides compensation for avoiding deforestation, these countries need an accurate way to calculate stored carbon and to track deforestation and reforestation.
“The paper is important for two reasons,” said co-author and WHRC senior scientist Richard A. Houghton.
“First, it provides a high-resolution map of aboveground biomass density for the world``s tropical forests. Previous maps were of much coarser resolution and yielded wildly different estimates of both regional totals and spatial distribution.
“Second, the paper calculates a new estimate of carbon emissions from land-use change in the tropics,” Houghton added.
This was done using the co-location of biomass density and deforestation to assign a more representative carbon density to the forests cleared.
Previous estimates used ‘average’ biomass densities that may have biased emissions`` estimates. In short, the approach will lead to better tracking of changes in biomass density resulting from degradation and growth.
The study has been published in Nature Climate Change.