Greenhouse Gas Emissions in the Brazilian Semiarid Region: Environmental, Climate and Social Constraints

Abstract:

Removing a forest to open new agricultural lands, which has been very intensive in countries like Brazil during the last decades, contributes to about 12% of the global anthropogenic emissions. Forest cover removal releases carbon dioxide (CO₂) and other greenhouse gases (GEE) like methane (CH₄) and nitrous oxide (N₂O), as a result of burning trees, followed by gradual decomposition of the forest biomass left on the ground while pasture or crop plantations are being established. In Brazil, the 2^nd Brazilian National Communication to the United Nations Framework Convention on Climate Change (UNFCCC) presents the mean annual net CO₂ emissions caused by changes in land use (LUC) in each Brazilian biome and the first place in the ranking is occupied by the Amazon Rainforest Biome (860,874 Gg), followed by Savannah (302,715 Gg), Atlantic Forest (79,109 Gg), Caatinga (37,628 Gg), Pantanal (16,172 Gg) and Pampa (-102 Gg) (MCT 2010). Despite these results, the estimates of CO₂ emissions caused by LUC in the Brazilian semiarid region (Caatinga) are very limited and scarce, and associated to uncertainties directly related to the estimated biomass in different types of vegetation which are spatially distributed within the biome, as well as the correct representation of the dynamics of the deforestation process itself, and the more accurate mapping use and land cover. Based on such facts, this project is estimating the emissions of the main greenhouse gases (CO₂, N₂O and CH₄) caused by land use changes in an area of Caatinga biome in Pernambuco State through the model INPE-EM. So far, it is known that from decades of 1940 up to 1995, Caatinga biome has contributed with about 3.2 % to total land use change emissions in the country, and recently (1990-2005), the contributions of Caatinga are even higher (over 30%), according to the 2^nd Brazilian National Communication (2010). By means means of the model INPE-EM (data still being acquired), we are trying to diminish the uncertainties and identify specific and integrated emissions of GHG, as well as the stocks and flows of C and N, in order to contribute to the current information about GEE dynamic in the Brazilian. Besides, the model will incorporate the temporal dynamics related to the deforestation process, and accounts for the biophysical and socioeconomic heterogeneity of the region in study.