Changes in Climate and Land Use Over the Amazon Region: Current and Future Variability and Trends

Abstract

This paper shows recent progress in our understanding of climate variability and trends in the Amazon region, and how these interact with land use change. The review includes an overview of up-to-date information on climate and hydrological variability, and on warming trends in Amazonia, which reached 0.6-0.7 • C over the last 40 years, with 2016 as the warmest year since at least 1950 (0.9 • C + 0.3 • C). We focus on local and remote drivers of climate variability and change. We review the impacts of these drivers on the length of dry season, the role of the forest in climate and carbon cycles, the resilience of the forest, the risk of fires and biomass burning, and the potential "die back" of the Amazon forests if surpassing a "tipping point". The role of the Amazon in moisture recycling and transport is also investigated, and a review of model development for climate change projections in the region is included. In sum, future sustainability of the Amazonian forests and its many services requires management strategies that consider the likelihood of multi-year droughts superimposed on a continued warming trend. Science has assembled enough knowledge to underline the global and regional importance of an intact Amazon region that can support policymaking and to keep this sensitive ecosystem functioning. This major challenge requires substantial resources and strategic cross-national planning, and a unique blend of expertise and capacities established in Amazon countries and from international collaboration. This also highlights the role of deforestation control in support of policy for mitigation options as established in the Paris Agreement of 2015.

Future Climate and Land Use Change Impacts on River Flows in the Tapajós Basin in the Brazilian Amazon

“…These trends were also identified for the historical period (Marengo et al, 2018;Sorribas et al, 2016), while drier conditions in line with the results illustrated in this study were projected for the eastern Amazon using an ensemble of five CMIP5 model outputs (Sorribas et al, 2016). These trends were also identified for the historical period (Marengo et al, 2018;Sorribas et al, 2016), while drier conditions in line with the results illustrated in this study were projected for the eastern Amazon using an ensemble of five CMIP5 model outputs (Sorribas et al, 2016).…”

“…The majority of this forest loss occurred between 1990 and 2005, the period of major expansion of agriculture in the Brazilian states of Mato Grosso, Rondonia, and Pará (Aragão et al, 2014;Lapola et al, 2013;Davidson et al, 2012;Lemos & de Silva, 2011;Soares-Filho et al, 2006;). However, the demand for land and natural resources in the Amazon area remains high and deforestation rates increased again after 2014 (Marengo et al, 2018), as governance measures were not maintained (Lapola et al, 2013;Rochedo et al, 2018). However, the demand for land and natural resources in the Amazon area remains high and deforestation rates increased again after 2014 (Marengo et al, 2018), as governance measures were not maintained (Lapola et al, 2013;Rochedo et al, 2018).…”

“…Changes in land use, land cover, and climate all threaten the environmental integrity of the broader Amazon (Aragão et al, 2014;Barlow et al, 2016;Marengo et al, 2018) and with this the water cycle of the region (Nobre et al, 2016). The combined effects of agricultural expansion, forest degradation, and climate change are expected to affect the region's hydrology and impact water-related sectors (Malhi et al, 2008).…”

“…In the first decade of the 21st century, the Brazilian government implemented actions to minimize the deforestation rates through new regulations and monitoring strategies (Lapola et al, 2013;Nepstad et al, 2014), which have been effective, substantially reducing the rate of deforestation in the past decade. However, the demand for land and natural resources in the Amazon area remains high and deforestation rates increased again after 2014 (Marengo et al, 2018), as governance measures were not maintained (Lapola et al, 2013;Rochedo et al, 2018). Brazil is among the top world producers of soybean, corn, and cattle, with substantially low efficiency in terms of production per unit of area (Battisti et al, 2018;Cohn et al, 2014;FAO n.d.).…”

“…The future extent and composition of the Amazon forest will be determined by decisions made both at local scales, in terms of land use and development of the area, and at global scales, in terms of climate change mitigation (Aragão et al, 2018 and2014;Kruijt et al, 2014;Lapola et al, 2013;Marengo et al, 2018;Nepstad et al, 2014;Sampaio et al, 2018;Soares-Filho et al, 2006). Overall, the level of uncertainty with the Amazon's future is high: the direct effects of climate and land use change on tropical forest ecosystems are not well understood, and in addition, the net response also depends on complex biosphere-atmosphere feedback mechanisms between the ecosystem and the region's climate (e.g., Aragão et al, 2014;Cox et al, 2004;Swann et al, 2015;Zhang et al, 2015).…”