Could Ecosystem Change over Amazonia Influence Climate over North America?

Abstract:

Earth system model experiments suggest that ecosystem changes in the Northern Hemisphere could influence climate over the Southern Hemisphere, or vice versa. In reality, whether an ecosystem change could have a detectable influence on climate variability in remote regions is not clear. Direct validation of such an influence based on available climate records is not feasible largely because we cannot isolate the influences of ecosystems from more dominant sources of climate variability from ocean and atmosphere. However, our observational analysis suggests that the variability of wet season onset over the Amazonia, which is significantly influenced by evapotranspiration of the rainforest, could influence the demise of the North American monsoon. Such a remote influence appears to be carried out by the influence of the Amazonia rainfall on the cross-equatorial flow and latitudinal propagation of the atmospheric waves, which in turn, influence wind and moisture transport over the North American monsoon region. These results suggest that perhaps the future reduction of evapotranspiration due to CO₂ fertilization and large-scale land use over the Amazonia will not only delay the wet season onset over this region, but also impact the demise of the North American monsoon.