Abstract
AbstractWe describe a climate mode synchronizing forest carbon losses from North and South America by analyzing time series of tropical North Atlantic sea surface temperatures (SSTs), landfall hurricanes and tropical storms, and Amazon fires during 1995–2013. Years with anomalously high tropical North Atlantic SSTs during March–June were often followed by a more active hurricane season and a larger number of satellite‐detected fires in the southern Amazon during June–November. The relationship between North Atlantic tropical cyclones and southern Amazon fires (r = 0.61, p < 0.003) was stronger than links between SSTs and either cyclones or fires alone, suggesting that fires and tropical cyclones were directly coupled to the same underlying atmospheric dynamics governing tropical moisture redistribution. These relationships help explain why seasonal outlook forecasts for hurricanes and Amazon fires both failed in 2013 and may enable the design of improved early warning systems for drought and fire in Amazon forests.
Highlights
Forests in eastern North America, Central America, and the Amazon region of South America cover more than 1 billion hectares and store more than 160 petagrams (Pg) of carbon in living biomass [Pan et al, 2011]
We describe a climate mode synchronizing forest carbon losses from North and South America by analyzing time series of tropical North Atlantic sea surface temperatures (SSTs), landfall hurricanes and tropical storms, and Amazon fires during 1995–2013
Tropical North Atlantic SSTs during spring and early summer were correlated with the number of landfall tropical cyclones reaching hurricane status and accumulated cyclone energy index (ACE) over land
Summary
Forests in eastern North America, Central America, and the Amazon region of South America cover more than 1 billion hectares and store more than 160 petagrams (Pg) of carbon in living biomass [Pan et al, 2011]. Warmer North Atlantic SSTs (relative to South Atlantic SSTs) during the boreal spring tend to modify the atmospheric circulation by shifting the intertropical convergence zone (ITCZ) to the north, thereby reducing tropical North Atlantic easterlies and moisture transport from ocean to land [Yoon and Zeng, 2010] This shift in circulation decreases precipitation and terrestrial water storage during the middle to the end of the wet season and limits evapotranspiration (ET) fluxes during the following dry season. We investigate the hypothesis that landfall tropical cyclones (including hurricanes and tropical storms) in North and Central America and fires in the southern Amazon are positively correlated because of their shared linkages to ocean-atmosphere interactions in the North Atlantic We assessed how this relationship may lead to an interhemispheric synchronization of forest carbon losses on seasonal and interannual time scales using SST, tropical cyclone, and fire time series. Our analysis may help to explain why seasonal outlook forecasts for hurricanes and Amazon fire risk simultaneously failed in 2013 and has implications for continental scale forest conservation efforts as climate change accelerates
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