Abstract:
Eastern South America can experience severe droughts that are accompanied by heatwaves as well as marine heatwaves in the western South Atlantic. Here, we show that these multivariate events have the same driver and modulator. Tropical convection in the Indian and Pacific oceans can cause persistent anticyclonic circulation over eastern South America that not only leads to severe droughts and heatwaves but also generates marine heatwaves in the adjacent ocean. The anomalous anticyclonic circulation prevents synoptic systems reaching the region while inhibiting the development of the South Atlantic Convergence Zone and its associated rainfall in austral summer. Increased shortwave radiation due to reduced cloud cover and reduced ocean heat loss from weaker winds are the main contributors to the establishment of marine heatwaves in the region. The proposed mechanism, which involves atmospheric blocking and droughts, explains approximately 60% of the heatwaves over land and marine heatwaves in the western South Atlantic. Their impacts include water and power shortages in southeast Brazil, a region that is heavily populated, home to more than 80 million people, and responsible for 60% of the Brazilian gross domestic product. They can reduce Brazilian soy, coffee and sugarcane production, impacting food supplies globally and increasing worldwide prices. They decrease the production of oysters and the catch of some commercially important fish species, while decimating clams along the southern coast of Brazil. They can affect human health by driving dengue fever outbreaks in urban areas. In addition, these compound events degrade ecosystems causing loss of land and marine biodiversity.
Author Bio:
Regina R. Rodrigues is a professor of Physical Oceanography at the Federal University of Santa Catarina (UFSC), Brazil. Before joining UFSC in 2010, she received her PhD from the Graduate School of Oceanography, University of Rhode Island and work for NOAA in the USA. She was Reviewer Editor of the IPCC Special Report on Climate Change and Land (SRCCL). Currently she is member of the CLIVAR Atlantic Region Panel and external editor of Nature new journal Communication Earth & Environment. Her research focus on understanding how tropical ocean basins interact and affect the extra-tropics leading to extreme events, using observations and modelling. Her research has also focused on the impacts of ENSO variability on the climate of South America and the Tropical Atlantic. More recently she has her attention on the physical mechanisms generating compound extreme events of droughts, land and marine heatwaves.
This seminar will be hosted online through Microsoft Teams, contact Philipp Breul for more information