Wildfires are not limited to the western U.S. At the moment, the Pantanal is burning at a record rate as well. The Pantanal is a massive tropical wetland, the largest in the world. It lies in Brazil, Bolivia, and Paraguay, and is the size of Washington state. Apparently its biodiversity rivals the Amazon rainforest; it has megafauna like jaguars, capybaras, caimans and anacondas, along with the many insects and birds and fish that one would expect in marshes. The flora must be spectacular.
Seasonal rains flood the area, transforming the ground into swampy grassland. Such a dramatic annual sequence reminds me of the Okavango Delta in Botswana, where a similar flooding event vitalizes the local ecosystem. I wondered how this terrain could catch fire.
The culprit, from what I understand, is the Atlantic Multidecadal Oscillation (AMO). This phenomenon involves the movement of warm and cool water in the Atlantic Ocean, similar to El Nino in the Pacific Ocean. Heated equatorial waters move north, then chilled temperate waters move south. This changes sea surface temperature, which influences rainfall and climate. These cycles are long-term; I've seen estimates ranging from 30 to 80 year cycles, much longer than El Nino or La Nina cycles. We are currently in a warm phase, which is fueling drought in South America by pulling moisture north of the equator (more hurricanes north, more fires south). How climate change impacts this natural variation remains to be seen.
Another interesting ocean system related to AMO is the Atlantic Meridional Overturning Circulation (AMOC). Info on that can be found here. These grand complexes, influenced by volcanoes and planetary motion and greenhouse gases and sea ice and salinity and time and many others things we don't even know are connected, invisibly shape the world around us. They are omnipresent, and in some ways omnipotent.
No comments:
Post a Comment