Drought in the Amazon May Not Be Over

Jim Giles has a story in last week’s Nature (sub. req.) pointing to some preliminary work linking warm Atlantic temperatures to last year’s devastating Amazon drought:

The drought first caught scientists’ interest because its cause was unusual. Dry spells in the Amazon usually occur in El Niño years, when warm water off the Pacific coast of South America sets up a pattern of circulating air that inhibits rainfall in the Amazon. But last year was not an El Niño year.

Instead, the drought was caused by a circulation pattern powered by warm seas in the Atlantic — the same phenomenon responsible for last year’s unusually intense Atlantic hurricane season. The result was a dry spell that hit particularly hard in the western Amazon, a region that normally has more rainfall than other parts of the forest.

Giles points to some interesting modeling work by Peter Cox that had predicted more frequent droughts in the future because of warmer Atlantic waters. At the time Cox published the work, people didn’t take it seriously, according to Giles, because the warm Atlantic-drought thing hadn’t been seen before. Cox is apparently being taken a bit more seriously.