A drier tomorrow? New study predicts less rain across planet

Expect things to get drier.  That's the alarming conclusion of a new study that projects large swaths of the Earth--including the Amazon, Central America, and Indonesia--to have fewer days with rainfall in the future.

No smoking, please.... (photo by Jedediah Brodie)

Precipitation is a notoriously difficult thing to predict.  For instance, different global circulation models--supercomputer simulations of future climates--often make wildly varying predictions about future rainfall.

But the new study, which seems surprisingly robust, focuses on how changing climates could affect daily rainfall in the future.  It finds that rainforests and Mediterranean ecosystems could have as many as 30 fewer days of rainfall each year.

In many parts of the world, such changes could lead to major tipping points.  For instance, large expanses of the tropics support rainforests that suffer periodic droughts and are already near their environmental limits.

The big worry is that declining rainfall could interact with rampant land-use change--such as habitat fragmentation, logging, and slash-and-burn farming--to create massive wildfires. 

In the late 1980s, for instance, wildfires scorched millions of hectares of forest in the Amazon and Borneo. 

The one-two punch of drought and human land-use change was fatal for many forests.