for National Geographic News
Thousands of people around the world have loaned the unused power of their personal computers to help scientists model Earth's past and future climate.
The project aims to illuminate the range of possible climate changes in the 21st century. Results so far suggest Earth's climatologic future is even more uncertain than previously believed.
"We've just started down the road to understanding uncertainty in climate change. This has not really been dealt with before," said David Stainforth, a climate physicist at Oxford University in England and chief scientist for the climateprediction.net project.
The initiative is helping scientists understand the complexity and chaos of global climate in a way that supercomputers cannot. Supercomputers typically run single versions of a state-of-the-art, software climate model, known as a general circulation model, or GCM.
GCMs are designed to represent, as accurately as possible, every aspect of Earth's climate system. The programs can represent some aspects accurately. But others, such as how quickly cloud droplets convert to rain, can only be estimated.
Given the chaotic nature of the climate system, where such estimates fall could determine, for example, how long a drought may last in Africa.
There are approximately ten GCMs in the world, according to Stainforth. He said that since climate scientists tend to collaborate, their models tend to be similar. For example, the researchers' estimates of variables, such as the cloud-to-rain threshold, cluster around what seems most probable.
"That's not a surprise. It's probably a sensible thing to do. When you only have one model, you want to make it the best you can. And to some extent that means making it similar to other models," Stainforth said. "But we don't care about that. We just want to explore what the models can do. We'll rule out the [scenarios] that aren't realistic or sensible."
To explore the range of climate possibilities, the climateprediction.net project uses the excess capacity of thousands of personal computers around the world to run unique versions of a GCM. Each version contains slight tweaks to variables that scientists know have a range of possibilities.
This allows climate scientists with the project to explore how climate may change in the next century under thousands of potential climate scenarios.
The project is based on the same distributed-computing technology as the popular SETI@home project. In the SETI (Search for Extraterrestrial Intelligence) case, millions of people have downloaded, via the Internet, a software program to help space scientists listen for radio signals beamed at Earth from extraterrestrial beings, should such a thing occur.
SOURCES AND RELATED WEB SITES