As climate changes,
so must the tools to model it
(page 2 of 4)
And including those small components is vital. “We just don’t have a clear understanding of how very fine-scale processes affect the large-scale climate,” says Ben Kirtman, professor of meteorology and physical oceanography at the University of Miami.
Take, for example, hurricanes. “When we do climate-change research, we use models that don’t produce hurricanes,” Kirtman says. “They produce stuff kind of like hurricanes but not really.” Part of the difference is that hurricanes transport heat upward, and today’s climate-change models “don’t simulate that heat motion correctly.”
Ocean features also could stand some improvement. At present, ocean models “don’t capture how eddies work because the models don’t resolve them,” Kirtman says. This shortcoming creates errors that require large numbers of repetitious simulations to resolve.
With exascale computing, Kirtman says, climate-change models can start to resolve physical properties like ocean eddies – and potentially resolve hurricanes. He and colleagues are studying eddies and how they transport heat from the tropics to the United States. These eddies maintain the Gulf Stream. “Until we get exascale,” he says, “we need lots of years of simulations” to model how these eddies affect heat transfer.
Even with exascale power, climate-change models will not replace weather models for simulating individual hurricanes. Still, exascale computing could help researchers forecast an active hurricane period, explain the relationship between sea ice and hurricane intensity, or predict how carbon dioxide levels in 50 years could affect hurricane patterns.
James J. Hack, director of the National Center for Computational Sciences and the Oak Ridge Climate Change Science Institute, says researchers also need a better understanding of the entire climate system. A couple degrees of global average temperature increase in 2100 might not seem like much to most people, but it could trigger 10-15 degrees of change in some areas.
“That may move storm tracks,” Hack says. “For example, it could trigger large stationary wave patterns in the atmosphere that could set up and sit there for a long time, leading to heat waves.”