MIT News: ...According to new research from MIT, the most recent global climate report fails to capture trends in Arctic sea-ice thinning and drift, and in some cases substantially underestimates these trends. The Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report, released in 2007, forecasts an ice-free Arctic summer by the year 2100, among other predictions. But Pierre Rampal, a postdoc in the Department of Earth, Atmosphere, and Planetary Sciences (EAPS), and colleagues say it may happen several decades earlier.
...After comparing IPCC models with actual data, Rampal and his collaborators concluded that the forecasts were significantly off: Arctic sea ice is thinning, on average, four times faster than the models say, and it’s drifting twice as quickly.
...Part of the problem, Rampal says, may be inadequate modeling of mechanical forces acting on and within the ice in the Arctic basin. Thus far, the IPCC models have largely focused on temperature fluctuations, which are one way to lose or gain ice. But according to Rampal, mechanics can be just as important: Forces such as wind and ocean currents batter the ice, causing it to break up. Ice that’s in small pieces behaves differently than ice in one large mass, which affects its overall volume and surface area. “If you make a mistake at this level of the model, you can expect that you are missing something very important,” Rampal says.
...Because “everything is coupled” in these intricate feedback loops, “it’s hard to predict the future of Arctic sea ice,” Rampal says. Doing so will require more thorough modeling and real-world observations, especially of mechanical forces and other ice phenomena that have been poorly understood. Rampal is now working on a project with researchers at MIT and NASA’s Jet Propulsion Laboratory, whose goal is to combine models and observations for a more accurate picture of the state of the world’s oceans....
William Bradford's 1875 painting, "Ice dwellers watching the invaders"
No comments:
Post a Comment