Many factors in climate change poorly understood

Although supercomputers have helped take much of the guesswork out of weather forecasting, climate models still have a long way to go before they can establish with any degree of certainty if and how global warming is taking place. Climatologists point to a host of variable factors that must be better understood.

That is not to say that progress hasn't been made in some limited areas. Supercomputers can model well the warming effects of carbon dioxide. But other factors less well understood do not allow mankind's use of fossil fuels to be blamed for global warming, say experts.

The processes that form clouds and determine their heat-trapping effects are complex and poorly understood.

Models can account only roughly for suspended particles, whether natural or created by people – such as aerosols.

Ships supply wind data, but winds vary on scales from minutes to years – so complete data can be difficult to obtain and model.

Terrains such as mountains and coasts – which can influence regional climates – are vaguely defined in even the best global models.

In addition, such factors as deep ocean currents, ice sheets and glaciers, land vegetation and others influence weather as they interact in varying degrees.

Although American research centres once dominated climate research, they have recently fallen behind centres in other countries. By many accounts, the dominant research effort is now at the Hadley Centre for Climate Prediction and Research, located near London.

Interestingly, the U.S. National Academy of Science reports that climate research efforts in the United States were hurt in the 1990s by a U.S. Commerce Department tariff of 450 percent on Japanese supercomputers. The tariff was lifted this year, but the limitations on climate modelling caused by the lack of computer power were vexing for American scientists.

Source: Andrew C. Revkin, The Devil Is in the Details, New York Times, July 3, 2001.

For text http://www.nytimes.com/2001/07/03/science/03CLIM.html
For text Global Warming http://www.ncpa.org/hotlines/global/gwhot.html


FMF\10 July 2001