Dear Tom,
If the reliability of weather forecasts diminishes rapidly beyond seven days, how can forecasts of global warming 100 years hence have any validity?
-- Robert J. Roeder, Des Plaines
Dear Robert,
Weather and climate are quite different. A weather forecast predicts the details of day-to-day weather, a process in which small errors grow as the forecast advances in time. These errors eventually overwhelm the accuracy, especially in predicting small-scale features of evolving weather patterns. Climate, however, is average weather over a period of decades or more. A number of the mechanisms that produce large scale alterations in the climate are quite well understood making predictions of climate change possible. Studies have shown that climate models using weather observations from decades ago can accurately predict changes up to the present.
If the reliability of weather forecasts diminishes rapidly beyond seven days, how can forecasts of global warming 100 years hence have any validity?
-- Robert J. Roeder, Des Plaines
Dear Robert,
Weather and climate are quite different. A weather forecast predicts the details of day-to-day weather, a process in which small errors grow as the forecast advances in time. These errors eventually overwhelm the accuracy, especially in predicting small-scale features of evolving weather patterns. Climate, however, is average weather over a period of decades or more. A number of the mechanisms that produce large scale alterations in the climate are quite well understood making predictions of climate change possible. Studies have shown that climate models using weather observations from decades ago can accurately predict changes up to the present.
