Forecasting Climate

Words on Weather and Climate — December 16, 2010

December 16, 2010 // 0 Comments

Forecasting Climate  by CRAIG JAMES  When it comes to forecasting the climate, many people say that since forecasters can’t get the weather forecast right for the next couple of days, how can they get the climate forecast right for the next 100 years? (They surely weren’t talking about my forecasts, were they?) The response given by the climate alarmists is that they don’t have to forecast each day’s weather correctly. Over time, the weather averages out and just predicting the long-term trend of warmer or colder is not as difficult as predicting how much snow will fall from the next snowstorm. Therefore, we can have confidence in the climate forecasts out to the year 2100 and beyond. I don’t buy into that response and here’s why. We pretty much know and understand all of the physics behind the atmospheric processes that control the short-term weather forecast. We can even construct computer models that do a fairly good job of representing how the atmosphere works over short time periods using the seven basic mathematical equations of motion for fluids. There are some approximations that have to be made when using these equations, but they work fairly well out to a couple of days. However, they do start to break down as they are run forward in time due to a lack of sufficient data and the inherent chaos of the atmosphere. Once we get out beyond a couple of days, there are additional complicated forces that begin to have an impact on the forecasts, and it is these forces we don’t understand very well and can’t even begin to adequately model in our computers. These natural forces include such things as whether the Atlantic or Pacific oceans are in their cold or warm phase, whether there is an El Niño or La Niña in progress, how temperature changes affect cloud cover, cooling or warming from aerosols, solar influences, and many others. An example of a natural force that over a long period of time affects the motion of fluids but has no effect in the short term is the Coriolis effect. The Coriolis effect is what causes our winds to rotate counter-clockwise around a low-pressure system in the northern hemisphere and just the opposite, or clockwise, in […]