Highly Uncertain Forecasts of Future European Climate
Woollings, T. 2010. Dynamical influences on European climate: an uncertain future. Philosophical Transactions of the Royal Society A 368: 3733-3756.
The future state of climate in Europe, in particular, is of immense concern, in light of the continent's large population and the degree and extent of its built-environment. But is it possible to project the climate of Europe with any degree of certainty at the present time? Wollings (2010) declares that it is not:
"The spread between the projections of different models is particularly large over Europe, leading to a low signal-to-noise ratio. This is the first of two general reasons why European climate change must be considered especially uncertain. The other is the long list of physical processes which are very important for defining European climate in particular, but which are represented poorly in most, if not all, current climate models."
As examples of key atmospheric processes affecting the climate of Europe that models currently do not simulate well, Woollings cites several, noting that (1) the location of the Jet Stream over northern Europe in most models is divergent from reality, (2) zonal flow is biased too far south in most models, (3) the models can't simulate or explain the North Atlantic Oscillation with sufficient magnitude to match historical data, and (4) heat waves and droughts, such as the summer-of-2010 Moscow heat wave and fires, are caused by blocking, which is a process the models are currently unable to simulate.
In addition, for several key processes, the models produce widely varying predictions. The atmospheric circulation response to warming in climate models, for example, is highly variable, as is the change in storm intensity, the projected change in the jet stream, and changes in temperature. And it is particularly noteworthy that Europe is predicted to warm less than most Northern Hemisphere sites due to the slowing of the Gulf Stream providing reduced northward heat transport.
Overall, current climate models are unable to achieve the degree of accuracy in the details of atmospheric circulation that are critical to replicating current weather events, such as droughts, heat waves and major storms in Europe. Thus, any assertion that these events can be forecast 100 years in the future under a changed climate is simply false; and claims about negative impacts of climate change in Europe are based upon no specific modeling skill.