Are the unusual or extreme weather events in my area caused by global warming?
Individual weather events, such as Hurricane Katrina or the European heat wave of 2003, are caused by a combination of factors, and teasing out the blame owed to natural variability and human-caused global warming is difficult. Climate does not directly dictate specific weather events. Rather, climate sets up a range of possibilities and a “range of likelihoods” for weather events. As climate warms, heat waves, droughts, and severe storms will probably become more likely. But it is not possible to say that any individual heat wave, drought, or storm occurred solely “because of global warming.” A good example of the complexity is the European heat wave of 2003, in which an estimated 22,000 to 45,000 heat-related deaths occurred in August. This heat wave resulted in part from a high-pressure system linked to clear skies and dry soils, which allowed more solar energy than normal to warm the land surface. Therefore, natural events beyond human control played a large role in this heat wave.
