Climate change is mostly thought of as an overall warming of the planet along with localized changes and more drastic weather events. Higher high temperatures, lower low temperatures, heavier rain and snowfalls, and longer periods of drought, as well as other sharp weather events. But there could also be longer term trends that change the fundamental behavior of weather patterns, and that could have a negative impact on wind power.
Large scale wind circulation patterns are driven by the temperature difference between the poles and the temperate regions. If the poles continue to warm faster than the rest of the planet, the temperature gradient will be smaller, and that could have drastic effects on wind patterns.
However, as with all of climate change, the reality of the matter is difficult to predict. Just as global warming became a difficult term because it didn't adequately describe all the local changes, different wind studies have found conflicting results. "A 2008 report from the U.S. Climate Change Science Program (USCCSP) noted that wind power could see either “significant positive or negative effects” as a result of climate change."
Wind turbines in some locations might be less affected by this, because some winds are driven more by local conditions than by overall climate. Coastal wind turbines, for example, may be driven more by the natural thermal difference between land and water (which is why it's almost always windy at the beach). Local geography and other factors can also influence this, too. Though there is no conclusive information to say which way things are going to go, this shows how complicated not only the issue of climate change itself can be, but how far the consequences can extend.
image: Dennis Murczak for openphoto.net CC:PublicDomain
via: North American Windpower