Spring 2011

Dialogue | What can you say to people who dismiss global warming when it is frigid or snowing heavily?

A few snowstorms or a cold snap during a short period of time do not prove much about climate change; they are simply the weather experienced in a specific location at a specific time. Climate, on the other hand, is the prevailing conditions—such as average temperature, precipitation, wind, humidity, and atmospheric pressure—observed over decades.

Climate data show that global warming is already having profound effects on precipitation patterns, intensifying rain or snowfall in places accustomed to such precipitation, while decreasing precipitation in areas or times of the year that typically receive little. Ironically, this can lead to both drought and flooding at different times of year in the same location.

Climate observations over the past decades also show that precipitation changes can vary greatly by region. For example, warmer temperatures that have decreased ice cover on the Great Lakes generate heavier “lake-effect” snowstorms because the exposed lake water releases more moisture into the atmosphere. Many other U.S. locations, however, have seen a decline in the total land area covered with at least a dusting of snow for more than 30 days.

These impacts are likely to become even more pronounced in the decades ahead if heat-trapping emissions continue unabated. To learn more about our efforts to address global warming and its risks, visit the UCS website at Climate 2030: A National Blueprint for a Clean Energy Economy.