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Extreme Weather Events Becoming the 'New Normal'


Climate Change, Warming Temperatures, and Extreme Downpours

Extreme weather events are increasing across the nation, and around the world. As temperatures continue to rise due to human-caused influences, most notably carbon emissions, weather patterns are shifting and extreme weather events are becoming the new normal.

A recent study suggested that extreme downpours associated with a rise in the intensity of weather events could increase 400 percent. The recent study, which took a year to complete, compared data from rainfall events that occurred between 2000 and 2013, and used a climate model that allowed for the projected 9 degrees Fahrenheit temperature increase by the end of the century if carbon emissions are not contained.

Study findings

Using these simplified models and averages, findings from the study showed that actual increases will vary across different U.S. regions. The Midwest, for example, could see the least amount of increase (up to 100 percent), while regions in the South, and especially along the Gulf Coast, could see significant rainfall increases of 200 to 400 percent.

Findings also indicated that individual extreme rainfall events could increase by nearly 70 percent in certain locations. As a result, an average storm rainfall amount of 2 inches today would increase by approximately 1.5 inches under these conditions in the future, to 3.5 inches of rain.

Impacts to the nation and society

Scientists pointed out that most storms with the highest hourly rainfall occur when air temperatures reach between 68 and 77 degrees Fahrenheit, and atmospheric moisture is high. As the global temperature warms, the air will be able to hold more moisture.

With climate change impacts, storms may continue to develop and intensify up to 86 degrees Fahrenheit, because the air contains higher levels of moisture. At such high moisture levels and temperatures, the intensity of storms will increase significantly.

That means that the strongest thunderstorm experienced today, and one that might happen just one time per year, is likely to occur at least five times a year, and with an increased intensity.

Other implications

Areas of the Midwest are expected to see a decrease in moderate rain events, but experience an increase in the frequency and intensity of extreme events.

While the increased rainfall is likely to help areas currently impacted by drought conditions, other concerns arise, including impacts on the nation's infrastructure and agriculture. More intense storms that produce higher rainfall amounts over a shorter period of time will increase the chances for flooding, landslides, and debris flows, negatively impact agriculture, and place strains on infrastructure including dams and reservoirs.
