Colorado's legendary floods a convergence of climate factors

View of washed out road from flyover Boulder, Jefferson and Larimer Counties

flickr, SenatorMarkUdall

Last week Coloradan communities experienced what has become chillingly common in America: an extreme weather event that left hundreds of homes destroyed and hundreds of people unaccounted for. 

Many have already called this storm a 1,000-year event, which means that there is a 1-in-1000 chance of a similar event happening in any given year. Historically, flash floods are periodic in this region, but this year's was far beyond any that have occurred in recent memory. For example, Boulder received half a year’s worth of rain in over just a few days, an average of 8 to 10 inches per 24-hour period.

View pictures of areas affected below:


Even more surprising is that the precipitation came on the tail end of a summer-long drought, conditions that have become typical for this region. Dry weather contributed to additional tragedy earlier this year - catastrophic wildfires.

These phenomena are related, all a part of the ongoing picture of how climate is changing across the nation. Scientists agree that climate change is a global reality, and many assert that it is related to extreme weather events. It will take time to gather and analyze evidence to relate it directly to floods in Colorado.

Still, it is known that increasing air and ocean temperatures cause more water vapor, which can generate extremes in precipitation. Most of the U.S. has been seeing increases in extreme precipitation events, a trend expected to continue, according to a National Climate Assessment report released in January.

Satellite loop of water vapor on Sept. 12, 2013. Credit: University of Wisconsin’s Cooperative Institute for Meteorological Satellite Studies

Colorado's extreme weather event was at least in part the result of higher temperatures. Heat waves had blocked moisture coming from the Gulf of Mexico for months, worsening a storm system that grew and hovered over the area. The fact that the region experienced massive fires earlier this year also made flood conditions worse, because there was less vegetation to absorb the torrents of rainwater once they started. 

As communities in Colorado work to recover from these disasters, we are reminded that public lands, like Rocky Mountain National Park, have also been affected. We also know public lands can play a critical role in addressing the threat of climate change, through renewable energy and protection of the Arctic.