Were 2013 floods caused by climate change? No seems to be the answer
Human fingerprints were not evident in the floods along Colorado’s Front Range in September 2013—at least not clearly.
“Because human changes have made the global atmosphere warmer and more moist, one can confidently state that all weather events are now subject to some influence of anthropogenic climate change,” says “Climate Change in Colorado.” A warmer atmosphere can hold more water, and the global atmosphere is estimated to have 3 to 5 percent more water as a result of anthropogenic, or human-caused, warming.
That alone “may have increased the source moisture for the event and increased the intensity of heavy rainfall,” the report adds.
But the weather pattern in September 2013 that dumped up to 18 inches of rainfall across portions of the Colorado foothills “was rare but not unprecedented, and climate change does not need to be involved to explain the pattern itself … The historical record strongly suggests that a flood event of the extent and magnitude of September 2013 could occur even in the absence of climate change.”
A report examining the link between anthropogenic warming and the 2013 floods is to be published by the Bulletin of the American Meteorological Society, but the conclusions there are not expected to conflict with these findings.