Recently, NRDC published a report explaining the potential water-related impacts of climate change on U.S. cities. The projected impacts include, among other things, more frequent and intense storm events. Now, some scientists say the effects of climate change are already contributing to more extreme weather events in the U.S. and elsewhere. Climate scientists from NCAR, Scripps and Weather Underground discussed their findings on a conference call today. Most of what was covered in the call can be found on the Climate Communication website.
As we have all seen, extreme weather events, such as blizzards, tornadoes, flooding, droughts, heat waves, and tropical storms, have occurred within the past few years both in the U.S. and across the globe. Scientists say record-breaking extremes are occurring as heat-trapping gases allow the atmosphere to warm and hold more moisture, which provides fuel to these events. They say the relatively small observed increase in average temperature over the 20th century (about 1°C) is causing large changes in extreme events.
Because human [industrial] activity has changed the background environment in which weather events develop, they have concluded that climate change is now a component of all weather events—on the scale of 5 to 10 percent. For example, analysis indicates that precipitation from Hurricane Katrina in 2005 was greater by 6 to 8 percent due to climate change, which may not seem that much but is equivalent to an additional inch of rain on top of a foot.