Climate Change

Recent weather events such as deadly heat waves and devastating floods have sparked popular interest in understanding the role of global warming in driving extreme weather. These events are part of a new pattern of more extreme weather across the globe, shaped in part by human-induced climate change.

As the climate has warmed, some types of extreme weather have become more frequent and severe in recent decades, with increases in extreme heat, intense precipitation, and drought. Heat waves are longer and hotter. Heavy rains and flooding are more frequent. In a wide swing between extremes, drought, too, is more intense and more widespread.

All weather events are now influenced by climate change because all weather now develops in a different environment than before. While natural variability continues to play a key role in extreme weather, climate change has shifted the odds and changed the natural limits, making certain types of extreme weather more frequent and more intense. The kinds of extreme weather events that would be expected to occur more often in a warming world are indeed increasing.

For example, 60 years ago in the continental United States, the number of new record high temperatures recorded around the country each year was roughly equal to the number of new record lows. Now, the number of new record highs recorded each year is twice the number of new record lows, a signature of a warming climate, and a clear example of its impact on extreme weather.1

The increase in record highs extends outside the U.S. as well. A similar two to one ratio of record highs to record lows recently has been observed in Australia.2 Over the past decade, 75 counties set all-time record highs but only 15 countries set all-time record lows. In 2010, 19 countries set new all-time record high temperatures, but not a single country set a new all-time record low (among those countries keeping these statistics). 3

- See more at: http://www.climatecommunication.org/new/features/extreme-weather/overview/#sthash.oVb0bEPt.d