According to a recent report from the National Oceanic and Atmospheric Administration (NOAA), the past 8 months have been the most extreme in US weather history.
The above chart shows past observations of extreme weather based on NOAA’s climate extremes index which tracks weather extremes from drought, precipitation, and temperature. And it indicates that this year has been the most extreme in the record by a substantial margin.
The fact that this new extreme weather record has been broken a full four months before the end of the year means that the index value for 2012 is likely to rise even higher before the end of this year.
Looking at weather trend information shown in the graph, it becomes clear that weather extremes have been steadily increasing since the 1970s with a big jump in the 2000s and a very sharp uptick at the beginning of this decade. Average weather for the past three years has now been twice as violent, according to the index, as any other three year period since record keeping began.
This sharp increase in extreme weather events comes as consensus builds among scientists that global warming is the primary driver of extreme weather. Just this year, the IPCC, NOAA, and NASA all established a strong link between extreme weather and global warming. In addition, a report in the Geophysical Research Letters shows how sea ice melt enables the formation of powerful blocking patterns that contribute to extreme weather events. Finally, the World Meteorological Organization came out with its strongest statement yet on global warming induced extreme events.
A recent interview with NASA scientist James Hansen on PBS provides a good basis for understanding why and how weather has gotten so extreme over recent years.
“In fact, [climate change] has now driven our climate outside the range that has existed the last 10,000 years…”