July 11, 2012
Extreme Weather Tied To Global Warming
Lawrence LeBlond for redOrbit.com - Your Universe Online
Global warming could be leading to extreme weather events in several areas around the world, but in some areas scientists have not been able to find any link between the two at all, according to new analyses released Tuesday.
Record heat waves in the UK, extreme flooding in Russia, and record drought in Texas, may have been the result of climate change, yet researchers are stopping short of blaming any single event on global warming.
The analyses come from the latest State of the Climate report, released by the National Oceanic and Atmospheric Administration (NOAA). While researchers cannot directly tie global warming to any single weather event, they do however, assess how climate change has altered the odds of such events occurring.
In the analysis of Texas´ record-breaking drought, Oregon State University researchers noted that the region suffered record heat in 2011. They contribute the heat and dryness to the La Nina weather pattern, which was produced by the cooling of the central Pacific Ocean. La Nina generally cools global temperatures but actually makes temperatures in the southern US considerably warmer and drier than usual.
By studying computer models for years with La Nina patterns, the OSU team found three years in the 1960s in Texas where the conditions were similar to the 2008 season. Due to lack of simulation data for the 2011 season, the team used the last dry period of 2008 as a basis.
The study was done to check the likelihood of such a heat wave both before and after there was a lot of man-made climate change, which primarily comes from the burning of fossil fuels like coal and oil. They concluded that global warming has made such a Texas heat wave about 20 times more likely to occur in a year with a La Nina pattern.
Oxford University researchers used a similar approach for analysis of the near-record heat seen in England last November, followed by the second coldest streak just a month later. Working with the British government, the Oxford team concluded that global warming could have made such a warm November 62 times more likely to occur, and half as likely to make such a cold December.
Kevin Trenberth, of the National Center for Atmospheric Research (NCAR), said the findings in the British study was reasonable, despite using a flawed climate model. He also noted that the Texas analysis could be a likely “underestimate” and could probably be increased.
While researchers were able to find evidence indicating a link between global warming and the Texas and UK weather events, there was a much different scenario in some regions, such as central and southern Thailand. There, researchers found no clear sign that climate change played a major role in the weather patterns. The scale of flooding was influenced more by factors like poor reservoir operations, said researchers.
“While we didn't find that climate change has affected the odds of all the extreme weather events we looked at, we did see that some events were significantly more likely. Overall, we're seeing that human influence is having a marked impact on some types of extreme weather,” Peter Stott of the UK´s Met Office and co-editor of the research, told The Independent.
Tying in with the research, the NOAA released its report on the climate for 2011, which included several statistics similar to what it had announced earlier.
Interestingly enough, 2011 was the coolest year since 2008 in terms of global average temperature, which was about 57.9 degrees Fahrenheit. Still, it remained among the 15 warmest years since records first began being kept (in the late 1800s), according to the NOAA.
Although researchers cannot easily find causal links between weather patterns and global climate change, Stott noted that recent research was evidence that “science has moved on.”