A recent report published in the Bulletin of the American Meteorological Society suggests that heat waves worldwide in 2013 were directly attributed to human-caused change. However, the same study also claims that the connection between climate change and other extreme weather events is not so evident.
The “Explaining Extreme Events of 2013 From a Climate Perspective” peer-reviewed report examined 16 different extreme events occurring on four continents. It includes 22 separate analyses conducted by distinct groups of scientists from the United States and Britain.
“Being able to physically understand extreme events is absolutely critical for our ability to predict future extreme weather and understand our role in changing the climate.”
Thomas R. Karl, director of NOAA (National Climatic Data Center) stated in a press briefing. While he explained that extreme events are often caused by multiple factors and that they are complex occurrences, he also noted that heat extremes were clearly connected to human influences on the climate.
Storms and Rains
Storms and precipitations are two different categories, however, where scientists need to be very careful, Karl noted. For instance, the five day heavy rain and flooding that struck Boulder, Colorado. Researchers explain that they initially believed it to have fitted the picture of climate change: the warmer atmosphere can hold more water than it used to so heavy rains occur more often. But this is not the case in northeastern Colorado, the BAMS report by Martin Hoerling (NOAA Boulder lab) shows. He and his colleagues compared the human-warmed climate to the pre-industrial climate that must have existed in the region and observed that there was no increase in the likelihood of exceptional rain events. They said that in September 1938, a similar one had hit the same region.
Hotter Heat Waves
Scientists contributing to the report observed five major heat waves that struck different areas in 2013: Europe, China, Korea, Japan and Australia. According to their findings, human-caused climate change (through fossil fuel burning) had been found to clearly increase the severity and the likelihood of those events.
Peter Stott, a report co-editor explained that research teams had also analytically approached the Australia heat-wave and their results were striking.
“They found the chances of observing such extreme temperatures in a world without anthropogenic [human-caused] climate change is almost impossible,”
Science is also progressing where extreme precipitation- or lack thereof- is concerned. Hoerling stated that researchers were getting closer, but that they can’t yet make definitive statements.