More than two dozen papers analyzing extreme weather events in from were published on Monday, September 29th in the Bulletin of the American Meteorological Society. This annual weather retrospective has become an increasingly big deal in the world of meteorology as scientists try to answer the question: Are these extreme weather events related ti human climate change?
In many cases, weather scientists were actually able to rule out human influence having any significant impact in causing some extreme weather events, but scientists were able establish strong statistical links between human impact and other extreme weather events such as the record 2013 Australian hear wave and drought.
Some extreme weather events not linked to human climate change
The growing amount of weather data available and improved software modeling techniques led researchers to determine that a number of extreme weather events in 2013 were not human climate change. The fact that the overall global warming trend has been definitively linked to human-related emissions in scores of papers is not at issue here. The fact that mankind contributes significantly to climate change is clearly established, but research claiming specific weather events are linked to human activity is often not well grounded.
For example, one group of scientists determined that the type of extreme rainfall that struck parts of Colorado last September had actually become less likely, rather more likely, in our warming climate. Other meteorological researchers reported there was no reliable evidence that the heavy rains and floods that hit much of Central Europe in June of 2103 were related to global warming.
Extreme heat events in 2013 clearly related to human impact
The new batch of studies was able to definitively connect human impact to a number of global extreme heat events in 2013. The research showed that extreme heat events in Australia, and also in Europe, China, Japan and Korea, were highly correlated with human climate change. In fact, the researchers determined in every case that global warming had made the extreme heat events more likely.
In the Australian case, supercomputers analyze what the climate would likely be in the absence of human emissions. No matter how they modeled the data, were unable to produce a year as extreme as 2013, and other analytical methods yielded similar answers. Furthermore, sophisticated big data analyses taking into greenhouse gases and the warming they are causing showed a greater likelihood of extreme heat waves in Australia.
“Five reports all showing the same thing is a very powerful signal,” explained Thomas C. Peterson, principal scientist at the National Climatic Data Center in Asheville, N.C., a unit of NOAA.