A handful of studies published by the Bulletin of the American Meteorological Society on Tuesday draw a direct link between human-caused climate change and last year's heat waves in Australia.
That means scientists were able to calculate how much human actions influenced a specific weather event, beyond any natural factors.
"It is perhaps the most definitive statement climate scientists have made tying a specific weather event to global warming,"Justin Gillis at The New York Times writes of the finding's significance.
For this study, five different research groups looked at factors related to record heat in Australia in 2013, NOAA said. All teams concluded that natural variability could not account for record-breaking temperatures alone. According to one computer model "the fraction of risk of these extreme events attributable to anthropogenic forcing [human factors] was 100% or close to 100%."
The evidence linking climate change to other extreme weather events — including droughts, heavy rain, and storms — was not as cut-and-dried.
"The influence of human-caused climate change on these kinds of events was sometimes evident, but often less clear, suggesting natural factors played a far more dominant role," NOAA writes.
Sixteen extreme weather events in North American, Europe, Asia, and Australia, were analyzed for the report, "Explaining Extreme Events of 2013 from a Climate Perspective."
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