National Oceanic and Atmospheric Administration (NOAA) scientists served as three of the four lead editors on the report published by the Bulletin of the American Meteorological Society.
Of the five heat waves studied in the report, human-caused climate change – primarily through the burning of fossil fuels – was found to have clearly increased the severity and likelihood of those events. On the other hand, for other events examined, such as droughts, heavy rains and storms, fingerprinting the influence of human activity was more challenging. The influence of human-caused climate change on these kinds of events was sometimes evident, but often less detectable, suggesting natural factors played a far more dominant role.
Confidence in the role of climate change in any one event is increased when multiple groups using independent methods come to similar conclusions. For example, in this report, five independent research teams looked at specific factors related to the record heat in Australia in 2013. Each team consistently found that human-caused climate change increased the likelihood and severity of that event. However, for the California drought, which was investigated by three teams from the United States, human factors were found not to have influenced the lack of rainfall. One team found evidence that atmospheric high-pressure patterns intensified due to human causes, but the influence on the California drought remains uncertain.
Thomas R. Karl, Director of NOAA’s National Climatic Data Centre said, “The science remains challenging, but the environmental intelligence the report yields to decision-makers is invaluable and the demand is ever-growing.”