Friday, 30 June 2017

Record Breaking Heat Wave Due to Man-Made Climate Change

Phew! June was a scorcher. The month of June 2017 was marked by high temperatures across Western Europe with heat waves triggering national heat-health plans and wildfires requiring evacuation in Portugal and Spain.

Record breaking heat gripped most of western Europe with mean temperatures 3 degrees above ‘normal’. England experienced the hottest June day since 1975. Belgium imposed water rationing because of record temperatures. In Switzerland a heat wave warning was issued, and in France and the Netherlands heat action plans were triggered.

France experienced the hottest June night ever recorded as the average nighttime temperature reached ​26.4 degrees Celsius on June 21st. Switzerland saw the second hottest day on record since records began in 1864. In England temperatures recorded at Heathrow reached 34.4 degrees Celsuis.

These high temperatures are no longer rare in the current climate, occurring roughly every 10 to 30 years.

So, was this heat wave a result of man-made global warming?

A detailed European collaborative study suggests it was, and warns that by the end of the century, these high temperatures will become the norm in Western Europe.

Scientists with World Weather Attribution (WWA) and partners in England, France and Switzerland conducted a multi-method analysis to assess whether and to what extent human-caused climate change played a role in the heat. The team found that climate change increased the frequency and intensity of such extreme events, which have at the very least doubled and in the south have increased by at least a factor 10.

First the team analysed the observed June temperature record in several Western European countries to assess whether or not there is a trend toward increasing temperature.

The next step was to assess whether and to what extent external drivers, in particular anthropogenic climate change, caused the positive June temperature trend in the observational data. To Answer this question they used climate models, in which the relative impact of various external “forcings” such as changes in solar insolation, volcanoes, and greenhouse gas concentrations can be quantified.

These model results indicate that past historical increases in greenhouse gases have raised the odds of a warm June in Belgium, France, the Netherlands, Portugal, Spain, Switzerland and the CET region of UK considerably. Furthermore, the observed trend is compatible with the effects of human-induced emissions of greenhouse gases.

Since past and projected future greenhouse gas increases will continue to increase the temperatures, the frequency of summer months like June 2017 should be expected to increase over the coming decades, and what is still an unusually hot June today would be a normal June later this century.




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