Summer heatwaves like 2003 are expected to become much more frequent toward the end of the century
In the current ie of the scientific journal Science, U.S. researchers publish a study according to which in the future increasingly intense and frequent periods of heat are to be expected both in Europe and in North America.
Geral’s A. Meehl and Claudia Tebaldi of the National Center for Atmospheric Research in Boulder examined climate data collected since 1961 to model future heat waves. They see clear signs of global climate change and note that, if greenhouse gas emissions remain constant in the 21st century, there will be no global warming. It is clear that in the twenty-first century there will be more intense and prolonged episodes of floatation in the regions of Europe and North America that were not accustomed to such heat shocks in the past.
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There is no universal definition of heat waves, but unseasonably hot days in a row have been shown to have serious consequences for mortality rates, regional economies and local ecosystems. Its effects are simply devastating (Heat Wave Awareness Project). This is especially true when they occur in cities that have not developed a tradition of dealing with particularly hot summer days and are consequently unprepared to deal with this problem. Scientists adopted two definitions, calling a period of at least three days of sustained, outstandingly high temperatures and no significant nighttime cooling a heat wave.
Heat waves are an expression of the worldwide increase in weather extremes (The weather is running amok) and symptoms of global climate change (Marine harbingers of climate change)?). They are the weather events that have claimed the most lives in the U.S. in the last fifteen years (Fatalities due to weather hazards).
Meehl and Tebaldi took a special look at the outstanding heat waves in Chicago in July 1995 and in Paris in August 2003. In Chicago 739 people died in five days (Chicago Heat Wave of 1995), in Paris during the summer of 2003 even 15.000 people (In the dispute over heat victims, Parisian family doctors go on the offensive). In addition, there are many unpaid dead animals, also in agriculture.
More frequent, more intense and longer lasting
Many climate researchers no longer consider the summer of the century in 2003 to be an accidental weather extreme, but rather an expression of increasing climate change with rising temperatures worldwide (Will Germany become a second Oklahoma?)?). In addition, large cities produce their own extreme microclimates, affecting the weather and atmosphere globally (this city can cause circulatory disturbances and impotence).
For their model study, Meehl and Tebaldi used the model developed by the National Center for Atmospheric Research in conjunction with the U.S. Department of Energy developed so-called Parallel Climate Model (PCM). With the help of the previous weather data they calculated the coming weather scenarios. In their calculations, they ame that the global emission of greenhouse gases and sulfur aerosols will continue as before. Under this amption, they foresee significantly more pronounced heat waves for the end of this century, the years 2080-2099, both in Northern Europe and North America as well as in the Mediterranean countries and in the Balkans.
In France, the risk of prolonged heat without real nighttime cooling increases by more than 30 percent, and the barely tolerable weather could last up to 13 days at the end of 21 instead of today. Twentieth century storms can last up to 17 days. At present, such a weather event is expected 1.6 times a year, in the future it will be more than 2 times. For Chicago, the increasing risk of this climatic phenomenon looks like this. Meehl comments on the results:
It is the extreme weather and climate events that will lead to the grossest stresses on human society this century as the climate changes.