Increased incidence of heat waves in the summer is directly related to global warming, and if half a century ago, "heat wave" captures only 1% of the land surface, they now affect up to 10%, says James Hansen (James Hansen) from the Institute for Space Studies Goddard (GISS ) NASA and his colleagues in a paper to be published in the journal Proceedings of the National Academy of Sciences.
Meteorologists and climatologists have previously spoken with caution on the possible link between climate change and the incidence of extreme heat. Thus, British and Dutch scientists in a paper published in the journal Geophysical Research Letters in February 2012 stated that abnormally hot weather in European Russia in the summer of 2010 godasvyazana to natural causes, although climate change to triple its probability.
Hansen's group used data about summer temperatures from 1951 to 1980 as a baseline, and compared them with modern values. The results showed that there was a significant improvement in the range of anomalies in the way of heat.
"Summer, which by the standards of climatology 1951-1980 year would apply to the category of cool, in that period was recorded in about a third of cases. Now cold summer is fixed only in 10% of cases, while the share of the hot summer season rose from 33% to 75 % "- the scientists say.
However, the most important change is the emergence of a new speedboat anomalies — periods of extreme heat, "heat wave", when the average temperature is much higher than normal.
"Such extreme periods were virtually absent in the base period, closing only a few tenths of a percent of the land surface, but in recent years, such heat waves are observed for 10% of the land" — the article says.
Meteorologists, write the researchers, tend to reject the global warming as the cause of extreme heat. Thus, the Russian hot summer of 2010, they explain blocking anticyclone, and the heat in Texas in 2011 — the effects of the La Niña phenomenon in the Pacific Ocean.
"However, the blocking antitsilony and La Niña have always been as extensive areas of extreme heat came only with global warming. Today's extreme anomalies are the result of the addition of certain weather events and global warming," — say the scientists.
The article stresses that hot weather can lead not only to drought, but also to much more heavy rains and increases the risk of flooding. In addition, warm winters, in particular, can lead to the loss of forests due to pests.
Hansen and his colleagues argue that an urgent need to take action to reduce carbon emissions in order to limit the increase in average temperature.