Meteorologists speculate that a half-degree increase in global temperature may be the main cause of extreme rainfall on the planet. In particular, the maximum summer temperatures have increased, thunderstorms and rainstorms have become more intense, in addition, periods of heat waves have become more prolonged.
In 2018, the Intergovernmental Panel on Climate Change intends to make a report on the consequences of an increase in global temperature indicators on the planet by 1.5 degrees compared to pre-industrial values. The researchers intend to tell what measures must be taken by mankind in response to the threat of climate change. According to experts from the Potsdam Institute for the Study of Climate Change, it is necessary to determine how the weather conditions can change if the temperature rises by half a degree. The average air temperature at the beginning of the twentieth century increased by about 1 degree.
According to preliminary studies using climate models, for regions that are vulnerable to extreme weather and climatic conditions (heavy rainfall and prolonged drought), the difference between an increase in temperature by one and a half or two degrees is of great importance. However, such models assume uncertainty, because some of the parameters (for example, describing the global ocean circulation) vary. Taking these factors into account, experts, in order to determine the consequences of an increase in temperature by half a degree, turned to the results of long-term meteorological observations.
Climatologists carried out a comparative analysis of two 20-year periods - 1960-1979 and 1991-2010. The average temperature on the planet during these periods increased by about 0.5 degrees. These data (GISTEMP) were obtained from observation posts in Antarctica, as well as marine and land meteorological stations of the National Atmospheric and Oceanic Research Administration. At the same time, it should be noted that the results of analyzes, which were carried out by specialists from the National Center for Climate Data and the University of East Anglia, indicate that the temperature rise was somewhat different. However, despite small differences, the results of all studies indicate that the global temperature on Earth, since 1980, has risen significantly faster.
Climatologists were interested in changes in weather hazard indicators for a given period of time, among them - precipitation intensity, maximum summer temperatures, duration of droughts (for the analysis, the GHCNDEX and HadEX2 climate databases were used). Based on the GISTEMP data, the estimate looks more conservative. That is, if weather conditions become more extreme, it will be the result of an increase in global temperature by half a degree. In another case, unbearable heat and severe rains are provoked by less warming, which is much worse for humanity.
The annual minimum and annual maximum temperatures were found to have changed significantly by 2010. In addition, the duration of hot periods has also changed: the annual maximum increased by one degree for about a quarter of the entire land surface, while the annual minimum increased by about 2.5 degrees. For half of the planet's surface, the duration of droughts increased by six days. All of these weather shifts do not fit within the framework of natural variability.
In addition, temperature extremes have also increased over South Asia and the African tropics, according to the analysis. The intensity of extreme snowfalls and downpours also increased, causing floods, damage to power lines, causing great damage to agriculture and paralyzing transport.
Extreme weather conditions manifest themselves in different ways in different regions of the planet. This is influenced not only by natural factors, but also by anthropogenic emissions of aerosols into the atmosphere. However, as the researchers found, for North America, Europe, Asia and Russia, changes in extreme weather conditions are caused precisely by global warming.
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According to scientists, the results obtained during the research can be used to assess the likely consequences of an increase in the average temperature of the planet from 1.5 to 2 degrees, even if the effects of warming are non-linear. At the same time, researchers say that at present, humanity has felt the effects of an increase in temperature indicators to the end. For this reason, all the experts' assumptions may be more optimistic, and in the future the situation may be much worse.
This assumption is consistent with the results of another study, which was published in June this year in Nature Climate Change. Climatologists have suggested that three quarters of the world's population by the end of the century will suffer from incredible heat. The most severe weather conditions are expected in the tropical regions of the Earth. As the authors of the study note, currently only a third of all humanity suffers from heat.