Intergovernmental expert group on climate change, predicting the active expansion of arid areas as a result of global warming, apparently mistaken. According to the results of a new study, it was found that current methods for estimating the strength of drought wrong. The situation is not so sad, as climatologists predict.

In order to assess the balance of precipitation and loss of moisture in the soil as a result of either direct evaporation or absorption of water by plants with subsequent evaporation through the leaves is applied index of aridity Palmer. Usually this method is used only temperature and the latitude. According to hydrologist Justin Sheffield from Princeton University in the US, the method became very popular primarily because of its simplicity. However, the simpler technology, so, naturally, the rougher the results.

Scientists have long known that evaporation is influenced by many other factors: wind speed, relative humidity, amount of sunlight that reaches the surface of the planet at different wavelengths. However, only recently the Sheffield with colleagues managed to reconstruct global data on these parameters until 1948. In their work they used data from satellites. Then scientists have calculated the force of drought from 1948 to 2008.

The results showed that indicators of drought greatly inflated. For example, according to the new method has turned out, that from 1980 to 2008, the areas in which there was a severe lack of moisture, increased by approximately 0.8% per year, which is seven times lower than the result obtained on the basis of only one temperature. These findings were confirmed by another test these same scientists who found that for the most part the drought was noted only in the 1950s and 1960s of the year, i.e. it does not depend on global warming.

Ashamed colleagues began to defend himself. According to Piers Forster of English, University of Leeds, in any case, droughts in Europe, Africa and China have become stronger in the second half of the XX century, regardless of the method of assessment of dry areas. Climate scientist stressed that the drought is not the only danger. Fever negative impact on agricultural and without it. In other words, although Sheffield with colleagues and found important shortcoming, it does not reduce the level of threat to the food industry due to climate change.

The authors of the new work does not dispute the latter conclusion. Moreover, according to them, the global warming effect was offset by a number of factor, otherwise, the drought would have been even stronger. The thing is that from the 1960s to the 1990s, there has been some reduction in the number of solar radiation reaching the planet, because of atmospheric pollution particles scattering the light with a certain wavelength back. Besides, in the considered period the wind velocity at the earth's surface has decreased, that has also reduced evaporation.