Higher temperatures to cause extreme rainfall in the tropics

Global warming and the resulting higher temperatures will likely account for extreme rainfall in the tropics. According to a latest MIT study every 1 degree Celsius rise in temperature in the tropics will result in 10 percent heavier rainfall extremes. This rainfall increase could have major impact on flooding in many populous regions in the tropics.

The researchers are convinced that rainfall extremes in tropical regions are more sensitive to global warming compared to other regions thought they are yet to understand the reasons why.

The basic principle of this increase in precipitation is well known. Greenhouse gases such as carbon dioxide enter the atmosphere, more greenhouse gases in the atmosphere means higher temperature, and this in turn leads to increases in the amount of water vapor in the atmosphere. More water vapor in the atmosphere means that there will be heavier rain because of the increased humidity, which fuels more intense storms.

The MIT scientists have used satellite observations of extreme rainfall between the latitudes of 30 degrees north and 30 degrees south, an area just above and below the Equator, and were looking at the several climate models, which are able to simulate the effects of both El Niño and global warming.

They have discovered one clear pattern, namely that models that showed a strong response in rainfall to El Niño also responded strongly to global warming.

The researchers issued warnings to policymakers saying that although the rainfall will increase in the wettest regions, the drier parts of the tropics will likely become even more drier, meaning that they should not only take into account more damaging flooding, but also less reliable rains from year to year.

Will climate change reduce or increase rainfall?

According to the latest scientific reports Earth is warming up rapidly, and this should in short-term increase the global amount of rainfall. The scientists have even calculated that the rainfall will increase globally by 2-3 per cent for every degree Celsius that the Earth's surface heats up, so by the current looks of it we are in for a heavy rainfall in years to come.

There are some scientists who do not totally agree with this theory claiming that this calculation won't work if the balance of factors causing global warming changes significantly. There are several different factors that will have significant effect on the amount of rainfall in years to come such as the level of solar radiation, the amount of greenhouse gases, etc.

One of the less known but still very important factors are dark aerosols that have the ability to absorb enough sunlight in the atmosphere to suppress the expected rainfall response to increased temperatures, and the immediate result of this could be less rainfall.

When discussing this rather interesting topic Dr Timothy Andrews, scientist at the University of Leeds, said that two effects should be counted together because they go in tandem: "a fast atmospheric response that is closely linked with the type of climate change mechanism, and a slower response to surface temperature change that happens regardless of the climate change mechanism."

According to him these slow effects do produce the predicted 2-3 per cent increase in rainfall but fast atmospheric response might change all of this, depending on factors involved (such as dark aerosols).

There will be more rainfall if the current balance of factors remains pretty much the same in years the come. If by any chance this balance changes due to increased significance of certain factor we can even expect less rainfall in years to come.