Rainfall in UAE to jump 30% in our lifetime - here's what that means

A rise in heavy precipitation events is likely but agricultural productivity may increase, researchers have said

Heavy rain and floods hit parts of the UAE in November. Antonie Robertson / The National

Rainfall in the UAE is set to increase as a result of climate change, a study has revealed.

Scientists at the National Centre of Meteorology have discovered that annual precipitation is expected to rise by up to 30 per cent over much of the country during the course of this century.

Heavy rainfall events are expected to happen more often and there will likely be a fall in the number of dry periods, with farmers possibly set to benefit from the new weather.

The findings come as the world struggles to limit global temperature increases to 1.5°C above pre-industrial levels, the threshold above which scientists say much more severe effects of climate change are expected to result.

The study analysed data in three phases: 2021-2050 (near future); 2051-2080 (mid future) and 2080-2100 (far future) using historical data between 1985 to 2014 as a baseline.

We know globally there’s an increase in the occurrence of heavy rainfall events, which is to be expected, because a warmer atmosphere holds more moisture

Bob Ward of the Grantham Research Institute on Climate Change and the Environment,
part of the London School of Economics

Scientists considered the possible outcomes under a variety of “shared economic pathways" (SSPs), which involve different levels of greenhouse emissions, with these depending upon how the world develops in future.

The model is used widely among climate researchers to carry out detailed analysis on future challenges for mitigation and adaptation to climate change.

The study found that, on average, the annual precipitation over the most of the UAE is expected to increase by about 15 per cent to 30 per cent during the current century under each phase, compared with the historical period.

Researchers suggested that extreme rainfall is expected to increase by up to 30 per cent, particularly between 2051 and 2080.

Globally, an average increase in rainfall is being experienced as a result of climate change and is expected to continue, because a warmer atmosphere is able to hold more moisture.

However, researchers have said there were particular factors affecting the Middle East, notably the northward movement of the intertropical convergence zone, a band of low pressure near the equator known to sailors as the doldrums.

Trade winds, which blow towards the equator from both the northern and southern hemispheres, converge in this zone, which is often linked to heavy rain.

Scientists said that the general pattern was that the added moisture in the atmosphere “results in more extreme precipitation events".

The study, which looked at the Arabian peninsula as a whole, with a particular focus on the UAE, was released earlier this month in Scientific Reports, and published by the scientific journal, Nature.

Modelling indicates that there will be an increase in “heavy precipitation days" in which there is at least 10mm of rainfall, in all emissions scenarios.

“The findings of the study indicate that the Arabian Peninsula may witness an increase in extreme precipitation events," the study said.

“This suggests that there may be a significant increase in precipitation on wet days across most of the land area towards the end of the century."

The UAE may experience a reduction in the number of consecutive dry days as a result of the increase in rainfall, according to the researchers.

“Changes in the precipitation indices under a warming scenario relative to the baseline period indicate progressive wetting across the UAE, accompanied by increased heavy precipitation events and reduced dry spell events," they said.

The study found that heavy rainfall events are expected to happen more often. Antonie Robertson / The National

The effects of the changes will not all be negative, with the researchers saying that the changes in rainfall “will likely contribute to increased agricultural productivity".

Changes in rainfall are expected to be “particularly intense" in the second half of the century under a range of emissions scenarios.

UAE climate researcher Dr Diana Francis, an assistant professor and head of the Environmental and Geophysical Sciences Lab at Khalifa University, who was not connected to the NCM study, said that over the last two decades a trend for increased rainfall in the UAE had already been seen.

She said this was expected to continue and added that it was “most likely" that there would be an increase in extreme rainfall events in the country because of the greater energy levels in the atmosphere.

In addition, the UAE is set to experience an increase in the levels of humidity as a result of climate change.

“This is also expected because for each 1°C increase in temperature in the atmosphere, an additional seven per cent of water vapour can be held in the same volume," she said.

However, Dr Francis cautioned that there remained “a lot of limitations and uncertainties" with climate models, saying that they did not, for example, take account of how tiny particles called aerosols interact with clouds.

She also highlighted some of her previous research, reported in The National, that indicated the carbon dioxide levels used in some models may have been overestimated, something that she said “could lead to biases when looking into temperatures and rainfall".

Bob Ward, of the Grantham Research Institute on Climate Change and the Environment, part of the London School of Economics, said that forecasts of increased rainfall in the UAE were “consistent" with the worldwide picture.

“We know globally there’s an increase in the occurrence of heavy rainfall events, which is to be expected, because a warmer atmosphere holds more moisture. When it rains, it rains harder," he said.

Mr Ward said that heavier rainfall events did not mean that areas would be shielded from droughts, as heavy rainfall events were not the same as steady levels of rainfall through the year.

He also warned that any benefits that higher levels of rainfall did bring would have to be weighed against other effects of climate change, such as increased temperatures and a rise in the frequency and intensity of heatwaves.