Is It Going To Rain In The Middle East? Climate Change Study Says No

Will the Middle East get some rain to quench their dry land? Maybe in 10,000 years, if the area’s ancient climate is any clue of what is to come.

Cave rock holds a measurement of how much water fell in the region many millennia ago through its chemical composition, which solidifies a record of the surrounding climate as it forms. According to an analysis of stalagmites from Iran published in the journal Quaternary Science Reviews, the patterns of precipitation going back almost 130,000 years show that there won’t be a pickup in rain until the amount of radiation from the sun picks up as well — and that isn’t projected to happen for another 10,000 years.

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Stalagmites are rocks that grow vertically from a cave floor, the counterparts to the stalactites that hang down from the top. Scientists took samples from the Qal'e Kord cave in Iran and tested their oxygen content, an indication of precipitation levels. The study says that the stalagmites show a link between the historical patterns of the sun’s energy on Earth’s surface and the amount of rainfall: that the two quantities increased and decreased together. Based on the timing of the last period when the sun’s energy reaching the surface increased and led to more rain, the planet “will not return to a similar solar configuration for 10,000 years” to produce such increased precipitation, the researchers explained.

The configuration they are referring to is the Earth’s orbital variations. Over periods of tens of thousands of years, Earth’s orbit cycles between being more elliptical and less elliptical, which affects the distance between us and the sun. There are also cyclical changes to the amount the Earth tilts on its axis — how much it bows toward or away from the sun. These factors affect the amount of the sun’s radiation that touches down, and influences the climate. When the Earth is tilted more toward the sun, for example, the winter and summer seasons can become more intense.

Rainfall in the Middle East countries was at its peak “at max configuration” for solar energy, the study says, so such a wetter period won’t come around again for a while.

“Local governments generally prefer the narrative that the region is only in a temporary dry spell and better prospects of water availability lay ahead,” lead author Sevag Mehterian said in a statement from the University of Miami. “Our study has found evidence to the contrary, suggesting that in fact, the future long-term trend based on paleoclimate reconstructions is likely towards diminishing precipitation, with no relief in the form of increased Mediterranean storms, the primary source of annual precipitation to the region, in the foreseeable future.”

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The researchers dated the two stalagmite samples to between 73,000 and 127,000 years ago, and between 6,500 and 7,500 years ago. After analyzing them for oxygen composition to determine the historical rainfall totals in the Middle East, they compared their findings to “similar records from other caves, ice cores, and sediment records as well as model predictions for water availability in the Middle East and west central Asia today and into the future,” the university explained.

Stalagmites are not the only indication of past rainfall and water resources. Scientists have previously studied samples taken from the Dead Sea, where the salt content of the sediment that accumulated during prehistoric time periods shows when the people in the Middle East suffered extreme droughts.

“We take what we have learned from the past climate and applied it to better understand what to expect moving forward with the current state of the changing global climate,” study co-author Ali Pourmand said in the statement.