New research by the Hebrew University shows that at the peak of the last interglacial period, precipitation in the Levant increased by about 20%, and that atmospheric warming and the strengthening of the Red Sea channels made the southern region a possible route for the migration of ancient humans from Africa.
A new study, combining ancient geological archives with advanced climate simulations, has found that the Levant region experienced a roughly 20% increase in precipitation at the peak of the last interglacial. The study shows that this wetting was due to a “thermodynamic” change: a warmer atmosphere held more water vapor, which descended into the desert via enhanced Red Sea channels. The findings suggest that such intense, localized, and focused weather patterns made the southern Levant a possible migration route for early humans out of Africa.
For the people of the Levant today, the Red Sea basin usually brings a brief, dusty transition between seasons. But 127 years ago, that same weather pattern may have been a real turning point in human history.
The new study, led by doctoral student Ephraim Brill, Prof. Adi Torpstein and Dr. Assaf Hochman from the Institute of Earth Sciences at the Hebrew University of Jerusalem, and published in the journal Climate of the Past , shows that at the height of the last interglacial, the Levant was not simply a dry land bridge between continents. It was a dynamic region with relatively wetter conditions, fueled by intense, localized rainfall events. This change in ancient weather patterns likely provided the water sources that allowed early humans to successfully complete the exodus from Africa.
The last interglacial, which lasted from about 129 to 116 years ago, was a warm period on a global scale, with sea levels and temperatures higher than today. Although the region was generally arid, geological “clues,” from sediment cores from the Dead Sea to ancient formations in Negev caves, indicate brief but very wet phases.
“Reconstructions based on indirect markers suggest that at the peak of the last interglacial, the southern Levant experienced relatively wetter conditions,” the researchers write. But how did a desert region get enough water to allow human migration?
To address this question, Brill and his colleagues used advanced climate models (PMIP4) to simulate how rain-bearing weather systems operated 127 years ago. They focused on the two main systems that still dictate precipitation patterns in the region today:
- Cyprus depressions: Winter storms that bring most of Israel's annual precipitation from the Mediterranean Sea.
- Red Sea troughs: systems that are usually at their peak in the fall, and are capable of drawing moisture from the tropics.
The study found that at the peak of the last interglacial period, both of these systems were about 20% more efficient than in modern times.
Winter rains in the Red Sea basin
The most striking finding concerns the southern Levant. While northern Israel and Lebanon received more winter rainfall than Cyprus, the arid south, including the Eilat region and the Negev, relied on a "particularly enhanced" Red Sea basin.
The researchers found that it wasn’t necessarily that these systems were occurring more frequently, but that they were physically different. Simply put, the ancient Levant became wetter because a warmer atmosphere acted like a bigger sponge. At the height of the last interglacial, significantly higher temperatures, especially in summer, increased the air’s ability to hold water vapor.
When the Red Sea basin passed through the region during the year, it had a much greater amount of atmospheric moisture at its disposal than is present today. This physical change in the air, and not just a change in wind patterns, was the main reason for the heavy rainfall events that made the southern desert a more suitable landscape for the transition.
Beyond the historical interest, the study also provides an important "mirror" for our future. In an era of modern global warming, it is of great importance to understand how natural variability has changed the water balance in the Levant in the past, in order to better predict the effects of the climate crisis in the future.
The study highlights that even in a normally dry region, certain types of weather systems can become very strong as temperatures rise. It’s a pattern that may already be starting to emerge in 21st-century projections. By combining ancient geological markers with advanced models, Brill and his colleagues mapped not only the possible path of our ancestors, but also the weather challenges our descendants may face.
The article, titled "Hydroclimatic variability and weather type characteristics in the Levant during the last interglacial", Published in the journal Climate of the Past
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One response
Many years ago I wrote this:
https://www.hayadan.org.il/realy-ice-age-0512095
A situation that is already happening today,
It is worth adding that observations show how the equatorial climate
In Africa, north of the equator,
This means that around the equator there is less rain and drier areas.
The north gets more rain,
In our Negev this is expressed in more storms and floods…