Ancient plant remains shed light on Israel’s climate change

About 20,000 years ago, winters in Israel were colder, with the lowest temperatures recorded in January about five degrees Celsius lower than contemporary ones, while the level of precipitation was similar to today, a group of researchers has found in a project. Innovative documenting some 10 millennia of climate in the area.

By analyzing botanical remains from 10,000 to 20,000 years ago from the Hula Valley in northern Israel, archaeologists from Tel Aviv University, Tel Hai College and the University of Montpellier in France were able to reconstruct how the climate evolved during that period. Their findings were recently published in the Quaternary Science Review.

“I have been very interested in environmental reconstruction and, by analyzing botanical remains, I have been working on the reconstruction of the climatic and ecological history of the region, which I believe is key to answering important questions about human evolution,” said the archaeobotanist of TAU, Dr. Dafna Langgut.

About 60 plant sediments were measured by radiocarbon and, for every several samples, pollens totaling several hundred were extracted. This allowed the researchers to develop a pollen-based paleoclimate model.

The period of about 20,000 years ago marked the peak of the last Ice Age, and although Israel and the Levant were not covered in ice like many other areas of the world, conditions were different than they are today.

As temperatures increased some 5,000 years later, species such as olive, pistachio and oak trees became more prevalent.

Finally, about 12,000 years ago, in a time known as the Younger Dryas period, the climate changed again. While in other areas of the world the period once again resembled the Ice Age slightly – colder and drier – in the Levant it became very unstable with intense fluctuations. However, rainfall was distributed throughout the year, including summer, something difficult to imagine in Israel today, when it is extremely rare to see even a drop of rain between June and September.

Among other things, these changes favored the development of leafy trees.

Fossil Pollen Grain Chart (Credit: COURTESY OF DR. DAFNA LANGGUT)

ACCORDING to the researchers, the evolution of the region’s climate offered an important contribution to the transition between the nomadic lifestyle of hunter-gatherers and the first settled settlements that lived off agriculture, as is also attested by the site where the hunter-gatherers were collected. botanical remains.

The samples were recovered at the Jordan River Dureijat prehistoric archaeological site.

Located on the banks of the Jordan River in the Hula Valley, the site was first discovered after a drainage operation in 1999.

About 20,000 years ago, small groups of hunter-gatherers found themselves at the southern tip of Paleolake Hula, where they identified a good place to fish and hunt. After those first visitors, the site would remain in use for the next 10,000 years, bearing extraordinary testimony to how the climate, vegetation, animals, and most of all, the ancient inhabitants of the land lived and changed throughout the ages. millennia.

“In the study of prehistory, this period is called the epipaleolithic period,” said Professor Gonen Sharon of Tel Hai. “At first, people organized into small groups of hunter-gatherers who roamed the area.

“Then, about 15,000 years ago, we witnessed a significant change in lifestyle: the emergence of village life and other dramatic processes that reached their peak during the Neolithic period that followed,” he explained. “This is the moment when the most dramatic change in human history occurred: the transition to the agricultural way of life that shaped the world as we know it today.”

The specific conditions of the site allowed archaeologists to find a vast set of vegetation remains, including pollens, wood, seeds and fruits, as well as branches and coals covered by mud.

“The fact that the botanical specimen remained under the mud for so long has allowed for a unique state of conservation,” Langgut said.


To shed more light on how the climate has evolved in the region, the researcher is currently working on another site: an ancient lake in the Negev, with botanical sediments dating back about 1.5 million years.

“It was a crucial period for the migration of the first humans out of Africa, and the climate was clearly very different as there was a lake in the desert,” he said.

“Understanding the history of climate change can provide us with important information to face current and future challenges related to climate change today,” he concluded.

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