Scientists at the University of California have found that the Sahara Desert has repeatedly turned into a green oasis during its existence – and in the future it may again expect the same transformation. Instead of sand dunes, dense vegetation will reappear, and heavy rainfall will turn arid caves into lakes.
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According to scientists, the changed weather conditions, which turned the once-blooming steppe into a desert, were associated with the planet's fluctuations, which were repeated every several thousand years. Due to the displacement of the Earth's tilt from 24.1 ° to the current 23.5 °, the Northern Hemisphere to the Sun is today closest to the Sun during the winter season, but in the era when the Sahara was a green oasis, this approach fell on the summer months. and therefore it was warmer. Because of this, the African monsoon intensified, when seasonal winds shifted over the region due to temperature differences between the ocean and land. Due to the increased heat over the Sahara, a zone of low pressure was formed, so moisture from the Atlantic Ocean began to move into the previously barren territory.
Researchers in the United States estimated that during this period, the Northern Hemisphere received 7% more solar heat than it does today. As a result, precipitation increased by 17-50%.
Analysis of ocean sediments has shown that the Sahara has become a green oasis more than once. According to forecasts, the next maximum summer insolation in the Northern Hemisphere is expected in 10 thousand years. It was then, the researchers suggest, that the region will be covered with grass and shrubs instead of sand.
Nevertheless, it is difficult for experts to predict anything now, since the natural cycle may be affected by greenhouse gas emissions.