11,000 to 5,000 years ago, after the end of the last ice age, Sahara Desert Transformed. The green vegetation grew on the sandy hills and turned the dry mountain into lakes as the rains increased. Nearly a million in North Africa. Million million square miles (million million square kilometers) turned green, as drawn in animals Hippos, Antelope, Elephants And ur roach (wild ancestors of domesticated cattle) who want to eat its growing grass and plants. This lush paradise is long gone, but will it ever return?
In short, the answer is yes. According to Kathleen Johnson, an associate professor of Earth systems at the University of California, the Green Sahara, also known as the African Humid Period, was due to the Earth’s ever-changing orbit around its axis. Irwin.
However, due to the wildcard – human Greenhouse gas emissions That has become a fugitive Climate change – It is unclear when the Sahara will turn new green leaves into the world’s largest hot desert at present.
Related: Has the earth ever been so hot before?
The green shift of the Sahara has changed as the tilt of the earth has changed. About 20,000,000 years ago, the tilt began to move from about 24.1 degrees to the current day’s 23.5 degrees, according to Space.com, a living science sister site. Previously reported. That tilted variation made a big difference; Right now, the Northern Hemisphere is closest to the sun during the winter months. (This may seem unfavorable, but due to the current tilt, the Northern Hemisphere winter season tends to tilt away from the sun.) During the Green Sahara, however, the Northern Hemisphere was closest to the Sun during the summer.
This led to an increase in solar radiation in the northern hemisphere during the summer months (in other words, heat). An increase in solar radiation leads to African growth Monsoon, Seasonal wind shifts in the region due to temperature differences between land and sea. Rising heat over the Sahara created a low-pressure system that drained moisture from the Atlantic Ocean into the desert. (Typically, winds from the arid lands blow to the Atlantic, scattering dust that fertilizes the Amazon rainforest and forms beaches in the Caribbean, Living science previously reported.)
This increased humidity previously transformed the sandy Sahara into a plain covered with grass and shrubs, According to the National Oceanic and Atmospheric Administration (NOAA). N.A.A. The report said that as animals evolved, so did humans, eventually rearing buffaloes and goats, and even arranged for the introduction of symbolic art in the area, the NOAA reported.
Earth trembling
But why did the earth’s tilt change in the first place? To understand this monumental transformation, scientists have turned their attention to the Earth’s neighbors in the solar system.
“The Earth’s axial rotation is accompanied by gravitational interactions with the Moon and periodic changes in the Earth’s orbit by larger planets,” said Peter D. Meno, director of the Center for Climate and Life at the Lamont-Doherty Earth Observatory in Columbia. Wrote in Nature. One such change is the “shaking” of the earth’s axis, he wrote.
Summer close to the Sun in the Northern Hemisphere in summer – those researchers call summer in the Northern Hemisphere maximum insulation every 23,000 years. Based on research first published in the journal Science In 1981, scholars estimated that the Northern Hemisphere saw a 7% increase in solar radiation during the Green Sahara. According to a 1997 study published in the Journal, this increase could increase the African monsoon by 17% to 50%. Science.
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What is interesting about climate scientists about the Green Sahara All of a sudden It appeared and disappeared. It took only 200 years to complete the Green Sahara, Johnson said. The change in solar radiation was gradual, but the landscape changed abruptly. “There is an example of sudden climate change on humans that humans will take note of,” he said.
“Records of sea silt [that the Green Sahara] “Frequent. Summer peaks in the next Northern Hemisphere – when the Green Sahara may reappear – are likely to recur in AD 12000 or AD 13000 about 10,000 years from now. But what scientists can’t predict,” Johnson told LiveScience. How are.Greenhouse gases will affect this natural atmosphere cycle.
Paleoclimate research “provides clear evidence of what it is [humans] “Even if people stopped emitting greenhouse gases today, these gases would rise by the year 1000,000,” Johnson said. He said.
He said there is geographical evidence of ocean currents that this level of moving Green Sahara events are similar to the Miocene era (2 million to 1 million years ago), in which atmospheric carbon dioxide was similar, and probably higher than the current level. The phenomenon is still very likely in the distant future. According to a March review published in General One Earth, rising greenhouse gases today could also have their own greening effect on the Sahara, although not to the extent of mandatory changes in orbit. But this idea is far from certain, due to the limitations of the climate model.
Meanwhile, there is another way to turn parts of the Sahara into a green landscape; If large-scale solar and wind farms were set up there, rainfall in Sahara and its southern neighbor, Semiard Sahel, could increase, according to a 2018 study published in the journal Science.
Wind and solar farms can increase heat and humidity in the surrounding areas, Previously live science report. Increased rainfall can in turn lead to vegetative growth, which creates a positive feedback loop, the researchers said in the study. However, this huge undertaking remains to be tested in the Sahara Desert, so humans will have to wait 12000 years or more until such a project is funded to see if the Sahara will be green again.
Published on Original Living Science.
