By Paul Homewood
Global warming is causing the Sahara desert to grow, new research suggests.
Scientists have found that the world’s largest desert has expanded by more than ten per cent over the last 100 years.
The study suggests the rest of the world’s deserts could be expanding too as widespread climate change continues to heat up the planet.
Meanwhile, back in the real world:
Satellite data shows the per cent amount that foliage cover has changed around the world from 1982 to 2010.
Credit: Image courtesy of CSIRO Australia
Emerging evidence is painting a very different scenario, one in which rising temperatures could benefit millions of Africans in the driest parts of the continent.
Scientists are now seeing signals that the Sahara desert and surrounding regions are greening due to increasing rainfall.
If sustained, these rains could revitalize drought-ravaged regions, reclaiming them for farming communities.
The green shoots of recovery are showing up on satellite images of regions including the Sahel, a semi-desert zone bordering the Sahara to the south that stretches some 2,400 miles (3,860 kilometers).
Images taken between 1982 and 2002 revealed extensive regreening throughout the Sahel, according to a new study in the journal Biogeosciences.
The transition may be occurring because hotter air has more capacity to hold moisture, which in turn creates more rain, said Martin Claussen of the Max Planck Institute for Meteorology in Hamburg, Germany, who was not involved in the new study.
“The water-holding capacity of the air is the main driving force,” Claussen said.
While satellite images can’t distinguish temporary plants like grasses that come and go with the rains, ground surveys suggest recent vegetation change is firmly rooted. In the eastern Sahara area of southwestern Egypt and northern Sudan, new trees—such as acacias—are flourishing, according to Stefan Kröpelin, a climate scientist at the University of Cologne’s Africa Research Unit in Germany.
“Shrubs are coming up and growing into big shrubs. This is completely different from having a bit more tiny grass,” said Kröpelin, who has studied the region for two decades.
In 2008 Kröpelin—not involved in the new satellite research—visited Western Sahara, a disputed territory controlled by Morocco.
“The nomads there told me there was never as much rainfall as in the past few years,” Kröpelin said. “They have never seen so much grazing land.”
“Before, there was not a single scorpion, not a single blade of grass,” he said.
“Now you have people grazing their camels in areas which may not have been used for hundreds or even thousands of years. You see birds, ostriches, gazelles coming back, even sorts of amphibians coming back,” he said.
“The trend has continued for more than 20 years. It is indisputable.”
Back in 1973, HH Lamb knew that the Sahel drought then was due to global cooling:
And scientists believe that future warming will continue to re-green the Sahel:
So how did the authors of this new paper come to their conclusion? This is what their news release says:
To single out the effects of human-caused climate change, the researchers used statistical methods to remove the effects of the AMO and PDO on rainfall variability during the period from 1920 to 2013.
Ah, good old “statistical methods”!