 |
| Figure 1: A young Sahelian farmer tends his garden (source) |
The brave 2 million inhabitants of the Sahel region in
Africa have faced sever prolonged droughts in recent decades as was explored in
the last blog. Since the 1960-1980's drought-period, societies have attempted to reclaim their land by stabilizing sand dunes, cultivating trees, building rock walls to stop erosion, and sowing seeds in pits which have been dug to catch rain (figure 1, 2). Advancing on this, new studies are emerging which suggest that global warming could
bring a glimmer of hope of a wetter, more tolerable climate. Issues
regarding desertification, water and food security could be made history
claimed the Guardian, as future climate change could stop the drying of the
Sahara. Already, scientists are reporting an increase in rainfall and the
regreening of the Sahara.
 |
| Figure 2: Sahelians fence sand dunes to prevent erosion (source) |
Haarsman et al., (2015) created a climate model of the Sahel
region and simulated the effects of global warming under different
representative concentration pathways (RCP) between 1980 and 2080. A
significant increase in rainfall within a couple of decades was found and the
study reports that the increase could strongly reduce the probability of future
prolonged droughts. The mechanism behind the changing climate in the Sahel
region is analogues to the polar amplification in the Arctic which is causing
significant increase in temperatures above the average global rate. Cook and Vizy (2015)
reports a substantial increase in Sahara surface temperatures at a rate of 2-4
times greater than the average tropical increase over the last 34 year period.
Global warming will increase land temperatures sooner than ocean temperatures.
While the warming across most of the globe involves the full depth of the
atmosphere, the warming in the Sahel region is concentrated at the surface
since the dryness of the desert is limiting the longwave radiation, changing the air pressure and the weather.
Already, in the southern Sahel, the band of rainfall has
moved northwards at a rate of 9 km per year since 1982. Dong and Sutton (2015) present observed data of a 0.3 mm increase per day in rainfall since 1996
against the average for the 1964-93 period. They suggest that the recovery of
the Sahel rainfalls to the levels pre 1960-1980 drought-period is a
response to anthropogenic greenhouse-gas and aerosol forcing, and they predict
that the recovery is likely to be sustained or amplified in the near-term. Satellite images from AVHRR (Advanced Very High Resolution Radiometer) sensors
demonstrate how the vegetation cover in the Sahel is responding to the change
in rainfall by expanding northwards by 3 km per year (figure 3). Animals which have not been seen in
some regions over the last few decades are returning such as gazelles and
ostriches to some areas of Morocco.
 |
| Figure 3: The same area in 1975 (left) and 2005 (right) in southern Niger (source) |
National Geographic (2010) interviewed Stefan Kropelin, a climate scientists who has been studying the climate
of the Sahara region for decades and he stated how in recent years shrubs are
expanding and different species of vegetation are appearing (figure 4). Kropelin states "the nomads there told me there was never as much rainfall as in the
past few years. They have never seen so much grazing land. Before, there
was not a single scorpion, not a single blade of grass. 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.”.
 |
| Figure 4: Sahelian women tending their shrubs (source) |
Desertification, drought, famine and conflict are the usual
stories that are entangled with future global warming. Yet, the accumulating scientific
evidence and the stories which are coming directly from the people living at
the forefront of climate change in the Sahel are indicating a different
scenario, a blossoming, regreening Sahara and possibly a more fruitful future for
the societies of the Sahel.