Snowfall in the Sahara goes viral

A spectacular snowfall hit the Sahara desert in late December. The photographer Karim Bouchetata captured a series of rare and beautiful images from the small Saharan town of Ain Sefra, Algeria. It is just the second time in living memory that snow has fallen here, the last occasion being in February 1979. The images went viral over the new year festive period, alongside a slew of social media commentaries. Many hav ebeen questioning whether global warming is indeed occurring. On the other hand, “a cold day in the Sahara does not disprove global warming any more than a heat wave in December proves it," says Steven Stoll, a professor of climate history at Fordham University, USA.

It is uncertain how rainfall in the Sahara will evolve this century, according to the latest assessment of the Intergovernmental Panel on Climate Change (IPCC). Future warming across Africa may range from 0.2°C per decade (low scenario), to more than 0.5°C per decade (high scenario), with the Sahara predicted to be one of the regions where warming will be greatest. However, arid lands can respond quickly to seasonal fluctuations. Analysis of 1980-1990 data tracking the limit of vegetative growth along the Sahara-Sahel margin revealed that the 1990 limit of vegetative growth lay 130 km south of its 1980 position.

There is widespread evidence that in the past the Sahara had a much milder, moister climate. Climatologists identify this period as the “Green Sahara.” Archaeological data from rock paintings, graves, and tools testify to abundant past settlements in the middle of what are arid, unproductive areas of the Sahara today. Fossils and artifacts further show that lime and olive trees, oaks, and oleanders once bloomed in the Sahara, while elephants, gazelles, rhinos, giraffes, and people used stream-fed pools and lakes. There is evidence of several moist periods in the Sahara, with similar lush conditions existing as recently as 25,000 years ago. Between the moist periods came periods of dryness much like today’s.