Extreme Sahelian storms have tripled in frequency since 1982 according to a new analysis of satellite data.
The increased storm frequency over just 35 years is likely a response to atmospheric warming, say the international team of scientists led by Christopher Taylor, who is based at the UK’s Centre for Ecology & Hydrology (CEH) and NCEO.
The study published in the journal Nature today (27th April) suggests that climate change will see the Sahel experience many more instances of extreme rain in future.
The team note that further strengthening of intense storms in the Sahel, known as Mesoscale Convective Systems (MCSs), will increase the risk of more frequent and severe flooding and disease due to poor sanitation in West African cities. The findings will be presented at the General Assembly of the European Geosciences Union at its meeting in Vienna, Austria this week .
The Sahelian storms are some of the most explosive storms in the world, containing clouds that can grow to a height of 16 km above the ground. In 2009 a downpour of 263 mm over several hours forced 150,000 residents of Ouagadougou, in Burkina Faso, to leave their homes.
West African Sahel storm (copyright Françoise GUICHARD / Laurent KERGOAT / CNRS Photo Library)
The scientists analysed trends from 35 years of satellite observations across Africa to gain unique insight into how some of the most violent storms in the world are responding to rising global temperatures.
Their findings indicate that MCS intensification is linked to increasingly hot conditions in the Sahara desert resulting from man-made greenhouse gas emissions. Saharan warming affects storm intensity across the Sahel, a band of semi-arid land to the south of the desert which is home to some of the most vulnerable populations on the planet.
Professor Taylor said, “Global warming is expected to produce more intense storms, but we were shocked to see the speed of the changes taking place in this region of Africa.”
Co-author Professor Douglas Parker, Professor of Meteorology at the University of Leeds, UK, said, “African storms are highly organised meteorological engines, whose currents extract water from the air to produce torrential rain. We have seen these engines becoming more efficient over recent decades, with resulting increases in the frequency of hazardous events.”
The research was funded by the Department for International Development (DFID) Future Climate for Africa programme under the African Monsoon Multidisciplinary Analysis 2050 (AMMA 2050) project and the Natural Environment Research Council (NERC).
Other institutions involved in the research included NCEO, the University of Leeds, the Centre National de Recherches Météorologiques, Université Grenoble Alpes, Université Paris Diderot and Sorbonne Université.
Case study – flooding in Burkina Faso
Dr Abdoulaye Diarra, Senior Researcher at the International Institute for Water and Environmental Engineering in Ouagadougou, Burkina Faso said:
“A total of 77 flood events have been recorded in Burkina Faso during the 31 year period from 1986 to 2016. The floods’ dynamics have increased in the Burkina from a frequency of 11 major events over 10 years (1.1 flood event/year) between 1986 to 2005 to 55 over 11 years (5 flood events/year) from 2006 to 2016.
“The damages are generally more important in the urban areas where runoff is very important and watercourses are limited. The 2009 flood (1 September), focused in Ouagadougou, caused heavy damage in the capital. More than 50 per cent of the city’s territory, including the main hospital of the city, was flooded.
“In total eight people died, more than 250 houses and 670 classrooms were destroyed, the main water purification plants for the city were out of use and nearly 150,000 people were affected within and around Ouagadougou.”
Contact details For interview requests and images contact Wayne Coles, Media Relations Officer, Centre for Ecology & Hydrology, UK, Mobile: +44 (0)7920 295384, Email: firstname.lastname@example.org
Lead author, Professor Christopher Taylor, Meteorologist, Centre for Ecology & Hydrology, UK, Email: email@example.com
Co-author, Professor Douglas Parker, Professor of Meteorology at the University of Leeds, UK, telephone: +44 (0)113 343-6739, mobile: 07747 505811, Email: D.J.Parker@leeds.ac.uk
Christopher M. Taylor, Danijel Belusic, Francois Guichard, Douglas J. Parker, Theo Vischel, Oliver Brock, Philip P. Harris, Serge Janicot, Cornelia Klein, Geremy Panthou, Frequency of extreme Sahelian storms tripled since 1982 in satellite observations, Nature, published online 1800 GMT/1400 US Eastern Time, 27 April 2017. DOI: 10.1038/nature22069