The secret link between deforestation and flooding in West Africa

coastal regions
Cape Coast Cityscape, Ghana © Golasza

The frequency of thunderstorms has doubled in the last 30 years, in some fast-growing West African coastal cities

Research led by the UK Centre for Ecology & Hydrology (UKCEH) has now revealed that more frequent storm activity in coastal areas is a second, previously unrecognised, way in which deforestation can increase flooding.

The removal of vegetation increases rainwater runoff and the risk of mudslides. This new study has been able to attribute much of this increase to the impact of deforestation on the local climate.

30 years of satellite data led to discovery

Analysing 30 years of satellite data in southern West Africa, scientists have been able track the changes in weather patterns through changes in the heating and moistening of the atmosphere. Due to large areas of woodland having been cut down, the effects of global warming had been felt to more extremes in coastal areas such as Guinea, Sierra Leone, Liberia the Ivory Coast and more, with flash flooding becoming more common and devastating.

In deforested areas it has been noted that the frequency of storms had doubled since 1991, while the increase in forested areas was lower at 40%.

Professor Chris Taylor from UKCEH and leader of the study, said: “The extent of increase in coastal storm activity is likely to vary in different regions, depending on the local climate, but we would expect deforestation to have a similar effect in other coastal deforested areas.

“Around 40 per cent of the world’s population lives within 100km of the coast, so increases in flash flooding causes disruption to millions of people’s lives. Our findings therefore provide a warning to fast-growing coastal cities across the world.”

Populations located by the sea have improved food access and economic benefits, explaining why population density is so high in coastal regions.

Why does climate change impact the coast specifically?

Climate change is continually affecting coastal regions around the globe – significantly more than other areas of land. Flooding is becoming more and more an issue that needs to be tackled and prevented by international governments. Providing safeguarding for coastal communities needs to be a high priority in a number of countries.

“Local weather patterns are dominated by sea breezes and deforestation strengthens these winds that carry moisture inland, triggering more afternoon downpours,” explains Dr Cornelia Klein of UKCEH, a co-author of the study.

This study is the first into the ways in which deforestation affects weather patterns and was funded by the Natural Environment Research Council (NERC). It will hopefully be influence in urging stronger protection of coastal regions against climate change and in the argument against deforestation.

Sarah Webb, NERC’s Associate Director for International, said “Research funded by NERC is helping global communities make future decisions on sustainable land management, urban planning and agricultural practices, as well as draw up emergency response plans. This is supporting them in adapting to, and mitigating, the effects of climate change, leading to greater resilience.”

Find the full study here.


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