NEWS - Forest loss exacerbates climate change by increasing temperatures and cloud cover, leading to reduced water. Deforestation over the past two decades has led to warming and a shift in cloud cover that threatens water supplies in Africa’s mountain forests.
Deforestation has led to warming and a shift in cloud cover twice as high as that caused by climate change. The clearing of 18% of Africa’s mountain forests has led to a 1.4 degree Celsius rise in temperature and cloud cover has shifted 230 metres higher over the past 20 years.
Mountain forests are often cloudy, wet and cool. They are rich in biodiversity and act as water towers by trapping water from fog and clouds, providing high-quality fresh water for millions of people in lowland Africa.
The shift in cloud cover to higher elevations reduces water harvesting, as clouds do not touch the forest canopy and mist does not settle on plant and soil surfaces. Bare mountaintops also reduce the surface area of forest cover, leaving no trees to store water and drying out the soil.
The researchers conducted the study in the highlands of Kenya, Tanzania, Ethiopia and South Africa using data from the Taita Research Station, run by the University of Helsinki in southern Kenya, since 2009.
“In the Taita Hills, we measured that every year on forested mountaintops, 20% more water falls to the ground than in unforested areas,” says Petri Pellikka of the University of Helsinki.
“This is caused by fog that clings to the trees, dripping to the ground as water droplets. This is in addition to rainfall. If the clouds are high up and do not touch the forest, this phenomenon does not occur anymore,” Pellikka says.
Many small forested peaks remain in the Taita Hills. Kenya’s most important water sources include Mount Kenya, the Mau Forest, the Aberdare Mountains, Mount Elgon, the Cherangani Hills and Mount Kilimanjaro.
“Around Africa’s highest mountain, Kilimanjaro in Tanzania, 50% of the forest has been lost since 1880,” says Andreas Hemp of the University of Bayreuth, who has been researching Kilimanjaro for 30 years.
Original research
Abera, T.A., Heiskanen, J., Maeda, E.E. et al. Deforestation amplifies climate change effects on warming and cloud level rise in African montane forests. Nature Communications 15, 6992 (2024). DOI:10.1038/s41467-024-51324-7
Deforestation has led to warming and a shift in cloud cover twice as high as that caused by climate change. The clearing of 18% of Africa’s mountain forests has led to a 1.4 degree Celsius rise in temperature and cloud cover has shifted 230 metres higher over the past 20 years.
Mountain forests are often cloudy, wet and cool. They are rich in biodiversity and act as water towers by trapping water from fog and clouds, providing high-quality fresh water for millions of people in lowland Africa.
The shift in cloud cover to higher elevations reduces water harvesting, as clouds do not touch the forest canopy and mist does not settle on plant and soil surfaces. Bare mountaintops also reduce the surface area of forest cover, leaving no trees to store water and drying out the soil.
The researchers conducted the study in the highlands of Kenya, Tanzania, Ethiopia and South Africa using data from the Taita Research Station, run by the University of Helsinki in southern Kenya, since 2009.
“In the Taita Hills, we measured that every year on forested mountaintops, 20% more water falls to the ground than in unforested areas,” says Petri Pellikka of the University of Helsinki.
“This is caused by fog that clings to the trees, dripping to the ground as water droplets. This is in addition to rainfall. If the clouds are high up and do not touch the forest, this phenomenon does not occur anymore,” Pellikka says.
Many small forested peaks remain in the Taita Hills. Kenya’s most important water sources include Mount Kenya, the Mau Forest, the Aberdare Mountains, Mount Elgon, the Cherangani Hills and Mount Kilimanjaro.
“Around Africa’s highest mountain, Kilimanjaro in Tanzania, 50% of the forest has been lost since 1880,” says Andreas Hemp of the University of Bayreuth, who has been researching Kilimanjaro for 30 years.
Original research
Abera, T.A., Heiskanen, J., Maeda, E.E. et al. Deforestation amplifies climate change effects on warming and cloud level rise in African montane forests. Nature Communications 15, 6992 (2024). DOI:10.1038/s41467-024-51324-7