Rainforest deforestation exacerbates climate change

The mountain forests in Africa are under significant stress due to increasing deforestation by humans. “On Kilimanjaro in Tanzania, over 50 percent of the forest area has already been destroyed since 1880,” explains Dr. Andreas Hemp, co-author of the study from the University of Bayreuth, who has lived and researched on Kilimanjaro for 35 years. Together with colleagues, he has now found out: Climate change is adding to this. 

Under the leadership of Marburg geographers, it was discovered that the average air temperature rises in areas that have been heavily cleared and the surrounding clouds are more than 230 meters higher. In mountainous regions such as Kilimanjaro, this means that the forests can “comb out” significantly less water from the clouds. “This has far-reaching consequences for the water balance and biodiversity in Africa,” says Dr. Dirk Zeuss from the Department of Geography at Philipps-Universität Marburg, explaining the results of a study with international research participation. The researchers report on their investigations in the journal “Nature Communications”.

Less production of fresh water for nature and humans

Tropical mountain forests are unique in terms of their biodiversity and their ecosystem services. The latter include, for example, the production of fresh water for nature and humans. Using satellite data, the Marburg research team has calculated that around 18 percent of Africa's mountain forests were lost between 2003 and 2022. The reasons for this include small-scale farming and logging. As a result of forest loss, other environmental conditions are also changing, the researchers found by combining a wide range of environmental data sets. For example, the air temperature rose by around 1.4 degrees Celsius and the lower cloud edge moved 236 meters upwards. “This shift in temperature and cloud formation is clearly not due to the already existing climate change, but to the loss of mountain forests,” says Dr. Dirk Zeuss, interpreting the results. Bayreuth researcher Andreas Hemp made a significant contribution to these findings: He is project leader in the DFG research group “The role of nature for human well-being in the Kilimanjaro Social-Ecological System (Kili-SES)” at the University of Bayreuth. Since 1996, Hemp has built up a meteorological network on Kilimanjaro, the data from which were decisive for the research results presented here. He was involved in the measurements for the current study with logistical and scientific support.

“This means that man-made interventions such as deforestation exacerbate climate change,” explains Marburg researcher Dr. Temesgen Abera. “We therefore need to focus much more on mountain forests and protect them from deforestation, as it threatens biodiversity, freshwater production and many other ecosystem services in the tropics.” Abera is currently a research fellow of the Alexander von Humboldt Foundation at the University of Marburg.