Improving climate models to reduce vulnerability
The different climate models of today project different outcomes regarding the effect of climate change on African ecosystems. Some models suggest that tropical rainforests serve as carbon sinks; other models that they become future carbon sources. One reason for this uncertainty, apart from the lack of historical climate data for the region, is that the interaction between ecosystems and climate change is not yet included in many models.
Climate researchers Minchao Wu and Markku Rummukainen are working on a climate model to project future climate changes in Africa, including the role and consequences of changes in the vegetation.
“In our model, vegetation is allowed to react to climate change, rather than being constant as in many other climate models. Future changes in the climate and vegetation can be studied in a more realistic way when we allow the impact from changes in the vegetation to feed back on the climate”, said Minchao Wu.
Their model shows that an increase in rainfall in coastal monsoon areas, such as West and East Africa, and in parts of the Saharan regions, together with increased carbon dioxide concentration in the atmosphere, may stimulate vegetation growth.
“If we were to stop here and look at the model results, the net effect would be an increase in carbon uptake”, said Minchao Wu.
However, when including the fact that an increase in water evaporation (caused by changes in vegetation due to climate change) will cool the surface climate in areas such as savannahs and arid land, preliminary results from the model show a different outcome. The local cooling effects will lead to less rainfall over the tropical rainforests in central Africa because of induced changes in wind systems, and subsequently, the dry season there will become even drier. This would make the rainforest more prone to turn into savannahs, with less carbon uptake as a result.
“We hope that this work will contribute to the understanding of climate change in Africa, and the consequences on a local, regional and global scale”, said Minchao Wu.
Text: Pia Romare from Lund University Research Magazine