Climate change: Planting trees increases European rainfall

Expanding European forest cover could enhance rainfall and partly counteract future drying trends expected with climate change, according to a paper published in Nature Geoscience this week.

Several countries worldwide are considering planting more trees in efforts to tackle rising global temperatures. Such widespread reforestation could also influence local rainfall by altering the transfer of water, energy and momentum between the land surface and the atmosphere. However, the extent to which reforestation may affect rainfall is largely unknown.

Ronny Meier and colleagues used an observation-based continental-scale statistical model to assess how forest cover influences rainfall across Europe. The authors found that converting agricultural land to forest triggers substantial changes, tending to increase both local and downwind rainfall. Based on these results, the team showed that a realistic reforestation strategy (based on a global reforestation potential map) could enhance European summertime rainfall by an average of 7.6%, and partly offset drying trends that are expected with climate change. On the other hand, the expansion of forests could exacerbate climate-induced intensification of rainfall in winter.

These findings demonstrate the relevance of land-management in the assessment of climate mitigation pathways. They also reveal the importance of considering impacts on rainfall when planning reforestation strategies.