Deforestation is happening over tropical mountainous regions, giving space for agriculture to expand. This changes the land surface properties through altered evapotranspiration and albedo which affect the radiation balance of the surface, thereby changing the local climate. However, these biophysical changes and their impact on climate have not be considered in the state-of-the-art climate models so far and remain unknown.
An international research team from China, USA, Thailand, France, Singapore, Korea, Japan, UK, and Sweden including Prof. Deliang Chen, Department of Earth Sciences at the University of Gothenburg, have investigated how the biophysical processes works in tropical mountainous areas in the world by integrating satellite-observed forest cover changes into a high-resolution land-atmosphere coupled model.
Height is a key factor
Looking at the Southeast Asian Massif, the Barisan Mountains in Maritime Southeast Asia, the Serra da Espinhaço in South America, and the Albertine Rift mountains in Africa, they found that mountain deforestation induces warming and elevation is the key factor in regulating the climate impacts of the areas investigated.
The research team established that the deforestation-driven local temperature anomaly can reach up to 2 °C where forest-to-agriculture conversion is extensive. The elevation dependent warming caused by mountain deforestation is a result of the intertwined and opposing effects of increased albedo causing cooling and decreased evapotranspiration causing warming.
As the elevation increases, the albedo effect increases in importance and the warming effect decreases, analogous to previously highlighted decreases of deforestation-induced warming with increasing latitude.
Affects the local climate
As most new croplands are encroaching lands at low to moderate elevations, deforestation produces higher warming from suppressed evapotranspiration.
"This finding has significant implication as ecosystems are often sensitive and economic development is often poor in these areas", says Deliang Chen.
On top of the global warming caused by anthropogenic greenhouse gases, impacts of this additional warming on crop yields, land degradation and biodiversity of nearby intact ecosystems should be incorporated into future assessments and planning for sustainable development.
The study is published by Nature Geoscience.
