Abstract
Abstract. In this study, we assess the climate mitigation potential from afforestation in a mountainous snow-rich region (Switzerland) with strongly varying environmental conditions. Using radiative forcing calculations, we quantify both the carbon sequestration potential and the effect of albedo change at high resolution. We calculate the albedo radiative forcing based on remotely sensed data sets of albedo, global radiation and snow cover. Carbon sequestration is estimated from changes in carbon stocks based on national inventories. We first estimate the spatial pattern of radiative forcing (RF) across Switzerland assuming homogeneous transitions from open land to forest. This highlights where forest expansion still exhibits climatic benefits when including the radiative forcing of albedo change. Second, given that forest expansion is currently the dominant land-use change process in the Swiss Alps, we calculate the radiative forcing that occurred between 1985 and 1997. Our results show that the net RF of forest expansion ranges from −24 W m−2 at low elevations of the northern Prealps to 2 W m−2 at high elevations of the Central Alps. The albedo RF increases with increasing altitude, which offsets the CO2 RF at high elevations with long snow-covered periods, high global radiation and low carbon sequestration. Albedo RF is particularly relevant during transitions from open land to open forest but not in later stages of forest development. Between 1985 and 1997, when overall forest expansion in Switzerland was approximately 4%, the albedo RF offset the CO2 RF by an average of 40%. We conclude that the albedo RF should be considered at an appropriately high resolution when estimating the climatic effect of forestation in temperate mountainous regions.
Highlights
The United Nations Framework Convention on Climate Change (UNFCC) declared in the Kyoto Protocol (Decision 11/CP.7) that changes in the carbon stocks of ecosystems, induced by LULUCF activities can be included in the greenhouse gas emission budget of the signatory nations (UNFCC, 2001)
In the temperate mountainous regions of Switzerland, the net radiative forcing (RF) associated with changes in forest cover varies greatly on small spatial scales
Our results indicate that it is very important to include albedo RF when estimating the impact on climate of changes in forest cover
Summary
The United Nations Framework Convention on Climate Change (UNFCC) declared in the Kyoto Protocol (Decision 11/CP.7) that changes in the carbon stocks of ecosystems, induced by LULUCF (land use, land-use change and forestry) activities can be included in the greenhouse gas emission budget of the signatory nations (UNFCC, 2001). LULUCF influences biogeophysical processes (Betts, 2011; Bonan, 2008), but these effects are not yet considered in current climate policies. Biogeochemical and biogeophysical effects tend to act in the same direction, since tropical forests cool climate through both evaporative cooling and carbon sequestration (Costa and Foley, 2000; Gibbard et al, 2005). At middle and high latitudes, biogeophysical processes tend to counter the biogeochemical effect (Gibbard et al, 2005; Betts, 2000; Govindasamy et al, 2001), making the net LULUCF effect more challenging to assess
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have