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Carbon storage versus albedo change: radiative forcing of forest expansion in temperate mountainous regions of Switzerland

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Schwaab J., Bavay M., Davin E., Hagedorn F., Hüsler F., Lehning M., Schneebeli M., Thürig E., Bebi P.,
Project Towards a more sustainable management of soil resources by redistribution of economic and ecological added and reduced values
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Original article (peer-reviewed)

Journal Biogeosciences
Volume (Issue) 12(2)
Page(s) 467 - 487
Title of proceedings Biogeosciences
DOI 10.5194/bg-12-467-2015

Open Access

URL http://doi.org/10.5194/bg-12-467-2015
Type of Open Access Publisher (Gold Open Access)

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 CO 2 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 CO 2 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.
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