Global climate response to idealized deforestation in CMIP6 models
Journal
Biogeosciences
Journal Volume
17
Journal Issue
22
Pages
5615-5638
Date Issued
2020
Author(s)
Boysen, L.R.
Brovkin, V.
Pongratz, J.
Lawrence, D.M.
Lawrence, P.
Vuichard, N.
Peylin, P.
Liddicoat, S.
Hajima, T.
Zhang, Y.
Rocher, M.
Delire, C.
Séférian, R.
Arora, V.K.
Nieradzik, L.
Anthoni, P.
Thiery, W.
Laguë, M.M.
Lawrence, D.
Abstract
Changes in forest cover have a strong effect on climate through the alteration of surface biogeophysical and biogeochemical properties that affect energy, water and carbon exchange with the atmosphere. To quantify biogeophysical and biogeochemical effects of deforestation in a consistent setup, nine Earth system models (ESMs) carried out an idealized experiment in the framework of the Coupled Model Intercomparison Project, phase 6 (CMIP6). Starting from their pre-industrial state, models linearly replace 20 × 106 km2 of forest area in densely forested regions with grasslands over a period of 50 years followed by a stabilization period of 30 years. Most of the deforested area is in the tropics, with a secondary peak in the boreal region. The effect on global annual near-surface temperature ranges from no significant change to a cooling by 0.55 ◦C, with a multi-model mean of −0.22 ± 0.21 ◦C. Five models simulate a temperature increase over deforested land in the tropics and a cooling over deforested boreal land. In these models, the latitude at which the temperature response changes sign ranges from 11 to 43◦ N, with a multi-model mean of 23◦ N. A multi-ensemble analysis reveals that the detection of near-surface temperature changes even under such a strong deforestation scenario may take decades and thus longer than current policy horizons. The observed changes emerge first in the centre of deforestation in tropical regions and propagate edges, indicating the influence of non-local effects. The biogeochemical effect of deforestation are land carbon losses of 259 ± 80 PgC that emerge already within the first decade. Based on the transient climate response to cumulative emissions (TCRE) this would yield a warming by 0.46 ± 0.22 ◦C, suggesting a net warming effect of deforestation. Lastly, this study introduces the “forest sensitiv- © Author(s) 2020. This work is distributed under
Other Subjects
biogeochemical cycle; climate change; climate modeling; CMIP; deforestation; global climate; tropical region; yield
Type
journal article