The biogeophysical climatic impacts of anthropogenic land use change during the Holocene
The first agricultural societies were established around 10 ka BP and had spread across much of Europe and southern Asia by 5.5 ka BP with resultant anthropogenic deforestation for crop and pasture land. Various studies (e.g. Joos et al., 2004; Kaplan et al., 2011; Mitchell et al., 2013) have attemp...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-04-01
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| Series: | Climate of the Past |
| Online Access: | http://www.clim-past.net/12/923/2016/cp-12-923-2016.pdf |
| Summary: | The first agricultural societies were established around 10 ka BP and had
spread across much of Europe and southern Asia by 5.5 ka BP with resultant
anthropogenic deforestation for crop and pasture land. Various studies (e.g.
Joos et al., 2004; Kaplan et al., 2011; Mitchell et al., 2013) have attempted
to assess the biogeochemical implications for Holocene climate in terms of
increased carbon dioxide and methane emissions. However, less work has been
done to examine the biogeophysical impacts of this early land use change. In
this study, global climate model simulations with Hadley Centre Coupled Model version 3 (HadCM3) were used to examine
the biogeophysical effects of Holocene land cover change on climate, both
globally and regionally, from the early Holocene (8 ka BP) to the early
industrial era (1850 CE).
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Two experiments were performed with alternative descriptions of past
vegetation: (i) one in which potential natural vegetation was simulated by
Top-down Representation of Interactive Foliage and Flora Including Dynamics
(TRIFFID) but without land use changes and (ii) one where the anthropogenic
land use model Kaplan and Krumhardt 2010 (KK10; Kaplan et al., 2009, 2011) was used to set the HadCM3
crop regions. Snapshot simulations were run at 1000-year intervals to examine
when the first signature of anthropogenic climate change can be detected both
regionally, in the areas of land use change, and globally. Results from our
model simulations indicate that in regions of early land disturbance such as
Europe and south-east Asia detectable temperature changes, outside the normal
range of variability, are encountered in the model as early as 7 ka BP in
the June–July–August (JJA) season and throughout the entire annual cycle by
2–3 ka BP. Areas outside the regions of land disturbance are also
affected, with virtually the whole globe experiencing significant temperature
changes (predominantly cooling) by the early industrial period. The global
annual mean temperature anomalies found in our single model simulations were
−0.22 at 1850 CE, −0.11 at 2 ka BP, and −0.03 °C at
7 ka BP. Regionally, the largest temperature changes were in Europe with
anomalies of −0.83 at 1850 CE, −0.58 at 2 ka BP, and
−0.24 °C at 7 ka BP. Large-scale precipitation features such as
the Indian monsoon, the Intertropical Convergence Zone (ITCZ), and the North
Atlantic storm track are also impacted by local land use and remote
teleconnections. We investigated how advection by surface winds, mean sea
level pressure (MSLP) anomalies, and tropospheric stationary wave train
disturbances in the mid- to high latitudes led to remote teleconnections. |
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| ISSN: | 1814-9324 1814-9332 |