Used planet: A global history
- aDepartment of Geography and Environmental Systems, University of Maryland, Baltimore County, Baltimore, MD 21250;
- bARVE Group, Environmental Engineering Institute, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland;
- cInstitute of Archaeology, University College London, London WC1H 0PY, United Kingdom;
- dCenter for Climatic Research, Gaylord Nelson Institute for Environmental Studies, University of Wisconsin, Madison, WI 53706;
- eNetherlands Environmental Assessment Agency (PBL), 3720 AH Bilthoven and Utrecht University (UU), 3584 CS, Utrecht, The Netherlands; and
- fInstitute for Environmental Studies, Amsterdam Global Change Institute, VU University Amsterdam, 1081 HV, Amsterdam, The Netherlands
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Edited by B. L. Turner, Arizona State University, Tempe, AZ, and approved April 3, 2013 (received for review November 6, 2012)

Abstract
Human use of land has transformed ecosystem pattern and process across most of the terrestrial biosphere, a global change often described as historically recent and potentially catastrophic for both humanity and the biosphere. Interdisciplinary paleoecological, archaeological, and historical studies challenge this view, indicating that land use has been extensive and sustained for millennia in some regions and that recent trends may represent as much a recovery as an acceleration. Here we synthesize recent scientific evidence and theory on the emergence, history, and future of land use as a process transforming the Earth System and use this to explain why relatively small human populations likely caused widespread and profound ecological changes more than 3,000 y ago, whereas the largest and wealthiest human populations in history are using less arable land per person every decade. Contrasting two spatially explicit global reconstructions of land-use history shows that reconstructions incorporating adaptive changes in land-use systems over time, including land-use intensification, offer a more spatially detailed and plausible assessment of our planet's history, with a biosphere and perhaps even climate long ago affected by humans. Although land-use processes are now shifting rapidly from historical patterns in both type and scale, integrative global land-use models that incorporate dynamic adaptations in human–environment relationships help to advance our understanding of both past and future land-use changes, including their sustainability and potential global effects.
Footnotes
- ↵1To whom correspondence should be addressed. E-mail: ece{at}umbc.edu.
Author contributions: E.C.E. designed research; E.C.E. performed research; J.O.K. and K.K.G. contributed new reagents/analytic tools; E.C.E. analyzed data; and E.C.E., J.O.K., D.Q.F., S.V., and P.H.V. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
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- Quantitative Global Modeling of Land-Use History
- Tale of Two Models: The Importance of Land-Use Intensification in Global Land Change History
- Land-Use Intensification Theory
- Land-Use Intensification in the Late Pleistocene and Early Holocene
- Adaptive Intensification in the Early Holocene
- Emergence and Expansion of Agriculture
- Adaptive Intensification and the Rise of Agricultural Populations
- Urbanization, Industrial Land-Use Intensification, and Forest Recovery
- Major Global Consequences of Early Land-Use Intensification
- Confirming the Past: A Quantitative Global Archaeological History of Land Use?
- Lessons from the Past and for the Future
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