Using Land Use Change Models to Assess Biophysical and Biogeochemical Consequences: The Future is Not Like the Past R. DeFries, [ Department of Geography and Earth System Science Interdisciplinary Center, University of Maryland College Park L. Bounoua, Dept. of Meteorology, UMD and Goddard Space Flight Center

Land Use Change Models Human Drivers of Land Use Change Biophysical/Biogeochemical Consequences of Land Cover Change Sustainability

Consequences of Land Cover Change for Ecosystem Services: Net primary production global terrestrial carbon model (CASA) Surface climate coupled land surface-general circulation model (SiB2-CSU GCM)

#1: What are the consequences of anthropogenic land cover change for net primary production and surface climate at regional and global scales? #2: How might consequences of future land cover change differ from the past? #3: How do the effects from land cover change compare with interannual variability?

Undisturbed (derived from Matthews, 1983) Existing (DeFries and Townshend, 1994) 2050 Future (derived from IMAGE 2.0) Broadleaf evergreen forest Broadleaf deciduous forest Mixed forest Coniferous forest Needleleaf deciduous forest Wooded grassland Grassland Shrubs and bare Tundra Bare Cropland Ice

% Difference in Net Primary Production (existing - undisturbed land cover) NPP lossNPP gain

% Difference in Net Primary Production (future - existing land cover) NPP lossNPP gain

Latitude Land cover change Interannual variability in 1980s Undisturbed to existing land coverExisting to future land cover IS EFFECT OF ANTHROPOGENIC LAND COVER CHANGE ON NPP SIGNIFICANT RELATIVE TO INTERANNUAL VARIABILITY?

Land cover change affects surface climate through: Morphology albedo surface roughness Physiology evapotranspiration balance between sensible and latent heat flux General increase in albedo (cooling) and decrease in latent heat flux (warming) with land use change

Hansen et al., 1995, Climate Forcings in the Industrial Era, PNAS. Govindasamy et al., 2001, Land use change and Northern Hemisphere cooling, GRL. Bonan, 1999, Frost followed the plow: Impacts of deforestation on the climate of the United States, Ecological Applications. Shukla et al. 1990, Amazonian deforestation and climate change, Science.

Land cover change Modelled interannual variability in 1980s wintersummer IS EFFECT OF FUTURE ANTHROPOGENIC LAND COVER CHANGE ON CLIMATE SIGNIFICANT RELATIVE TO INTERANNUAL VARIABILITY? future coolingfuture warming future coolingfuture warming

#1: What are the consequences of anthropogenic land cover change for net primary production and surface climate at regional and global scales? Depends on type of land cover conversion Large regional disparities Temperate conversion: increase in NPP, surface cooling Tropical conversion: decrease in NPP, surface warming Global averages mask regional differences

#2: How might consequences of future land cover change differ from the past? Past conversions predominantly in temperate regions for mechanized agriculture Future conversion likely to be predominant in tropics Predominant effect in future likely to be opposite in sign to past

#3: How do the effects from land cover change compare with interannual variability? Consequences of past land cover change mostly within decadal-scale interannual variability Consequences of future changes outside of interannual variability

The past is not prologue to the future km Deforestation in Southern Bolivia