The U.S. Geological Survey (USGS) developed future scenarios of land use-land cover (LULC) change in the United States as part of a national carbon sequestration assessment required by the U.S. Congress (Energy Independence and Security Act of 2007). Future potential demand, or the area of land required for each LULC class, was based on a set of scenarios from three Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios (SRES) (Nakicenovic et al. 2000): A2 (emphasizes economic development with a regional focus), A1B (emphasizes economic development with a global orientation), and B1 (emphasizes environmental sustainability with a global orientation). To develop LULC change scenarios that were logically consistent with SRES storylines, Sleeter and others (2012) took projected national LULC change data from the Integrated Model to Assess the Global Environment (IMAGE) (Strengers et al. 2004) and allocated them to U.S. Environmental Protection Agency (EPA) Level III ecoregions based on land-use histories from the USGS Land Cover Trends project (Loveland et al. 2002), as well as expert knowledge. The LULC classification scheme of the scenarios closely followed the National Land Cover Database (NLCD) (Vogelmann et al. 2001) and includes broad classes such as cropland, hay/pasture, development, grassland, forest and wetlands.
The USGS used a probabilistic LULC model, FOREcasting SCEnarios of land-use change (FORE-SCE) to distribute future regional LULC change on the landscape for each LULC change scenario (Sohl et al. 2008; Sohl et al. 2012). The allocation was based on probabilities of occurrence determined by present-day LULC associations with biophysical and socioeconomic characteristics of the landscape, such as slope, elevation, soil carbon, climate and distance to roads and cities. For this LCC-funded project, we ran FORE-SCE dynamically with future downscaled global climate model (GCM) outputs, meaning that LULC change was modeled based on socioeconomic demands, as well as changing climate. Two statistically downscaled GCMs were selected for each emissions scenario to provide representative future climate projections for California– one that represents a warm, wet future and one that represents a hot, dry future. GCMs were selected that included variables for minimum or maximum temperatures, which were considered important determinants of vegetation distribution. Climate variables—including 10-year averages of precipitation, summer maximum temperature, winter minimum temperature, potential evapotranspiration, and climatic water deficit—were updated in the model at 10-year intervals. Downscaled climate and hydrological data were generated by the USGS Basin Characterization Model at 270 meter resolution (Flint and Flint 2012), resampled to 250 meters to match spatial resolution of the growth model.
We ran the FORE-SCE model for two EPA Level III ecoregions, Central Valley and Chaparral and Oak Woodland. The extent of these ecoregions matches the high priority conservation focus area map in use by the California Rangeland Conservation Coalitition. Model outputs are maps of LULC change generated yearly from 2006 to 2100 at a spatial resolution of 250 meters. Outputs for six scenarios are available: two climate projections each for A1B, A2 and B1 SRES scenario.
References:
Flint, L.E. and Flint A.L. 2012. Downscaling future climate scenarios to fine scales for hydrologic and ecologic modeling and analysis. Ecological Processes 1:2. Available online at: http://www.ecologicalprocesses.com/content/1/1/2
Loveland, T.R., Sohl, T.L., Stehman, S.V., Gallant, A.L., Sayler, K.L., Napton, D.E., 2002. A strategy for estimating the rates of recent United States land-cover changes. Photogrammetric Engineering and Remote Sensing 68(10), p. 1091-99.
Nakicenovic, N., Swart, R. (Eds.), 2000. IPCC Special Report on Emission Scenarios. Cambridge University Press, Cambridge, UK.
Sleeter, B. M., Sohl, T. L., Bouchard, M. A., Reker, R. R., Soulard, C. E., Acevedo, W., Griffith, G., Sleeter, R. R., Auch, R. F., Sayler, K. L., Prisley, S., Zhu, Z., 2012, Scenarios of land use and land cover change in the conterminous United States: Utilizing the special report on emission scenarios at ecoregional scales. Global Environ. Change, 22(4): 896-914. http://dx.doi.org/10.1016/j.gloenvcha.2012.03.008.
Sohl, T. and K. Sayler. 2008. Using the FORE-SCE model to project land-cover change in the southeastern United States. Ecological Modelling 219:49-65.
Sohl, T.L., Sleeter, B.M., Sayler, K.L., Bouchard, M.A., Reker, R.R., Bennett, S.L., Sleeter, R.R., Kanengieter, R.L., and Zhu, Z., 2012. Spatially explicit land-use and land-cover scenarios for the Great Plains of the United States. Agriculture, Ecosystems and Environment 153: pp 1-15.
Strengers, B. et al. 2004. The land-use projections and resulting emissions in the IPCC SRES scenarios as simulated by the IMAGE 2.2 model. GeoJournal 61:381-393.
Vogelmann JE, Howard SM, Yang L et al (2001) Completion of the 1990s National Land Cover Data Set for the conterminous United States. Photogrammetric Engineering and Remote Sensing 67:650-652.
