Regional Climate and Hydrologic Change:
Internally Consistent Future Climate Projections for Resource Management
Planning for the effects of climate change on natural resources often requires detailed projections of future climate at finer spatial scales consistent with the processes managers typically consider. While it is numerically possible to produce downscaled climate at very fine scales (< 5km), accurate estimation at these scales is difficult and less certain without very detailed local information. Both the absence of a sufficiently dense network of long-term climate observations and the presence of local factors such as topography and land surface feedbacks from vegetation and snowpack contribute to the uncertainties of localized projections. To meet the needs of managers for developing adaptation strategies, vulnerability assessments, climate impacts assessments, and specific resource modeling at landscape scales, we downscaled projections from the coarser scales of global climate models (GCMs) to more local scales. The R1/R6 project was designed primarily to provide climate information consistent with manager requests and to create a basis for more detailed work or for a more comprehensive approach to downscaling and regional climate modeling. The objectives of this project were to:
- Develop consistent historical and future downscaled climate and hydrologic data and projections using the same methodology for several major river basins in the western United States, Columbia, upper Missouri, upper Colorado, and Great Basins (Figure 1), and
- Summarize that information with the needs of the funding agencies in mind, including descriptions of where to get the information, methods, results, uses of and uncertainties associated with the data and projections.
Methods and Products
We analyzed global climate models (GCMs) available from the IPCC AR4 assessment to better understand the projected future climate by region and individual model sensitivities within regions. We then developed an ensemble of climate models that have the best capability in the 5 basins and projected downscaled climate and hydrology based on an ensemble delta method and two bracketing scenarios. Applying the downscaled climate data to the historical (1916-2006) and two future timeframes (2030-2059, "2040s"; 2070-2099, "2080s") at 1/16th degree (~6km), we estimated hydrologic output tailored for impacts assessments (e.g., snow water equivalent, soil moisture, potential evapotranspiration, actual evapotranspiration, and runoff). The result is a consistent set of downscaled climate and hydrologic projections at ~6km for the entire Columbia, upper Missouri, and upper Colorado basins and 12km for the Great and lower Colorado basins. The data are summarized at monthly time scales for Bailey's Ecosections (Figure 2), Omernik Level III Ecoregions (Figure 3), and 8-digit Hydrologic Unit Code (HUC 4) basins; but are also available in raw form on a grid-cell basis at daily time steps and in ascii grid (ArcGIS) format for observed and future climatologies.
The USFS has developed a website that serves the project data:
The CIG maintains a database of products from this project that are available at the following links:
- Trend maps (graphics) and station tables for Historical Climate Network trends
These maps and the associated tables show trends at HCN stations for maximum and minimum temperatures and for precipitation during three historical timeframes: 1915 - 2006, 1950 - 2006, 1970 - 2006. The maps are provided for each major basin: CO (Colorado), GB (Great Basin), MB (Missouri Basin) and PNW (Columbia).
- Bias analysis of all available GCMs (B1, A1B, A2) by region
- Data, graphics, future projections summarized by subregion
Summaries are provided for Bailey ecosection, 8-digit Hydrologic Unit Code (HUC) and Omernik ecoregions (Environmental Protection Agency delineations).
- Western US ascii grids of 23 monthly climatic and hydrologic variables
The monthly climatologies are available for the historical (1916 - 2006), A1B ensemble (2030 -1959), ensembles for miroc 3.2 and pcm 1 (A1B 2070 - 2099).
- Ratios of April 1 SWE to cool season snowpack, by 10 digit HUCs
- Variable Infiltration Capacity hydrologic model output for historical period and future scenarios (note: tar.gz bulk download)
- Regional climate models: WRF projections from CCSM3 and ECHAM5 GCMs
This project was funded by a consortium of federal agencies that required new regional and summary data on projected climate changes for planning purposes and impacts studies. Funding was provided by the United States Forest Service (USFS) Region 1, United States Fish and Wildlife Services (USFWS), USFS Rocky Mountain Research Station Boise Aquatic Sciences Lab, and USFS Region 6. The project builds on the considerable research effort and funding already devoted to similar goals in the Climate Impacts Group's Washington Climate Change Impacts Assessment (WACCIA) and The Columbia Basin Climate Change Scenarios Project, and would not have been possible without the resources and personnel associated with those projects.
Littell, J.S., M.M. Elsner, G. Mauger, E. Lutz, A.F. Hamlet,, and E. Salathé. 2011. Regional Climate and Hydrologic Change in the Northern US Rockies and Pacific Northwest: Internally Consistent Projections of Future Climate for Resource Management. DRAFT report available online here.
Littell, J.S., D. McKenzie, B. K. Kerns, S. Cushman, and C. G. Shaw. 2011. Managing uncertainty in climate-driven ecological models to inform adaptation to climate change. Ecosphere 2:102. Available here.
McKelvey, K.S., J. P. Copeland, M. K. Schwartz, J. S. Littell, K. B. Aubry, J. R. Squires, S. A. Parks, M.M. Elsner, G.S. Mauger. 2011. Climate change predicted to shift wolverine distributions, connectivity, and dispersal corridors. Ecological Applications. Pre-print available here.
McWethy D. B., S. T. Gray, P. E. Higuera, J. S. Littell, G. T. Pederson, A.J. Ray, and C. Whitlock. 2010. Climate and terrestrial ecosystem change in the U.S. Rocky Mountains and Upper Columbia Basin: Historical and future perspectives for natural resource management. Natural Resource Report NPS/GRYN/NRR—2010/260. National Park Service, Fort Collins, Colorado.
McKelvey, K.S., J. P. Copeland, M. K. Schwartz, J. S. Littell, K. B. Aubry, J. R. Squires, S. A. Parks, M.M. Elsner, G.S. Mauger. In press. Climate change predicted to shift wolverine distributions, connectivity, and dispersal corridors. Ecological Applications. Pre-print available here.
Wasserman, T.N., S. A. Cushman, A. S. Shirk, E. L. Landguth , and J. S. Littell. In press. Simulating the effects of climate change on population connectivity of American marten (Martes americana) in the northern Rocky Mountains, USA. Landscape Ecology.
Wenger, S.J., D.J. Isaak, C.H. Luce, H.M. Neville, K.D. Fausch, J.B. Dunham, D.C. Dauwalter, M.K. Young, M.M. Elsner, B.E. Rieman, A.F. Hamlet and J.E. Williams (2011) Flow regime, temperature, and biotic interactions drive differential declines of trout species under climate change. Proceedings of the National Academy of Sciences doi:10.1073/pnas.1103097108