Regional Climate and Hydrologic Change:
Internally Consistent Future Climate Projections for Resource Management
Climate information is a key component of prioritizing adaptation actions and conducting vulnerability assessments. However, despite the increasing availability of climate information in the Western United States, a consistent set of hydro-climatic projections does not exist for the region at large. Furthermore, managers require information on the uncertainty in climate projections, in particular for changes in climatic extremes, which affect aquatic and terrestrial ecosystem vulnerability. The goal of this project is to address these needs.
This project is an update to a previous "quasi west-wide" climate change dataset, with the addition of the follwing:
- Climate and hydrologic projections for California, so that the dataset now covers the entire Western U.S. (Figure 1 shows the full domain as well as the dominant river basins),
- Statistically dowsncaled results from two additional climate models (echam5 and hadgem1), so that the ensemble projections can now be compared to "bracketing" scenarios that roughly span the range of projections for changes in temperature and precipitation,
- Dynamically downscaled results using the Weather Research and Forecasting (WRF) Regional Climate Model, forced by projections from the echam5 Global Climate model, and
- Analyses that focus on changes in climatic and hydrologic extremes, and particular assessing extremes of soil moisture, floods, and low flows.
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 6 major river basins (Columbia, Upper Missouri, Upper Colorado, Lower Colorado, Great Basin, and California) and projected downscaled climate and hydrology based on an ensemble delta method and four bracketing scenarios. Bracketing scenarios were chosen to span the range from cooler/drier (less winter flooding) to warmer/wetter (more winter flooding) and from cooler/wetter (less summer drought) to warmer/drier (more summer drought) -- i.e., spanning the four "corners" of changes in temperature and precipitation. Figure 2 shows the projected changes for all IPCC AR4 models, and highlights the changes for the 10 models included in the ensemble, as well as the 4 bracketing models.
click image to enlarge
Figure 2 Precipitation (Oct-Mar) and temperature (Annual average) projections for all IPCC AR4 models, for A1b 2040s. Models included in the ensemble are highlighted in blue and green, those that are not included in the ensemble are shown in gray. The ensemble average projection is denoted by the plus ("+") symbol, and the four bracketing models are highlighted in green.
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, California, and upper and lower Colorado basins and 1/8th degree (~12km) for the Great basin. The data are summarized at monthly time scales for Bailey's Ecosections (Figure 3), Omernik Level III Ecoregions (Figure 4), and 8-digit Hydrologic Unit Code (HUC 4) basins. Raw data are also available in raw form on a grid-cell basis at daily time steps and in ascii grid (ArcGIS) format for historical and future climatologies.
The CIG maintains a database of products from this project that are available at the following links. We would appreciate it if you could send a brief note describing how you plan to use the data (contact information below).
Trend maps for COOP surface station trends
These maps show trends at US COOP stations for mean annual maximum temperature, minimum temperature, and total annual precipitation during three historical time frames: 1915-2006, 1950-2006, and 1970-2006. The maps are provided for each major basin: CA (California), CO (Colorado), GB (Great Basin), MB (Missouri Basin) and PNW (Columbia).
Subregion Summaries. Organized by subregion
Summaries are provided for Bailey ecosection, 8-digit Hydrologic Unit Code (HUC) and Omernik ecoregions (Environmental Protection Agency delineations).
Subregion Summaries. Organized by variable, month
This directory contains the same summaries as above, except that the data are organized by variable: each data table contains summaries for all of the above Bailey/Omernik/HUC regions for one variable, month.
- Ratio of April 1 SWE to cool season snowpack. Organized by 10-digit HUCs
This is table lists the mean ratio of April 1st Snow Water Equivalent to October to March Precipitation for each 10-digit Hydrologic Unit Code (HUC) domain within the study region. Values are reported for historical as well as each of the 10 future climate scenarios.
Full Western US domain. ascii grids of 23 monthly climatic and hydrologic variables
Monthly time series files (ascii), along with gridded monthly climatologies (ArcInfo ascii-grid format) for 23 hydro-climatic variables. Data are available for the historical (1916-2006) period, along with 10 future climate projections: A1B scenario, 2040s/2080s, ensemble (or composite, "comp") and 4 bracketing scenarios (echam5, hadgem1, miroc_3.2, and pcm1).
- Regional climate model results: WRF projections from ECHAM5 GCM
Daily and monthly time series files (ascii), along with gridded monthly climatologies (ArcInfo ascii grid format). As for the full Western US domain, data are available for 23 hydro-climatic variables for the historical period as well as 10 future climate projections.
Pacific Northwest domain
(as above for CA domain)
Upper Missouri basin
(as above for CA domain)
(as above for CA domain; includes both upper and lower Colorado basins)
(as above for CA domain)
This research was funded through a grant from the US Department of Interior Northwest Climate Science Center.
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
Questions regarding this dataset can be directed to:
- Guillaume Mauger (gmauger at uw dot edu)