Climate assessment reports synthesize what is known (at the time they are published) about recent and likely future climate changes and impacts for a particular geography (nation, region, state, city) and/or sector.
They can be especially helpful when you need summary statements, or basic maps and figures, for a given area. Often you can just use what the assessment provides without needing to visit a climate portal. The catch is that your location of interest and information needs might not align with what’s provided in existing assessments.
We highlight eight recent assessments (since 2013) that cover all or part of the Mountain West.
To compare features of these assessments, see our comparison table.
We also provide context on the IPCC and highlight other reports that, while not full climate assessments, provide additional climate change information relevant to the Mountain West.
Fourth National Climate Change Assessment (NCA4; 2018)
U.S. Global Change Research Program
- Summary statements on observed and projected climate trends and impacts (National: Ch. 1, Ch. 2; Regional: Ch. 24 – Northwest, 25 – Southwest)
- Maps of future change in U.S. temperature, precipitation, and other variables (Ch. 2)
- Sector impacts covered: Many (Ch. 3-17)
- State summaries can be viewed here: https://statesummaries.ncics.org
- CMIP5 LOCA downscaled projections
Climate Change in New Mexico over the Next 50 Years: Impacts on Water Resources (2022)
- Summary statements on observed (Ch. I) and projected (Ch. II-X) climate trends and impacts in New Mexico
- Maps and time series charts of future change in temperature, precipitation and other climate variables (Ch. II)
- Sector impacts covered: Ecosystems (Ch. IV), Soils (Ch. V), Landscape change, fire, and erosion (Ch. VI), Water supply (Ch. VII), Stormwater management (Ch. VIII), Water quality (Ch. IX)
- CMIP5 MACA (v2-METDATA) downscaled projections
- NM Bureau of Geology and Mineral Resources
Greater Yellowstone Climate Assessment (2021)
- Summary statements on observed (ES, Ch. 3) and projected (ES, Ch. 5, 6) climate trends and impacts in the Greater Yellowstone area
- Maps and time series charts of future change in temperature, precipitation, and other climate variables (Ch. 5, 6)
- Sector impacts covered: Water (Ch. 7)
- CMIP5 MACAv2 downscaled projections
- Greater Yellowstone Coalition and Partners
Fifth Oregon Climate Assessment (2021)
- Summary statements on observed and projected climate trends and impacts in OR (ES; State of Climate Science)
- Maps and time series charts of future change in temperature, precipitation, and other variables (State of Climate Science)
- Sector impacts covered within the report: Natural Systems, Built Environment, Public Health, Tribal Cultural Resources, Social Systems
- CMIP5: both non-downscaled and MACA downscaled projections; CMIP6 non-downscaled projections for some variables
- Oregon Climate Change Research Institute
California’s Fourth Climate Change Assessment (2019)
- Summary statements on observed and projected climate trends and impacts in CA (Brochure)
- Maps and time series charts of future change in temperature, precipitation, and other variables (Climate Scenarios Technical Report; Cal-Adapt portal)
- Sector impacts covered as separate reports: Water, Agriculture, Forests & Wildfire, Energy, Human Health (see full list of technical reports)
- CMIP5 LOCA downscaled projections (10 GCMs selected from full dataset of 32 GCMs)
- State of California
Montana Climate Assessment (2017)
- Summary of observed and projected climate trends and impacts in Montana (ES, Ch. 2)
- Maps and time series charts of future change in temperature, precipitation, and other climate variables (Ch. 2)
- Sector impacts covered: Water (Ch. 3), Forests (Ch. 4), Agriculture (Ch. 5), Human Health (separate report, 2021)
- CMIP5 MACAv2 downscaled projections
- Montana State U. and U. of Montana
Climate Change in Colorado (2014)
- Summary statements on observed and projected climate trends and impacts in Colorado (ES, Ch. 2, 4, 5)
- Maps and time series charts of future change in temperature, precipitation, and other climate variables (Ch. 5)
- Sector impacts covered: Water (Ch. 5)
- CMIP5: both non-downscaled and BCSD downscaled projections
- Western Water Assessment & Co Water Conservation Board
Climate Change Impacts and Adaptations in Washington State: Technical Summaries for Decision Makers (2013)
- Summary statements on observed (Sec. 2) and projected climate trends and impacts in Washington (Sec. 5-12)
- Maps and time series charts of future change in temperature, precipitation, and other climate variables (Sec. 5)
- Sector impacts covered: Water (Sec. 6), Forests (Sec. 7), Plants and animals (Sec. 8), Coast and ocean (Sec. 9), Infrastructure (Sec. 10), Agriculture (Sec. 11), Human Health (Sec. 12)
- CMIP5 projections, not downscaled; some CMIP3 projections, both not downscaled and NARCCAP-downscaled
- Climate Impact Group & Washington State Department of Ecology
The IPCC Climate Assessment Reports
The most globally influential climate assessment is produced by hundreds of scientists worldwide under the auspices of the Intergovernmental Panel on Climate Change (IPCC). An updated set of IPCC assessment reports (or ARs) has been released every five to eight years since 1990.
In August 2021, they released the first report of the most recent IPCC AR, AR6 Working Group 1: The Physical Science Basis (https://www.ipcc.ch/report/ar6/wg1/). IPCC reports provide a comprehensive synthesis of available climate science as evident in the 1,300 pages of the AR6 Physical Science report, which references 14,000 research papers. The Summary for Policymakers (SPM), a 40-page summary of the main report, provides a much more accessible “big picture” of the state of climate change science.
These and other IPCC reports do provide some regional information, but the regions are often larger than what decision-makers need. For example, IPCC’s “Western North America” region covers the Mountain West, extends from off the West Coast to longitude 105 W, and from just north of the Canadian border down to far southern Arizona and New Mexico.
To accompany the report, the IPCC also offers a new interactive portal, the IPCC WGI Interactive Atlas. It allows users to view projected climate changes for Western North America and other regions, and for large river basins, including the Colorado River Basin. We describe this portal in Portals for visualizing climate change data, targeted.
Other reports with climate-change information for the Mountain West
Climate Change Vulnerability and Adaptation in the Intermountain Region (2018)
USDA Forest Service & Intermountain Adaptation Partners
Climate Change, Water Resources, and Potential Adaptation Strategies in Utah (2020)
U. of Utah & Utah Department of Natural Resources
Colorado River Basin Climate and Hydrology: State of the Science (2020)
Western Water Assessment
- Focus: Water-supply impacts
- See Chapter 11: Climate-change informed hydrology
Water Reliability in the West – 2021 SECURE Water Act Report (2021)
Bureau of Reclamation
- Focus: Water impacts
- See Basin Reports for each of the major river basins in the Western U.S.
- See Interactive Web Portal for an overview of more technical report content
- West-Wide Climate and Hydrology Assessment provides the technical details for the (much shorter) SECURE Water Act Report
