1 Climate Future: Science and Policy Randall M. Dole NOAA-CIRES Climate Diagnostics Center Introduction Mountain Climate Sciences Symposium Lake Tahoe, CA May 25, 2004

2 How might this accomplished in the present budget environment? A Key Symposium Goal Key Symposium Goal Develop support for long-term, interdisciplinary, integrated climate and climate-related research and monitoring in the western mountains.

3 1) Make explicit connections to goals in the Climate Change Science Program (CCSP) strategic plan. Suggested strategies for success Strategies for Success The guiding document for federal research on climate and related environmental issues for the next decade. Responds to Administration’s request to provide the best possible scientific information to support public discussion and decision-making on climate-related issues. Describes the overall strategy for developing knowledge of climate and related environmental and human systems, and for encouraging application of this knowledge.

4 Overarching question: How will variability and potential change in climate and related systems affect climate and related systems and our way of life? CCSP Goals related to MCSS: CCSP Goals 1)Improve knowledge of the Earth’s past and present climate and environment … 4)Understand the sensitivity and adaptability of different natural and managed ecosystems and human systems to climate and related global changes. 5)Explore the uses and identify the limits of evolving knowledge to manage risks and opportunities related to climate variability and change. Core Approach:Develop improved science-based resources for decision- Core Approach: Develop improved science-based resources for decision-making.

5 CCSP Research elements especially relevant to the MCSS: Research Elements Climate Variability and Change (chapter 4). Global water cycle (chapter 5). Land use/land cover change (chapter 6). Ecosystems (chapter 8). Human contributions and responses (chapter 9). Decision support resources development (chapter 11). Observing and monitoring the climate system (chapter 12).

6 From the Climate Variability and Change chapter, some MCSS- related issues: Example of issues, one element A few examples Potential for changes in extreme events at regional to local scales. Possibility of abrupt change. Development of approaches to inform decision-making. CCSP High-priority synthesis products State-of-knowledge of thresholds of changes that could lead to sudden changes in some ecosystems and climate-sensitive resources. Relationship between observed ecosystem changes and climate change. Use and limitations of observations, data, forecasts, and other projections for selected sectors and regions.

7 Consider focusing issues 2) Consider focusing issues Example: The Western Drought The western U.S. has been experiencing a severe, sustained, large-scale drought over the past several years. This drought has attracted: Intense media attention, including from major national media outlets. Raised grave management concerns. There is discussion of the possibility for the first-ever “call” on the Colorado River under the terms of the Colorado River Compact. We know that a large majority of the water supply in the western U.S. is deposited in the form of snow at high elevations and later released in snow melt, but observations of this natural storage, and how it may be changing, are woefully inadequate. Dillon Reservoir, Colorado

8 Severe Hydrologic Shortages Lake Powell Water Level (ft) Filled 1980 Lake Powell is at 42% capacity Lake levels have dropped ~ 120 feet Reservoirs above Lake Powell are currently at 62% of capacity Net flow of water for WY 2004 to date is 58% of average. Glen Canyon Dam

9 Potential Western water supply crises and conflicts by 2025 (USBR) US Bureau of Reclamation analysis of potential water supply crises and conflicts by the year 2025 based on a combination of technical and other factors, including population trends and potential endangered species needs for water. Note: There is an underlying assumption of a statistically stationary climate.

10 What are Observed Western Climate Trends?

11 Observed and modeled SW winter temperature trends Observed trends are consistent with trends obtained in climate models forced by observed GHG changes. However, models forced by observed SST over this period also show warming, so both anthropogenic and natural factors are likely contributing.

12 Western U.S. Streamflow Trends From Stewart, Cayan, and Dettinger (2004 ) There is a marked trend toward an earlier melt out and earlier peak flows throughout almost all of the West, consistent with a winter warming trend. Such warming increases evaporation, extends the growing season, and likely also increases the demand for water resources.

13 U.S. West climate trends projections from transient-forced runs (8 models, 18 runs )

14 Projected temperature and precipitation trends

15 What would a warmer future climate imply for the mountainous west and adjacent regions, e.g., for water resources, ecosystems, recreation? What are some potential implications? A few possibilities: Less efficient water storage and release. Less efficient water storage and release. Increased vegetative stress - species, ecosystem losses. Increased vegetative stress - species, ecosystem losses. Longer growing season, increased evaporation, and increased demand for already scarce water resources. Longer growing season, increased evaporation, and increased demand for already scarce water resources. Western fires, Retreat of South Cascade Glacier, Washington

16 3) Make connections to other ongoing priorities, such as natural disaster reduction, observations. Examples: Drought, COOP modernization (both have NOAA, USDA attention). 4) Focus on key regional issues. 5) Consider multiple stressors. Above all, aim toward end products that improve decision support and demonstrate value to taxpayers. Other suggestions

17 The End