Global Climate Change: The science, regional impacts, and implications for PNW power producers Amy Snover, PhD UW Climate Impacts Group September 7, 2005 Northwest Independent Power Producers Coalition Annual Meeting

Presentation Outline UW Climate Impacts Group UW Climate Impacts Group Global and regional climate change Global and regional climate change Regional impacts of climate change Regional impacts of climate change Planning for climate change Planning for climate change

Climate Impacts Group One of 8 U.S. regional integrated assessment teams based at the University of Washington Evaluating the impacts of climate variability and climate change on the PNW environment and its social systems Primary research areas: climate dynamics, water, salmon, forests, coasts Outreach & decision support Ultimate goal: to help the region become more resilient to natural climate variability and human-caused climate change

Global Climate Change

Facts beyond dispute  There is a natural greenhouse effect “Greenhouse” gases (H 2 O, CO 2, CH 4, N 2 O,…) warm the Earth (surface temperatures) by ~33°C (60°F)  Humans are increasing the greenhouse effect by adding greenhouse gases to the atmosphere CO 2 up 31%  There is considerable evidence that Earth has warmed in the last 100 years 0.6  0.2°C (1.1  0.4°F) since 1900  Without drastic changes in current emissions trends, greenhouse gas concentrations will increase dramatically over the next century and beyond Source: The Intergovernmental Panel on Climate Change (IPCC),

Source: OSTP

A Picture Worth A Thousand Words (Bronze Plaque at Mauna Loa Observatory)

Some evidence that Earth is warming “An increasing body of observations gives a collective picture of a warming world and other changes in the climate system.” (IPCC 2001)  Global average surface temperature increase (1.1  0.4°F) computed using thermometers includes correction for small urban heat island effect  Permafrost, glaciers melting  Arctic ice thinning  Frost-free season longer in many places  Borehole temperatures indicate warming

Some evidence that humans are responsible  Rate of warming unusual  Hard to explain as natural (e.g., volcanoes, solar or oceanic variations)  Warming of last 30 years consistent with basic physics, greenhouse gas changes

Natural Climate InfluenceHuman Climate Influence All Climate Influences “There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities.” (IPCC 2001)

Change in Motion? Trends in 20 th Century PNW Climate

Temperature Trends by Station 154 stations with long records Almost every station shows warming – average increase of 1.5 F / century Urbanization not a major source of warming Cooler Warmer Mote 2003(a) 3.6 °F 2.7 °F 1.8 °F 0.9 °F

Precipitation Trends by Station 165 stations with long records Most stations becoming wetter – average increase of 2.9 inches/ century (14%)… …however, it is more difficult to assess trends due to challenges in measuring precipitation Mote 2003(a) Decrease Increase

Snow Water Equivalent Trends Trends in April 1 SWE, Results based on data from 824 snow course collection sites Most stations (73%) showing a decline in snow water equivalent Numerous sites in the Cascades with 30% to 60% declines Mote 2003(b) Decrease Increase

Other Observed Trends Timing of peak snowpack trending towards earlier calendar dates Peak spring runoff moving days earlier in year throughout western US & Canada  Increasing proportion of annual flows in March; decreasing proportion in June (e.g., Cedar R) Summer water availability is declining  e.g., N.F. Clearwater R, Cedar R, S.F. Tolt Dramatic retreat of South Cascade glacier in 20 th century Earlier bloom dates for the purple common lilac and honeysuckle Q: Is this climate change? A: It’s too soon to tell, but changes are consistent with predictions.

Where Are We Headed? 21 st Century Climate Change Projections

Source: IPCC TAR 2001 “Human influences will continue to change atmospheric composition throughout the 21 st century.” IPCC 2001 CO 2 in the 21 st century

Global average temperature projected to rise °F by 2100 Global average temperature projected to rise °F by 2100 Other changes too: sea level rise, extreme events, etc. Even if CO 2 emissions ended tomorrow, warming would continue through 21 st century Due to atmospheric persistence of greenhouse gases Changes over next several decades are independent of emission paths Today’s choices matter for longer-term changes Source: IPCC TAR 2001 IPCC 2001 Global climate change model uncertainty emissions uncertainty

Projected PNW Climate Change 2020sTemperaturePrecipitation Low+ 0.9°F+ 2 % Mean+ 2.7°F+ 7% High+ 4.7°F+ 14 % 2040sTemperaturePrecipitation Low+ 2.7°F- 3 % Mean+4.1°F+ 7% High+ 5.8°F+ 14 % Based on an increase in equivalent CO 2 of 1% per year. Benchmarked to the decade of the 1990s. Projected changes in average annual PNW temperature and precipitation for the decades of the 2020s and 2040s. high confidence lower confidence Warmer, wetter winters … Warmer summers

Regional Impacts

s2090s Main Impact: Less Snow Main Impact: Less Snow Changes in Simulated April 1 Snowpack

Hydrologic characteristics of PNW rivers

Impacts on Streamflow Low elevation snow basin: Spokane River Transient (rain/snow) basin: Quinault River 2040s Snow dominant basin: Columbia River (at The Dalles)

Impacts on hydropower generation NWPCC 2005

Simulated reliability of water resources objectives for “middle-of-the-road” scenarios

Impacts on Hydropower & Fish Flows

Impacts on Demand ?? NWPCC 2005 Sailor et al. 1997

Natural Streamflows at Dworshak Cool PDO 2040 Warm PDO 2040 Q: Will global warming be “warm and wet” or “warm and dry”? A: Probably BOTH!

Planning for Climate Change So what do we do about it?….

Preparing for Climate Change Assess changes in electricity demand (based on projected temperature increases) Assess changes in electricity demand (based on projected temperature increases) Assess changes in hydroelectric generation (based on projected streamflow changes) Assess changes in hydroelectric generation (based on projected streamflow changes) Identify actions to mitigate potential energy shortfalls Identify actions to mitigate potential energy shortfalls Identify actions to mitigate potential impacts on fish & wildlife Identify actions to mitigate potential impacts on fish & wildlife (Approach used by Northwest Power and Conservation Council)

Planning Resource: The Climate Impacts Group Sector-specific meetings with technical resource staff and senior decision makers:  Fall climate and water forecast meetings (Oct 13 & )  Climate and water policy meetings  Climate Impacts on salmon management and recovery Resources at CIG (case studies, scenarios) Research consultancies and collaborations

Climate Change Streamflow Scenario Tool for the Columbia River Basin Climate-adjusted streamflow data for 2020s and 2040s available on web site for 90+ locations in the Columbia River Basin pt/ccstreamflowtool/sft.shtml Partners: Northwest Power and Conservation Council Idaho Dept of Water Resources US Bureau of Reclamation US Army Corps of Engineers

Effects of a changing climate are already becoming apparent, but there is very likely much more change to come Regional warming (3-5°F by 2040s) likely to be faster than global warming (1-4°F by 2040s) In the PNW, climate change is expected to:  Reduce winter snowpack & summer streamflow  Increase winter flooding, alter the amount and timing of streamflows with consequences for urban and irrigation water supplies, hydropower production, instream flows  All scenarios point to better situations in winter (less demand and more hydro generation) and worse situations in summer (less generation, more demand, lower & warmer instream flows) Knowledge & tools exist to support planning now  Historic streamflow record increasingly inadequate for statistical forecasting and long-range planning Summary

For More Information … Amy Snover UW Climate Impacts Group Climate Science in the Public Interest

source: Mann et al. 2003, EOS Northern hemisphere temperatures, the long-term context

(drought comparable to water year 1992, using data from ) x 2 x 4.7 x 1.3 Warm/dry scenario Frequency of drought in the Columbia River