Preparing for Climate Change in the Pacific

Northwest

http://www.yakima.net/ UW Climate Impacts Group UW Climate Impacts Group

UW Climate Impacts Group

UW Climate Impacts Group

UW Climate Impacts Group

A (Brief!) Overview of Global Climate Change

A Perspective on Climate Change:

Climate change is not new on a geologic time scale…

ex: Glaciers in the Puget Sound region

…and systems have adjusted

ex: Species migration and extinction

Past Climate ChangePast Climate Change

• CO2 concentration levels

– Appear to be higher than any time in past ~ 23 million yrs

• The human footprint

– Human activities altering the climate system

– Human systems based on expectation of certain climate conditions

– Population growth, political boundaries, resource dependency/depletion, habitat fragmentation limit ability of natural and human systems to tolerate rapid change

Present Day Climate Change: What is Different?

Greenhouse gases (water vapor, CO2, CH4, N2O) play a critical

role in determining global temperature

Rapid increases in greenhouse gases are changing this natural balance

• Atmospheric concentration has increased 31% since 1750

• ~70% of CO2 emissions come from fossil fuel burning

• Accounts for ~ 60% of warming

Carbon Dioxide (CO2)

From a long term perspective, these changes are enormous

Methane (CH4)

• Atmospheric concentration has increased ~150% since 1750

• Current concentration is highest in last 420,000 years

• Slightly more than 50% of CH4 emissions originate from human activities

• Accounts for ~20% of warming

Figure source: IPCC 2001

Nitrous Oxide (N2O)

• Atmospheric concentration has increased 17% since 1750

• Current concentration is highest in last 1,000 years

• About 33% of current N2O emissions originate from human activities

Figure source: IPCC 2001

Where do these increases come from?

• Human sources:– Fossil fuel burning (oil, coal, natural gas) (CO2, CH4, N20)

– Deforestation and land use change (CO2)

– Agricultural practices (CO2, CH4, N20)

– Energy extraction (CO2, CH4)

– Ruminant (e.g., cows) (CH4)

– Cement production (CO2)

– Landfills (CH4)

• Natural sources– Wetlands (CH4)

– Oceans, soils (CO2, N20)

– Decomposition of organic matter (CO2, CH4)

Changes in Global Average TempChanges in Global Average Temp

• With these changes in greenhouse gases, the Earth’s average global temperature has been increasing

• Since 1900, the planet has warmed 0.60.2°C (1.10.4°F)

• The significance of this temperature increase is more evident when you look over the longer term.

Source: IPCC 2001

How do we get perspective on these changes?

• Instrumental data

• “Proxy” data

– Ice cores

– Pollen

– Tree rings

– Corals

– Landscape

• Observed changes in natural systems (20th century)

– The extent and thickness of Arctic sea ice is in decline (extent is down 10-15%; thickness is down 40%)

– Permafrost at northern latitudes is thawing

– The growing season has lengthened 1-4 days per decade during the last 40 years in the Northern Hemisphere.

– Plants are flowering earlier, birds are arriving earlier, and insects are emerging earlier in the Northern Hemisphere,

Getting perspective (cont’d)

• 20th century observed changes, cont’d

– Increased frequency of coral bleaching, particularly during El Niño events

– Weather-related economic losses are increasing (partly due to choices about where we live and work)

– Mid-elevation mountain snowpack is in decline and melting earlier

– Glaciers are in widespread retreat

Getting perspective (cont’d)

2004

1941

Riggs GlacierGlacier Bay National Park

Nearly every glacier in Nearly every glacier in the Cascades and the Cascades and

Olympics has retreated Olympics has retreated during the past 50-150 during the past 50-150

yearsyears

Photos courtesy of Dr. Ed Josberger, USGS Glacier Group, Tacoma, WA

South Cascade South Cascade Glacier, 1928 (top) Glacier, 1928 (top)

and 2000 (right)and 2000 (right)

Projected range of global-scale warming by 2100: 2.5-10.5°F (1.4-5.8°C)

Warming expected through 21st century even if CO2 emissions end today due to persistence of greenhouse gases.

21st Century Global Warming

Figure source: IPCC 2001

Carbon Dioxide ~60% of warming 5 to 200 years

Methane ~20% of warming 8 to 12 years

Nitrous Oxide ~6% of warming ~120 years

CF4 (Perfluoromethane) >50,000 years

Estimated atmospheric

lifetime of major greenhouse gas

(per molecule)Data source: IPCC 2001

20th century PNW climate trends

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PNW Temperature Trends by Station

• Average annual temperature increased +1.5F in the PNW during the 20th century (+2.3 F in the Puget Sound)

• Almost every station shows warming

• Extreme cold conditions have become rarer

• Low temperatures rose faster than high temperatures

Annual variability present throughout the warming trend

3.6 °F

2.7 °F

1.8 °F

0.9 °F

Cooler Warmer

Mote 2003(a)

Snow Water Equivalent Trends

• Similar trends seen throughout the western United States - 73% of stations show a decline in April 1 snow water equivalent

• Most PNW stations showing a decline in snow water equivalent

• Numerous sites in the Cascades with 30% to 60% declines

Decrease Increase

Trends in the Timing of Spring Runoff

• Advances of 10-30 days between 1948-2000

• Greatest trends in PNW, Canada, and AK

• >30% of trends are statistically significant at the 90% level, especially in the PNW

Stewart, I., Cayan, D.R., and Dettinger, M.D., 2004, Changes in snowmelt runoff timing in western North America under a "Business as Usual" climate change scenario: Climatic Change 62, 217-232.

+ 20 days later- 20 days earlier

Peak of spring runoff is moving earlier into the spring throughout western US and Canada

21st century PNW climate change

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UW Climate Impacts Group

UW Climate Impacts Group

Projected 21st century PNW climate

 

2020s Temperature Precipitation

Low + 0.7ºF (0.4ºC) - 4%

Mean + 1.9ºF (1.1ºC) +2 %

High + 3.2ºF (1.8ºC) +7%

2040s Temperature Precipitation

Low + 1.4ºF (0.8ºC) - 4%

Mean + 2.9ºF (1.6ºC) + 2%

High + 4.6ºF (2.6ºC) + 9 %

All changes are benchmarked to average temperature and precipitation for 1970-1999

• Projected rate of warming: 0.2-1.0°F (~ 0.5ºF average) per decade through at least 2050 (compared to 1.5°F over 20th century)

• Temperatures will increase across all seasons; most models project the largest temperature increases in summer (June-August)

• High confidence in projected temperature changes, low confidence in precipitation changes

Projected Effects on PNW Resources

Less Snow

Warmer temperatures contribute to more winter precipitation falling as rain rather than snow, particularly in transient (mid-elevation) basins

“Current” Climate ~ 2040s (+3°F) ~ 2060s (+4.5°F)

-44% -58%

Changes in Simulated April 1 Snowpack for the Cascade Range in WA and OR

(mm)

Altered Streamflows

• If more winter rain → higher winter streamflows

• Warmer temperatures → earlier snowmelt and a shift in the timing of peak runoff

• Lower winter snowpack → lower spring and summer flows

(note: under new scenarios, light blue bands are more likely to be seen mid-century (2050s) rather than 2040s

+3.6 to +5.4°F(+2 to +3°C)

Projected streamflow changes in the Quinault and Yakima Rivers

Implications• Water supplies:

– Increased vulnerability to drought,

– Increased competition for water during summer as demands increase with population growth and climate change

• Water quality:

– Altered water quality (water temp, dissolved oxygen, salinity, nutrients, fecal coliform)

– Impacts vary with parameter and location

• Flooding and stormwater management:

– Increased risk of winter flooding in mid- and low-elevation basins

– Changes in urban flooding less clear (importance of frequency and intensity of storm events)

Implications (cont’d)

• Hydropower:

– Increased winter generation due to higher streamflows (but lower demand)

– Reduced summer generation due to lower streamflows (but increased demand)

• Salmon:

– Increased stress due to lower summer and fall streamflows, warmer water temperatures, and increased potential for winter flooding.

– Unclear how coastal or open ocean conditions will respond

• Marine ecosystem and function:

– Impacts reverberate through the food web from the bottom-up (e.g., phytoplankton) and top-down (e.g., marine mammals).

– Magnitude of change hard to predict at this point but broad reorganization of systems observed with subtle changes in natural variability

• Forests:

– Increased vulnerability to severe forest fires and insect outbreaks

– Reduced regeneration and growth at dry low elevation sites (with some benefit at higher elevations)

– Shifts in some species ranges over time

• Agriculture:

– Overall impacts vary with crops and availability of water

– Increased crop yields where there is sufficient soil moisture or irrigation water

– Increased weed growth and risk of pest outbreaks

And let’s not forget about…• Skiing:

– Increased risk of shortened ski season at lower elevation ski areas due to lack of snow or poor snow quality

– Could improve customer access to ski areas

Implications (cont’d)

How will tree growth change in a warmer climate?

The Pacific Northwest has wet winters and dry summers potential for summer moisture stress

• Growth may decrease in dry, eastside forests

• Growth may decrease slightly in low-elevation, westside forests

• Growth will increase in many high-elevation forests

Are forests responding to climatic change?

Growth increases at high elevation

Regeneration increases at high elevation throughout western North America

What could cause these patterns?

From McKenzie et al.

(2001)

How will climate change affect wildfire?

Years with fire area > 80,000 ha

National Forest data, 1916-2005

Warm-phase PDO Cool-phase PDO

Idaho 14 7

Oregon 14 5

Washington 10 2

TOTAL 38 (73%) 14 (27%)

Area burned, western U.S.

Total Wildfire Area Burned 1916-2002USFS, NPS, BLM, BIA Lands

1920 1930 1940 1950 1960 1970 1980 1990 20000

1x106

2x106

3x106

4x106

5x106

WA, OR, ID Wildfire Area Burned 1916-2002USFS, NPS, BLM, BIA Lands

1920 1930 1940 1950 1960 1970 1980 1990 20000

500x103

1x106

2x106

2x106

3x106

3x106

Fire suppression Fire exclusion Fuel accumulation

Some fire Much less fire Lots of fire

Cool PDOWarm PDO Warm PDO

Acr

es b

urn

ed

Future wildfire?

From McKenzie et al. (2004), Conservation Biology 18:890-902

Analysis of wildfire data since 1916 for the 11 contiguous Western states shows that for a 2oC increase that annual area burned will be 2-3 times higher.

Stress interactions, disturbance

Increased fire risk• Higher fire frequency• Higher fire intensity, esp. in eastside forests

Increased insect outbreaks• Postfire stress• Low vigor stands with high stem density

Carbon in forest ecosystems

Carbon dioxide (CO2) is emitted by human activities -- Fossil fuel combustion (autos, industry)

CO2 is emitted by natural processes -- Fire, decomposition, respiration

Trees conduct photosynthesis by assimilating CO2, a limiting factor for productivity and growth.

Forests take up and store large quantities of carbon on a global and regional basis-- But annual uptake in Washington only ~20% of emissions

Forest carbon budgetsStorage (quantity) vs. uptake (rate)

Young forest Storage Uptake Mg/ha Mg/ha/yr

50-100 5-10

Old forest 400-1000+ + 1.0?

(600?)

• Mitigation activities focus on reducing emissions of greenhouse gases

– Ex: Kyoto Protocol, West Coast Governors’ Climate Change Initiative

• Adaptation activities focus on developing the capacity to manage the change that occurs as mitigation strategies are debated and enacted.

– Ex: Developing more robust water supply systems, migration corridors for wildlife, relocation of coastal communities in NW Alaska

• “Mitigate we might, adapt we must”

Responding to Climate Change: Responding to Climate Change: Mitigation and AdaptationMitigation and Adaptation

Can forest management help mitigate climate change?

Best case scenario: On a global basis, forests could store up to one-third of total carbon emissions.

Longer rotations; bigger effect on westside than eastside

Retain woody debris on site or utilize it for products

Extend the life cycle of wood products; encourage recycling, re-use

Protect forests from crown fire (suppression, fuel management)

Potential market for carbon credits?

Can forest management help adapt to climate change?

Use nursery stock tolerant to low soil moisture, high temperature

Use a variety of genotypes in nursery stock

Consider planting mixed species stands

Retain woody debris on site

Maintain "healthy" stands-- Appropriate stocking (density)-- Reduce risk from insects, fungi

Cooperate with your neighbors!

Climate change will force resource managers and planners to deal with increasingly complex trade-offs between different management objectives. Planning for climate change is needed if the region is to adapt to climate change.

Climate Impacts Group

USFWS WA Dept. of Ecology Climate Impacts Group

Planning for Climate Change

• Become familiar with effects of climate change• Recognize that the past is not a dependable guide to the

future• Take actions to increase the adaptability of regional

ecosystems to future change• Monitor regional climate and ecosystems for ongoing

change• Expect surprises and design for flexibility to changing

conditions.

Planning for climate change is needed if the region is to adapt to climate change. Options for policy makers, planners, and resource managers include:

Planning Opportunities….

• National Forest management plans

• Northwest Forest Plan

• Watershed planning

• Salmon recovery

• Water supply and water quality management

• Local land use planning

• Flood control planning

• Nearshore and coastal planning

SummarySummary• Warming will continue. The PNW will continue

warming through the 21st century even if greenhouse gas emissions were stopped today. Even the lowest projected warming would alter PNW climate significantly.

• Human choices matter. Human activities affect PNW ecosystems and ultimately affect the resilience of these systems (negatively or positively).

• Knowledge and tools for planning exist. Taking early action will increase capacity to adapt to changes, monitor resource conditions, and design for flexibility.