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Download IPCC Average global temperature has increased 0.8°C since 1906.
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Effects of Climate Change on Pacific Northwest Ecosystems Dave Peterson Climatic Variability and Change – A Brief Introduction Radiative Forcing Components of Global Warming 1.6 Watts ------------- 1 meter ------------ ----------- 1 meter ----------- Source: IPCC Average global temperature has increased 0.8°C since 1906. IPCC (2007) Average global temperature has increased 0.8°C since 1906. Warmest 12 years 1998,2005,2003,2002,2004,2006, 2001,1997,1995,1999,1990,2000 IPCC (2007) Projected 21st Century Global Warming IPCC “best estimate” range of global-scale warming by the 2090s: 1.8 - 4.0°C Warming expected through 21st century even if CO2 emissions end today due to persistence of greenhouse gases Data source: IPCC 2001 Projected Temperature in Northwest 14.4°F Choice of emissions scenario matter more after 2050s +3.3ºC ( +1.9ºC 7.2°F ( °C 10.8°F +1.2ºC 3.6°F 0°F Rate of change per decade expected to be 3 times greater through mid-21st century Changes relative to 1970-1999 Winter winds and pressure over the North Pacific Summer winds and pressure over the North Pacific L L H H Aleutian Low Subtropical High El Niño Southern Oscillation Southern Oscillation Index For the Pacific Northwest: Positive (El Niño) = Warm, dry winter Negative (La Niña) = Cool, wet winter Pacific Decadal Oscillation • An El Niño-like pattern of climate variability • 20 - 30 year periods of persistence in North American and Pacific Basin climate Warm, dry Cool, wet Droughts were more common prior to 1950 Gedalof et al. (2004) Streamflow for the Columbia River, reconstructed from tree-ring data Why extremes matter The distribution of weather events around the climatic average often follows a ‘bell-shaped’ curve. Climate change can involve change in the average, or the spread around the average (standard deviation), or both. A shift of 1 standard deviation makes a 1 in 40 yr event into a 1 in 6 yr event Standard deviation 1 in 40 yr high range A shift in the distribution of temperatures has a much larger relative effect at the extremes than near the mean. Temperature trends (°F per century) since 1920 cooler warmer 3.6°F 2.7°F 1.8°F 0.9°F Nearly every glacier in the Cascades and Olympics has retreated during the past 50-150 years South Cascade Glacier, 1928 (top) and 2007 (right) Photos courtesy of Dr. Ed Josberger, USGS Glacier Group, Tacoma, WA Snow Water Equivalent Trends • Most PNW stations show a decline in snow water equivalent • Numerous sites in the Cascades with 30% to 60% declines Decrease Increase Altered Streamflow • More winter rain, less snow → higher winter streamflows • Warmer temperatures → earlier snowmelt and shift in timing of peak runoff Projected streamflow changes, 2050s +3.6 to +5.4°F (+2 to +3°C) Forest vegetation varies over time The Disease Spiral From Manion (1991) A pathological model is applicable to forest ecosystems Warmer climate Soil moisture stress (+) Growth and vigor (-) Growth and vigor are affected by human-related factors Exotic plants, pathogens, insects Forest harvest practices Air pollution Fire exclusion Thresholds are important Temperature Increase Climate Critical Threshold Climatic Variability Time October 2002 Pinyon pine - juniper Jemez Mountains, NM May 2004 Pinyon pine dead Jemez Mountains, NM Climate change and tree growth Subalpine forests: Less snowpack; longer, warmer growing seasons = Growth increase Mid elevation forests: Warmer summers, less snow pack = Depends on precipitation Low elevation forests: Warmer summers, less snow pack = Large growth decrease Subalpine forests Mid elevation forests Low elevation forests Westside forests Eastside forests Disturbance drives ecosystem change Climate change Warmer temperature More severe droughts Fire resets succession, alters temporal scale of fire rotation. Mature trees buffer effects of warmer climate without disturbance. Habitat changes New fire regimes Fire frequency ↑ Extreme events ↑ Area burned ↑ The disturbance pathway is faster Species responses Annuals & weedy species ↑ Deciduous and sprouting species ↑ Fire-sensitive species ↓ Specialists with restricted ranges ↓ Landscape homogeneity ↑ Fire-adapted species ↑ Forest cover ↓ Species refugia ↓ How will climate change affect wildfire? Area burned – Western U.S., 1916 - 2007 Area burned – Western U.S., 1916 - 2007 Fire suppression Fire exclusion Fuel accumulation Area burned – Western U.S., 1916 - 2007 Warm PDO Fire suppression Cool PDO Fire exclusion Warm PDO Fuel accumulation Area burned – Western U.S., 1916 - 2007 Warm PDO Cool PDO Warm PDO Fire suppression Fire exclusion Fuel accumulation Lots of fire Much less fire Lots of fire Years with fire area > 80,000 hectares Warm-phase PDO Cool-phase PDO Idaho 15 7 Oregon 14 5 Washington 11 2 TOTAL 40 (74%) National Forest data, 1916-2007 14 (26%) Future wildfire? Analysis of wildfire data since 1916 for the 11 contiguous Western states shows that for a 2.0oC increase that annual area burned will be 2-3 times higher. McKenzie et al. (2004), Conservation Biology 18:890-902 Fire – a component of stress complexes Lodgepole pine forest McKenzie et al. (2009) Effects of temperature increase on mountain pine beetle • Population synchronized by temperature (onset of spring) • Rate of generation turnover increases with temperature increase Tree Mortality Mountain Pine Beetle 1980 - 2004 Shaded areas show locations where trees were killed. Intensity of damage is variable and not all trees in shaded areas are dead. www.fs.fed.us/r6/nr/fid/data.shtml Mountain Pine Beetle outbreaks British Columbia Courtesy of Mike Bradley, Canfor Corporation Forest carbon budgets Storage (quantity) vs. uptake (rate) Young forest Storage Uptake Mg/ha Mg/ha/yr 50-100 5-10 400-1000 + 1.0 Old forest Options for planners and resource managers???