Transcript IPCC Average global temperature has increased 0.8°C since 1906.

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 ------------
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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???