Transcript Pacific Decadal Oscillation

ATM S 111, Global Warming:
Understanding the Forecast
DARGAN M. W. FRIERSON
DEPARTMENT OF ATMOSPHERIC SCIENCES
DAY 11: 05/04/2010
Assignments
 Should have read “Impacts on Ecosystems and
Agriculture” p.147-168

Finish reading “Keeping Track” (Climate Records) p.171-192
for next time
 Quiz today during second half of class
 Better have your scantron and #2 pencil
 New extra credit opportunity
 Read & write a 1-2 page summary/response of one of the two
news articles posted on the class website
Last Time…
 Impacts on agriculture
 Tropics/subtropics will likely be hit hard


This is where many of the food insecure of the world live
Case study: Indonesia
Example of changes in precipitation leading to decreased food
production
 Late onset of the monsoon rainy season leads to inability to plant
rice a second time as in a normal rainy season


In many tropical locations, temperature is the most
important factor

Higher temperature means decreased yields for most staple crops
Today
 Climate impacts on the Pacific Northwest (PNW)
 Impacts on ecosystems
 Specifically terrestrial ecosystems
Pacific Northwest Changes
 Is the Pac. NW warming?
113 stations with
long records
Almost every station
shows warming
Urbanization is not a
major source of warming
Temperatures in the Puget Sound
 There’s lots of decadal variability in our region
though
Temperatures in the Puget Sound
 There’s lots of decadal variability in our region
though
Decadal changes
are mostly due to an
oscillation in the
ocean called the
“Pacific Decadal
Oscillation”
Pacific Decadal Oscillation
Warm phase
Cool phase
Pacific Decadal Oscillation is very important for PNW climate: we’ll come back to this
Predictions for Future of PNW
 Temperatures will increase
 1-3o C (2-5o F) by 2040, 1.5-5.5o C (3-10o F) by 2080
 Precipitation is uncertain
 We’re kind of on the border between drying to the south
and moistening to the north
 Not clear which of these we’ll experience, or if there will be
little change
How about glaciers?
 Glaciers are affected by both temperatures and
snowfall
South Cascade Glacier in Upper Skagit River Basin, Washington
Snowpack is Most Important for PNW Society
 Glacier melt leads to enhanced warming due to ice-
albedo feedback


Also some sea level rise
But otherwise not as important as snowpack
 Snowpack = seasonally melting snow
 Falls in winter, melts in summer
 Important for:
 Water resources in the summer
 Hydropower
Snowpack Changes
 With warmer temperatures, more rain falls as snow,
and earlier melt
 Leads to water stress in the summer
Is snowpack declining?
 Yes, in much of the western US

Some of this is due to changes
in the PDO
 Also temperatures are increasing
on days with precip in March,
and more rain is falling vs snow
 Changes in the near future will
likely be dominated by PDO.
 Global warming will make a more
clear mark eventually.
 Global warming plus a strong PDO
phase: the worst impacts.
Impacts on Ski Industry
 Ski conditions at Snoqualmie Pass could degrade in
the relatively near future (2025)



Likelihood of opening by Dec 1 reduced by 50%
Average season length declined by 28%
Likelihood of rain when ski area is open increased by 25%
 Stevens Pass is at higher elevation and is safer
 Likelihood of Dec 1 opening reduced by 25%
 Season length declined by 14%
 Likelihood of rain when ski area is open increased by 50%
Coasts
Rising sea levels will increase the risk of
flooding, erosion, and habitat loss along
much of Washington’s 2,500 miles of
coastline.
• Global SLR: 7-23” by 2100
50”
40”
30”
20”
• Medium estimates of SLR for
2100:
+2” for the NW Olympic
Peninsula
+11” for the central/southern
coast
+13” for Puget Sound
• Higher estimates (up to 4 feet in
Puget Sound) cannot be ruled
out at this time.
13”
10”
6”
6”
3”
2050
2100
Projected sea level rise (SLR) in Washington’s waters
relative to 1980-1999, in inches. Shading roughly indicates
likelihood. The 6” and 13” marks are the SLR projections for
the Puget Sound region and effectively also for the central
and southern WA coast (2050: +5”, 2100: +11”).
PNW Sea Level Rise
 Sea level rise will be less on the Olympic Peninsula
because this area is rising

Due to plate tectonics
 Puget Sound may be a little worse
 Due to slight sinking of this area
Changing Coastal
Flood Risk
Increased storm surge and related
episodic flooding will present a
greater near-term challenge.
For much of Puget Sound…
• A one foot of sea level rise
turns a 100 year flood event
into a 10 year event.
• A two foot sea level rise turns
a 100 year flood event into an
annual event.
Numbers and photos courtesy of Hugh Shipman, Washington Dept. of Ecology
Risks from SLR
Increased risk of:
• coastal flooding
• inundation of low-lying
areas
• coastal erosion
• salt water intrusion into
coastal aquifers
• contamination from
coastal landfills/toxic sites
• loss of nearshore habitat
• bluff landsliding
Impacts are highly dependent on location and
daily to seasonal fluctuations in sea level, not
just changes in mean sea level.
Inundation Levels in Olympia from Current and
Projected Changes in High Tides
A. Tidal datum elevation 18 feet
B. Tidal datum elevation 19 feet
Olympia has
17 feet tides
2-4 times per
year
C. Tidal datum elevation 20 feet
D. Tidal datum elevation 22 feet
Sea level rise
inundation
scenarios (twofeet, four-feet,
and six-feet) for
Harbor Island,
Seattle
Source:
Petersen 2007
Salmon
 Salmon are affected by many different factors
 Their physical environment
 Availability of food
 Competitors for food
 Predators that prey on salmon
 Natural climate variability affects salmon abundance
 The Pacific Decadal Oscillation
Pacific Decadal Oscillation (PDO)
Warm PDO: left
Cold PDO: right
Pacific Decadal
Oscillation (PDO)
• PDO impacts on
salmon catches  
• PDO tells you whether
they’re biting in Alaska
or Washington
From Mantua et al (1997)
(UW research)
PDO
Salmon Impacted Across Full Life-Cycle
Floods
Early
peak
flows
Warm, low
streamflow
??
Salmon
 Important aspects include:
 Changes in frequency/magnitude of flood events


Low flow speed in spring/summer


High winter flow can lead to flooding out eggs in streambeds
This takes the juveniles out to sea: if timed wrong or weak flow
they may not make it out
Summertime stream temperature

There’s an upper limit of temperature the fish can handle when
returning to spawn
 Threshold depends on the species
 Will likely be important by mid-century
Species distributions change with temperature,
affecting the overall food web
From the Seattle Post-Intelligencer, October 20, 2005
134 lb marlin caught
40 mi. west of
Westport, WA, Sept 2,
2005
Photo obtained from the Seattle Times
American Pika: A Vulnerable Species
 Pika
American Pika
 Lives in mountains in western US/Canada
 Makes a distinctive whistling noise
 Dense fur, well-suited to cold temperatures
Pikas and Global Warming
 Pikas can get heat stroke & die after brief exposure in
temperatures above 78 F


Heat can lead to less time for foraging in addition to direct
harm
Also lack of insulating snow in the winter can be harmful
Pikas and Global Warming
 Local extinctions have occurred in several
populations in the US already


They live essentially on high-altitude islands of colder
temperatures
Migration to higher altitudes or more northern locations is not
always possible
Other Vulnerable Species Worldwide
 Amphibians & reptiles
 Cold-blooded and close to ground lead to vulnerabilities
 Many species are disappearing
 Diseases spreading more easily due to climate has been
implicated in some extinctions
 Often fragmentation of ecosystems, pollutants are to blame for
unhealthy populations
 Butterflies
 Certain species are climbing to higher elevations
“Disrupted Synchrony”
 Disrupted synchrony is when things used to happen
at the same time, but are shifting


Ex 1: Caterpillars hatching later. Bird no longer hatches at
same time that caterpillars are out, so birds go hungry
Ex 2: Plantains in California are dying off earlier due to heat.
Caterpillars/butterflies can’t use these as foods.
Parasitic Diseases
 Many will likely increase with warmer and moister
climates
 Malaria: carried by mosquitoes



Cold weather kills mosquitoes
Spreading into regions of African highlands not previously
seen
Short-term variations in rainfall is also very important
Insects & Forests
 Bark beetle:
 Spreading across North America due to
warmer winters & increased drought
 Montana, Wyoming, Colorado pine
forests particularly hard-hit
 Often attack already weakened trees
(by drought etc)
 Bad for timber industry
Red trees are damaged by bugs