DARGAN M. W. FRIERSONDEPARTMENT OF ATMOSPHERIC SCIENCES
DAY 11: 05 /04 /2010
ATM S 111, Global Warming: Understanding the Forecast
Assignments
Should have read “Impacts on Ecosystems and Agriculture” p.147-168 Finish reading “Keeping Track” (Climate Records)
p.171-192 for next timeQuiz today during second half of class
Better have your scantron and #2 pencilNew 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 PDOAlso 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
• Global SLR: 7-23” by 2100
• 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.
Rising sea levels will increase the risk of flooding, erosion, and habitat loss along much of Washington’s 2,500 miles of coastline.
3”
6”
30”
50”
2050 2100
13”
40”
20”
10”
6”
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
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.
Changing Coastal Flood Risk
Increased storm surge and related episodic flooding will present a greater near-term challenge.
Numbers and photos courtesy of Hugh Shipman, Washington Dept. of Ecology
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
Risks from SLR
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
C. Tidal datum elevation 20 feet D. Tidal datum elevation 22 feet
Olympia has 17 feet tides2-4 times peryear
Sea level rise inundation scenarios (two-feet, 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: leftCold PDO: right
• PDO impacts on salmon catches
• PDO tells you whetherthey’re biting in Alaska or Washington
From Mantua et al (1997)(UW research)
Pacific Decadal Oscillation (PDO)
PDO
Early peak flows
Floods
??
Warm, lowstreamflow
Salmon Impacted Across Full Life-Cycle
Salmon
Important aspects include: Changes in frequency/magnitude of flood events
High winter flow can lead to flooding out eggs in streambeds
Low flow speed in spring/summer 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
From the Seattle Post-Intelligencer, October 20, 2005
Species distributions change with temperature, affecting the overall food web
134 lb marlin caught 40 mi. west of Westport, WA, Sept 2, 2005
Photo obtained from the Seattle Times web-archives
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 populationsButterflies
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