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 whether

they’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