CLIMATE CHANGE SCENARIOS FOR YUKON FLATS

NATIONAL WILDLIFE REFUGE, ALASKA

Anna Springsteen University of Alaska and The Wilderness Society

Wendy Loya The Wilderness Society

Climate Change in the Northern Latitudes

• Since 1950, temperatures have already risen 2.2ºC statewide and 3.9ºC in the Interior

• Changes in Precipitation suggest increases, although lack of monitoring makes it difficult to tell

• Need for closer examination of climate change in northern-latitudes

Global Circulation Models (GCMs)

Used in IPCC 4th Assessment (2007) to look at potential climate change under several emissions scenarios.

We chose 5 models to run under the “A1B” emissions scenario: • Greenhouse gas emissions are expected to rise at rates similar

to today but eventually decline due to the use of more renewables and more efficient technologies.

5 ModelsEcham5 Gfdl2.1 Miroc3.2MR HadCM3CGCM3.1- And a composite(average) of the 5 models.

Past 2040 2080

Glo

bal E

mis

sion

s (G

t C /

yr)

0

5

10

15

20

25

A1B

Yukon Flats National Wildlife Refuge

Climate Change Predictions for the Refuge:

• Past and Future trends for Temperature and Precipitation

• Length of the Growing Season

• Change in Potential Evapotranspiration (PET) to estimate wetter or drier conditions

Year

Tem

pera

ture

(C)

1980 2000 2020 2040 2060 2080 2100

-10

-50

5

Cccma

Echam5

Gfdl2.1

Hadley

MirocMR

Composite

Regression of Composite

1961-1990 Mean

+ 2.74 C + 4.94 C

y = -108.8+0.052(Year)

TemperatureAll 5 models predict temperature increases over time.

Temperature

Annual Temperature Change (ºF)

• Annual temperatures increase 9ºF by 2080, or about 1ºF per decade

• This is an increase from 22ºF to 31ºF on average

Temperature

Winter Temperature Change (ºF)

• Winter temperatures increase 12ºF by 2080

• This is an increase from -3ºF to 9ºF on average

Temperature

Growing Season Temperature Change (ºF)

• Growing season temperatures increase 6ºF by 2080

• This is an increase from 52ºF to 55 to 58ºF on average

Growing Season

1980 2000 2020 2040 2060 2080 2100

100

140

180

Mean Modelled Length of Frost-Free Season

YEAR

Leng

th (D

ays)

PRISM152 days

167 days 178 days

+2.6 days per decade

• Date of freeze-up occurs 1.3 days later per decade

• Date of break-up occurs 1.3 days earlier per decade

• Thus, the “growing season” lengthens by ~3 days per decade to increase in length by 26 days

Precipitation

Annual Precipitation (inches)

• Annual precipitation increases from 10 to 13 to 15 inches.

• An increase of 0.5 inches per decade

Precipitation

Winter Precipitation (inches)

• Winter precipitation increases 63% by 2080

• This is an increase from 40 to 60 inches of snowfall

Precipitation

Growing Season Precipitation (inches)

• Growing season precipitation increases by 33%

• This is an increase from 7 to 9 inches of rainfall

Potential Evapotranspiration (PET)• Despite increases in Precipitation, conditions will

become drier

• Due to warmer Temperatures and a longer growing season, the Refuge may become considerably drier

Time Period

1961-1990 2035-2044 2075-2084

Wat

er D

efic

it

-25

-20

-15

-10

10% Drier

25% Drier

Overview

…Interior Alaska is projected to warm more in the next 40 years than it did in the last 150

…and become drier by up to 25%.

• Warmer temperatures will be found in all seasons, along with an increase in precipitation.

• However, evaporation will increase water demand more than precipitation will fill it.

• In addition, because the growing season will lengthen by a month, the period over which water demand occurs will increase as well.

Implications: Permafrost

• Thinning of discontinuous permafrost due to annual temperatures above 32ºF by 2100

- Shrinking of wetlands

- Unpredictable landscape changes

Implications: Forests

Hotter, drier growing seasons:

• More forest fires

• Switch to more deciduous vegetation

• Potential for more invasive plant and insect outbreaks

Implications: Wetlands & Rivers

• Unpredictable freezing and ice break-up

• Earlier pulse of spring runoff, less or more runoff?

• Possible lower river levels and drying wetlands

• Warmer water temperatures affecting river and lake food webs

Implications: Wildlife

• Increased habitat for certain species, decreased quality habitat for others

• Extended breeding and rearing seasons

• How will weather variability change with climate--more extreme weather events?

Conclusions

Climate models are not perfect and there are still many unknowns, but…

• Climate change is already visible in interior Alaska.

• The combined warming and drying of the future are likely to cause stress on vegetation, wildlife, and people

• Need to plan for the effects of climate change in a quantitative way

Contributors

Scenarios Network for Alaska Planning (SNAP)John WalshScott RuppBill ChapmanMark Olson

For More Information:

Summary Available at:

The Wilderness Society Websitewww.wilderness.org/library under "What's New"

orScenarios Network for Alaska Planning Website:

http://www.snap.uaf.edu/

Growing Season

1980 2000 2020 2040 2060 2080 2100

250

270

290

Mean Modelled First Date Below Freezing

YEAR

Dat

e (D

ays

sinc

e Ja

n. 1

)

+1.3 days per decade

PRISMSep. 26Day 269

Oct. 4Day 278sd=2.5

Oct. 9Day 283sd=1.5

1980 2000 2020 2040 2060 2080 2100

6080

120

Mean Modelled First Date Above Freezing

YEAR

Dat

e (D

ays

sinc

e Ja

n. 1

)

PRISMApr. 27Day 117

Apr. 20Day 111sd=4.2

Apr. 14Day 105sd=3.2

-1.3 days per decade

1980 2000 2020 2040 2060 2080 2100

100

140

180

Mean Modelled Length of Frost-Free Season

YEAR

Leng

th (D

ays)

PRISM152 days

167 days 178 days

+2.6 days per decade

Potential Evapotranspiration (PET)

PET(mm)

Precipitation-PET(mm)

PRISM 625 -4602040 700 -5002080 790 -565

Time Period

1961-1990 2035-2044 2075-2084

Wat

er D

efic

it

-25

-20

-15

-10

10% Drier

25% Drier

-625

-500

-375

-250

Year

Pre

cipi

tatio

n (m

m)

1980 2000 2020 2040 2060 2080 2100

1020

3040

5060 Cccma

Echam5

Gfdl2.1

Hadley

MirocMR

Composite

Regression of Composite

1961-1990 Mean

+ 6 mm/mo + 10 mm/mo

y = -183.6+0.104(Year)

Precipitation