Climate change impacts on water resources in the southeastern

U.S. – Can we adapt?

 

Peter CaldwellUSDA Forest Service, Eastern Forest Environmental Threat

Assessment Center

Raleigh, NC

SWPBA Annual Meeting, November 2011

Climate change- The scientific basis

IPCC AR4, 2007

Unprecedented rate of change

IPCC AR4, 2007

The evidence of change

IPCC AR4, 2007

Temperature

Sea level

Snow cover

IPCC AR4, 2007

“Global warming is unequivocal and primarily human-induced” USGCRP, 2009

Change

Variability

Variability v. Change

Bottom of Hill (current climate)

USGCRP Global Climate Change Impacts in the United States, 2009

Precipitation

USGCRP Global Climate Change Impacts in the United States, 2009

Temperature

Extremes: Drought

USGCRP, 2009

Extremes: Heavy precipitation

USGCRP, 2009

Global Circulation ModelsCoupled land &

atmosphere modelsGlobal coverageCoarse resolution

(e.g. 2° - ~100x100 km)

Have BiasesSpatial resolutionModel

parameterizationScale not appropriate

for impact studies

Bias correction and downscaling

Maurer, 2009

2° resolution(100x100 km)

1/8° resolution(12x12 km)

Dynamic or

statistical downscalin

g

Emission scenarios

IPCC AR4, 2007

Predicted global temperature

IPCC AR4, 2007

Temperature changes

IPCC AR4, 2007

A1B Scenario, change in temp from 1900-1950 mean, multi-model mean and range

A1B Scenario, change in temperature from 1980-1999 by 2080-2099, multi-model mean

Precipitation changes

Annual precipitation changeNumber of models

predicting increased precipitation

IPCC AR4, 2007

A1B Scenario, change in precipitation from 1980-1999 by 2090-2099, multi-model mean

Key Issues for the SoutheastHeat-related stresses for people, plants,

and animalsDecreased water availabilitySea-level rise, likely increase in hurricane

intensity and storm surgeEcological thresholds likely to be crossed

throughout the region

USGCRP, 2009

US Forest Service: A Legacy Water Resources ManagementOrganic Act of 1897

“…securing favorable conditions of water flows…”Weeks Law of 1911

“…..regulation of the flow of navigable streams or for the production of timber.”

Sustained Yield Forest Management Act of 1944“….. maintenance of water supply, regulation of stream

flow, prevention of soil erosion, amelioration of climate, and preservation of wildlife.”

National Forest Management Act of 1976“…multiple use and sustained yield of the products and

services obtained…the coordination of outdoor recreation, range, timber, watershed, wildlife and fish, and wilderness.”

The future of USFS water resources management

Supply Demand

Climate Landuse change Population

ReservoirGW Infrastructure

Economics

J. Am. Water Resour. Assoc. 44:1441 – 1457, 2008

Water Supply Stress Index (WaSSI) Model

Water BalanceET = f(PET, LAI, PPT, SM)Q = PPT – ET +/- DS

Carbon BalanceGEP = f(ET)Re = f(GEP)NEE = Re - GEP

BiodiversityBIO = f(ET)-Birds -Amphibians-Reptiles -Trees-Mammals -Vertebrates

PPT

ET

Q

GEP

Re

Watershed and Land Cover Based

Climate and Population Scenarios

Baseline (2001-2010) vs. Future (2051-2060)

Climate Scenario

Precipitation

PET

CSIROMK2-B2 14%CSIROMK3.5-

A1B5% 11%

HADCM3-B2 7% 15%MIROC32-A1B 8% 19%

Simulated 2001-2010 water yield

Predicted trend in water yield

100

150

200

250

300

350

400

450

2010 2020 2030 2040 2050 2060

Wat

er Y

ield

(mm

)

(b)

Predicted trend in water yield2011-2060

Simulated 2001-2010 streamflow

Predicted change in flow by 2051-2060

Change in water demand by 2051-2060

Water Supply Stress Index (WaSSI)

Water Stress: Average annual WaSSI ≥ 0.4

• United Nations (Raskin et al., 1997)• World Water Council (Alcamo, 2000; Cosgrove &

Rijsberman, 2000)• Vörösmarty et al., 2000

WaSSI =Demand

Surface + Groundwater Supply

Mean WaSSI in 2051-2060

Predicted trend in mean annual stream temperature 2010-2060, mean among four scenarios

Stream temperature changes

Sediment delivery changes

Predicted change in rainfall erosivity (R) by 2050

What can we do? Mitigate

Reduce carbon emissionsEnhance carbon sequestration

AdaptEnhance ecosystem resilienceEnhance infrastructure resilienceEmbrace uncertainty

“If mitigation is about carbon, then adaptation will be about water”

Peter Caldwellpcaldwell02@fs.fed.us

919.515.1560www.forestthreats.org

Thank you!