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Climate Change Impacts & Resource
Management
Stephen T. GrayWater Resources Data System
WY State Climate OfficeUniversity of Wyoming
The Scientific Consensus
• The earth as a whole is getting warmer (>99 in 100 chance)*– Approximately 1°F over past 100 years
• Most of this warming is very likely (9 in 10) caused by human activities
• Warming will very likely (9 in 10) continue for centuries to come
*EPA 2006 and IPCC 2005, 2007
How do we know the earth is warmer?
Measured by thermometers and satellite observations
Hansen et al. 2006, PNASBrohan et al. 2006, JGR
1932 Boulder Glacier
Agassiz Glacier1913
“The place we used to call Glacier National Park”
1932 1988Boulder Glacier
Agassiz Glacier1913 1998
“The place we used to call Glacier National Park”
The Scientific Consensus
• Multiple lines of evidence show that the earth’s climate is changing– Instrumental observations– Observations of physical and biological
systems
• Rate and magnitude of changes unsurpassed in (at least) the last 2000 years
• Spatial extent of changes unsurpassed for many 1000’s of years
IPCC 2005, 2007
Temperature increase and other climatic changes will continue for many centuries to come
IPCC 2007
The “Greenhouse Effect”
Ice cores and other archivesgive us information on past climate and CO2
Orbital changes and the amount of solar radiation reaching Earth’s surface
Trumps otherclimate drivers
CO2
etc.
GLOBAL
CLIMATE
Earth’sOrbit &
Tilt
DustAerosols
Ash
SolarOutput
CO2GLOBAL
CLIMATE
Earth’sOrbit &
Tilt
DustAerosols
Ash
SolarOutput
Ecosystem Management in the Western US
Regional Impacts:
Predictions for future precipitation trends
-Small increases possible by end of 21st century-Predictions within the range of variability over the past 1,000 years
Predictions for future climate in the Central Rocky Mountain RegionBased on regionalized output from seven leading climate models
Source: Natl. Acad. Sciences
temp change vs. 1951-1980 mean
All assessments agree — the West will be WARMER!
2 to 4 °C (3.6 to 7.2 °F)within our lifetimes
Small Warming, Big Changes
• Small increases in regional temperature would have major consequences for the West’s natural resources, even in the absence of major precipitation change
Warming = Perpetual Drought?
Source: Hoerling and Eischeid - SW Hydrology, 2007
No significant changeIn precipitation plus1.4 °C temp. increase
No significant changeIn precipitation plus2.8 °C temp. increase
Small increases in temperature lead to
increased evaporation and decreased
water yield to streams
Calculated Palmer Drought Severity Index Values
2007: Melt-out Comes 4 to 8 Weeks Early
Rain vs. Snow• Rain is likely to run off immediately
rather than soaking into the soil• Rain may not be as effective as snow
for recharging groundwater supplies• Shifting towards more rain will likely
intensify late-summer droughts• Switching from snow to rain may
have significant consequences for Western ecosystems
The West’s Desert Climate
Our #1 Vulnerability
Average Annual Precipitation
(inches)
Source: NRCS http://www.ncgc.nrcs.usda.gov/products/datasets/climate/data/index.html
Wyoming Average Annual Precipitation: 1961-1990
Wyoming: Areas with < 16” Annual Precipitation
71% of Wyoming averages less than 16” of precipitation each year
Western Regional ClimateSTATE Rank Ann PPT
Nevada 1 10.68”
Arizona 2 13.13
Utah 3 13.90
New Mexico 4 14.93
Wyoming 5 16.84
Colorado 7 18.55
National Average 37.74
TNC Invasives Project
Challenges to Management
•Communities in transition•Cycles of rapid change•Novel associations•Exotic species
Conclusions•Wyoming and the West are extremely vulnerable to all types of climate change, natural and otherwise
Conclusions•Wyoming and the West are extremely vulnerable to all types of climate change, natural and otherwise•The West will be drier
•Less water overall•Potential for major changes in seasonal climate
Conclusions•Wyoming and the West are extremely vulnerable to all types of climate change, natural and otherwise•The West will be drier
•Less water overall•Potential for major changes in seasonal climate
•Many factors will impact natural resources in the West
•Climate will interact with land-use change, land-cover change, fire, etc.
And now the good news…We know enough to start
acting TODAY Adaptation is not
dependant on causation
Thanks! Thanks!
