Transcript Global Variations in Water and Energy Cycles

California Climate
Impacts
Alex Ruane
ESP Forum: Fall, 2006
From http://www.water.ca.gov/maps/allprojects.cfm
Overview
• Unique aspects of California water
management
• Observations of climate change on
California’s water resources
• Climate scenario predictions for California
• Potential impact on California water resources
Geography of California
• Population and
agricultural centers
are apart from rainfall
maxima
Major rivers
State projects
Federal projects
Local projects
From http://education.usgs.gov/california/maps/
From http://www.water.ca.gov/maps/allprojects.cfm
California Water System
Lake Oroville: From http://orovillerelicensing.water.ca.gov/pdf_docs/bin2%20q5%20many%20photos.pdf
• Man-made reservoir
operators must meet
needs of:
- Agricultural use
- Municipal use
- Domestic use
- Hydropower
Generation
- Local and
downstream
wildlife
- Recreational use
- Flood prevention
• Canals carry water
around state from local
and distant sources
All-American Canal: From http://www.usbr.gov/dataweb/html/allamcanal.html
California’s Natural Water System
From http://dommy.com/alan/pix/lone-pine.jpg
• Snowpack in Sierra Nevada
provide natural reservoir
- Accumulate water during
the winter
- Melt during the spring
and summer
- Crucial to meeting
California’s water needs
From http://www.sierranevadaphotos.com/geography/snow_depth.asp
Observations of Climate Change in California
• Changes in the onset of “springtime”
(see Cayan et al., 2001)
– Lilac and Honeysuckle blooms
– First pulse of springtime runoff
• Distribution of Runoff:
•
•
•
•
Biological changes
Invasive species
Increased fire risk
Sea-level rise
From California Water Plan Update, 2005
Observations of Climate Change in the West
Changes in April Snow Water Equivalence, from Mote et al., 2005.
• Temperature, precipitation and
snowpack are changing across
the West
– Regional changes
– Interactions between natural
variability and climate change
caused by humans
• Water resources are shared
across the region
From Mote et al., 2005.
Climate Scenarios
• Multiple pathways for the world
– The Intergovernmental Panel on Climate Change (IPCC)
has dozens of climate scenarios that express potential
societal development
– Changes can be both gradual and sudden
• Three scenarios for
California explored in
CA DWR Water Plan
Update, 2005:
– Current Trends
– Less Resource
Intensive
– More Resource
Intensive
Changes from 2000 - 2030
Climate Scenarios
Changes from
2000 - 2030
• The South Coast of California is very vulnerable
under both the current trends and resource intensive
scenarios
Climate Scenarios
• Various
computer
simulations
show an
expected loss
of CA
snowpack in
the future
– Only extend
to 2099
Percent changes in snowpack by elevation, from Hayhoe et al., 2004.
– Used A1fi (economically driven growth) and B1 (ecologically driven growth)
IPCC scenarios
– Particularly strong impact on lower elevations, models do not fully agree
Projected Impacts
• Barnett et al., 2004:
– Ran simulations
using a coupled
ocean/atmosphere
model with the
“business as usual”
emissions scenario
• Assumes dominant
societal focus is on
growth
– Regionally
downscaled the
results to focus on
the Western USA
Projected Impacts from “business as usual” scenario
• By mid-century, Colorado River System will not be able to meet its
demands
– Reservoirs will be reduced by over 1/3 and releases by as much as 17%
– Hydropower generation will be reduced by as much as 40%
– The fully allocated Colorado system is “at the brink of failure”
• It will be impossible to meet current water needs in the Central Valley
– Reduced reliability in water deliveries, hydropower, and river flow rates
– A dramatic increase in salinity in the Sacramento Delta is possible
• In the Columbia River system (in WA and OR), policy-makers must choose
between water for hydroelectric power or salmon runs, but not both
• Increased summertime temperature and reduced humidity are likely
– Longer and more severe fire season
From Barnett et al., 2004.
– According to theory and many simulations (e.g. CA DRW studies), increases in
evapotranspiration will result in higher irrigation needs
Uncertainties
• In the size of natural and human-induced variabilities
– There is still a significant spread in potential emissions scenarios and
climate outlooks
• Which pathway will be chosen?
– The West Coast of the USA is strongly influenced by interannual and
interdecadal oscillations (ENSO, PDO, etc.)
• In the Models
– Downscaling and regional outlooks are still difficult
• In the interactions between climate components
– Snowpack vs. T
– Snowpack vs. P
– Snowpack vs. SST
References
• Journal Articles
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Barnett, T., R. Malone, W. Pennell, D. Stammer, B. Semtner, and W. Washington, 2004: ‘The effects
of climate change on water resources in the West: Introduction and overview’. Climatic Change 62:
1-11
Cayan, D.R., S.A. Kammerdiener, M.D. Dettinger, J.M. Caprio, and D.H. Peterson, 2001: ‘Changes
in the onset of spring in the Western United States’. Bull. Am. Meteorol. Soc., 82(3): 399-415
Mote, P.W., A.F. Hamlet, M.P. Clark, and D.P. Lettenmaier, 2005: ‘Declining mountain snowpack in
Western North America’. Bull. Am. Meteorol. Soc., 86(1): 39-49
Hayhoe, K., D. Cayan, C.B. Field, P.C. Frunhoff, E.P. Maurer, N.L. Miller, S.C. Moser, S.H.
Schneider, K.N. Cahill, E.E. Cleland, L. Dale, R. Drapek, S.C. Sheridan, and J.H. Verville, 2004:
‘Emissions pathways, climate change, and impacts on California’. PNAS, 101(34): 12422-12427
Miller, N.L, K.E. Bashford, and E. Strem, 2003: ‘Potential impacts of climate change on California
hydrology’. J. of the American Water Resources Association (JAWRA) 39(4):771-784
• California Department of Water Resources
– Climate Change and California Water Resources: A Survey and
Summary of the Literature, 2005
– California Water Plan Update 2005, 2005
– Progress on Incorporating Climate Change into Management of
California’s Water Resources, 2006