California Climate Impacts

1
California Climate Impacts

• Alex Ruane
• ESP Forum Fall, 2006

From http//www.water.ca.gov/maps/allprojects.cfm
2
Overview

• Unique aspects of California water management
• Observations of climate change on Californias
  water resources
• Climate scenario predictions for California
• Potential impact on California water resources

3
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
4
California Water System

• 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

Lake Oroville From http//orovillerelicensing.wat
er.ca.gov/pdf_docs/bin220q520many20photos.pdf
All-American Canal From http//www.usbr.gov/dataw
eb/html/allamcanal.html
5
Californias 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 Californias water needs

From http//www.sierranevadaphotos.com/geography/s
now_depth.asp
6
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
7
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.
8
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

Changes from 2000 - 2030

• Three scenarios for California explored in CA DWR
  Water Plan Update, 2005
• Current Trends
• Less Resource Intensive
• More Resource Intensive

9
Climate Scenarios
Changes from 2000 - 2030

• The South Coast of California is very vulnerable
  under both the current trends and resource
  intensive scenarios

10
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

11
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

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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
• According to theory and many simulations (e.g. CA
  DRW studies), increases in evapotranspiration
  will result in higher irrigation needs

From Barnett et al., 2004.
13
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

14
References

• Journal Articles
• 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 Californias Water Resources, 2006