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South Orange County Watershed Management Area
IRWM Plan FINAL JULY 2013
12 CLIMATE CHANGE
Climate change is a shift in the average weather that a given region experiences. This
is measured by changes in the features that we associate with weather, such as
temperature, wind patterns, precipitation, and storms. The Earth’s climate has always
been changing, however, the current climate change we are seeing today differs from
previous climate change in both its rate and its magnitude. As part of this IRWMP
Update, a climate change analysis was completed. The Climate Change and
Vulnerability in the South Orange County IRWM Planning Region, provided in Appendix
J, presents an assessment of the potential impacts of climate change on the water
resources of South Orange County.
Because of the importance of imported water supply to South Orange County, potential
impacts of climate change to water resources must be examined over a region broader
than the IRWM planning area. Changes in observed climatic variables in this larger
region representing the Western U.S. have been examined through data collected in the
20th century. Over this period, particularly in winter and spring, temperatures have risen
significantly across western North America. In the second half of the 20th century, the
warming in the mountainous western North America has led to a higher rain-to-snow
ratio, lower snow water content, decline in March snow cover, and a shift toward earlier
annual snowmelt timing by 5 to 30 days. These observations strongly support the need
for incorporating climate change into long-term water resources planning efforts.
For estimating future climate conditions, global climate processes are represented using
atmosphere-ocean general circulation models (AOGCMs or GCMs, also known as
“global climate models”). Using these models, the projected data summary for the South
OC IRWM planning region show a small decrease in precipitation of slightly over an
inch per year by mid- to late-21st century periods (Table 12-1). They also show an
increase in temperature from >2 to >5 oF over the same periods (Table 12-2). In
general, climate models project more adverse conditions (i.e., warmer and drier) in the
latter part of the 21st century compared to conditions observed in the second half of the
20th century.
Table 12-1: Average projected change in Precipitation in IRWM Region 16 GCMs
Time period and average change
Emission Scenario
2010-2039
2040-2069
2070-2099
A2
-0.37
inches
-1.06
inches
-1.54
inches
B1
0.02 inches
-0.67
inches
-0.94
inches
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Table 12-2: Average projected change in temperature in IRWM Region 16 GCMs
Time period and average change
Emission
Scenario
20102039
20402069
o
3.37 F
o
2.70 F
A2
1.59 F
B1
1.58 F
20702099
o
5.81 F
o
o
3.73 F
o
Several major planning studies have been performed in South OC water supply regions
that consider the impacts of climate change. Projected climate change conditions,
typically obtained from statistical downscaling of an ensemble of models, have been
used for developing plans in in both regions. A key feature that stands out from the
comprehensive analyses that have been performed is that both California and the
Colorado Basin are severely water constrained, where it will be challenging to meet
current allocations in future years. In both regions, planning model projections indicate
years where deliveries will sometimes fall short of allocations, over planning horizons
that range from 20 to 50 years into the future, under conditions where no changes are
made to the existing operational infrastructure of the system. Because the regions
jointly affected by these basins are continuing to experience relatively rapid population
growth, and anticipated increased in municipal demands, water planners must address
the dual challenge of reduced supplies and increased demand.
Although variable at different points along the coast due to regional factors, in general,
sea levels are rising globally due to climate warming including expansion of ocean water
and melting of land ice. Along the Pacific Coast, the highest values of sea level rise in
Southern California have been reported at Newport Beach, near the study region, where
the observed increase is 2.22 mm/year. These rates are projected to accelerate over
the 21st century. A recent review of different calculation approaches by the National
Academy of Sciences reported that global sea level is estimated to rise 8–23 cm (3-9
inches) by 2030 relative to 2000, 18–48 cm by 2050 (7-19 inches), and 50–140 cm (2055 inches) by 2100. This review projects that sea level in Southern California is slightly
higher than the global average because of land subsidence, and will rise 4–30 cm (2-12
inches) by 2030 relative to 2000, 12–61 cm (5-24 inches) by 2050, and 42–167 cm (1766 inches) by 2100. Maps illustrating the effects of sea level rise to 2100 and a 100-year
flood were developed for the South IRWM planning region to identify areas that are
vulnerable. An example map is shown in Figure 12-1.
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IRWM Plan FINAL JULY 2013
Figure 12-1: Zoomed-in area of South OC Coastline
Areas (identified in yellow on Figure 12-1) are under flooding threat due to the combined
effects of a 100-year flood and sea-level rise to 2100 (55 inches). Numbers along the
coastline are FEMA’s base flood elevation values in feet.
Greenhouse gas emissions associated with the water sector were estimated for the
South OC planning region. The General Reporting Protocol, Version 3.1, developed by
the California Climate Action Registry is used to calculate indirect emissions of
greenhouse gases (GHG) from electricity used for the water system in south Orange
County. The water sector is the largest user of electricity in the state of California. The
bulk of water for southern California specifically is transported over long distances up
steep gradients and is therefore more energy expensive than local sources. Energy use
for water is quantified via energy intensity, or the gross energy required for the water
system to use a specific amount of water at a specific location. Under baseline
conditions, the water sector in the region generates GHG emissions of over 93,000
metric tons in terms of carbon dioxide equivalent. The seven high priority projects
identified in this IRWM were evaluated for their relationship to climate change and
greenhouse gas emissions. The projects identified have the potential to save about
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17,000 metric tons of CO2-equivalent emissions annually, nearly 18% of the current
total water sector emissions.
An overall assessment of vulnerability to climate change for South OC following a
checklist presented in the Climate Change Handbook for Regional Water Planning, and
specifically recommended for IRWM climate change planning was performed and is
included in Appendix J. As noted above, the major water supply system vulnerabilities
in this region are not unique, but are tied to the water supply system in California and
the Colorado River Basin that are being evaluated through statewide or regional efforts.
Besides water supply, other areas of potential concern for this planning region are
coastal flooding due to sea level rise, increase in fire risk, and impacts to ecosystems.
Climate change assessment is an integral part of the water resources related planning
in the South OC region, as well as the larger region, spanning the Southwestern U.S.,
that supplies its water. The best current understanding of climate change has been
incorporated in the assessment of impacts, especially those relating to water supply and
sea level rise. Looking forward, it is expected that these plans will be updated as better
information on climate projections, including extreme events become available, and
impacts to other sectors, such as water quality and habitats will be similarly evaluated.
12.1 Legislative and Policy Context
While there are numerous pieces of policy and legislation dealing with climate change,
three pieces are important regarding the State’s response to climate change, including
how IRWM planning efforts analyze climate change on a project level. Executive Order
(EO) S-3-05 and the California Global Warming Solutions Act of 2006 (AB 32; amending
California Health and Safety Code Division 25.5, §38500, et seq.) lay the foundation for
California’s response to climate change. Senate Bill 97, signed by the Governor on
August 24, 2007 initiated formal changes to the CEQA Guidelines that provides
guidance for the way climate change is analyzed in CEQA documents by adding
Section 21083.05 to the Public Resources Code.
EO S-3-05 made California the first state to formally establish GHG emissions reduction
goals. EO S-3-05 includes the following GHG emissions reduction targets for California:
•
By 2010, reduce GHG emissions to 2000 levels
•
By 2020, reduce GHG emissions to 1990 levels
•
By 2050, reduce GHG emissions to 80 percent below 1990 levels
The final emission target of 80 percent below 1990 levels would put the state’s
emissions in line with estimates of the required worldwide reductions needed to bring
about long-term climate stabilization and avoidance of the most severe impacts of
climate change (Intergovernmental Panel on Climate Change (IPCC, 2007).
AB 32 further details and codifies the mid-term GHG reduction target established in EO
S-3-05. AB 32 also identifies the California Air Resources Board (CARB) as the state
agency responsible for the design and implementation of emissions limits, regulations,
and other measures to meet the target.
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SB 97 directed the Governor’s Office of Planning and Research (OPR) to develop
CEQA Guideline amendments for the analysis of climate change in CEQA documents
for the approval of the Natural Resources Agency.
12.2 Consideration of Effects of Climate Change to Region
The Integrated Regional Water Planning Act, CWC §10541(e)(10), states that IRWM
plans must include an evaluation of the adaptability to climate change of water
management systems in the region. However, tools to properly assess the risk of any
one effect of climate change on a region are not developed, and the abilities of different
regions to use these tools vary considerably.
Local governments and agencies within the South Orange County WMA play an
essential role in fulfilling California’s emissions reduction targets and in reducing the
local effects of climate change in the Region. Local governments have broad influence
and, in some cases, exclusive authority over activities that contribute to significant direct
and indirect greenhouse gas emissions through their planning and permitting
processes, local ordinances, outreach and education efforts, and municipal operations.
Land use planning and urban growth decisions are also areas where successful
implementation of climate change strategies relies on local government. Local
governments have primary authority to plan, zone, approve, and permit how and where
land is developed to accommodate population growth and the changing needs of their
jurisdictions. Decisions on how land is used will have large impacts on the greenhouse
gas emissions that will result from the transportation, housing, industry, forestry, water,
agriculture, electricity, and natural gas sectors.
A resource management strategy is a project, program, or policy that helps local
agencies and governments manage their water and related resources 82. Chapter 5 of
this IRWM Plan outlines a comprehensive and diverse set of resource management
strategies to help meet the water-related management needs of the Region. These
strategies can be combined in various ways to meet the water management objectives
of the Region. Future decisions will factor in strategies for adapting to and mitigating
climate change impacts.
The IRWM Group understands that the Region’s water supply is contingent upon
amount, intensity, timing, quality, and variability of runoff and recharge, as well as on
water imported from outside the region. Therefore, the IRWM Group is committed to
addressing the effects of climate change on the Region’s water supply by incorporating
climate change considerations into the Region’s resource management strategies.
Likewise, as IRWM projects are developed and selected for implementation,
consideration of adapting to the effects of climate change will be a part of the project
review process (see Chapter 6).
82
California Water Plan Update 2009
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Among the various sources of information on climate change, the IRWM Group
considered the following three documents during the development of resource
management strategies and the selection of projects.
1. The Climate Change Scoping Plan that was adopted by CARB in 2008 discusses
different business sectors including water management and recommends specific
strategies that may help reduce GHG emissions.
2. DWR published a white paper, Managing an Uncertain Future: Climate Change
Adaption Strategies for California’s Water (2008),urges a new approach to
managing California’s water and other natural resources in the face of climate
change. The recommendations from the White Paper are incorporated into
Volume 1 Chapter 7 of CWP Update 2009.
3. The California Natural Resource Agency (CNRA) has a report currently in draft
form entitled 2009 California Climate Adaptation Strategy that discusses
statewide and sector specific vulnerability assessments.
When it comes to water management considerations, water managers must include
both adaptation and mitigation into their planning strategies.
•
Adaptation refers to the ways in which our society and culture will need to
change to cope with a changing climate. Several of the resource management
strategies and projects in this Plan will help the Region adapt to climate change.
•
Mitigation refers to the reduction of GHG emissions from water-related energy
use. Water management results in the consumption of significant amounts of
energy in California and the accompanying production of GHG emissions,
especially where water must be pumped from long distances; from the ground; or
over significant elevations. Water utilities use energy to reliably provide quality
water to customers, while wastewater utilities in turn use energy to safely collect,
treat, and dispose of wastewater to protect public health and the environment.
GHG emissions reduction is a critical responsibility of water managers, and
efficiency in water and energy use should be pursued at every opportunity. At
the same time, water provides California with hydroelectric power, the state’s
largest source of GHG emissions-free energy.
The IRWM Group is aware of the detriment and cost that inaction on climate change
would have on the Region. A warming California climate would generate more smoggy
days by contributing to ozone formation while also fostering more large brush and forest
fires. Continuing increases in global greenhouse gas emissions at current rates would
result, by late in the century, in California losing 90 percent of the Sierra snow pack, sea
level rising by more than 20 inches, and a three to four times increase in heat wave
days. These impacts will translate into real costs for California, including flood damage
and flood control costs that could amount to several billion dollars in many regions.
Water supply costs due to scarcity and increased operating costs would also increase.
Failing to address climate change also carries with it the risk of substantial public health
costs, primarily as a result of rising temperatures. Sustained triple-digit heat waves
increase the health risk for several segments of the population, especially the elderly.
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But higher average temperatures will also increase the interactions of smog-causing
chemicals with sunlight and the atmosphere to produce higher volumes of toxic
byproducts than would otherwise occur. Low-income communities are
disproportionately impacted by climate change, lacking the resources to avoid or adapt
to these impacts. For example, low-income residents are less likely to have access to
air conditioning to prevent heat stroke and death in heat waves. Taking action to help
mitigate the impacts of climate change will help slow temperature rise. This in turn will
likely result in fewer premature deaths from respiratory and heat-related causes, and
many thousands fewer hospital visits and days of illness83.
It is anticipated that as more information regarding the effects of climate change on the
region becomes available, and as new technologies arise to slow or offset the impacts,
the IRWM Group will revise and update this Plan accordingly.
83
Climate Change Scoping Plan, CARB, October 2008
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