Climate Experts Release Latest Science on Sea Level Rise Projections to Support California Policy Guidance
From the California Natural Resources Agency:
In a compelling analysis of the factors that affect how much the ocean will rise along California’s coast in coming decades, a seven-member team of experts has provided the State with a report on the best-available sea-level rise science — including recent scientific advances on the role of polar ice loss.
The report includes new information on the expected sea level changes that will occur based on different greenhouse gas emission scenarios. For example, with very successful mitigation efforts, the report states that there is a 67 percent probability that the Bay Area will experience sea level rise between 1.0 foot and 2.4 feet by 2100. However, if no significant mitigation efforts are taken, that range increases to 1.6 to 3.4 feet.
The report also emphasizes the importance of preparing for extreme but uncertain scenarios involving the rapid loss of the Antarctic ice sheet, which would have an enormous impact on coastal regions. In one such scenario, sea levels along California’s coastline could rise up to 10 feet by 2100 – about 30-40 times faster than sea-level rise experienced over the last century.
“Although our scientific understanding is rapidly increasing, waiting for scientific certainty about the rate or ultimate amount of sea-level rise is neither a safe nor prudent option” said Dr. Gary Griggs, Chair of the science team and professor at University of California Santa Cruz. “The sea-level rise projections presented in this report provide the scientific foundation for taking action today, preparing our coastal communities and mitigating hazards, and preventing much greater losses than will occur without action now.”
An estimated 75 percent of California’s population lives in coastal counties. Sea-level rise, already underway, threatens hundreds of miles of roads and railways, harbors, airports, power plants, wastewater treatment plants, coastal wetlands, beaches, dunes, bluffs, and thousands of businesses and homes.
The new science report was requested by the California Ocean Protection Council and the California Natural Resources Agency, in collaboration with the Governor’s Office of Planning and Research, the California Energy Commission, and the California Ocean Science Trust. Expertise on the scientific team includes risk assessment, climatic change, ice sheet behavior, and statistical modeling.
The science report will be presented on April 26 at a meeting in Sacramento of the Ocean Protection Council. The report provides the scientific basis for updating statewide policy, which guides state and local decisions along California shorelines.
“California leads the way in both addressing climate change and protecting our coastal and ocean communities and resources,” said Jenn Eckerle, Deputy Director of the Ocean Protection Council. “Our statewide policy on sea-level rise is another example of that leadership. We provide guidance to state agencies and local governments for incorporating sea-level rise projections into planning, permitting, investment, and other decisions, so it is critical that it is grounded in the best and latest science.”
The current State of California Sea-Level Rise Guidance Document, released in 2010 and updated in 2013, included a range of projections over various timescales, but did not estimate the likelihood that such levels would be met. The scientific team’s new report includes information on the likelihood of specific scenarios and provides a framework for evaluating risk, adaptive capacity and consequences from rising seas. This will allow local and state stakeholders to weigh the costs and benefits of taking action now against the potential harmful effects of inaction.
The science report will inform California’s sea-level rise guidance document, which will help cities and counties as they comply with state law that requires them to incorporate climate change into their planning efforts. The updated guidance document will also assist state agencies prepare for, and adapt to sea level rise, as directed by Governor Brown’s April 2015 Executive Order on climate change. Public input will be integrated into the final guidance document update, which is scheduled for adoption by the California Ocean Protection Council in January 2018.
The seven scientists who synthesized the latest science as a working group of the Ocean Protection Council’s Science Advisory Team, convened by the California Ocean Science Trust, are Gary Griggs, University of California, Santa Cruz; Dan Cayan, Scripps Institution of Oceanography; Claudia Tebaldi, National Center for Atmospheric Research; Helen Amanda Fricker, Scripps Institution of Oceanography; Joe Arvai, University of Michigan; Rob DeConto, University of Massachusetts; and Robert E. Kopp, Rutgers University.
Among their key findings:
Scientific understanding of sea-level rise is advancing at a rapid pace. Projections of future sea-level rise, under high emissions scenarios, have increased substantially over the last few years, primarily due to new and improved understanding of mass loss from continental ice sheets.
The rate of ice loss from the Greenland and Antarctic Ice Sheets is increasing. These ice sheets will soon become the primary contributor to global sea-level rise, overtaking the contributions from ocean thermal expansion and melting mountain glaciers and ice caps.
Mountain glaciers contain enough ice to raise sea levels by only about 1.5 feet. In contrast, the Greenland and Antarctic ice sheets contain enough ice to raise global mean sea level by 24 feet and 187 feet, respectively. Although these ice sheets are not expected to melt completely, even on century or millennial timescales, the loss of even a small fraction of either of these huge ice sheets could have devastating consequences for global shorelines.
For California, ice loss from Antarctica, and especially from West Antarctica, causes higher sea-level rise in than the global average. For every 1 foot of global sea-level rise caused by loss of ice on West Antarctic, sea-level will rise approximately 1.25 feet along the California coast.
After 2050, sea-level rise projections increasingly depend on the trajectory of greenhouse gas emissions.
While model results have revealed the potential for high rates of ice loss and extreme sea-level rise during this century if greenhouse gas emissions continue unabated, the precise magnitude and timing of when the Antarctic Ice Sheet may begin to contribute substantially to rising sea levels is uncertain.
It is clear that sea-levels are rising. As cities, counties, and state agencies make decisions about adaptation and hazard mitigation efforts, it is increasingly important to incorporate long-range planning for sea-level rise. Consideration of high and even extreme sea levels in decisions with implications past 2050 is needed to safeguard the people and resources of coastal California.
For a schedule of upcoming listening sessions, and more information on the process of updating the State’s sea-level rise guidance document, please visit:
LADWP Runoff Preparations Underway in the Eastern Sierra Region
From the LA DWP:
The Los Angeles Department of Water and Power (LADWP) is working proactively to prepare for the arrival of anticipated massive runoff water resulting from this year’s near record snowpack in the Eastern Sierra Nevada Mountains. These efforts are in partnership with Inyo County, the Inyo Sheriff’s Department, Bishop Police Department, Cal-Trans, Southern California Edison and others, as a member of the Inyo County Interagency Emergency Preparation team.
Work to prepare for the anticipated high water flows began in late February. The efforts have been assisted by an Emergency Declaration from the Mayor of the City of Los Angeles to allow LADWP to take immediate steps to protect infrastructure and aid in managing flood waters while also protecting public safety. Inyo County issued a similar declaration.
To maximize the beneficial use of runoff water to the fullest extent, LADWP is spreading water throughout the aqueduct system to replenish local groundwater aquifers. Current spreading is moderate and will increase as runoff occurs in larger quantities later this spring and summer. LADWP is also maximizing flows in the LA Aqueduct by lowering reservoirs to create more storage space for runoff water and supplying the City of Los Angeles with aqueduct water in place of purchased water and groundwater wherever possible to manage excess flows. Further, LADWP crews are hard at work preparing, cleaning, and repairing water conveyance ditches, spreading basins, sand traps, and other facilities located on City of Los Angeles property, areas controlled by LADWP, and along the Los Angeles Aqueduct, in order to manage the anticipated runoff.
Water that exceeds what can be spread to recharge local aquifers and which does not make it into the LA Aqueduct system will end up on the Owens Lakebed, the natural terminus point for waters flowing down the Owens River. Once there, it will add to the existing 30 sq. miles of saline brine pools and is expected to cause significant flood damage to dust control infrastructure managed and constructed by LADWP over the past 17 years. These measures, spread over nearly 50 sq. miles of dried lake, have effectively reduced dust pollution in the area by 96 percent. Damage to these dust control areas may result in increased air pollution that could threaten the health of the public after the runoff evaporates in 12 to 18 months.
LADWP is also concerned by the potential of water overflow in and around the towns and communities of the Eastern Sierra and is actively providing assistance in preventing and controlling runoff that could impact the public. Emergency assistance will be provided on lands throughout the valley should flooding threaten the property of a partner agency or the public.
“Inyo County is no stranger to emergencies and disasters,” Inyo County Sheriff Bill Lutze said. “Our resilience comes from a strong unified command made up of local, state and federal agencies as well as a public that is proactive in emergency preparedness. We continue to be grateful for our strong working relationships with our allied agencies, including Department of Water and Power, as well as with our residents.”
In order to keep the public informed of the steps being taken to manage runoff to the greatest extent possible and minimize the impact to dust control measures, LADWP will issue regular updates of its runoff management efforts.
Click here for a list of management activities.
Emergency Runoff Management Activities undertaken by LADWP as of April 11, 2017, include:
Pleasant Valley to Tinemaha Reservoir – 23,500 acre feet (AF)
Tinemaha Reservoir to Haiwee Reservoir – 7,600 AF
South of Haiwee Reservoir – 5,200 AF
Total Spreading Water 36,300 AF
Maintenance and Construction Activities
Crowley Lake will be lowered to 80,000 AF to make room for anticipated runoff. Current level – 107,000 AF
Completed Long Valley Dam and spillway inspections (Work will be ongoing)
Snow removal to better access Long Valley Reservoir Dam (Complete)
Currently very little work is being conducted in the Mono Basin due to heavy snow. Equipment is planned to be staged at critical structures and areas likely to see high water conditions, such as Lee Vining Intake and Rock Creek sand trap at Toms Place. This will take place once site conditions allow.
Pleasant Valley Reservoir to Tinemaha Reservoir
Applied for variance from Department of Water Resources Division of Safety of Dams to raise Pleasant Valley Reservoir water level (Complete)
Work to repair and upgrade existing spreading ponds and diversion structures in the Laws/Five bridges area include:
Reinforce and increase size of pond berms to increase spreading capacity and durability. Installing additional head walls and diversion pipes and culverts to provide greater flexibility during spreading operations (90% complete)
Preparing to raise portions of patrol roads adjacent to the canals to provide additional free board and greater conveyance capacity in both the Upper and Lower McNally Canals. This work will provide the ability to spread over 100 cubic feet per second (cfs) into the nearby spreading ponds or to spreading areas located further downstream (Project starting this week)
Preparing portions of the McNally Canals East of Hwy 6 to accept water by mowing and cleaning (Complete)
Work on canals, ditches and ponds in the Bishop area include:
Cleaning the George Collins and the A.O. Collins Canals and repairing/replacing diversion and spreading structures (Complete)
Cleaning, mowing and repairing diversion structures on the Rawson Canal (Complete)
Cleaning, mowing and repairing diversion structures on the Ford Rawson Canal (Complete)
Cleaning and mowing Bishop Creek Canal (Complete)
Modifying irrigation ditches off Bishop Creek to maximize spreading potential (Complete – Additional work will be needed over the summer months to remove aquatic vegetation to maintain capacity in the canal)
Filling Farmers Ponds, located on the West side of Hwy 6, and installing new culvert and diversion structures to convey water to the ponds located on the East side of the highway (Complete)
Round Valley area work includes:
Hand crews cleaning all open diversions on Horton Creek and Lower Rock Creek (Complete – Work will be ongoing in the area with both equipment and hand crews cleaning ditches, installing culverts and diversion structures to maximize spreading potential.)
Big Pine area sand trap and diversion structure work includes:
Cleaning the Baker Creek sand traps, diversion structures and ponds (50% complete)
Cleaning and mowing the Big Pine Canal (Complete – Further work will be needed throughout the summer to maintain capacity once aquatic growth begins to restrict flows.)
Tinemaha Creek and Red Mountain Creek diversions cleaned and marked. (75% complete – Further work will be needed to direct flows into existing catch basins and spreading ponds located in the adjacent areas.)
Tinemaha Reservoir to Haiwee Reservoir
Repairing/rebuilding spreading basin infrastructure (70% complete – Able to spread in excess of 200 cubic feet per second at this time)
Work in the Black Rock Ditch area includes:
Rebuild/repair/replace culverts, check structures and distribution pipes (Complete)
Clean and/or repair distribution channels (70% complete)
Work in the Stevens Ditch area includes:
Mowing, cleaning and adding spreading culverts (Complete – Currently at 50% of capacity)
Prepare Thibaut area ditches and berms (Complete)
Work to prepare the two canals located east of the Owens River to divert imminent flow into the LORP includes:
Clearing McIver Ditch from East of Goose Lake to south of Mazourka Road (100% complete. Currently flowing 15 cfs during Owens River pulse flow. Evaluating additional work for maximum flows and spreading.)
Clearing the Eclipse/East Side Ditch from Mazourka Road to south of Owenyo area (100% complete – Currently flowing 13 cfs during Owens River pulse flow. Evaluating additional work for maximum flows and spreading.)
Cleaning the Unlined section of the LAA (75% complete – Cleaning will be needed throughout runoff season)
Cleaning the Lined section of the LAA to the Alabama Gates (100% complete – Cleaning will be ongoing as needed)
All requested heavy equipment has been rented and received based on forecast needs. Equipment is performing preparation tasks, will be staged during spreading and cleaning operations.
Work to prepare the Lower Owens River Project (LORP) intake includes:
Cleaning the Forebay (Complete – Will need to be cleaned throughout the year.)
Cleaning the measuring section (Complete)
Jetting the Langeman Gate area (Complete)
Cleaning the LORP tail bay and 100 Yards downstream (Complete)
Continually preparing the alluvial fan creek diversions west of the LORP:
DWP lands: 95% complete
Bureau of Land Management areas: 70% complete
Forest Service areas. 100% complete
Armoring of berms, northwest area Owens Lake (Work not yet commenced, in purchasing for contract award)
Construction of new trenches northwest area of Owens Lake (5% complete)
Lower Owens River Pump-back Station (Pump-back Station) work includes:
Placement of temporary barriers, gravels, sandbags and related components around the Pump-back Station to protect it from inundation (Waiting to receive approval from the respective agencies)
Widen the path of water within the Lower Owens River across from the Pump-back Station through creating a temporary channel allowing for greater conveyance of water. This temporary measure is intended to prevent ponding of the water in the vicinity of the Pump-back Station and decreasing the potential for water elevation rising in the vicinity of the Pump-back Station (Waiting to receive approval from the respective agencies)
Lower Owens River Temporary Flow Modification work includes:
Placement of temporary barriers and related components to redirect the water away from the Corridor 1 Road and the T36 DCA northern berm. This temporary measure is intended to prevent inundation and damage to the existing managed vegetation area in the T36 DCA (Waiting to receive approval from the respective agencies)
Modify the east bank of the Owens Lake Delta and tamp down the existing vegetation (tulles) along east side of the Owens Lake Delta to improve water conveyance capability and create a preferred pathway (Waiting to receive approval from the respective agencies)
Western High Density Polyethylene (HDPE) Pipeline work includes:
Temporarily securing in place about 825 feet of the irrigation supply lines from T36 dust control area (DCA) to T37 DCA. This measure is intended to prevent the existing three, 18-inch-diamater plastic pipelines from potential floatation and damage (Waiting to receive approval from the respective agencies)
Zonal Mainline work includes:
Placement of temporary plastic lining and related components to protect the Zonal Mainline from damage due to inundation and erosion of the slope of westerly berm road, the Brady Highway, from wave action due to high winds (Waiting to receive approval from the respective agencies)
South of Haiwee Reservoir
As of 4/2/17, LADWP has discharged a total of 4,600 from the Los Angeles Aqueduct at three locations: Rose Valley south of Haiwee Reservoir, Freeman Wash west of Ridgecrest, and Cameron Wash north of Mojave.
Working on reestablishing the Maclay Highline, which diverts LAA water to the Pacoima Spreading Grounds (20% complete)
Structuring the Power Plant One Slide Gate to place water into San Francisco Creek (Currently pursuing permits for this).
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About News Worth Noting: News Worth Noting is a collection of press releases, media statements, and other materials produced by federal, state, and local government agencies, water agencies, and academic institutions, as well as non-profit and advocacy organizations. News Worth Noting also includes relevant legislator statements and environmental policy and legal analyses that are publicly released by law firms. If your agency or organization has an item you would like included here, please email it to Maven.