A group of climate experts commissioned by the state of California have published a draft 71 page report that details the factors that affect how much the ocean will rise along California’s coast in coming decades.
This contains the best available and latest information on sea-level science.
There is no one universal conclusion here. What we face are different greenhouse gas emission scenarios. For example, if efforts to mitigate climate change are successful, then there is a 67% probability that the bay area will still experience a sea level rise of between 1.0 and 1.6 feet by the year 2100.The alternative is that if no mitigation efforts are undertaken, then that rise will be between 1.6 and 3.4 feet.
They do also lay out other extreme possibilities that need to be considered and prepared for. If the Antarctic ice sheets rapidly melt, then a rise of ten feet by 2100 could happen. This is unlikely, but still needs to be considered because it is one of the worst case possibilities.
“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.”
Thinking things through now is rather important because 75% of the Californian population lives in costal counties. Sea level rise is a distinct threat that can’t just be ignored.
Who Commissioned this report?
It was specifically 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.
The Ocean Protection Council is a state agency whose mission is to ensure that California maintains healthy, resilient, and productive ocean and coastal ecosystems for the benefit of current and future generations.
The California Ocean Science Trust is a nonprofit organization established by the State of California to build trust and understanding in ocean and coastal science. Serving as a liaison between governments, scientists, and citizens, the Ocean Science Trust supports decision- makers with sound, independent science.
Who wrote it?
Expertise on the scientific team included risk assessment, climatic change, ice sheet behavior, and statistical modeling.
The seven scientists who synthesized the latest science as a working group were …
- 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;
- Robert E. Kopp, Rutgers University.
They list out these seven findings at the start of the draft report.
- 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.
Draft Report Presentation
On 26th April, the draft report will be formally presented at a meeting in Sacramento of the Ocean Protection Council.
“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.”
This is an update of previous reports. First issued in 2010 and then previously updated in 2013.
To be clear … this is a draft and is not final.
During the summer there will be a series of public workshops with state, regional, and local stakeholders to share the science findings and to solicit feedback. It will then be issued for formal public comment during the autumn of 2017 with the goal of formally adopting it in January 2018.
- The draft report itself – Rising Seas in California
- For a schedule of upcoming listening sessions, and more information on the process of updating the State’s sea-level rise guidance, please visit:
- Ocean Protection Council – http://www.opc.ca.gov/climate-change/updating-californias-sea-level-rise-guidance/
- Ocean Science Trust – http://www.oceansciencetrust.org/projects/updating-californias-sea-level-rise-guidance/