Sea level rise experts urge more science

Paul Mann
Mad River Union

ARCATA — Local sea rise experts have alerted the California Coastal Commission that the state’s pending update of sea level science findings overlooks two crucial studies of the North Coast’s vulnerabilities.

At a commission hearing June 7 at Humboldt State University, veteran environmental planner Aldaron Laird of Trinity Associates, Arcata, testified that it is imperative that the state’s synthesis of the latest sea rise science include research by Cascadia Geoscience and Northern Hydrology & Engineering, both of McKinleyville.

The studies highlight the coast’s uniquely high exposure to rising sea levels from tectonic land subsidence.

Laird underscored that subsidence – sinking land – in the Humboldt Bay region makes the threat of sea-level rise two to three times greater than anywhere else in California.

Placed in jeopardy is the whole of the Humboldt Bay-Eel River Delta region, which has the county’s highest concentration of people, development and coastal agriculture.

Speaking on behalf of his own research and that of Cascadia Geoscience and Northern Hydrology, Laird said, “We feel that the high rates of tectonic land level change unique to the Humboldt Bay region [are] as critical to understanding relative sea-level rise rates in this area, especially up to the year 2100, as the polar ice sheet losses are to long-term global sea-level rise.”

Laird and his counterparts are worried about missing North Coast science in a pending state report, “Rising Seas in California: An Update on Sea-Level Rise Science, 2017.”

State agencies are currently seeking comments on the report’s companion guidance document; hence Laird’s appeal at last week’s California Coastal Commission hearing for attention to the North Coast.

The pending guidance document must use the best available science to inform local and state decision makers of their areas’ exposure, particularly north of Cape Mendocino to the Humboldt Bay region, Laird admonished.    

He warned more than two years ago that sea level rise is “not going to slow down or stop by 2100. It will likely continue for centuries and rise 10’s of feet (Union, March 4, 2015).”

Humboldt Bay has the highest rate of sea level rise in all of California, a menacing 18.6 inches per century. The ongoing subsidence compounds the threat and NOAA warns that a “grand mal” earthquake could sink the coast three feet instantaneously, accompanied by a tsunami inundation.   

State agencies say in the new “Rising Seas” report that scientific understanding of sea-level rise is advancing rapidly, based on continental ice sheet loss and analysis of climbing carbon emissions.

Regarding ice loss, The New York Times and other news agencies reported at the end of last week that a fast-moving crack 120 miles long or more in Antarctica’s fourth largest ice shelf is on the verge of producing an iceberg the size of Delaware.

A serious contributor to the emissions crisis, ocean warming and rising seas is the immense amount of fossil fuel consumed in the production of plastics. New plastics are projected to consume 20 percent of all oil production within 35 years, four times the estimated 5 percent today.

Only about 5 percent of plastics are recycled effectively and The Economist magazine, London, reported recently there are 5 trillion pieces of plastic in the ocean; 8 million tons are added each year. At current rates of dumping and leakage, the oceans may contain a ton of plastic for every three tons of fish by 2025 – a scant eight years away.

By 2050, the oceans may contain more plastics than fish by weight, even as global warming driven by carbon emissions heightens melting and sea levels in a vicious ecological circle.

In that connection, the California Ocean Protection Council and the state’s Natural Resources Agency assert in their “Rising Seas” analysis, “The direction of sea level change is clear. Coastal California is already experiencing the early impacts of a rising sea level, including more extensive coastal flooding during storms, periodic tidal flooding and increased coastal erosion. 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.”

“Rising Seas” carries a stark warning: “New scientific evidence has highlighted the potential for extreme sea-level rise. If greenhouse gas emissions continue unabated, key glaciological processes could cross thresholds that lead to rapidly accelerating and effectively irreversible ice loss. Aggressive reductions in greenhouse gas emissions may substantially reduce, but do not eliminate, the risk to California of extreme sea-level rise from Antarctic ice loss.”


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