Jen Kalt, Humboldt Baykeeper Director
The Humboldt Bay King Tides Photo Initiative began in 2011 as a community science project to document the highest tides of the year in areas vulnerable to rising sea level. The King Tides are extreme high tide events that occur when the sun and moon’s gravitational forces magnify one another. King Tides tend to be more dramatic in the winter when storms cause increased wind and wave activity along the coast. These high-water events give us a glimpse into how flooding from rising sea level will impact our beaches, coastal areas, and shoreline communities in the not-so-distant future.
This winter, we asked our crowd-sourced photographers to focus on the old defunct rail line around Humboldt Bay to gather information on the impacts of reviving the railroad for coal export (see No Coal In Humboldt by Alicia Hamann in the Dec. 2021 issue of EcoNews). During the first weekend of December, the King Tides were slightly higher than predicted. But in the first weekend of January, a major storm resulted in nearly one foot higher tides than predicted, resulting in more flooding and erosion than we usually see.
The Humboldt Bay area is experiencing the fastest rate of relative sea level rise on the West Coast. That’s because tectonic activity is causing the ground beneath the bay to sink – coincidentally, at the same rate the ocean is rising, so doubling the current effective rate of sea level rise around Humboldt Bay.
According to the California Ocean Protection Council’s 2018 projections, sea level in the Humboldt Bay area is expected to rise 1 foot by 2030, 2 feet by 2050, and 3 feet by 2060. But these projections may be outdated: in December, scientists at the American Geophysical Union Fall meeting reported that Antarctica’s Thwaites Glacier is likely to collapse within 5 to 10 years, which could result in an additional 2 to 10.8 feet in sea level rise.
The primary impacts from sea level rise are increased flooding and erosion. Sea level rise will expand the area vulnerable to flooding during major storms, as well as in the rare but catastrophic event of a major tsunami. Sea level rise will also push groundwater closer to the surface, compound flooding and impede drainage, pollute wells with saltwater, and mobilize contaminated groundwater in low-lying areas.
People, infrastructure, and property are already located in areas vulnerable to flooding. Sea level rise will cause more frequent—and more damaging—floods to those already at risk and will increase the size of the coastal floodplain, making new areas vulnerable to flooding.
As sea levels and groundwater rise, flooding will become more and more of a nuisance, impacting road access, sewer and water lines, and other major infrastructure. We need to start planning now for what we know we’ll be facing in the coming decades. We can debate the precise year Highway 101 will be flooded on a monthly basis, or we can plan for the inevitable before it becomes an emergency. We have the choice of planning relocation or waiting for a catastrophe that puts people, property, and the environment at risk.