SAN FRANCISCO - A new report warns that the sea-level is rising at an accelerated rate along U.S. coasts, including here in the Bay Area.
Researchers at Virginia Institute of Marine Science (VIMS) issued their annual report card which looked at tide-gauge records for 32 coastal locations, stretching from Maine to Alaska. The analysis included 51 years of water-level observations, from January 1969 through December 2019.
“The key message from the 2019 report cards is a clear trend toward acceleration in rates of sea-level rise at 25 of our 32 tide-gauge stations," said VIMS emeritus professor John Boon.
The Bay Area was home to two of those stations: one in Alameda and one in San Francisco, which both recorded a year-over-year rise.
San Francisco's rate of sea-level rise last year was 1.91 millimeter, and Alameda saw a yearly increase of 1.10 millimeter. The sea-level acceleration rate measured at 0.03 mm and 0.05 mm, respectively at those tide-gauge stations. Researchers projected that if this continues, sea level in San Francisco and Alameda will be almost .5 feet higher in 2050 compared to 1992.
While figures showed a relatively slower rise along the West Coast compared with other regions, scientists suggested that will likely change, driven by a shift in wind patterns associated with an El Niño-like pattern of climate variability.
“Models have been predicting that it will start to rise faster. The report cards from the past three years support this idea,” said VIMS marine scientist Molly Mitchell.
In Alaska, where four tide-gauge stations were located, the report found sea level actually fell at increasingly rapid rates. Scientist attributed the decline to mountain-building in the coastal regions, which can lead to a drop in sea level by elevating the area of the ocean floor.
The report found that the three highest rates of sea-level rise in 2019 occurred along the Gulf Coast. Grand Isle, Louisiana was home to the biggest spike at 7.93 millimeters per year. Rockport, Texas followed at 6.95 mm. Rockport also topped all 32 stations in its rate of acceleration, at 0.26 mm per year, with the sea level projected to be 0.82 meters (2.69 feet) higher in 2050 compared to 1992, according to the report. Grand Island, Louisiana, saw a nearly 8 millimeter increase, which was double the global average.
Researchers said the rise in the Gulf region was due in part to the history of water and mineral extraction in the area. "Pumping of groundwater and oil can cause land subsidence, which contributes to relative sea-level rise," the report explained.
Overall, they pointed to global warming as "the obvious suspect," citing the rate at which glaciers and ice sheets were melting, causing water to expand.
Scientists warned the findings of the report should lead to infrastructure changes and other action to prepare.
“We have increasing evidence from the tide-gauge records that these higher sea-level curves need to be seriously considered in resilience-planning efforts,” researchers stressed, adding, "local rates of relative sea-level rise give a direct indication of the extent to which homes, buildings, and roads are at risk of flooding."