By 2050, sea level along US coasts could rise up to 30 centimeters above the current waterline, according to a new NASA study.
Analysis of nearly three decades of satellite observations by the NASA Sea Level Change Team could help refine near-term projections for coastal communities Bracing for increases in both catastrophic and nuisance flooding in the coming years, the space agency reports.
Global sea level has been rising for decades in response to a warming climate, and multiple lines of evidence indicate that the rise is accelerating.
New Findings Support Higher-Range Scenarios described in an inter-institutional report published in February 2022. That report, developed by various federal agencies, forecast a rise in the level over the next 30 years by region. They projected 10 to 14 inches of increase on average for the East Coast, 14 to 18 inches for the Gulf Coast, and 4 to 8 inches for the West Coast.
Building on the methods used in that earlier report, a team led by scientists at NASA’s Jet Propulsion Laboratory in Southern California took advantage of 28 years of satellite altimeter measurements of sea surface height and correlated them with NOAA tide gauge records dating back to 1920 continuously measuring the height of the surrounding water level, tide gauges provide a consistent record to compare with satellite observations.
The researchers noted that the accelerating rate of sea level rise detected in satellite measurements from 1993 to 2020, and the direction of those trends, suggest that future sea level rise will be in the upper range of estimates for all regions. Trends along the US Southeast and Gulf coasts are substantially higher than those along the Northeast and West coastsalthough the range of uncertainty for the southeastern and gulf coasts is also larger.
This uncertainty is caused by factors such as the effects of storms and other climate variability, as well as the natural subsidence or displacement of the land surface along different parts of the coast.
"A key takeaway is that sea level rise along the US coast has continued to accelerate over the last three decades"said Ben Hamlington of the Jet Propulsion Laboratory (JPL), team leader and co-author of the new study and the previous one, in a statement.
Hamlington noted that the team wanted to determine if they could refine sea level estimates for communities facing imminent change. "We have heard from practitioners and planners along the coasts that they need more information on shorter time scales, looking not 70 or 80 years in the future, but 20 or 30 years in the future."said. "The bottom line is that as we look forward to what we might experience in the coming years, we need to consider these higher possibilities.".
The dangers of sea level rise are amplified by natural variations on Earth.
For example, by the mid-2030s, all of the US coastlines will experience more intense high tide flooding due to a wobble in the Moon’s orbit that occurs every 18.6 years. Hamlington said this lunar cycle, in combination with rising sea levels, is expected to worsen the impacts of high tide flooding during the 2030s and 2040s.
Variabilities from year to year, such as El Niño and La Niña effects, can also make it difficult to forecast how high and how fast sea level will rise annually. Hamlington said the forecasts will continue to be refined as more data from satellites come back over time.