Greater variability in sea level is expected as Earth warms

A team of researchers from the University of Hawai’i (UH) at Mānoa School of Ocean and Earth Science and Technology (SOEST) identified a global trend for future sea levels to become more variable as oceans heat this century due to increasing greenhouse gas emissions. Sea level change changes during cycle and improves the risks of flooding and erosion on shore above changes related to sea level rise.

Rising sea levels occur as Earth warms due to two main factors: melting of ice on land, such as glaciers and ice sheets, and the expansion of seawater as it warms – called thermal expansion. It was previously unknown whether the rate of thermal expansion, which accelerates with warming, will also affect the variability of sea level.

In a study published this week in Communication Earth and environment, the team led by Matthew Widlansky, associate director of the UH Sea Level Center, assessed future projections at sea level of global climate models. The team found that although future changes in sea level variability at many locations are uncertain, almost all 29 models they analyzed agreed on a general tendency for the variability to increase on seasonal-to-annual time scales.

“While it is well understood that the rate of global average sea level rise will accelerate with future warming, partly due to the oceans expanding rapidly at higher temperatures, it was not previously investigated how this non-linear thermal expansion property of seawater will affect future sea levels. affect variability, “Widlansky said.

“Under thermodynamic laws, sea level variability increases in warmer climates because the same temperature variations, for example related to the seasonal cycle, cause greater buoyancy and fluctuations in sea level,” added Fabian Schloesser, a researcher at the UH Sea Level Center. t collaborated on the study.

In places where changes due to ocean thermodynamics and other processes for climate variability coincide, the team found the largest increases in future sea level variability.

Coastal flooding is occurring more and more frequently due to a combination of steadily increasing sea levels and ocean variability. The new findings therefore further emphasize the importance of monitoring and forecasting at sea level.

“Forecasting could potentially provide warnings months in advance if sea levels are likely to cause tides than otherwise expected,” Widlansky said.

While the science team investigates how to better develop forecasting articles, the UH Sea Level Center actively monitors extremes through a worldwide network of tidal gauge observations, including in Honolulu, Hawaii.