Climate Watch

By Rick Thoman Alaska Climate Specialist Alaska Center for Climate Assessment and Policy International Arctic Research Center/University of Alaska Fairbanks

The 2023/2024 sea ice season in the Bering Sea is on the way out, with remaining shorefast and high concentration ice being increasingly patchy as open water areas continue to expand.

Also on the way out is El Niño. Although you won’t know it from Alaska weather this past winter, by NOAA’s usual measure this was the fourth strongest El Niño in the past 50 years. Because of the relative importance of El Niño to winter weather (especially in the Lower 48), people regularly ask “What does El Niño (or its flip side, La Niña) mean for sea ice in the Bering Sea?”

And this year simply reinforced what we already knew: El Niño just does not have much influence on the early spring sea ice extent.

The graphic shows the February through April average ice extent for each year 1979 through 2024, with the El Niño seasons highlighted. It's clear that sea ice extent during El Niño is often similar to that in the non-El Niño years immediately before and after.

Since the start of the satellite era in autumn 1978, when we have daily estimates of sea ice extent, there have been 15 El Niño winters, and the average February through April sea ice extent is only 1 percent different than the average in the 31 other springs that were either La Niña or neutral (neither El Niño or La Niña). To give you an idea of how small that is, the typical year-toyear variability in sea ice extent in the Bering Sea during the early spring is over 20 percent.

NOAA’s Climate Prediction Center has high confidence that La Niña conditions will emerge over the equatorial Pacific Ocean later this summer, but we already have the answer to “What does La Niña mean for sea ice in the Bering Sea?” And that answer is: Not much.