Barge caught after drifting Climate Watch loose in Bering Strait
By Rick Thoman
Alaska Climate Specialist Alaska Center for Climate Assessment and Policy, UAF With winter settling in across the region, this is a good time to step back and take a look at how the ocean fared this past ice-free season.
The graphic plots the satellite-derived ocean surface temperature from May through October at 30 miles due south of Nome, far away from immediate coastal effects. There are a number of ocean temperature data sets available. This particular data set starts in the mid-1980 and is the highest spatial resolution (about 10 square miles) of any of the satellite-based products that is routinely available. Other ocean temperature products combine historical ship-based observations and more recent satellite observations to extend much further back in time but with much lower spatial resolution (about 10,000 square miles). These satellitebased ocean temperatures are critically important to environmental monitoring in western Alaska because there are no long-term direct measurements of ocean surface temperatures anywhere in western Alaska. The farthest north NOAA buoy is about 150 miles west of St. Paul Island.
For the ice freeze season in 2021, Norton Sound water temperatures were generally quite close to the 30year average except for about a month from mid-June to mid-July when waters were decidedly warmer than normal. Overall, the average May through October ocean surface temperature was 44.2°F, about 0.6°F above the 30-year average.
In the past, if this information had been available, this would not have been terribly exciting. However, after recent years with very warm ocean temperatures, “normal” seems decidedly unusual, and for ocean surface temperatures this was the coolest May through October since 2014.
But a warming environment does not imply that year to year variability goes away, or that every year is warmer than the last. Rather, the changing baseline means that what we used to think of as warm is now average, and what was average now seems cool.