First off, because places like Anchorage and the Matanuska-Susitna Valley are downwind. But more importantly because changes appear to be afoot in the Bering Sea and the north Gulf of Alaska.
As regards the former, the National Snow & Ice Data Center reports Arctic “sea ice extent increased at a faster than average pace through November…(and the) extent was above average in the Bering Sea….”
This would be above the long-term, 1981 to 2010 average and not the average of the last several years which has seen Alaska usually warm.
Meanwhile, out in the Gulf, all the warm water once there seems to have moved south and east, and the Pacific Decadal Oscillation (PDO) is crashing. The PDO is a measure of sea surface temperatures that have historically altered between warm and cold phases every couple of decades or so but seemed to be generally stuck in the warm or neutral phase since shortly after the new millennium.
Bye, bye Blob
The Gulf was especially warm in “The Blob” years, and the interaction between the atmosphere and all the warm water in the Gulf then influenced the movement of air around the globe from east to west.
“The change in location of the cold and warm water masses alters the path of the jet stream,” notes the Jet Propulsion Laboratory, a National Aeronautics and Space Administration (NASA) agency, at the California Institute of Technology.
Anyone resident in Alaska’s urban core for the last several winters knows what this means.
These are what can happen when those warm-cold waters in the Pacific act to influence the atmosphere so that the “jet stream” bends like a snake and starts to run more south to north than east to west through the central Gulf.
Then, instead of the “jet stream” delivering warm water from near Hawaii to the historically soggy Pacific Northwest, the stream pushes the warm air and water farther north to slam into Alaska’s underbelly.
Until late 2020, this sort of atmospheric flow appeared to be on its way to becoming the new norm for the Anchorage metropolitan area home to more than half the state’s population. Now, things are looking more like a shift might be underway back to the old normal, which “The Weather of the Pacific Northwest,” a book by University of Washington atmospheric scientist Cliff Mass, describes in this way:
“Typically, the eastern Pacific jet stream weakens during the summer when it heads northward into Alaska. But during September and October, the jet stream over the eastern Pacific strengthens and begins a southward journey, reaching the Pacific Northwest in November and bringing wind and rain. There it stays through February, after which the jet stream weakens and starts its slow northward return to northern latitudes. Too slow for most.”
Whether that last line, an editorial comment by Mass, was directed at Seattle and Portland residents tired of gray skies and rain, or at Alaskans shivering in the cold and dark of a normal winter is unclear.
It could be aimed at either or both, given that historically Alaska temperatures, even in coastal Alaska where most Alaskans live, were significantly colder than temperatures in Seattle until Alaska’s largest city started to look like Seattle north.
Anchorage temperatures started sliding at the start of November and have remained largely below normal since. On Sunday night at Anchorage’s Campbell Creek Science Center, it was 22 degrees below zero – a relatively uncommon temperature for the state’s largest city since the start of the new millennium.
The chilling PDO hasn’t attracted much attention from the global-warming obsessed mainstream media that suggests every heatwave is a sign of warming and largely ignores any cold snap that can be ignored. Many journalists, it would appear, don’t believe average readers can accept the idea the atmosphere around the planet is warming overall while the huge, annual and monthly variations in weather continue as usual.
But some scientists have noted the declining water temperatures.
As early as April, the Climate Impact Company, a private weather consultancy, was reporting that the “PDO analog forecast suggests the PDO has entered a possible multi-year cool regime last observed in 2010-12, 2007-09 and with the strong La Nina of 1998-00. There is a tendency for -PDO regimes to run parallel with La Nina. In each of the previous multi-year -PDO regimes of the past 25 years La Nina was present at varying intensity.”
La Nina is the name given a coldwater version of the east-flowing, Pacific Ocean current that upon reaching Central American turns north and surges along the west coast of the continent. La Nina is the opposite of El Nino, a warm flow of that equatorial current.
La Nina is now pulsing into the Gulf. La Nina and a cold PDO are likely to put a dagger in the regional warming, at least in the near term.
NOAA records show that 1999 – in the heart of that La Nina/PDO cold snap mentioned by the Climate Company – was the coldest year in Alaska since the mid-1970s when there was a marked shift from the old, cold 49th state to a newer, friendlier, warmer 49th state.
Anyone resident in Interior Alaska in the years prior to 1975 well remembers what winters were like then. Winter temperatures regularly dropped to 40 or 50 degrees below zero and stayed there.
The cold year of 1999 was a couple of degrees colder than the 1949 to 2011 average, according to NOAA. From 1955 to 1975, by way of comparison, seven of the years were colder than 1999, some significantly colder, and five were near as cold.
Only six winters registered above normal from 1955 to ’75 and often just barely above normal. Since 1975, however, above-normal annual temperatures – often up to 2 degrees above normal – have been the norm for Alaska.
“Associated with the seasonal temperature changes…are changes in the length of the frost-free season and the growing season,” NOAA observed. The frost-free season increased by two to three weeks between 1950 and 2011 in the Central Alaska city of Fairbanks. NOAA noted most of that change has come since the mid-1980s.
Still, the reality is that Alaska has been steadily warming since at least the 1700s as recorded by the retreat of glaciers and the northward march of trees.
The fading glaciers of the Bay are not alone.
“Today, 95 percent of Alaska’s 100,000 glaciers are currently thinning, stagnating, or retreating, and more importantly, the rate of thinning is increasing,” the agency says. “Glacier Bay’s glaciers follow this trend. Recent research determined that there is 11 percent less glacial ice in Glacier Bay than in the 1950s. However, heavy snowfall in the towering Fairweather Mountains means that Glacier Bay remains home to a few stable glaciers, a rarity in today’s world.”
None of this, however, is a guarantee that the weather won’t turn cold and stay cold for a span of years. History would indicate the PDO is due for a significant switch back to the cold phase, which should mean colder temperatures even in a warmer world.
Then again, the build-up of carbon dioxide in the atmosphere attributed to human combustion of hydrocarbons since the Industrial Revolution could have so upset the apple cart that big swings toward cold PDOs are themselves history.
Only time will tell.