The Arctic influences weather around the globe
The record early departure of the sea ice March 12 offshore Nome and ice gone missing from Norton Sound astounded weather experts and certainly the crabbers who lost their pots, and curtailed indigenous hunting for marine food resources.
Never in their memory, folks are saying, has ice that covers Norton Sound left its shores this early, never, even in March, but more likely two months later, in May.
Everybody talks about the weather, the saying goes, and for the last week or so, weather talk has taken on dramatic tones.On top of the effect on local harvests from the sea, ice departure in the Arctic has influenced climate elsewhere. As weather and climate is concerned, what happens in the Arctic does not stay in the Arctic.
First off, an effect called “albedo” refers to the whiteness of snow covered land and ice reflecting heat back into space. Albedo is a measure of reflexiveness of heat off the surface of water and land, a big factor in winter sliding into spring. Snow on tundra and ice reflect and toss the heat of the sun back into space. Dark forests and dark open water absorb heat.
As an illustration, the average temperature around Fairbanks takes about 39 days to rise by 10 degrees Fahrenheit from the “bottom of the barrel” in mid to late January, but rises much more slowly in the Nome area, about the same latitude, taking about 75 days to gain 10 degrees, according to Rick Thoman, climate scientist with Alaska Center for Climate Assessment and Policy University of Alaska Fairbanks.
“That difference this time of year is from albedo,” he said.
Effects of open water sooner in the season will spread to a great extent. “The main impact in the Northern Hemisphere is there is going to be less ice—much less ice much earlier in the season,” Thoman said. “So what this guarantees is that this summer, the surface temperatures in the Bering Sea are going to be much above normal, if for no other reason that we have two months more that the sun will work on warming the water instead of melting snow and ice. That water will flow north through the Bering Strait into the Chukchi Sea which means it virtually guarantees the Chukchi Sea is going to be very warm relative to normal again this summer, which means sea ice is guaranteed to form late again in the fall, so this re-enforcing cycle which we are confident has ramifications around the globe, goes on.
“So in particular, it will take awhile, the fact there is no ice today does not particularly affect the weather tomorrow in New York, but it will, especially as we go through the summer into the fall, once again, the Pacific side of the Arctic with way less ice blocks the heat being pumped into the atmosphere during the fall that would historically been covered by ice at that point so that slowing down of the jet stream, and the idea that it becomes wavier will come into play. So Western Alaska will be contributing to that whole process.”
What happens in the Arctic climate sends weather south and brings weather back.
The jet stream, a narrow band of fast wind, forms a barrier between hot and cold and push air masses around, transports cold and warm air back and forth affecting weather patterns near and far.
The jet stream flows rapidly from west to east at about six to seven miles above the earth. This rapidly turning wind belt affects climate, weather and even airplane flights. The jet stream can keep Alaska warm and, recently, the Midwestern states cold.
The Rossby Wave is a characteristic of the jet stream. That is, the jet stream does not whirl about the earth in a perfect circle like a planetary ring. It has dips and ridges that fill with warm and cold air.
“The air masses follow the wind direction in the midlevels of the atmosphere. The air masses go with the winds. The big mountain ranges will have an effect on that,” Thoman said. “So when the winds are blowing from north to south, in Northwest Territories down across Canada into the Lower 48, the cold air is going to follow those winds.
“Here, we are on the back side of that pressure, so we’ve got winds blowing from the south to the north, so it’s got the warm air is following those winds into Alaska,” he said
The peaks and troughs — waves— in the jet stream are about 2,000 to 4,000 miles apart.
When the jet stream zips southward making a trough, it pulls cold air from the north, feeding it into the middle of North America, into the Midwest, southeastern, northern Mexico, for example. When the “Rossby wave” loops north, it allows warm air to flow north.
Pass the salt?
Another current— traveling through the ocean—also influences climate and weather. The thermohaline current transports water circulating from polar areas through the oceans like a conveyor belt. According to a National Oceanic Atmospheric Administration educational website, winds drive currents through the upper 100 meters of the ocean’s surface. However, thousands of meters below the surface, differences in density of the ocean water resulting from salinity (haline) and temperature (thermo) drive ocean currents.
When polar water forms sea ice, the water gets saltier and heavier, because the ice lets the salt drop out. As the water’s salinity (saltiness) increases, it becomes heavier and sinks. Then other water is pulled in as replacement, which becomes salty and sinks. In this way deep ocean currents drive a global conveyor belt. Scientists say it takes about a thousand years for a packet of water to follow this route as it laces around the continents.
All in all, the arctic region serves as an air conditioner and helps to control the climate and weather elsewhere on the globe.
It is likely some coastal villages along Norton Sound have not seen the last of ice this spring.
Ice may return
“For the rest of the week and the weekend, there will be northerly winds and near to normal or a little below normal temperatures, so thin ice is going to continue to grow,” Thoman said. “While there will be a tendency for a while to push the ice away from Nome, but the weather models are in pretty much agreement that once we get to next week, we will, at least for a while, be going back into a pattern with a storm track off the Bering Sea.
“So the return of the southeast wind regime, would mean for Nome whatever ice gets blown out into Norton Sound, and whatever little bit of new ice forms, looks like next week that ice would blow back onto the Seward Peninsula coast, so it would be like it was in mid-February, except less ice, of course,” Thoman said.