Scientists blame record-setting warm winter temperatures on Arctic oscillation, a global jet stream that circles the upper Northern hemisphere and is keeping cold air trapped around the North Pole
- Climate researchers say the Arctic oscillation has kept winter temperatures high
- The AO is a ring of high speed wind that circles the Arctic
- During some periods, the ring is reshaped into a kind of sine curve shape
- This pushes colder air from the Arctic down across the rest of the hemisphere
- The jet stream is currently in a flatter ring shape that’s kept the cold air trapped
The record-breaking January temperatures appear to be caused by shifts in the Arctic oscillation, a wavy ring of powerful wind that circles the Arctic at around 20 degrees latitude.
Shifts in the AO have a direct impact on global weather by influencing how much cold air from the Arctic is pushed down and spread across the rest of the northern hemisphere.
Throughout the year, the Arctic oscillation varies its shape, reflecting differences in atmospheric pressure.
Record high temperatures in January appear to be connected to the Arctic oscillation, a band o of wind that circles the Northern Hemisphere and either keeps cold air trapped near the poles or pushes it downward to the rest of the hemisphere
According to the National Scow and Ice Data Center in Boulder, Colorado, a climate research group, the unseasonably warm January temperatures are likely due to an extended positive phase of the AO
During a positive phase, the jet stream is a comparatively flat ring of air, and during its negative phase, the band of wind becomes much more uneven, resembling a sine curve.
The AO is currently in a positive phase, which, NSIDC director Mark Serreze told NBC News, is keeping the colder air around the Arctic at bay.
This has not just kept winter temperatures up but minimized the number of seasonal storms the AO would otherwise help cause during a negative phase, as large volumes of air with different pressures collide.
‘Storms tend to develop along the jet stream and are guided by it,’ Serreze said.
‘What we’re seeing is the polar front jet stream shifted north and that Arctic air is just trapped at high latitudes.’
During a negative phase (left) the jet stream around the Arctic becomes uneven and resembles more of a sine curve, channeling cold air farther down into the hemisphere. During a positive phase (right) the jet stream forms a tighter ring that keeps air trapped near the pole
According to Serreze, changes in the Arctic oscillation aren’t easy to model or predict, which can make larger seasonal patterns difficult to anticipate.
‘This is actually an area of active research because if we could forecast it, we could really enhance longer-term predictability of weather conditions,’ he said.
‘If you could say in November that the coming winter is going to be preferentially in a positive phase, that would be valuable for aviation or cities planning snowplow budgets, for example.’
According to global averages, January was the hottest month in recorded history, and the fifth hottest in US history
The relationship between regional weather and global climate phenomena like the Arctic oscillation is still unclear, but scientists say changes in one part of the world will inevitably effect other parts of the world, though saying how is not always easy
The exact relationship between the AO and global warming isn’t fully understood, but Serreze says changes in one part of the planet will inevitably have affect other areas.
‘We’re already seeing the Arctic warming at an outsize rate compared to the rest of the planet,’ he said.
‘If we’re changing the temperature gradient between higher and lower latitudes, the jet stream is going to respond to that.’
