the Arctic environmental system has reached a 'new normal'
I sincerely doubt if anyone will step forward and admit to having writing that grossly misleading sentence but the implication -- that some sort of new 'equilibrium state' or pause in Arctic Amplification has set in -- is dead wrong.
The downward trend that continued in 2017 -- with record-setting delays in freeze-over in the western portal (Chukchi) -- is the exact opposite of the meaning of steady state in the physical sciences.
There is nothing normal about this trend. It is ever-worsening human disruption of climate by atmospheric emissions pollution.
Its consequences for mid-latitude weather are belatedly under discussion but will surely be exacerbated and possibly elevated to tipping point status as the trend takes us in the near term to even more extreme states.
In my view, the climate is undergoing unprecedented and largely unpredicted rapid change already, though very unevenly depending on location, eg the western coast of North America is hyper-sensitive to changes in the adjacent Pacific whereas as other areas might plod along at a barely noticeable 2ºC-by-2100.
For this reason, model papers that build on Old Arctic conditions should be rejected at the time of peer-review. It's not at all uncommon to read a December 2017 paper only to discover in the fine print that it assumes an entirely pre-2014 foundation.
Whoa ... a whole lot has happened since then, even with a discount for natural variation. Why wasn't that change in baseline conditions incorporated? A four year delay is unacceptable, long beyond the shelf life of utilizability. Only an eight of that is attributable to journal review.
I follow near-real and annual changes quite closely and have provided several thousand time series so that carefully sourced current data is readily available to even the laziest scientist on the planet. So what's the excuse for all the dilatory papers?
Perhaps the most disturbing example of not acknowledging the walrus in the tent is the Beaufort Gyre, which appears long-gone. In my view, it won't ever be coming back to what it was.
If you are too new here to remember the Beaufort Gyre, it was a quasi-stationary pattern in atmospheric highs and lows give rise to winds that caused a portion of the ice pack to circle tightly around for years in the Beaufort Sea. The same floes would thicken each winter and melt some each summer, extruding brine from recrystallizing ice and giving rise to a large reservoir of slightly less salty water (called a freshwater pool in oceanography).
I've reposted NSIDC's 1979-2015 sea ice age animation here many times. It uses weekly intervals which are very effective in displaying the years and seasons in which the Beaufort Gyre, TransArctic Drift and Fram Strait export were actually active.
Those don't include the most recent years. The weather pattern is just not re-establishing itself except episodically. Even when it does, there's
no gyre, only a counter-current to the Alaskan Coastal Current that takes the ice -- now 79% first-year -- into the killing fields of the Chukchi. Remember the route traced by Big Block last year?
The Beaufort Sea today melts out completely every August and is late to refreeze. There is zero multi-year ice circling the Beaufort Gyre, though you would never know it from journal articles that go on and on about ye Olde Gyre like there was no tomorrow.
All gradients tend to dissipate. That's the second law of thermodynamics. Without continuing energy inputs from wind and current, there's nothing here to sustain former temperature, salinity, buoyancy gradients in the Beaufort Gyre center. They're dissipating. Gradients in nature are not sustained by claims in dead-on-arrival model papers.
The Arctic is changing too fast for the modeling community to keep up. It's better to stay in the present. So sleep well, the AMOC isn't safe but it won't be the Beaufort Gyre that does it in.
I'll post the year-in-review videos in due course.