Thursday, 3 November 2016

Sea Ice Loss as Start of Arctic De-Wintering

Drifting into Arctic Un-Winter


2 November, 2016

Many call it global weirding. But weird just barely describes what’s happening in the Arctic right now. To the consternation of some, I’ve warned that the process we are now witnessing is the start to a kind of death of winter that will assuredly happen if we don’t stop burning fossil fuels soon. But we could just as well call it un-winter. Or de-wintering. Whatever you want to name it, and regardless of whether your initial inclination is to downplay it or to shout it from the hills, what’s happening in the Arctic right now is unprecedented and more than a little scary.

Sea Ice Loss as Start of Arctic De-Wintering

The Arctic Ocean has lost a great deal of its ice coverage during summer over recent years. Darker oceans reflect less of the sun’s rays. And more heat gets transferred to the water’s surface. As summer transitions into fall, this added energy loading creates a latent heat barrier to ice refreeze. Without its traditional ice coverage, the ocean then ventilates this heat into the Arctic environment — keeping air temperatures abnormally warm, increasing water vapor content, and thickening the Arctic atmosphere.
Over recent years, this process has generated the powerful winter warming that we call polar amplification. It has disrupted the Jet Stream and contributed to other changes to global weather patterns. But fall of 2016 has so far seen some of the worst instances of this climate change related heating of the world’s frozen regions.

Current Arctic Heat is Unprecedented

arctic-temperature-anomaly-november-2-2016
(Temperature departures for the entire Arctic have exceeded 6 C above average for three out of the past four days. The delay of the usual fall progression of cooling toward winter is a month or more behind schedule for this region of our world. Image source: Climate Reanalyzer.)

Today, the temperature above the Arctic Circle is averaging 6.21 degrees Celsius above average. Large local areas are seeing temperatures in the range of 15 to 20 degrees Celsius above average with locally higher peaks. Beyond the 80 degree north latitude line,temperatures are currently about 12 degrees Celsius above average. The result is that most places in the Arctic are about 25 to 40 days behind the average cooling trend line and that temperatures are more reminiscent of late September or early October than early November.

Sea Ice Record Lows Are Likewise Extreme

Not only is the added ocean heat pumping season-wrenching warmth into the Arctic atmosphere, it is also generating a self-reinforcing feedback loop with record low sea ice departures that have been worsening with each passing day. According to JAXA, current Arctic Ocean sea ice extents are now 710,000 square kilometers below the previous record low set in 2012. That’s an area larger than the state of Texas. But when you compare this new record low to averages seen in the 1980s, a region the size of Texas, Alaska, and California combined have been lost.
jaxa-sea-ice
(Arctic sea ice extents of 7.03 million square kilometers on November 1 of 2016 are about equal to end summer sea ice minimums during the 1990s. So much open ocean is having a dramatic warming effect on the Arctic atmosphere during the Fall of 2016. Image source:JAXA.)

All that naked ocean dumping heat into the atmosphere is having a marked effect. One that is producing these extreme temperatures even as it generates a self-sustaining cycle that prevents refreeze.
Over recent days, the heat in the Arctic has created a situation where ocean refreeze rates have essentially moved sideways on the graph. This has created a well-earned hubub by weather and Arctic experts across the net. Bob Hensen at WeatherUnderground recently tweeted: the Arctic Ocean appears to have forgotten it’s supposed to be refreezing right now.‘ To which PHD student Zack Labe responded: it’s crazy… the daily data shows the recent flat line.‘ Meanwhile, the Arctic Sea Ice forum has basically gone nuts over the very odd behavior of sea ice this all.

Will it Continue? ENSO Adding to the Heat Transfer Bias

How long this vicious tug of war will continue to last is anyone’s guess. It ultimately boils down to how much heat the Arctic Ocean has taken in and how much energy is still being transferred in that direction. With La Nina forming in the Pacific, ocean and atmospheric heat transfer toward the Arctic would tend to ramp up. And we may well be seeing a kind of teleconnection type handshake between polar amplification and the ENSO cycle now.
To this point it’s worth noting that the most recent big heat pulse in the Arctic started with the powerful 2015-2016 El Nino. And this traditional natural variability related heat transfer is likely to continue to push the scales for Arctic heat content through 2017 and possibly into 2018. The question in this case is whether or not climate change related warming is being enabled by this periodic flux to hit a new tipping point. And from the perspective of this fall, things don’t look very good for the Arctic.
Links:

Scientific hat tip to Dr Jennifer Francis
Hat tip to Colorado Bob


No comments:

Post a Comment