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Joe Wentrup

I opt for A. To create awareness you have to be in the media - and recent arctic records have always been measured and have raised attention in terms of "first year in history".

Aaron Lewis

There was a time when continuous and competent Arctic sea ice separated the Arctic atmosphere from the Arctic ocean. From continent to continent, the atmosphere was cold and dry, allowing heat to radiate off freely. Greenland was also cold and dry.

Now, the diminished and cracked sea ice allows water vapor (latent heat) to move into the Arctic atmosphere. This reduces the amount of heat radiated off, so that heat from the Arctic Ocean is trapped. A warmer Arctic means that latent heat from the south is not condensed and radiated off.

Water vapor in the Arctic atmosphere changes the density of the air, impacting global atmospheric circulation patterns.

Loss of sea ice is long process of partition and equilibrium. The effects began when ice began to diminish and crack, allowing water vapor into the atmosphere. Increasing water water vapor in the Arctic atmosphere changes our weather. Today most our infrastructure was designed using engineering standards based on the climate of 50 years ago. Cracks in ice affect people, NOW.

Some horses can get out of a barn if the barn door is closed, but not latched. Measuring whether the barn door is 12 feet open or a full 16' open does not really tell you much whether your animals can get out of the barn. At this point the Arctic barn door (ice separating air and water) is open enough that all the “weather animals” can come and go as they please. As a result, for the last few years we have seen weather patterns never before seen, and which were not included in our engineering basis of design. The 4 options are about measuring the width of the barn door opening as the horses come and goes.

The important question about sea ice is, “Can water vapor move from the ocean to the atmosphere?” At this point, the ice is both diminished and fractured, and water vapor can move from the Arctic Ocean into the Arctic Atmosphere. AGW unlatched the Arctic Barn Door at least 20 years ago.

More water vapor in the Arctic atmosphere means more precipitation on Greenland. In 1970, rain on Greenland was almost unknown. Starting in 2002, I tracked rain on Greenland for for 60 consecutive months, and rain was reported somewhere on Greenland every month. If it is raining, then there is water vapor in the air, and water vapor melts ice.

Long story, short: There is excellent observational evidence that loss of sea ice competence affects GL melt. A fractured tea cup is not a “tea cup”, and fractured sea ice does not behave as traditional competent sea ice.


Nice commentary, Aaron.

I think you've also put your finger on a key point: Our civil engineering and domestic architecture was designed for the climate of 50 years ago, not what is evolving.

We can see the consequences of that in many of this winter's weather events across the US, Britain and elsewhere.

I think coping with it will be a huge, previously unforeseen problem. The cost of infrastructure changes required will be enormous.


@ arron,

You say, '...water vapor melts ice.'

Is this what we should ultimately be worried about?

Chris Reynolds

Aaron, Neven,

Hanna 2012 "Increased Runoff from Melt from the Greenland Ice Sheet: A Response to
Global Warming"

That finds that Greenland run off is mainly dominated by the intensity of the Greenland Blocking index and resultant high pressure -> clear skies -> increased surface insolation. This has been particularly strong since 2007.

This intensity in GBI since 2007 has been a result of increased Arctic Dipole anomaly in the summer. The Arctic Dipole has a role in wider weather impacts. e.g. European summer rainfall.

Overland et al find suggestions of wide impacts. (Overland et al "The recent shift in early summer Arctic atmospheric circulation")

The suggestion that recent (2007–2012) magnitudes of the early summer AD pattern are associated with enhanced North America and Greenland blocking events in the 700 hPa composite height field (Figure 3c) may imply a mechanism linking high-latitude change with mid-latitude weather in early summer...

...The June
2012 700 hPa geopotential height and temperature patterns (not shown) are similar to the Russian heatwave of 2010 [Dole et al., 2011], and the anomalous circulation may also have contributed to dryness and forest fires plaguing central and western US during the 2012 summer. Meanwhile, an enhanced southward dip in the jet stream leeward of the increased ridging over Greenland has caused generally cool wet summers in the U.K. since 2007, with record rains and floods in 2007 and 2012 [e.g., Hanna et al., 2008b; Met Office, 2012].

We often concentrate on N America, Europe and Eurasia. But the effects are found in east Asia...

Wu et al find a link betwee the Arctic Dipole and summer rain in China.

Zuo et al find predictablilty of China's winter cold with sea ice extent
Which leads onto a growing body of study showing potential linkage between low summer sea ice and cold winters.

Honda "Influence of low Arctic sea-ice minima on anomalously cold Eurasian winters"
Cohen "Arctic warming, increasing snow cover
and widespread boreal winter cooling" http://web.mit.edu/jlcohen/www/papers/Cohenetal_ERL12.pdf

All this is before we get to the issue of extreme weather and the planetary wave linkage to Arctic Amplification.
(Just look at the author list on that - it's a who's who of the leading experts in the issue)


There is a growing picture of year-round weather impacts across the entire northern hemisphere due to the loss of Arctic sea ice. Some of the details remain to be sorted out, but the overall pattern is clear.

Determining the criteria for declaring an ice free Arctic is useful. I'd favour <1M km^2 as the first year of ice free, that may be followed by some years above 1M, I can't decide between Ridley et al's C and D for determining when the transition to a seasonal pack is complete.

But Neven is correct, the consequences of sea ice loss are already here and are already having impacts.

Anyway, rambling over, back to lurking.

Tor Bejnar

It always serves us when we see you un-lurk, Chris!

If my opinion counted, I'd advocate for A & D. "A" for first ice free autumn, "D" for 'the transition' is complete.

Jon Hurn

That we are even discussing the event is indicative on how much the situation has changed in the last 20 years.

Chris Reynolds


Thanks, I've had to withdraw from most discussions and have barely been to the forum because I'm now in management, so I'm cash rich :D, but time (and energy) poor :( . Ho hum.

I'm the only one of the management team without a status car. VBEG

Anyway, yes, I think I'd like D, but for the purposes of betting it puts a payout even further into the future. So for betting I'd prefer the first year.

That rambling on weather impacts is symptomatic of a building urge to re-read loads of papers get up to date with some more, and do a map of impacts. It's also driven by things like this:


The winter just gone (2016) and winter 2014 have been absolutely insane! Is it linked to the Arctic? I don't know.


Indeed, in the 1990s it was being discussed in the literature whether the decline in ice extent was part of a cycle (with the 1930s). The impact of AGW was considered in doubt by serious scientists.

Nobody serious thinks that way now.



The infinite Monkey Cage covers global warming.

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