There was much media attention a couple of weeks ago when this year's sea ice extent minimum broke all records: it was down almost 50 percent from the 1979-2000 average. Little attention, though, accompanied a possibly even more significant figure, released a few days ago: those who run the PIOMAS sea ice volume model at the Polar Research Center showed the 2012 sea ice volume minimum was down almost 50 percent not from decades ago -- but from 2007! That's right: the volume of arctic sea ice this September minimum was probably about half of what it was, just back in 2007. This figure should deeply trouble any reasonable human being, as it strongly suggests reaching an ice-free arctic sea ice minimum within half a decade, and, since there is little dispute that some summer sea ice will persist to the north and west of Greenland for much longer, the first "near-ice-free" point will likely arrive in just the next few years, as sea ice expert Peter Wadhams has pointed out, and the London-based policy group and think tank Ameg has maintained.
How should we respond? Greenpeace recently started a "Save the Arctic" campaign. That's great -- but you can only save the arctic by saving its ice. And, unfortunately, it is now clear that this can no longer be achieved through emissions reductions alone. It's too late for that. Greenpeace held a meeting on the polar emergency in New York City, by chance on the same day the record extent minimum was called, and while on the surface it seemed pretty ordinary, it was at heart very odd. Nobody suggested any change of approach, any specific re-strategizing, to respond to the accelerating situation. The word emergency was a common currency passing all lips, but in fact it was unclear whether people were really speaking the same language, especially as concerns that most precious thing in emergencies -- time. And there seemed to be no translator in the room, saying "this is the timescale of this, that's the timescale of that."
The meeting's two scientists, Wieslaw Maslowski (on ice) and James Hansen (general climate), themselves focusing on somewhat different time scales, were followed by the 'social/political' panel discussing what we should do: the panel discussed green energy, solar power, how we shouldn't move towards nuclear, that kind of stuff. But Jim Hansen had said in answer to a question (mine), "We are going to lose that sea ice," and also said that to save it, "You could do some quick things." As I'll discuss in my next post, Hansen meant geoengineering. Greenpeace Director Kumi Naidoo later couldn't even remember the word -- geoengineering. But if he's going to save the arctic, I'm afraid he's going to need to know it.
A big issue in whether to consider something an important 'threshold' is its reversibility, and we will discuss the reversibility of this one further in the next episode. At the meeting, since Maslowski focused on sea ice modeling failures, and Hansen on the whole climate picture, many of the potential immediate physical impacts of allowing this coming ice loss remained poorly or not at all elaborated -- although they are important for Greenpeace, and everyone else, to understand, I feel. Hansen showed a slide of three major tipping points which he said place us in a climate 'emergency,' because one can lose control around tipping points. One was methane hydrate, for example. But what Hansen didn't show were what I might dub the 'minor tipping points,' far more immediate changes stemming from this coming loss, which could make it hard to turn around, and could lead us straight to those more major ones Hansen fears, in a slippery slope.
Keep in mind that what we're talking about here is losing almost as much summer ice cover in just the next few years as we have over the last few decades, and that these are all circularly interrelated reinforcing mechanisms. Sorry, if it seems a bit mind-numbing for some readers, but here's my list:
1. Greatly increased arctic water vapor, increasing arctic warming (water vapor is a potent greenhouse gas) but also fundamentally altering arctic hydrology and hence weather patterns.
2. Immediately and fundamentally altered arctic atmospheric chemistry, causing increased arctic methane lifetime, among other basic changes.
3. Certain increase in acceleration of arctic warming, from increased solar energy entering the arctic ocean (this engenders 1.) and the release of latent heat into the atmosphere during autumn's rapid re-freezing.
4. Consequent increased potential for large arctic storms like the Great Arctic Cyclone this summer.
6. Consequently an increase of seabed methane emissions -- including from seabed permafrost, shallow methane hydrate, and from thawing of either or both of these and increased gas migration pathways allowing free gas from underneath the hydrates to outgas.
(For full PowerPoint PDF, scroll down to Topic/Title Methane Release from Eastern Siberian Shelf.)
7. This increase in seabed permafrost thawing leads to a subsequent increased risk that a random seismic event could suddenly release large amounts of methane from the above combination of thawing sources, or from other thawed arctic carbon stores (see PowerPoint above).
8. Increased risk of general degradation of shallow methane hydrates leading to slope failure and consequent methane release.
10. The increased arctic methane lifetime (2.) is indistinguishable from an increase in its arctic abundance.
11. Increasing continued rate of ice (and snow) loss as the ice-free-period subsequently lengthens, from all the above, particularly significant as the insolation increases earlier in the season to around the solstice in June (discussion here, scroll down to An Ice-free Solstice).
And here are some immediate potential global impacts to chew on:
12. Recent research suggests that ice (and snow cover) loss is at least one causative factor in recent extreme weather -- drought, flood, fires, etc. -- and if so this could quickly be amplified.
13. Consequently, recent global impacts on food security could increase proportionally.
14. Economic losses from each of those (12., 13) would probably increase proportionally, and potentially could amplify into global economic recession or even depression.
16. If the ice-free period expands significantly, altered arctic tropospheric oxidation could rapidly start to impact high latitude urban areas, making cities with large populations rapidly become more difficult to live in (good discussion here at GISS, where Hansen is himself director).
No one said a word at the Greenpeace meeting, seemingly dismissing it as a major threshold at all. No one ever said, "Let's fight this." But I am suggesting that you should see skull and crossbones hanging above this threshold crossing. Like playing around high voltage wires or train tracks, allowing this threshold to be crossed will add considerable risk. And I'm suggesting that it will be crossed in just the next few years, unless we do something about it.
As I'll discuss next time, it might prove much harder to reverse than many assume within the climate world. Therefore, as Energy Secretary Steven Chu said about allowing an eventual runaway arctic permafrost carbon feedback, we must all say loudly now about this initial step onto that vast and treacherous slippery slope: "We cannot go there!" And if we don't want to go there, there's now no longer any question -- geoengineering will have to be part of the remedy.