

In his predictable assault on my piece on past and future sea ice patterns, causes and consequences, Joe Romm proposed a bet on the state of Arctic Ocean sea ice (presumably the peak summer melt):

The Arctic is all but certain to be virtually ice free within two decades (barring extreme volcanic activity). I’m happy to make bets with any bloggers, like Andy Revkin, that the Arctic will have under half the ice it has today by 2020, thus equaling or surpassing the lowest level identified in this Science paper. The death spiral continues. [More.]

My rough guess is that the odds are 50/50, with or without volcanoes.

It’s a bet about as ill advised (to propose or accept) as the dicey behavior of this Russian worker when I spent time on the sea ice near the North Pole in 2003:

(He was using a board to test the edge of a “lead” in the ice exposing water that is 29 degrees Fahrenheit and about 14,000 feet deep.)

Here’s the science explaining the flaw in Romm’s bet:

I have no doubt that Ignatius Rigor, Marika Holland, Mark Serreze and the many other ice analysts are right when they see a sustained buildup of greenhouse gases resulting in a largely open-water Arctic Ocean in late summer later in this century. I’ve explored this closely since 2001.

But I’ve long recognized the complexities in ice behavior that will probably result in some ice persisting, even in summer, through that span in some places and that also guarantee the path toward largely open Arctic waters will not be smooth. This was evident to Arctic researchers as far back as 2005, as I wrote in our “Big Melt” series at that time:

Arctic researchers caution that there is something of a paradox in Arctic trends: while the long-term fate of the region may be mostly sealed, no one should presume that the recent sharp warming and seasonal ice retreats that have caught the world’s attention will continue smoothly into the future. “The same Arctic feedbacks that are amplifying human-induced climate changes are amplifying natural variability,” explained Asgeir Sorteberg, a climate modeler at the Bjerknes Centre for Climate Research in Bergen, Norway. Indeed, experts say, there could easily be periods in the next few decades when the region cools and ice grows. [Read more.]

It’s important to note that Sorteberg’s comment above applies to both warm and cool flickers. In fact that outsize sensitivity of the Arctic, noted today by Lubos Motl, makes it likely that we’ll see larger swings in conditions there than in more temperate regions, where it is still inevitable that there will be cool spells in a warming climate.

In my piece on the big 2007 Arctic ice retreat, I quoted Holland, a climate and ice modeler at the National Center for Atmospheric Research:

Natural variations could turn around and counteract the greenhouse-gas-forced change, perhaps stabilizing the ice for a bit.

Now a new study, co-authored by Holland with two colleagues at the research center, adds further credence to this view. As the lead author, Jennifer Kay, put it in the news release:

The computer simulations suggest that we could see a 10-year period of stable ice or even a slight increase in the extent of the ice. Even though the observed ice loss has accelerated over the last decade, the fate of sea ice over the next decade depends not only on human activity but also on climate variability that cannot be predicted.

The study, being published in Geophysical Research Letters, also looked back at recent ice behavior and concluded that “internal variability explains approximately half of the observed 1979–2005 September Arctic sea ice extent loss.” (The third author is Alexandra Jahn.)

This all reinforces the importance of not putting too much stock in upward or downward fluctuations on short time scales in assessing the fate of the planet — and particularly the extra-responsive Arctic — under a building influence from greenhouse gases.

And it also explains why I won’t take a 50/50 bet about Arctic ice behavior in nine years, even while I will advocate for a transition to an energy menu that works for the long haul.

After I sent the post to a group of climate communicators, including Romm, he replied to the group with what’s posted below, along with my response:

Romm:

The mistake you are making, Andy, is to believe that this one study — using a model that the authors themselves acknowledge is flawed — somehow represents the definitive truth of the matter. [I’m assuming you are conceding all of the other critiques in my post that you don’t address here.] I believe that this GRL analysis, which not only uses a flawed model but which focuses on extent, not volume, underestimates what is in fact happening in the Arctic. That doesn’t mean the short-term trend isn’t noisy. And, yes, it may be the case that the trend of the past two decades will stop this decade (or even briefly reverse itself), as this model says COULD happen. But other projections, including ones based on volume, come to a different conclusion. I am willing to put my money where my blog is — and you aren’t. You can hide behind this one study, to avoid making a bet, but that just confirms you don’t even really believe this one study. And in any case, this does not erase the shockingly unjustifiable pair of statements you wrote:



I’m not worried about the resilience of Arctic ecosystems and not worried about the system tipping into an irreversibly slushy state on time scales relevant to today’s policy debates. This is one reason I don’t go for descriptions of the system being in a “death spiral.” The only thing more shocking than the first sentence above is your statement in the comments that the “time scales relevant to today’s policy debates” you were referring to was “this century”!! Seriously? I say we have passed the de facto tipping point, but the physical tipping point will be long before mid century and probably before 2030 — assuming we keep doing nothing or do something little like an energy quest.

Revkin:

One study? Did you read the post? This is line of reasoning that goes back through studies before 2005. And I guess clarity is required. Is your bet on VOLUME or extent? It sure looked like a bet about area/extent given that you cast the wager in the context of the Science study. If it’s volume, it has hardly any meaning to the main point of contention between us — which is whether coming Arctic changes are calamitous to ecosystems, and human affairs, or not. Polar bears, walruses, seals and sub-ice algae and cod don’t depend on sea-ice volume. Like most life forms they live on surfaces (which are measured in area). As a Dot Earth commenter pointed out today, the albedo amplification also is a function of ice area far more than thickness. The surface trends aren’t following your script so you try to shift the discussion to volume. * I’ll repeat that volume mainly matters to cryologists (and the lack of it to ship captains). The layers in multi-year ice (mainly formed when sheets of thin first-year ice pancake) do help baby seals, but polar bears happily walk on first-year ice thin enough to see through (don’t take my word for it; watch the film Arctic Tale). One bet I will make is that Arctic sea ice will not play a significant role in climate policy debates (as opposed to US summer heat, e.g.) in our lifetimes (no stroke factor here; my grandfather had a midlife stroke but lived to be 98). A major reason is Bob Brulle’s shifting-baselines reality.

[* I’m cutting this line, which Joe Romm strongly complained is inaccurate given his frequent references, as far back as 2006, to the work of Wieslaw Maslowski. Given that I haven’t had time to do a search to quantify a shift in Romm’s rhetoric, I agreed. It was inappropriate.]