The National Snow and Ice Data Center (NSIDC) has just announced that Arctic ice cover has reached its minimum extent for 2012, far below the previous record[1]. Peter Doherty discusses some of the implications here. As far as the broader debate about climate change is concerned, there are some big implications.
* First, this is irrefutable evidence that the climate is changing, and that the idea that climate change stopped or slowed down after 1998 or 1995, as delusionists have regularly claimed, is nonsense. On the contrary, the loss of Arctic ice is accelerating, far ahead of model predictions{2] In this context, I have yet to see any “sceptics” actually accept the evidence proving them wrong. But, with a handful of exceptions, we have silence rather than the usual rash of talking points to explain the evidence away. A notable example is Andrew Bolt, who ran lots of posts claiming there was no problem (most recently here), but hasn’t mentioned the topic since the minimum extent record was broken nearly a month ago.
Update While the blog was off-air, Bolt came up with a snark about the Antarctic, which presumably is supposed to offset the long string of posts he made claiming that there was no problem in the Arctic. As usual, Bolt’s talking point has already been debunked, here at Skeptical Science, but you can do it yourself. Compare Bolt’s graph of the Antarctic, showing a small increase in the winter maximum, to the NSIDC graph of the Arctic showing the summer minimum collapsing. End update
* Second, the “catastrophic” part of the delusionists favorite acronym “Catastrophic Anthropogenic Global Warming” is looking a lot more likely. Not only will an ice-free Arctic produce a bunch of feedbacks that accelerate warming, but it will substantially affect climate conditions in Northern Europe, though exactly how remains to be seen.
On the other side of the coin, there’s one predicted catastrophe that didn’t happen. As elsewhere in the world, the introduction of the carbon tax did not “send a wrecking ball through the economy”. In fact, adverse effects are barely detectable. Of course, a lot more action is needed, but the near-universal view of economists that the cost of stabilising the global climate will be of the order of 1 per cent of income is certainly supported by the evidence from the initial steps in this direction.
fn1. The record is for the period of satellite data, going back to 1979. But as I mentioned a while ago, the fact that the Northwest Passage, sought unsuccessfully for centuries, is now routinely navigable in summer shows that this melting is unprecedented in the last 1000 years or so. Other research suggests that ice cover is probably the lowest in 8000 years
fn2. For those whose claimed “scepticism” rests on distrust of models, this is a useful reminder that models can be wrong in both directions.
John Quiggin 
On the subject of Arctic methane release, people should read what the RealClimate team have to say about it. Some of the salient points:
1. Despite higher current estimates, Arctic release remains modest compared to that from low latitude wet lands.
2. The system response time appears to be slow and the influence may be more in the long tail of the warming event than in short term effects.
3. There is no convincing evidence of large methane pulses in the previous inter glacials
4. It is (or can be) incorporated into climate models by adjusting the net carbon flow of land in the carbon cycle.
http://www.realclimate.org/index.php/archives/2012/06/methane-game-upgrade/
http://www.realclimate.org/index.php/archives/2012/01/much-ado-about-methane/
Or maybe better still wait for IPCC AR5 before hitting the panic button.
@TerjeP
Well,it depends on the average sea ice extent for summer. Are you presuming that it will be anomalously high,because of the current spike of the last month? The satellite record shows average summer Antarctic sea ice extent barely has any trend.
Solar passive design for whole suburbs is worth a look. As an added bonus it creates, I think, very interesting architecture.
http://www.lowtechmagazine.com/2012/03/solar-oriented-cities-1-the-solar-envelope.html
Again, Quokka, you are attempting to isolate and marginalise environemntal effects that work in concert, not solo performance.
http://www.zeeburgnieuws.nl/nieuws/mb_permafrost.html#carbon_time_bomb
@BilB
I’m doing what? And again? Whatever you want to believe if it makes you happy.
There is an excellent highly detailed study of a domestic solar installation on The Oil Drum right now
http://www.theoildrum.com/node/9499
There is also a highly detailed refutation of the recent Maugeri “oil to burn” paper by a long term oil industry analyst.
Quokka,
I may be being a little harsh, but saying at this stage “don’t push the panic button” is bad advice.
We are in unprecedented global change territory on exceeded in speed of change by massive meteor strike.
The last change that took global temperatures up 5 degree C was due to planetary orbital change and axis tilt, slow changes relative to our 200 year and rapid escalation of CO2 atmospheric release.
The current pace of change is in geological scales instantaneous. Last week I viewed a documentary of a Russian scientist standing in the tundra saying that he was standing on 25% of stored atmospheric CO2. I don’t know how accurate that is but if true it poses a huge threat. There is a recent atmospheric model study that reexamines the 50 million year ago event and is able to create the climatic change in the model using the stored carbon in the permafrost. And that is with the continents as they were at that time which is substantially different to how they are now. This time around the permafrost zone is much larger, the Arctic seas are shallower, and the current circulations are very different.
The possibility of a rapid permafrost melt is quite high. The recent heat wave in Moscow triggering massive forest fires points to the mchanism that has the potntial to trigger large scale melt with self sustaining year round decomposition of peat bogs. Here is an example of how that can work
http://www.washingtonpost.com/national/health-science/efforts-begin-to-put-water-back-into-peat-bogs/2012/02/10/gIQA4PiA6R_story.html
As I said, it is the sum of all events that is our risk, not any one threat in isolation.
@BilB
I agree with you BilB but people are sick of my gloom and doom posts so I won’t say much. It will take a series of salutary and frightening disasters to actually force people to see what is happening. Logical, rational, scientific argument is not enough when you see the forces arrayed on the other side. Ignorance, selfishness, blindness, stupidity, greed, advertising, propaganda, duplicity and denialism rule the scene. Not until the equation becomes very simple, ie. change or die, will we see movement on this issue.