Around 2040 all of the winter sea ice will have gone, so ice to melt through spring and summer. So an upwards spike around then will not be at all surprising. For all that we like smoothing trends, nature does seem to go for the steps. Although I do totally agree with the point you make.

3.25 million square km Watching the numbers, we are due for a dead cat bounce. Looking at the ice it could be very low. Over 4 would surprise me, just under 2 would not. Clearly I am putting too much faith in the bounce of numbers.

Maslowski's 2016 looks better than ever for an ice free Arctic minimum. We can probably lop off 2013 and 2019 as possibilities. So my two cents worth: record minimums every year from here on in. That includes this year.

Re: Nevin and scientists. Nevin is not subject to the sensitivities of the people he works with, he is free to say it how he sees it. Nevin does not have a reputation to protect (probably not true anymore) again freeing him to say it how he sees it. To those actual scientists who comment here thank you too. Correcting our misunderstandings is valuable. Proviing those details is valuable. The combination of very knowledgeable amatures and scientists makes this a come to site for up to the minute information on the ice. Thank you Nevin, thank you all.

How about some penetrometer readings. We are hearing so much about rotten ice some penetrometer readings could put some numbers to the rottenness.

The sea ice is going and soon we will see a zero minimum. Even after this has happened we may still be arguing over what is the best fit and it may well be, that the answer is not at all clear. What will be clear is that there will be consequences. I am not at all sure that a Gompertz curve is the best fit. But I suspect that it may be. Regardless after we see a zero minimum a zero month and then a zero season will not be far behind. Perhaps even more frightening is that a zero maximum may only be a few decades away. I do not want to believe that, but look at the fit.

Perhaps I should have made myself clearer. When I say the refreeze will start earlier, this will happen when what is now late melting ice has gone earlier. Presently the freeze up begins long before the melt has finished. As the ice melts out earlier further and further north, eventually the freeze will overtake the melt earlier. In any one position the freeze up will not be earlier. Remember the Arctic is huge and goes right to 90 degrees north, Although the North Pole sunset is not until September 24 it is so low on the horizon long before that that even tiny bumps of ice cast a huge shadow. So while the bigger lumps of ice may be still melting, large areas of surrounding sea are freezing. Towards the poles it is surfaces that tend towards the vertical that receive the most light.

Why exponential rather than linear? Because that is what is happening. The trend is so clearly non linear. Why Gompertz? Because the refreeze starts well before the melting has finished, the refreeze is fast in extent and as the minimums get ever lower the refreeze gets faster. If this is correct then we may see the minimums get even lower, but also get earlier. The eventual zero sea ice could be Early August. The thinning of the ice will be even faster than the loss of extent. Huge areas of very thin ice are possible in the dark. As someone else here has already noted that is what the trends tell us. In truth I am only guessing and know far less than many here. But do think of the geometry. (I can see no mechanism to discount an exponential fit of the July figures.)

Slightly off topic. Last year you did a post about the effect of rivers, at the time I thought you were overstating the case. But it looks pretty obvious this year.

Any bets that in time will be held responsible for more than 100% of the ice loss? That we will work out that without an anthropogenic influence the ice would have grown.

I didn't put in an estimate as I thought I had missed the boat and it had already happened.

My two estimates (er guesses) were significantly different, but fell in the same bracket. Originally I thought about 4.1, now almost 4.5

The Healy is rated at 4 foot continuous or eight foot back up and ramming. So if it maintaining a speed of more than three and a half knots that could suggest that the ice is less than four foot. Given the relatively direct couse there cannot be much ice over eight foot. On a side note The Russians will have effective controll of the Arctic given the disparity in availability of icebreakers.

Great job Nevin, assuming 100% coverage was reasonable until now, (or maybe last year) I had thought of it as an upcomming issue, but you have put much more thought into it. Tony