When will Arctic ice be gone?

The short answer, before I give you all the qualifiers needed to make sense of it, is 2035, give or take 7 years.

The curve above will take some explaining. But first some other important clarifications:

Often, people don't distinguish between types of ice. So you'll hear them talk about 'ice is growing', when what they mean is the center of the Greenland ice cap, or Antarctic sea ice. My comment is specific to Arctic sea ice.

Another trap people fall in to is not paying attention to what sort of statement about ice is being made. There are two parts to this. I'm referring to sea ice extent, not area (well, at 0 extent you also have 0 area, but it's still something to keep in mind). Also, I'm referring to the monthly average for September. If some day showed zero ice cover before my 2035, give or take, that doesn't disprove the prediction. It takes a solid calendar month, September, of no ice to support or refute the prediction.

Then there's the fact that it's a probabilistic prediction.  2035 is the mid-point.  By my estimation method, there's about a 50% chance (54%) that 2035 or some year before that will show zero ice extent for September.  It's only 6% that we'd see zero ice in 2029 (or before) .  And rises to 96% that we'll see zero ice (for the month) in 2042 or before.  The 'or before' is important.

How I got to those predictions turns on the probability thing I mentioned in this year's sea ice estimation note, of it sometimes being easier to work with the probability of something not happening, than trying to figure out directly the chances of it happening.

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Sea Ice Estimations

It's time to start making our estimates of sea ice for September.  I'm submitting two this year to the Sea Ice Outlook, one based on a coupled air-sea-ice model, and one based on a more mature version of my statistical method from last year.  You can join the fun by submitting a guess in the poll I'll put at the bottom of the blog.  Remember, what we're trying to predict is the September monthly average extent.  This is not the minimum daily extent, nor is it the area of ice.  Keep your eye out for these details when comparing what different people say.

I'll start by summarizing predictors:

• Climatology 1979-2000: 7.03 million km^2
• Climatology 1979-2008: 6.67 million km^2
• Linear Trend 1979-2009: 5.37 million km^2
• Wu and Grumbine modeling: 5.13 million km^2
• Grumbine and Wu statistical ensemble: 4.78 million km^2
• Grumbine and Wu best fit statistical: 4.59 million km^2

In doing this year's estimates, I worked with Xingren Wu.  As usual, talking out ideas with somebody made them better.  That is part of why you see two statistical predictions.

The basis of the statistical prediction starts with my eyeball reaction to this figure (this particular copy is from Julienne Stroeve by way of the Weather Underground).  It is comparing IPCC model estimates of ice against observations:

My version for predictive purposes looks like this:

(vertical axis is September average extent in million km^2; the red/orange are observations, blue is the best fit curve.)

So what's going on?

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Science and health

Ordinarily a subject line like 'science and health' would be followed with a note about how science was doing good things for health, or how we understood more about health because of some recent research. Instead, it's time for some reflections about looking from a scientific perspective at health issues that you might have.  Two things prompt this.  One, you're unsurprised to hear, is that I'm having a nuisance that has contributed to not being here.  The other was email I received recently about running with diabetes.  On the latter, it's important to note that you can run with diabetes.  You have to be more thoughtful and attentive about it than the usual beginner.  But it can be done.  That article was written by a runner with diabetes (Rob Carr).  The diabetes prompting him to start the running.

Whatever is at hand, you rapidly get taken to a chance to think scientifically.  My take being, remember, that science is about understanding the natural world.  Your body is a pretty important part of your natural world.  A different aspect of the consideration is that I think science, and thinking scientifically, enrich your life.  At least it does mine, and I think it's for reasons you can share.

I confess at the moment one of the attractions of the science is distraction from my body.  What happened is that I caught something in my eye.  Blown hard enough that it scratched the cornea.  It turns out that a scratched cornea is very painful, so looking at the anatomy and physiology of the eye is helpful for distracting me from that.  (Seriously: One thing that helps with pain management is aiming your attention hard on something else -- reading books, knitting, your left big toe (assuming that the pain is somewhere else, maybe the right.))

It turns out that there is very little guidance on exercising with diabetes.  So you have to do your own experimentation to understand what's going on and what you need to do, what you can get away with doing, and what you definitely cannot do.  It's imperative because exercise is an important part of managing diabetes, particularly adult-onset diabetes.

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Still kicking

Didn't mean to disappear and no, no problems were involved.  Just doing other things and didn't realize how much time was passing here.  One of those other things was making progress on my running.  Last week I reached 30 minutes straight running, having started with 1 minute run 1 minute walk in February.  Well, starting with physical therapy in January.

There are quite a few comments in the queue.  If you haven't seen yours, it should be coming up soon(ish).  Keep an eye at the 'most recent comments' section at the bottom. 

One of the things that brought my attention back to the blogosphere was an email from Coby Beck, who had mentioned my Does CO2 correlate with temperature?.  There was an interesting (to me at least) question from 'maxwell' which gave me the opportunity to mention a blog post a commentor to my article had made, and a professional article: David J. Thomson's Dependence of global temperatures on atmospheric CO2 and solar irradiance, PNAS, 94, 8370-8377, 1997.  My examination was intentionally pretty simple.  See Thomson for what it looks like when done professionally.  You might enjoy some of the comments in the thread at Coby's.  And, if you haven't already been doing so, take a look at his blog.

Solar Science and Solar Cycle 24

Time for the sun!  Coincidence had a question about solar cycle 24 (what is it, how long are they) hitting my email box the day before I ran in to an astronomer friend who is working with the recently-launched solar dynamics observatory.

For the first, the obvious answer is the correct -- this is the 24th time since records started that the solar cycle has been on the increase.  'solar cycle increase' meaning, in part, the sunspot counts are increasing.  But the sun does a lot more than just get spots.  The Space Weather Prediction Center keeps an eye on the sun, including these other things (go have a look, see the sun as if you had x-ray vision!).  And, naturally, tries to predict things that are influenced by solar activity.  The cycles average something like 11 years, but vary greatly from cycle to cycle (8-15 years).  The activity minimum we are now leaving was unusually deep and unusually long.

On the second, I'll mention that he (William Bridgman) blogs at Dealing with creationism in astronomy.  An article that I'll be taking a look at, and encourage the more technical readers to do likewise, is his The Cosmos in Your Pocket: How Cosmological Science Became Earth Technology. I 
Here's his abstract:
Astronomy provides a laboratory for extreme physics, a window into environments at extremes of distance, temperature and density that often can't be reproduced in Earth laboratories, or at least not right away. A surprising amount of the science we understand today started out as solutions to problems in astronomy. Some of this science was key in the development of many technologies which we enjoy today. This paper describes some of these connections between astronomy and technology and their history.