Graph Of The Year - PIOMAS Yearly Minimum Arctic Ice Volume

[hatrack]

I saw two particularly depressing trend lines this week. Both were confronting enough to make me stop, sit back and just contemplate. It was not as though these came as a great surprise — I’d been following these data for years. But for some reason, the seriousness of them really struck home like never before.

The first was a report on Arctic sea ice volume. Here is the graph that shocked me:



It shows the minimum northern hemisphere sea ice volume yearly from 1979 to 2011, and a simple time-series forecast based on a fit of the exponential-decline model. You can read about the details here: PIOMAS September 2011 (volume record lower still), where various related charts are also shown. One can argue about the precision of the projection line, but the general fit is remarkably robust and, on this basis, it is reasonable to conclude that unless some remarkable turn around occurs, the Arctic summer ice volume will be near-zero by 2020.

One explanation for this greater-than-expected decline is given in this new paper in Journal of Geophysical Research. Rampal et al. show that as the ice thins, it drifts more — increasing ‘export’ of ice to lower latitudes and accelerating melting. This may also explain the deviations seen between sea-ice extent (see left chart) and volume (both are bad, but volume is looking worse). Perhaps the gaps between small aggregations of ice are not showing up in the satellite data, with the mushy residual ice spreading out evenly to close gaps, thus appearing to maintain or even increase its extent, especially as the thinning summer ice becomes more ever more vulnerable to wind dispersion. As we approach zero volume, we will obviously get a clearer picture on positive feedbacks, but all that we can be sure of for now is that we are entering unknown territory.

The second depressing trend that disturbed me was the latest global carbon dioxide emissions data. The core problem is summarised here: "The world pumped about 512 million tonnes more of carbon into the air last year than it did in 2009, an increase of 6 per cent. That amount of extra pollution eclipses the individual emissions of all but three countries – China, the US and India, the world’s top producers of greenhouse gases."

EDIT

http://bravenewclimate.com/2011/11/06/depressing-climate-trends/

[izquierdista]

1. Somebody needs to work on their math skills

A 95% confidence interval with 33 points shouldn't have 3 outliers with a fourth on the line. But even a small correction in the math is not going to change the prediction of an ice-free arctic much sooner than has been predicted elsewhere.

[XemaSab]

2. 2020? I'm reading that graph slightly differently...

[pscot]

3. It may be time to retire

the "greater/sooner than expected" meme.

[XemaSab]

4. The hell you say!

:o

[pscot]

5. You get a dispensation

:P

[XemaSab]

7. Thank you

:D

[hatrack]

6. Oh, come on! That's like saying Grovel-Bot should ride off into the sunset . . . .

Oh, wait . . .

:hi: