It’s that time of year again, time to submit forecasts of this year’s upcoming September Arctic sea ice extent to ARCUS.
I don’t intend to submit a forecast (except here on my blog). But I thought this would be a good time to re-iterate my forecast, and add another, which turns out to be not substantially different.
The “original” forecast method is quite simple: fit a quadratic to September Arctic sea ice extent data from NSIDC and extrapolate that one year into the future. Use the standard deviation of the residuals to define a 2-sigma error range. That gives a forecast of 4.15 +/- 0.98 million km^2.
I also have a modified version of the lowess smooth, which I can use to estimate future values as well. That gives a forecast of 4.13 +/- 0.96 million km^2. As you can see, the two methods make essentially the same prediction.
Note that these forecasts are based on historical data from NSIDC, so should be compared to actual NSIDC figures after nature reveals the answer.
Note also that the uncertainty level is substantial. The range by method 1 is from 3.17 to 5.13 million km^2, by method 2 from 3.17 to 5.09 million km^2.
And for those who like graphs, here’s the September data from NSIDC together with the forecasts: