You may recall the guest post from Jeff Id of the Air Vent I carried about a week ago called Global Sea Ice Trend Since 1979 – surprising
In that post, a note of correction was issued because that we were led to believe (by Tamino) that the entire post was “invalidated” due to an error in accounting for ice area very near the pole. Both Jeff and I were roundly criticized for “not reading the documentation”, which was one of the more civil criticisms over there at Tamino’s site.
After further investigation It turns out that the error was in NSIDC’s public documentation, and they have issued a correction to it. Even more importantly the correction now affects NSIDC’s own trend graph, and they are considering how to handle it.
This episode illustrates how citizen science can be useful. Sometimes people too close to the science they publish can make mistakes, (we’ve all been there) which is why peer review of papers is important. But “web review” in this day and age of instant publication is equally important. It also illustrates how mistakes, however embarrassing initially, can be useful if you learn from them and study the cause. There is no shame in mistakes if they are corrected and you learn from them. But, the blogospheric noise of angry and sometimes juvenile criticism (on both sides) really isn’t useful as it often masks the real issue. The key is to put that aside and find the truth behind the error. Jeff has done that. His update follows below.
Merry Christmas to everyone! – Anthony
Based on The Air Vent post carried by Watts Up With That, the National Snow Ice Data Center has issued several corrections to the documentation of their sea ice area time series.Guest post by Jeff ID
Most will remember my earlier post which plotted global sea ice trends. After initially concluding that the global ice level wasn’t decreasing measurably Tamino pointed out a problem in my analysis. After issuing my corrections, thanks and apologies to Tamino and the um…..thousands of readers of Watts Up With That, I went back to work investigating what was really happening to the ice area time series.
It was actually quite lucky that Tamino mentioned the step in the data and criticized me for not reading carefully (something which was mentioned in several comments on the various threads). When I first learned of it, I found the criticism was based on an entirely different set of ice area data with different source documentation. Still, I checked closely and found the tiny step in the time series and was convinced that I had missed something. I had spent a huge amount of time learning the data before I made my post so it was frustrating to say the least. Understand, I used several resources to check my work; not the least of which was the National Snow Ice Data Center (NSIDC) anomaly graph which has the same shape as the one I generated.
The first graph below is from the NSIDC website, the second is my calc. Differences in the noise between the two are explained by the daily resolution used in my graph compared to what my eyes tell me must be monthly data for their plot. They also seem to have an additional year (2007) in their data plot which is not available in the bootstrap time series I used.
Read the rest click link below