Since the inception of this blog in 2010 a small community has developed of people who are interested in everything concerning Arctic sea ice and the science surrounding it. Though not climate scientists, a lot of these people have certain skills due to their work or education, and so it was hardly surprising that several of them, including myself, started playing around with data and make graphs based on them.
A couple of days ago an article on the BBC website appeared that discusses geoengineering to stave off a possible major methane release (we discussed this here). Based on written evidence by professor Peter Wadhams and the Arctic Methane Emergency Group for the Environmental Audit Committee of the British House of Commons that was published on February 24th (followed by oral evidence as delivered on February 21st, and published on March 8th), this graph appeared in the article:In the bottom right corner there was a caption saying 'PIOMAS project' (it has now been removed). Unfortunately the graph had nothing to do at all with PIOMAS or the Polar Science Center or its scientists, who decided to provide the data after popular request. The graph is made and regularly updated by ASI blog commenter Wipneus, who has a collection of graphs based on PIOMAS data and other sources on his ArctischePinguin site.
There are two things I'd like to make clear with regards to this:
1) Although professor Wadhams and AMEG did refer to the images' web links in the reference list of their written evidence, I hope that from now on they will make it more clear that these graphs come from a blog, not from research papers or scientific presentations. And that they are made by a community of people who like to speculate about what is going to happen to Arctic sea ice in the short and long term. Not because I view these graphs as copywritten material or feel that the ASI blog and its community deserve their dues, but because I don't want this to turn into a strawman used to smear scientists when the Arctic becomes virtually ice-free (below 1 million square km at the end of the melting season) later than the extrapolated exponential curves suggest.
If this isn't made clear from the onset, the media (even the BBC's excellent reporters) run off with it, leaving the wrong impression on readers. The situation in the Arctic is serious enough as it is, and so there is absolutely no need for 'embellishments' that could eventually backfire and be used by people and organisations who still have an urgent need to deny the existence or potential seriousness of Anthropogenic Global Warming.
2) The second thing that should be clear, is the caveat that should accompany these graphs. It is worded perfectly by FrankD in a comment on the Stoat blog:
The graph that has been used here emerged from a long-running and free-wheeling discussion at Neven's Arctic Sea Ice blog, which began a year ago with (in effect): Exponential fits past data better than linear, but are there better fits again? (and there were).
All (or at least most of) the participants in those discussions were well aware that it was a curve-fitting exercise, with little physics involved, although proponents of one or other curve would usually have some physical basis for their choice. But no "serious" claim was intended beyond saying that exponential and Gompertz curves fit past data better than the linear trend (published on the PIOMAS anomaly graph).
However interesting it is as a statistical exercise, extrapolating trends based on past data into the future does not mean much by itself. Past performance is no guarantee of future results, especially in relation to the Arctic sea ice. Which is why this graph on the top of Wipneus' PIOMAS-page is my favourite, as it shows all the different outcomes of different statistical approaches: