Arctic ice: what is “normal”?

Although I respect the expertise of Wadhams, a puzzling thing was the insistence that the downward trend since the measurements is necessarily “abnormal” and caused by our emissions. I have no problem accepting that he saw drastic changes in the Arctic concerning the height / volume of the polar cap during his long career and that this was the reason why he thought that the Arctic would be ice free soon.

For the record, I have no problem whatsoever believing that the Arctic underwent changes in the last 40-50 years. But logically, we only start measuring the ice of the poles since the end of the 1970s. If we only started to measure AFTER the supposed cause started, then logically what is the “normal” extent and volume of the Arctic?

Advertisement

An ice free Arctic: the shift from volume to extent to show the prediction still holds

Central in previous post were the predictions of an ice free Arctic by Peter Wadhams. While reading his predictions several things stood out. One of these things was that his early predictions seemed to refer to the diminishing volume over time (he referred to the PIOMAS volume data and/or the model of Maslowski that apparently showed a similar trend). However, in 2016 he referred to the diminishing extent to show that the prediction still holds.

That was rather puzzling. First, why change from volume to extent when confirming basically the same prediction? Second, when I first started looking into the global warming issue, an often heard argument from the alarmist side was that, even when the extent looked as it was stabilizing, it was the volume that was most important. This made it seem even more odd to me, that an alarmist prediction would go back to extent figures after relying on volume in the past. That is the reverse of what I expected.

The reason for this shift became clear when I found an explanation of what convinced Wadhams to make the 2015 prediction. It was explained as part of a rebuttal he wrote on March 7, 2012 (the second year that he made the 2015 prediction). Here is how he explained it (my emphasis):

An ice free Arctic: predict early, predict often

The “Arctic could become ice-free for the first time in more than 100,000 years, claims leading scientist”, that was the surprising title of an article from the Independent. That leading scientist is Peter Wadhams from the university of Cambridge and it was explained that satellite data showed there was just over 11.1 million km² of sea ice on June 1^st this year, compared to the average for the last 30 years of nearly 12.7 km². Therefor on track to be ice free this year (or next year) for the first time in more than 100,000 years.

That seemed odd to me. I didn’t know that June 1^st was such an important date for the Arctic sea ice. My take was that the most important moment was in September, when the extent of ice is at its smallest. When we look at the NSIDC data I indeed noticed that it is lower than usual. But prizes are awarded at the finish, not in the middle of the race and going from 11.1 to 1 million km² in roughly three months would require quite a steep drop. Not entirely impossible though, in 2012 ice extent dropped from 12.3 on June 1^st to 3.4 at its minimum, but then it has to deviate from its current course soon to get from 11.1 to 1 in the same time frame.

Reminder: things have (not) gotten much worse since An Inconvenient Truth

After writing previous post I bumped into the blog post titled: Reminder: Things Have Gotten Much Worse Since An Inconvenient Truth. As the title suggest, the post explains that things got worse after the movie “An Inconvenient Truth” came out in 2006. It starts with a fiery hot chart followed by a bold introduction (my emphasis):

In 2006, Al Gore’s An Inconvenient Truth spread the idea of human-caused climate change far and wide in what is now considered a watershed moment for the science. But today, on the ten-year anniversary of the film’s release, we’ve made little progress toward addressing the grave planetary concerns Gore raised. In fact, by practically every metric, things have gotten much worse.

Much worse? By practically every metric? That is interesting. There are many things that have been invalidated after the movie came out, like for example the melting of Kilimanjaro snow (which had nothing to do with global warming anyway and reversed), a 20 foot sea level rise (which is way off anything projected and reality), low-lying Pacific atolls will drown (rather unlikely because these are atolls, not islands), polar bear dying, hurricanes getting stronger (on the contrary), droughts getting worse, shutting down the ocean conveyor and so on. So, by practically every metric, really?