First, thank you Neven for practically immediately releasing my profile and welcoming me into the ASIF community. Also, thank you Archimid for starting this thread, and thank you Andre, Jim Hunt, jai mitchell, Jim Williams and oren, for your replies/comments.
Jim Williams, you ask: “OK...What is dangerous about it, and why should he [Ding et al] not make a dangerous argument?”
The argument that the demise of Arctic sea ice is in large part due to “natural climate variability” is dangerous because it feeds the rhetoric of the “merchants of doubt”, that climate change - as much as they accept that there is anything at all like climate change going on – is a “natural” phenomenon, etc. The ultimate conclusion of any such argument being that we don’t need to slow down or stop mining/extracting fossil carbon, and burning such fossil carbon and emitting GHG’s. In other words, let's keep the fossil carbon industry going.
Or, as jai mitchell put it in much better words than mine:
“… there are factions within the scientific community that work within the normal frameworks to provide contrarian views to reduce the mitigation imperative.”
Kevin Anderson and Glen Peters think along similar lines when they discuss the reliance of various emissions scenarios on negative emissions, the technology for which, as of March 2017, simply doesn’t exist. (see http://www.geoengineeringmonitor.org/2016/10/the-trouble-with-negative-emissions/
) Negative emissions are a neat doublethink-like trick to justify the convenient concept of a “carbon budget”, in other words, how much extra carbon we can still burn if we want to keep global warming under 2C.
Michael E. Mann has previously calculated that if we wanted to keep global warming under 2C, we would have to keep CO2 concentration under 450ppm; that was allowing for a 0.5C overshoot for a few decades, AND the widespread use of negative emission technologies after 2050. Without the widespread use of negative emission technologies after 2050, we would have to keep CO2 concentration under 405ppm. (see https://www.scientificamerican.com/article/earth-will-cross-the-climate-danger-threshold-by-2036/
We are already at 405ppm. In other words, without relying on negative emissions technologies that as of March 2017, do not exist, our “carbon budget” is zero.
We have to stop emitting GHG’s right now (the “mitigation imperative” that jai mitchell mentions). Bad news for fossil fuel companies? No, not really. Even the Paris agreement doesn’t consider the possibility of immediately implementing zero net emissions worldwide.
And, one can expect the next IPCC report to fully rely on emissions scenarios that include increasingly massive negative emissions beginning at around 2050. Are IPCC climate scientists – or even Michael Mann – going around claiming that the 2C limit is unrealistic? No they aren’t.
Similarly, the complete disappearance of Arctic sea ice – not only during summer, but year round – is by now totally inevitable in the space of a few decades, as one of the charts I posted in my first comment shows. Unfortunately, the argument made by Ding et al in their paper will lead to the following cynical discourse, which will be duly relayed to the general public by mainstream media:
But hey, if it’s due to “natural climate variability”, it has nothing to do with the fossil carbon industry, right?
And to all those who claimed that Arctic sea ice was “the canary in the mine” of climate change here is the news for you: Science says it ain’t so. The canary may be dying or have died, but it was from natural causes.
So, while we waste time discussing whether or not the paper by Ding et al is scientifically correct, "Bad Science" or just crap, or should have been worded differently, Arctic sea ice will continue to silently melt away and the fossil carbon industry will keep digging/extracting millions of tons of fossil carbon, to be released as GHG’s into the atmosphere.
Eric Steig, one of the authors of the paper, asks (thank you Jim Hunt for posting the exchange): “[Should we] Not [have] published the paper, lest we inadvertently help the “skeptics”?” The answer, imho, is pretty obvious.