In a recent post, after reviewing the extreme Arctic warming event of late 2015, Professor John Baez quotes an earlier interview with Dr Gregory Benford, who is arguing for a geoengineering effort to restore the frozen Arctic. I do not know whether that is a good idea or not. Surely, something like that appears to be needed, both because a disrupted Arctic appears to be affecting weather systems worldwide, and there is increasing danger of a shutdown of the AMOC, with evidence for a slowdown underway, in hand.

Dr Benford has some choice phrases, which I like very much. For example, he refers to our present time as the Decade of Dithering, and the upcoming decade, the 2020s, as the Deadly Twenties. In fact, he expects that once the Deadly Twenties get underway, people worldwide will be screaming for somebody to do something, and thinks that this will usher in large scale geoengineering experiments.

Of course, these are, in themselves, are dangerous, since it is very difficult to do a full and proper risk assessment. Also, professionally speaking, it is not clear to me how you construct an experiment to detect whether or not a particular intervention is working. It seems that it might need to run a long time. It’s also not clear how to detect unintended consequences. For example, when a new drug is tried in a cancer intervention, there are stopgaps for stopping the trial if it looks like the intervention is causing fatalities or serious side effects. I don’t know what the comparable stopgaps would be in a geoengineering experiment.

I also think this would need to be set up formally and properly, with a full design, having success or failure criteria defined, rigid, and not updated prior to the start. The design and process and conduct of said experiment should be thoroughly transparent.

It is extremely unfortunate that it has come to this. I daresay I doubt countries, governments, and the public have any capability to properly judge whether or not such a thing should be attempted, given that, it appears, for the most part they don’t get the basics of climate change physics.

Some of the other proposals Dr Benford suggests, such as enriching phytoplankton growth via iron fertilization, have been tried on a limited scale, and don’t seem to work. Part of the problem is that we don’t understand the life cycle of these plankton. The “cartoon version” says when they expire, their Carbon-laden bodies sink to the ocean floor, but the facts seem more complicated than that. In particular, it seems they are consumed on the way down, and the Carbon returned to the upper reaches of ocean, where it in principle is formed into CO₂ again, with potential for exchange with atmosphere.

These are not the kinds of things it’s advisable to proceed with a “Let’s try it and see what happens” attitude.

Simon Nicholson from the Forum for Climate Engineering Assessment has some additional thoughts: