One of the more disturbing pieces of news recently is that the Thwaite glacier is melting, and a lump of ice of area the size of Uruguay and of uncertain thickness will slide off the West Antarctic land mass and fall into the sea over the next couple of hundred years, thus raising the world sea levels by something like 3 - 4 meters. The problem is, it is melting from below, thanks to ocean warming. This, of course, is probably not the only ice sheet under threat, so serious sea level rising must be expected unless we do something to counter it. Before going further, however, it is important to note that the oceans are warming, specifically with an average net power input of 0.64 W/m^2 (Lyman, J. M. and 7 others, 2010. Nature 465:334-337.)
 
That raises the question, what can we do? One thing is very clear: raising carbon taxes or introducing emissions trading certificates is not going to do anything to stop this, although it will presumably raise government revenue, and/or traders' revenues. The fact is, if we stopped burning carbon today, the CO₂ levels would remain at about 400 ppm for a century or so, and the present net heating of the ocean would continue over that time. Since we currently burn about 9 Gt of carbon per year from fossil sources, minor cutbacks simply will not achieve anything of value. Then there is the question of whether any cutbacks are practical. There have been plenty of earnest pledges over the past two decades, but emissions have actually increased.
 
So, what can we try? I do not know. Like many people, I have some rough ideas, but I have no idea whether they would work. In this context, I am reminded of a statement by General Wesley Clark on strategy, which was something like this. There are two sorts of plans: those that won't work and those that might work. You must take one that might work and make it work. The question now is, are there any that might work, or are the changes inevitable? I am optimistic that there are probably plans that might work, but how do we go about considering them?
 
Time to get unpopular! What I have noticed is that we are spending quite large sums of money measuring various emissions. I think much of this work could cease, because we have reached the point where we know more or less what is happening, and further such spending will not make any difference to our future, other than to make us more gloomy. Instead, that money should be redirected towards action that might make our future better.
 
The issue as far as sea level rising is very simple. There are two options only to prevent it. The first is to ensure that the rate of permanent snow deposition is equal to or exceeds the rate of ice melting. If we manage that, sea level stays constant because there is no net inflow of water. In practice, that means generating increased snow deposits in Antarctica and Greenland. The second is to ensure that the oceans receive a net negative power input for some period until balance is restored. Note that neither of these options directly affects carbon emissions. Are either of these options possible? In theory, yes, but in practice, I do not know. They require serious geoengineering. We can come up with plausible physical processes that may or may not work, but even if they do work, the costs and the secondary consequences are unclear. The political problems are enormous, and may be insurmountable because changing climate on this sort of scale will seriously disadvantage some. But failure to do anything will seriously disadvantage all coastal cities, all coastal farms, at least a third of Bangla Desh, and probably everyone from grossly enhanced storms. So, what should we do? Your thoughts, please.