I’ve mentioned several times what I call the “Archer bonus” that we’re granting ourselves by artificially limiting our vision to what happens up to the year 2100. Archer is, of course, David Archer, author of the excellent book The Long Thaw. The bonus is 40%, as in 40% of the warming from our emissions up to 2100 won’t happen until after that date. Even if we somehow manage to restrain emissions enough to keep warming to 2C over pre-industrial times by 2100, that means we’ll have another 0.8C in the pipeline.

Personally, I don’t think our chances are good of keeping it under 2C, even before 2100. That’s not a comment born of Copenhagen disappointment, simply my assessment of our political realities–China and India valuing economic growth over emissions reductions, and the US being totally incapable of finding the political will to make the aggressive cuts needed to hit that goal. Another major factor is the steady thrum of bad news on the climate front, not least of which being the recent finding about the surge of methane emissions from the Arctic (see Another methane surge detected). It’s too soon to consider that “the” tipping point or the beginning of runaway warming or however else you want to cast it; but if it is the first step in a major methane ramp up, then there’s nothing we can do to stop it short of some very aggressive geoengineering steps. Simply cutting CO2 emissions won’t be enough, given all the warming already in the pipeline.

All of which brings me back to the question that prompted me to write this: Why are we so sanguine about this arbitrary selection of 2100 as the limit of our planning horizon? As best I can tell, no one seriously disputes the 40% bonus, yet I’ve seen practically no discussion (except for Archer’s book) about what comes after 2100. Are we being willfully blind to this nasty detail simply because including it would make the problem that much tougher to solve? Are we making implicit calculations that even our children will very likely have died before then, so it’s therefore acceptable for us not to care? Or is it yet another thing that got started arbitrarily and then became “the” standard metric for such discussions, only to soldier on, unchallenged?[1]

However it happened, I find it bizarre that so many people are so concerned about keeping warming under 2C by 2100, yet we all but fall mute once the discussion extends beyond that date.

Anyone here have the answer?

[1] I could easily imagine that we fell into the pattern of talking about what happens over the next century, and that morphed into the year 2100 roughly around the year 2000. Since then, it simply became convention and it stuck.


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