Richard Alley, The Two-Mile Time Machine

Climate change: it feels not entirely unmanageable, doesn't it, if we think of it in terms of gradual change occurring across a span of decades, maybe generations. The oceans will rise by [x] centimetres by 2050 here in Victoria, but by a full [y] centimetres in Miami, and while that's big news, most of us will be dead or will have shifted residence a couple of times since then, Jeffersons-style.* There just has to be enough resilience and redundancy in the underlying system to let humanity survive this type of climate change with a pretty low ratio of cannibalism, or we would've been doomed multiple times in the past.

Which is why we need, so very much, books like Richard B. Alley's The Two-Mile Time Machine: Ice Cores, Abrupt Climate Change, and Our Future. We need to be much more afraid than we are, and Alley's book is very helpful in that respect.

I should say, first, that Alley's book is engrossingly and endearingly nerdy, in the way that it tries so very hard to be accessible to The Casual Reader. Not many casual readers are going to wade through lengthy explanations (even if in relatively accessible prose) of the history of the Antarctic ice-core drilling projects, or of the forms of mathematical analysis that allow for the interpretation of ice-bubble gas composition as representative of particular historical climatic conditions. One sentence at a time, it's a very helpful book to understand climate change and ice-core research, but overall it's an awful lot to take in.

But to business: How abrupt is the sub-titular "abrupt climate change" Alley's talking about? Well, that all depends, but the Antarctic ice-core data illustrates pretty conclusively that at least a few times, global temperatures increased by 5 to 10 degrees Celsius within a decade or two. The last ice age ended within three years. Climatic variability means that some places would have warmed by considerably less than that, but others would have warmed by considerably more: maybe 20 degrees Celsius.

Generally, it takes centuries for the gradual cooling to ratchet things back down again, and for sea-level to drop by the few metres by which it would almost certainly have risen.

If you've read this far into the post, you'll be nerdy enough to know already that all of human history -- well, the comfortable bits, anyway, since the invention and spread of agriculture -- has occurred within a period of relative climatic calm. If there's any native resilience in being human, it evolved to suit a change of a few degrees. Richard Alley, in The Two-Mile Time Machine, gives us a world that seems more likely to destroy us than to spur our creativity:
"the climate of the last few thousand years is about as good as it gets--most of the last 110,000 years have have involved larger, faster, more wide-spread climate changes." (p.192)
Good times.

It does give you perspective on those deadlines that zoom up at you.

* "Yeah, we're moving' on up
(Moving on up!)
To the East Side …."


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