1. Set up systems for mass migrations

Six degrees or warming will, to put it mildly, severely challenge the habitability of vast swathes of Earth, most of which are highly populated. As the local carrying capacity falters, tens or hundreds of millions of people will have to move.

This isn't a technical problem as much as a political one, as most nation states, including those which, like Japan, have demographic issues that would be helped by large-scale immigration, have during the late 20th century closed their frontiers to the kind of migration that global warming will induce.




2. Move and rebuild our breadbaskets

One of the most important achievements of the last couple of centuries is the global food trading network, which has made possible a world that, despite the unjustifiable continuation of hunger in some areas, is both more populous and better fed than at any other time in history.

The problem is that this network magnifies the impact of even local weather events, turning bad growing seasons in, say, the US, into high prices and social unrest half across the world. Six degrees of warming will basically wipe out globally important food growing areas, and unless we set up elsewhere the soil, water, and tehcnical infrastructure necessary to replace them, we might face global food shortages of a massive scale.

(As an aside, note that food "going local" is not an option; small, local food sources simply cannot sustain the species at our current population level.)

3. Pull our cities away from the shores, or vice versa

For good historical and technical reasons, many of the world's largest cities lie on sea shores, and for good physical reasons, many of them will not be able to stay there. Sea level rises compatible with six degrees of warming haven't been seen for millions of years, and many cities are going to have to be either rebuilt far away from where they are now, or massive systems of dams replicating the Dutch achievements of the last centuries are going to have to be set up to keep them from drowning.

All this, by the way, while more people than ever continue to flow into cities. Half of humankind lives on cities right now, and most people who doens't is expected to move in during the century.

4. Rebuild our energy systems

Did I mention that while all of this happens we will also need to figure out how to replace fossil fuels? Because if 6C looks like a disaster movie, it's nothing compared with what happens later if we don't replace fossil fuels. There's such a thing as too much climate disruption for our society to survive.


5. Deal with widespread health issues

What happens to life expectancies when what we call heath wave becomes mild summer?

We will have to make sure our public health systems are ready to cope with environments that are in many cases much less kind to human life than what they used to be.

6. Build infrastructures capable of dealing with "superstorms" as regular events

I'm writing this on the wake of "Superstorm Sandy," which briefly shut down New York. Assuming New York is still there by the end of the century (given the expected raise in sea levels, if it is, it will be behind a rather impressive series of dams), New Yorkers will look back fondly to such rare and mild events. Sea temperature is the main energy source for large storms, after all, and 6C of extra energy will... Well, I don't know what's scarier: that we will have to change our climate models to cope with what's going to happen, or that their current predictions are accurate.

* * *

These aren't problems I wanted the 21st century to have to deal with. They aren't issues of managing shiny hyper-technology or science pushing yet again the limits of what we thought possible. They are "mundane" problems of rebuilding cities, moving people, setting up infrastructure, and getting enough food for everybody, things that we thought the 20th century had more or less solved.

But we didn't solve, and, really, never even attempted to solve, the also ultimately mundane problem of maintaining global climate more or less the way we liked it, so now we have to deal with the fallout.

Let's just hope we prove better at dealing with the consequences of unattended threats than we were at dealing with threats themselves.