Monday, June 25, 2007

Slightly-fresher lake chronicles

So I finally read Hansen et al's article which I asked for last week. (Oh, readers, how I appreciate you so.) Hansen argues that we're much closer to a climate disaster than, for example, the IPCC. Basically, the IPCC doesn't take in to account the latest understandings of ice-sheet collapse, which seriously affects their estimates of sea-level rise. Hansen, on the other hand, relies on the historical data: the last time the temperature of the Earth was where it's headed if we don't change course the sea level was at least 45 feet higher, and may have been as much as 90 feet higher. My understanding is that for anything more than 15 metres of sea-level rise we'd have to melt East Antarctica (which so far seems stable, praise Buddha) but just melting Greenland and Antarctica would be more than enough to, uh, destroy the global economy.

To take my favorite example, global container shipping requires massive, specialized ports which a) require billions of dollars of investment, and b) are (duh) all built at the current sea level. It wouldn't take anything close to the 15-metre rise that Hansen is worrying about to make global shipping a total mess. And ask yourself: what happens when we can't get anything from China anymore?

The IPCC has downplayed the threat of sea level rise, and it kind of went out of the headlines for a while. But it is the single biggest economic threat posed by climate change -- global infrastructure at risk measures in the tens of trillions of dollars, and the global population at risk, directly and not, measures in the billions of people.

The key to worry about here is positive feedback: the Earth has, historically, warmed up very quickly and taken much, much, much, much, much longer to cool off. A warming phase might only last centuries, or even decades, but the cooling phases last millennia. The reason for this is simple: all the mechanisms to cool the planet off (and there are many) operate on much slower cycles than the mechanisms that exacerbate warming. The natural process for sequestering CO2 in ocean sediments, for example, is much slower than the ice/water albedo flip, where liquid water retains 90% of the energy it absorbs when, as ice, it would have reflected 90% of the energy away.

So if we get to the point where the Arctic is ice-free in the summer, the Greenland ice sheet is probably doomed. A Greenland that is surrounded by a liquid ocean is going to be a Greenland that is bathing in much warmer water than can support the ice sheet, and the collapse (while it won't be "fast" by human terms) will probably be unavoidable at that point.

There are some extremely speculative ways we might avoid disaster if faced with rapid sea-level rise. The weirdest one is simply pumping the water in to high basins -- the Taklamakan desert in China, for example. This would basically abandon any idea of "fighting" climate change, though -- the creation of a new, inland Mediterranean in North Asia most certainly qualifies as catastrophic climate change. And I'd hate to think of the energy bill to move all that salt water. So basically, the best option for dealing with sea level rise is to stop it before it starts.

6 comments:

Closet Liberal said...

Re-work the plan to pump the water into Death
Valley
to recreate Lake Manly

That'll get the attention of a lot of people.

But it probably would be argued, we're turning a "useless desert" into a "useful resource" and returning to the "natural balance" created 22,000 years ago.....

ADHR said...

I'm missing something. Why wouldn't we expect the large industries that depend on shipping to invest in building new equipment in whatever new ports come into existence?

john said...

"Why wouldn't we expect the large industries that depend on shipping to invest in building new equipment in whatever new ports come into existence?"

Two main reasons. One is the simple scale of the new construction -- rebuilding new ports would require huge amounts of land, capital, and political will (people who lived on the new shorelines would have to be moved, etc.)

The second is that in the worst-case scenario (which is what we're talking about, really) there would be a substantial window between the time sea level rise made the old ports obsolete/submerged, and the time that sea level rise actually stopped. For example (number pulled from ether) a port would probably be useless under more than a meter of water, but if the sea level rises another two meters after that, it would presumably be decades before the shore stopped receding. Certainly, nobody would want to rebuild their ports a third time, so the smart money would be to wait until sea level rise was arrested, one way or the other.

ADHR said...

Not sure I buy the first point. After all, we're talking about multiple multi-billion dollar corporations who rely on the well-functioning of these ports. Unless they want their profits to vanish, they will, eventually, invest to rebuild the ports -- whether it's directly or through some sort of P3.

The latter is a fair point. You wouldn't want to build a new port every five years or something. (Unless we could put the port on wheels....)

Wouldn't countries like the US and Canada, who do a lot of land-based trade, be less affected by this sort of problem than countries (like, say, the UK) heavily-dependent on sea trade?

john said...

"Wouldn't countries like the US and Canada, who do a lot of land-based trade, be less affected by this sort of problem than countries (like, say, the UK) heavily-dependent on sea trade?"

Presumably, yes. But you'd have some sectors that would basically face disaster (toys, clothing, anything else from China) while other sectors would be unable to export their surpluses (US cars, car parts, and food especially.) Meanwhile, the contraction in US oil supplies when coastal terminals stop working would throw the whole continent in to recession.

In short, even more insulated countries like the US and Canada would face a disaster.

Closet Liberal said...

This port issue is an interesting one. The gov of Canada has an impact map showing expected sea level rise on our coasts.

For safe investments, the Great Lakes will remain safe ports for container shipping. Especially ports on Lake Ontario. The west coast's vulnerability could be ameliorated by proper planning, as there are "low" impact zones.

I expect other mountainous coastlines and/or inland lakes and seas would also provide safe harbors for worldwide shipping. Of course the movement of the supporting staff, rail lines, highways and other infrastructure could prove an insurmountable challenge for some ares. Just because a shore is accessible from sea, does not mean it is easily accessible from inland.

I am still struck by the lack of excitement over this issue. You would think the potential flooding of many of the worlds major cities would be provoking action on many fronts. It seems by the lack of information that we still haven't learned our lessons from the New Orleans sea level management fiasco.