It is time to stop quivering in our boots in pointless fear of the future and just roll up our sleeves and build it.
- Ray Pierrehumbert

Tuesday, September 1, 2009

Ice and Fire

Perhaps the most fraught ethical question in the whole sustainability universe is our obligation to the deep future. Specifically, the question of whether, if we could obtain substantial certainty that our present actions would have significant consequences in the deep future, whether we have any obligation to prevent such an outcome.

As David Archer often points out when he raises this question, people do weigh such questions in deciiding on the ethics of nuclear power, but they don't do so in considering the ethics of carbon releases.

Methane clathrate is a form of water ice that contains a significant fraction of methane molecules caged in the ice crytal mesh. It is unstable at standard pressure and evanesces gradually, but it has the eye catching property that it's flammable. It forms under pressure at low temperatures. At some locations on the sea floor, naturally occurring carbon rain from detritus of plankton and similar life forms decays, producing methane, which creates the conditions for formation of clathrate.

Some of the clathrate may be economically recoverable, and as such may be considered as part of the potential reserves of natural gas. Because methane has 20 times the global wamring potential (more or less) of carbon dioxide, a large release of methane could be a serious matter. A methane release from clathrates is still, as far as I know, a leading candidate for the cause of the Paleocene-Eocene Thermal Maximum of 55,000,000 (error fixed, thanks Penguin) years ago, the previous really drastic global warming event, in which humans obviously played no role.

How did the world suddenly contrive to release all its clathrates? It might have a consequence of some other warming trend, which propagated warm temperatures to the ocean depths, perhaps destabilizing the clathrates. Wikipedia quotes estimates of 1500 Gt carbon released, about triple anthropogenic emissions to date. The extent to which this forcing was multiplied by the extra global warming potential due to the carbon being in methane form depends on the time period over which the release took place.

Archer and Buffet 2004 looked at the global inventory of sea-floor methane and came up with a total on the order of 2000 Gt, about equivalent to economically viable fossil fuel deposits today.

Presuming that most of the clathrate is not economically recoverable, Archer & Buffet argue that the anthropogenic warm signal will propagate down to the depth (below the sea floor) of the clathrates, causing a significant release in the distant future creating a second global warming crisis, that one of longer duration than the one we are now so eager to precipitate.

I know that David was trying to get this work published for quite a while, with a baffling lack of success. I suppose that predictions on a time scale much longer thna a human lifespan are arguably not testable.

Therefore the most salient quote I found remains this abstract from an AGU presentation:
Mechanistic models for the distribution of methane clathrate in marine sediments predict a steady-state inventory of 5000 Gton C. These models also predict a strong sensitivity to changes in ocean temperature. Increasing the ocean temperature by 1.5° C is expected to decrease the steady-state inventory by roughly a factor of 2. The time scale for adjustment to a new steady state is not well known. However, we can parameterize the time-dependent behavior using first-order rate constants. Methane accumulation is expected to occur on time scales of several million years, whereas methane release could be comparatively fast. We calculate the rate of methane release by dividing the clathrate reservoir into fast and slow parts. The fast part responds through slumping of continental margins, whereas the slow part responds by diffusion and oxidation of methane below the seafloor. The evolution of the clathrate reservoir through geologic time is sensitive to the choice of rate constants. When the time scale for the fast part is too short, runaway melting is caused by the positive feedback from radiative forcing (assuming CH4 has oxidized to CO2). Thus the existence of the present-day inventory imposes a constraint on the rate of release. The time scale for accumulation must by greater 5 Myr to avoid unrealistic fluctuations in δ13C during glacial cycles, but shorter than 10 Myr to allow the clathrate reservoir to build up during the geologically recent cooling. The constrained model predicts a methane release of 200 GTon C or less on deglaciations. Future methane releases of 2000--4000 GTon C are expected in response to a 2000 GTon C anthropogenic carbon release. Anthropogenic climate change differs from deglaciations in that it warms the ocean to temperature not seen in millions of years.
Emphasis added.

So this raises an ethical question which economics will "discount" to zero, and which I have trouble accepting as having zero value. Presuming the Archer/Buffett work holds water, what are our ethical responsibilities to the distant future?

Update Sept 3: Alex Steffen takes on the question at WorldChanging . It's short and I'm tempted to paste the whole thing, but Alex deserves the hits. Here are my favorite bits:
Think of this example: If someone set a bomb to go off in a public square 100 years from now, is he committing a crime? Should he be stopped? Almost everyone would say yes. Should he be tried before a court of law and prevented from doing further harm? Most of us would agree that he should.

Now, here's the tricky part: climate change is the bomb, and your great-grandkids are the victims.

...

Put it another way: ethically, our riches are not our own. We hold the planet in trust, and as long as we don't use more of the planet's bounty than can be sustainably provided in perpetuity, we have the ethical right to enjoy the best lives we can create. But the minute we stray into unsustainable levels of consumption, we're not in fact spending our own riches, but those of future people, by setting in motion slow-fuse disasters that will greatly diminish their possibilities.


Unfortunately, nearly everyone in the developed world now enriches their lives at the cost of future generations. As Paul Hawken says, “We have an economy where we steal the future, sell it in the present, and call it G.D.P."
--
Burning ice image via PinkTentacle probably from Asahi.com

12 comments:

Penguindreams said...

Typo: PETM was 55 Mya, not 65. 65 Mya was the Cretaceous-Tertiary boundary, not the Paleocene-Eocene.

Lou Grinzo said...

Speaking as an economist, I don't see this as an issue of ethics, but a purely pragmatic one. I don't distinguish between something awful happening to me or it happening to one of my nieces or to one of the children they'll have years from now. Catastrophic impacts from global climate change are so bad that the traditional discounting methods don't apply.

On a more basic level, the Arctic Carbon Issue scares me spitless. Between the methane deposits and the 1.6 trillion tons of carbon in permafrost, we're sitting on one heck of a keg of climate dynamite, one that we're getting dangerously close to setting off with our emissions. The conspicuous rise in atmospheric methane levels since late 2006 is very unnerving. As I've said repeatedly over on The Cost of Energy, it could be nothing more than another multi-year run-up, as we've seen in the recent past, or it could be the first indication that the mother of all feedbacks is beginning.

Steve Bloom said...

The answers may not alter the ethics, but 2k GT C relates to what level of CO2 and how far in the future would the associated clathrate release be?

There's also the parallel although presumably smaller-scale issue of methane release due to rapid permafrost loss.

Also see this press release on a recent paper finding that the current deglaciation didn't see a significant clathrate release.

Steve Bloom said...

See also this press release on a recent study showing the available supply of permafrost methane to be about 1500 gigatons.

Martin said...

I agree that this is a pragmatic issue. Discounting reflects not so much that some bad event far in the future would be "less bad", but rather that we have time to build up resources that will come in handy to prevent it from happening. E.g., means of pulling down already released CO2.

My real worries are 1) that we won't have that time; here's to hoping that this is indeed a deep-future threat. And 2) that the ongoing stupidity of not believing doggy bites until bitten, will perpetuate.

Dano said...

IMHO (and evolutionary psychologists' HOs), we are not wired for this type of thought.

Which is why we have constructs such as ethics and morals and so on, and we are back to how do we get folk to adopt this 'future-oriented' or 'other-regarding' ethic.

As an undergrad we had a good chunk of a quarter reading about this stuff, and I got rid of the texts but perhaps I should see if the GF still has them...

Best,

D

Dano said...

Perfect!

This is a passage from Resilience Science blog, posting about Ian McEwan's new novel about climate change:

"These eminent inhabitants of the Cape Farewell project’s vessel the Noorderlicht began to decline into a kind of genteel chaos. Someone mislaid his boots and, not wishing to delay the departure of a party itching to head out on an exploration, grabbed the nearest pair of a similar size he could find. A domino-effect of similar “borrowings” ensued. Good people, McEwan wrote at the Time (this was March 2005), were impelled to take what was not their own: “With the eighth Commandment broken, the social contract is ruptured too. No one is behaving particularly badly, and certainly everybody is being, in the immediate circumstances, entirely rational, but by the third day, the boot room is a wasteland of broken dreams.”

“I thought ‘well, this is a highly self-selected group of climate change people’,” he says now. “In the evenings we were discussing how to save the planet, and a few feet away through a bulkhead was this utter chaos! And I thought ‘that’s perfect, that’s the human angle on this that I want’. If one thinks of literature and novels in particular as investigations of human nature, then human nature suddenly became at the centre of our problem about climate change: that we’re sort of cooperative but selfish, we’re not used to thinking in long-term eras beyond our own lifespans or immediate spans of interest."

Fire and ice.

Best,

D

David B. Benson said...

An infinite future disutility remains infinite in the present under any (finite) discount rate.

Michael Tobis said...

David, that may well be part of the problem.

As I understand it, conventional economics does not place any value at all on natural capital, never mind an infinite one.

the_heat_is_on said...

@Lou Grinzo,
I'm also concerned about the Arctic because it concentrates 3 big feedbacks in a (relatively) small area:
- The methane deposits in the ocean floor.
- The carbon stored in permafrost.
- The albedo effect of ice.
I'd really prefer to be in denial than knowing about the consequences of pulling the trigger on one or more of these feedbacks.

the_heat_is_on said...
This comment has been removed by a blog administrator.
David B. Benson said...

Michael Tobis --- Then conventional economics is psychopathically deranged. Surely terminating H. sapiens has an infinite disutility.