Just as the end-Permian had been kicked off by the immense Siberian traps volcanism, so in the Eocene, volcanism had again, it seemed, been the trigger. Off the coast of Norway, in deep sediments under the ocean, lava had funneled up from deep magma chambers and seeped into the hydrate layers along the continental slopes. The lava hadn’t even broken the surface; this was minor as volcanic events go. But as the lava had dumped its heat, the icelike crystals that contained the gases had melted, and the lid had come off the hydrate deposits. We stared at images of layers of sediments that had collapsed over emptied-out hydrate layers, and at great vertical ruptures, the remains of conduits where the released gases had forced their way to the surface.
The methane had reached the ocean floor, bubbling up in immense spouts like the one that Tom had lived through, and causing, no doubt, plenty of local damage. But that was just the start.
Once the methane reached the ocean and the air there had been a complicated series of chemical reactions. The methane cheerfully reacted with oxygen, a process that itself released heat. The products of the reactions were more hydrocarbons, water — and carbon dioxide, gigatons of it, more greenhouse gas.
“And the rest,” Shelley said, “is history. The event wasn’t nearly so severe as the end-Permian catastrophe, because only a fraction of the global hydrate load was released. But it was a huge sloshing, a perturbation of the entire carbon pool of Earth’s surface. You can still see traces of it in isotopic imbalances and the like. Eventually the excess carbon dioxide was drawn back down out of the atmosphere by Earth’s systems — photosynthesis, weathering. But that took millennia, maybe megayears. And in the meantime there was a spike of warming.”
Sonia said, “So in the Eocene the trigger was this undersea volcanism. But in the present day—”
“In the present day,” Shelley said, “the trigger is anthropogenic global warming. Gea is right, as far as I can tell, Michael. The carbon dioxide and other crud we’ve dumped into the air has done the damage, more than enough to replicate the volcanic perturbations of the past. The anthropogenic warming of the climate we have already induced will cause the hydrate deposits to become unstable. At least we know what’s coming,” she said sepulchrally. “Different causes but same effects: the fossil record can teach us that much.”
Tom said, “And the timescale—”
“As Gea said,” Shelley told us. “A decade or less. In fact the destabilization is already happening — as you know.”
We let this sink in.
As she went about her self-appointed task of recording all this Sonia’s small face was pursed into a frown. The practical soldier was having some trouble with thinking about these huge scales in space and time, I thought. “OK,” she said. “So we can’t afford to let these hydrates go up. That’s the consensus, right? So what do we do about it?”
We all looked at each other warily. This was the crucial question — and the tricky part.
We were a guilt-ridden generation. President Amin and the Stewardship had taught us we had to change our ways; now we all lived a lot cleaner, and had stopped fouling the pond. But a legacy of the new thinking was that one of the worst insults was to be called an instrumentalist, in jargon that dated from Amin’s time: a meddler. To imagine that we could actively fix planet-sized problems seemed as hubristic and arrogant as the mind-sets that had got us into this mess in the first place. So to ask Sonia’s question — what do we do? — was to confront a modern taboo square in the face.
Shelley said reasonably, “Look at it this way. We don’t trust ourselves not to make a mess even worse. But those gas hydrates have no conscience, no soul, no sympathy; they will blow however we feel about it.”
Tom surprised me. “All right, so let’s play the instrumentalist game. If the crud we’re injecting into the atmosphere is going to cause the hydrates to tip over into instability, let’s just stop doing it.”
I caught Sonia’s eye and remembered her rules. I said, “What I like about that is that in the long term it has to be the right solution. To remove the root cause of a problem has to be a better strategy than to tinker with the symptoms.”
Tom said cautiously. “Let’s hear the but—”
“But it’s too late.”
Shelley backed me up.
We’d already done a great deal by eliminating most of the automobiles. But even if we shut down all the factories and power plants tomorrow, carbon dioxide would still be injected into the air from, for instance, rotting deposits on the dying seabeds. We were dealing with planet-sized systems; the vast inertia of Earth’s processes would ensure that the rise in carbon dioxide content continued to rise for decades, and the warming with it.
Sonia recorded all this. “So it won’t help if we stop putting the stuff into the air. Why don’t we try taking it out again?”
Shelley said, “That’s such a good idea that people are already doing it.”
It was true; there were “geoengineering” projects going on in various corners of the globe — tentative, deeply unfashionable. Most of them focused on modest efforts at what was called “carbon sequestration,” drawing down carbon dioxide from the air faster than natural processes could manage.
“So we just accelerate those programs,” Sonia said. “Maybe we should make the carbon dioxide snow out, like it does on Mars.”
That was one from left field, the kind of wacky idea that I imagined Sonia’s own process was supposed to generate. We played around with it a bit. The difficulty was that Mars is much colder than the Earth. You’d have to reduce the global temperatures to make carbon dioxide freeze, which was precisely the problem we were dealing with anyhow. Or maybe you could somehow tinker with the atmosphere, add some kind of freeze factor to the air… None of us knew enough chemistry to come up with a plausible way of making this happen.
Tom clasped his hands behind his head and sat back in his chair. “I hesitate to say this in front of an arch-instrumentalist like you, Dad, but maybe we’re thinking too big here. After all we aren’t interested in cooling down the whole damn planet. Just stabilizing the hydrate sediments would be enough — wouldn’t it? So why don’t we just think of a way to refrigerate the poles?”
Shelley said, “Actually there have been a lot of schemes proposed in the past for cooling down selected portions of the Earth’s surface.” She ran through this quickly, what she could remember or retrieve through her softscreen, and we chewed it over.
Most of these ideas involved shadowing a chunk of Earth’s surface, thus cutting it off from the sunlight. You could inject crud into the air, aerosols of various kinds to screen out the light. Or, even more simply, you could send fleets of planes over the poles dropping shards of some silvered material onto the ice or the water. If you made the material smart, we thought, you could make it self-assembling, a self-knitting, self-repairing mirrored cap. You could even program it to break up on command. It was quite a thought, to wrap a significant chunk of the world in silver foil.
Or, we thought, you could put some kind of solar-shield system into orbit. The Russians had played with this idea in the past. You would get a lot more control over the light you let through than with systems in the atmosphere or on the ground. For a few minutes Shelley and I disappeared into happy elaborations of this idea. You would be looking at a massive, unprecedented program of space launches, but we knew that if we turned our minds to it our Higgs-energy engines could fuel the booster fleet required. But the dynamics of positioning a shield so as to provide an effective screen to the poles would be tricky. The equator would be comparatively easy to protect; there you could throw your shield up to geosynchronous orbit where, orbiting once every twenty-four hours, it would seem to hover over a single point on the surface of the turning Earth. Geosynchronous wasn’t the only solution, though; Shelley dug up some esoteric material on complex orbital patterns the Russians had once used to provide twenty-four-hour comsat coverage to their scattered, far-from-the-equator domains.