Crude oil in the gulf yields good TV images, but BP and its contractors have untapped a geyser not only of oil, but of methane--more than 20 time as effective as CO2 at holding heat. The percentage of the gush that's methane is roughly estimated at 40-50%, subject to verification.
While oil fouls the shoreline, coats birds, creates a slick bigger than whole states as well as forming in plumes and perhaps on the bottom in pools, the methane initially dissolves in seawater and, to the extent that it bubbles into the air, would be invisible.
But whatever harm is done by methane from this one well, apart from the explosion on April 20, the constant flow since then reminds us that methane from many sources is definitely reaching the air.
Most of the attention of environmentalists has focused on CO2 because that's what humans can, in theory, do something about, by reducing sharply the amount of fossil fuels we burn. By contrast, much methane comes from livestock guts, garbage dumps, other plant decay (such as rice plants), and microorganisms. Its release is not directly anthropogenic, except that it's we who eat livestock and rice, and make garbage.
However, as the planet warms from other causes, such as coal-fired power plants and internal combustion vehicles, it triggers release of methane from marginally frozen tundra, for example. (The difference between ice and water can be as little as part of a degree.)This melting can set up a dangerous positive feedback loop, as the methane released further heats the planet and melts a bit more tundra.
Nobody knows when the tipping point would be reached. If it nearly were reached, the only possible response would be geo-engineering (human manipulation of the climate). This could cost much less than cutting CO2 emissions. The only problems are that it might not work, it would almost surely have unintended negative consequences, it would remedy only some of the problems caused by greenhouse gases, we have no regime for doing it, liability remains wholly unclear, and once begun we'd have to keep doing it.
Nonetheless, while focused on one set of awkward problems, such as the current undersea oil geyser, we are so far not cutting emissions (except by unwanted economic slowdown) and we have no clear way of knowing when we are about to reach a tipping point. So another problem with geo-engineering is that we wouldn't know when to act.
The big questions are these:
Are we willing to take the risks of continuing to spew CO2 from a civilization heavily based on fossil fuels, or can we live with a substantially reduced amount of these energy sources? If the latter, how do we arrange a cutback that's necessarily global? And if so, how do we get as much relatively safe energy end-uses as possible, especially during a transition?
These questions are much larger by orders of magnitude than the drama in the gulf, however disastrous that turns out to be. The drama, however, may do what mere scientific findings have not. The prospect of a runaway feedback loop involving methane may play a crucial role. If so, thanks to the other half of the geyser for a reminder.