Earth-shaking gas from the center of the earth
From three fronts the enemies assail
Not far from the age of the great millennium
The brilliance of the translator will come to fail
Levels are increasing again since 2006, but at a steady rate like CO2, not a bomb.
Is now the time to get frightened?
No. CO2 is plenty to be frightened of, while methane is frosting on the cake. Imagine you are in a Toyota on the highway at 60 miles per hour approaching stopped traffic, and you find that the brake pedal is broken. This is CO2. Then you figure out that the accelerator has also jammed, so that by the time you hit the truck in front of you, you will be going 90 miles per hour instead of 60. This is methane. Is now the time to get worried? No, you should already have been worried by the broken brake pedal. Methane sells newspapers, but it’s not the big story, nor does it look to be a game changer to the big story, which is CO2.
Could this be the first modest sprout of what will grow into a huge carbon feedback in the future? It is possible, but two things should be kept in mind. One is that there’s no reason to fixate on methane in particular. Methane is a transient gas in the atmosphere, while CO2 essentially accumulates in the atmosphere / ocean carbon cycle, so in the end the climate forcing from the accumulating CO2 that methane oxidizes into may be as important as the transient concentration of methane itself. The other thing to remember is that there’s no reason to fixate on methane hydrates in particular, as opposed to the carbon stored in peats in Arctic permafrosts for example. Peats take time to degrade but hydrate also takes time to melt, limited by heat transport. They don’t generally explode instantaneously.
For methane to be a game-changer in the future of Earth’s climate, it would have to degas to the atmosphere catastrophically, on a time scale that is faster than the decadal lifetime of methane in the air. So far no one has seen or proposed a mechanism to make that happen.
As the threat of global warming grows more urgent, a few scientists are considering radical—and possibly extremely dangerous—schemes for reengineering the climate by brute force. Their ideas are technologically plausible and quite cheap. So cheap, in fact, that a rich and committed environmentalist could act on them tomorrow. And that’s the scariest part.
If you look at the most recent report of the International Energy Agency, the 2011 World Energy Outlook, they lay out a policy pathway for their 450ppm scenario - the scenario which they say equates to a 50/50 chance of keeping global climate change below 2 degrees C. Their policies define a pathway to 2020 based on carbon price equivalents, or shadow values, which measure the stringency of regulations on a common footing with carbon taxes or cap-and-trade policies by looking at the net costs imposed on firms. Most importantly, they impose similar actions rather than similar reductions on all industrialized countries. Their pathway? Make sure that all emissions reduction opportunities costing less than about $40/ton in industrialized countries are realized by 2020, and all of those costing less than $120/ton are realized by 2050.
Temperature record for the last 20,000 years (source). Climate changes naturally (angle of the sun, volcanic activity, weathering of rocks), but it's been stable for the past 10,000 years, which as far as we're concerned might as well be infinite--that's 100 lifetimes.
Greenhouse effect (source).
Carbon cycle (source).
CO2 emissions: current (source), historical (source).
CO2 levels: current (source), historical (source).
Estimates of climate sensitivity to doubling CO2 (source).
The growing consensus of scientists and governments around the world is that to reduce the damage from climate change to an acceptable level, the atmospheric concentration of CO2 should be stabilized at 450 to 550 ppm, which is about one and a half to two times the pre-industrial concentration. Since global energy demand is projected to grow at least threefold over the next 100 years, stabilization at this level implies that energy-related CO2 emissions must fall by 75 percent to 90 percent from current levels in the course of this century. Given the inertia of long-lived capital stocks (transportation infrastructure, energy distribution networks, buildings, electricity generating stations, large industrial plants, petroleum refineries and mines), GHG emissions must be reduced during the next three decades if the longer-term goal is to be reached.
The scientists say the carbon released from the permafrost will be an "important amplifier" of climate change, and is in some ways more problematic than fossil fuel emissions: "It occurs in remote places, far from human influence and is dispersed across the landscape."
"Trapping carbon emissions at the source — as one might do at power plants — is not an option," they say. "And once the soils thaw, emissions are likely to continue for decades, or even centuries."
It’s important to keep these details—including the difference between terrestrial and oceanic permafrost emission—in mind, because they have direct bearing on the “list of scientific concerns about global warming” that Gillis mentioned, and on how we might prioritize various measures to address climate change.
For instance, the forty-one scientists writing in Nature emphasized that, “despite the massive amount of carbon in permafrost soils, emissions from these soils are unlikely to overshadow those from the burning of fossil fuels, which will continue to be the main source of climate forcing.”
Comments like that should make people think twice about proposals to geo-engineer a cooling effect in the Arctic, such as one recently presented at the American Geophysical Union and described in an article at New Scientist.
How problematic methane (and carbon dioxide) from Arctic permafrost will be remains a mystery. A useful 2010 overview in the journal Science, titled “How Stable Is the Methane Cycle?”, emphasized the importance of resolving lingering uncertainties. Thankfully, researchers are on the case, according to a December 19 article in Nature, which highlighted the fact “permafrost science is heating up in the United States.”
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