The media are also full of a new methane scare. An article in Science is said to claim that the Siberian Arctic bubbles release much more methane to the atmosphere than expected (by someone who had wrong expectations). For example, the Daily Mail says:
The concentration of methane in the atmosphere is really tiny, just 1.8 ppm. That's still 150% above the 0.7 ppm preindustrial level. The ice ages saw 0.3 ppm - 0.4 ppm of it. (Recall that the analogous numbers for CO2 are 388 ppm, 280 ppm, 180 ppm.) Methane only stays in the atmosphere for 10 years or so, well below the time for CO2.
One-third of the man-made methane is produced in agriculture. The natural gas contains 87% of methane. The gas is also released when coal is mined. And only one-third of the people produce farts with methane. Despite widely believed misconceptions, the gas, CH4, is actually odorless and non-toxic. The smell of farts mostly comes from hydrogen sulfide (and the so-called mercaptans). But yes, methane burns and explodes pretty nicely.
The Siberian Arctic sea bubbles are the largest localized natural source of methane. It's been reported in the article that 8 million tons are being released from that place every year. There exists no evidence that this amount has increased in any way during the recent millennia; the articles usually quote scientists who admit this fact but this fact is conveniently hidden near the end of the articles so that most readers will never get there because that would weaken the "message" of the "story".
Multiply 8 million tons by a factor of twenty - see EPA - and you will see that this amount creates the same greenhouse effect as 160 million tons of CO2. That's just 6% of the annual man-made CO2 emissions. The man-made CO2 may create something like 0.006 °C of warming per year - assuming that the whole 20th century warming was man-made (add or remove a factor of two according to your taste). So the methane causes an extra 0.00036 °C of global warming per year.
Will you survive an extra heat of this magnitude? Have you seen a single article that would actually tell you what the expected warming caused by this "scary" methane is?
Recall, once again, that the gas only survives in the atmosphere for 10 years or so. Even if the Siberian Arctic methane emissions increased by a factor of 100, for unpredictable reasons, it would still not be a problem. Everyone who puts his face into a worried shape because of this "issue" is an irrational sourball.
You will never learn such basic and relevant numbers from the stories in the media - and sometimes not either from the scientific articles - because they're inconvenient. Some heretical readers could even dare to suggest that 0.00036 °C of warming per year is a smaller catastrophe than a collision with a huge asteroid ;-) so it's better to show no inconvenient numbers at all, right? The very point of all these articles is to scare the people which is why it is important for the writers to hide all the basic facts. Any of these basic facts shows that there is absolutely nothing to be worried about. So when you read headlines such as
Whatever holds for CO2 is even more true for the methane: its effect on the climate is negligible. Methane concentrations have been, much like CO2 concentrations, correlated with the temperature during the glaciation cycles but the causal relationship goes from the temperature to the methane. Warmer oceans and seabeds can't store so much methane so they release more of it to the atmosphere. But that means almost nothing else.
As I have emphasized many times, the very accurate historical correlation between CH4 and CO2 concentrations during the glaciation cycles shows that none of them could have been responsible for the temperature swings because such a theory would have no explanation for the correlation of CO2 and CH4 between one another.