
I saw this piece from Euan Nisbet, Professor of Earth Sciences, Royal Holloway University of London, a few days ago, but wanted to know more about how credible it was. Now I see that Stefan Rahmstorf tweeted it out, so that makes me take it more seriously.
A lot of panic about methane levels has centered on the so-called “Methane bomb” of undersea frozen clathrate deposits, which a number of pretty good scientists have told me is a bit over-done.
In recent years, however, an observed spike in global methane levels has been convincingly traced to wetlands in the tropics, which seem to be pumping out more of the gas as rainfall and temperatures increase.
Also, Beavers involved.
Euan Nisbet in The Conversation:
Continue reading “Is Rising Methane an Ominous Indicator?”Since 2006, the amount of heat-trapping methane in Earth’s atmosphere has been rising fast and, unlike the rise in carbon dioxide (CO₂), methane’s recent increase seems to be driven by biological emissions, not the burning of fossil fuels. This might just be ordinary variability – a result of natural climate cycles such as El Niño. Or it may signal that a great transition in Earth’s climate has begun.
Molecule for molecule, methane is a much more potent greenhouse gas than CO₂ but it lasts slightly less than a decade in the atmosphere compared with centuries for CO₂. Methane emissions threaten humanity’s ability to limit warming to relatively safe levels. Even more troubling, the rate at which methane is increasing in the atmosphere has accelerated recently. Something like this has happened before: sudden surges in methane marked the transitions from cold ice ages to warm interglacial climates.
Methane was about 0.7 parts per million (ppm) of the air before humans began burning fossil fuels. Now it is over 1.9 ppm and rising fast. Roughly three-fifths of emissions come from fossil fuel use, farming, landfills and waste. The remainder is from natural sources, especially vegetation rotting in tropical and northern wetlands.
Methane is both a driver and a messenger of climate change. We don’t know why it is now rising so rapidly, but the pattern of growth since late 2006 resembles how methane behaved during great flips in Earth’s climate in the distant past.






