Say the words 'global warming', and the chances are that the perp you'll conjure up is a smoke-stack, coughing carbon dioxide into the atmosphere. The world has been fixated on the black-stuff – carbon – ever since scientists put the plot-lines of rising CO2 levels and global temperatures next to each other – and started to worry.
|Photo credit : Nadia Hatoum|
But today's release of the 7th Greenhouse Gas Bulletin sees the World Meteorological Office shining the light on a pair of oft-neglected gaseous jokers – methane and nitrous oxide. It seems that these greenhouse gases are on the rise too – and eager to take the spotlight away from big bad CO2. Because, while CO2 levels continue to rise remorselessly – despite all our decades of carbon hand-wringing – we haven't been able to stop this pair of jokers from playing tag-along.
That matters. Methane and nitrous dioxide – or laughing gas – may be at much lower levels, but they pack a lot more warming-bang-per-buck, than CO2. The potency of a greenhouse gas depends a lot on its shape, and these two gases are shaped just right for planet-warming. They soak up heat that the earth emits, as it is warmed by the sun; and the more of the gas there is, the more of that emitted heat is trapped.
No laughing matter
So what does the WMO Bulletin have to say on these two tricksy greenhouse gas players? For methane, the story is of a newly renewed strike upwards – after a decade in the doldrums. Last year, methane rose by 5 part per billion, building on three years of similar sized increases. As tiny as that increase may sound, methane is 18 times more powerful a greenhouse gas than CO2. And the level of methane now in the atmosphere is two-and-half times that which lingered around on 18th century Planet Earth.
The worrying thing is where the recent methane rise is coming from. Previously – from the late 1990s until a few years ago – methane appeared to stop its climb upwards, and simply straight-lined it. Many put this down to the economic malaise, in the big-time methane emitters of the old Eastern Bloc countries. But this recent rise is not fully understood, and could herald a new climate tipping point.
Is it related to the coal-burning excesses of China? Is it the first signs of the long-heralded 'Methane Belch' from the melting Arctic? The WMO Bulletin doesn't try to pin this down – but it does say that most of the factors pushing methane higher may be 'biogenic'. So maybe cows, maybe rice paddies, maybe Arctic bugs – or more likely all three.
On the flip-side of the greenhouse jokers is nitrous oxide. And this is one greenhouse gas that is no laughing matter. It has 300 times the warming potential of carbon dioxide, and hangs around in the atmosphere for centuries. Luckily it is at relatively low levels, even with a 20% increase since the preindustrial age. But its rise over the last few decades shows no sign of slowing. It has moved past another greenhouse gas wild-card – CFC-12 – into the third-place in the GHG rankings, says the WMO Bulletin.
New deck please?
But we do still have tricks to pull out on these two climate jokers. Methane emissions reduction could come from better cow (and human) waste-handling; from improved biomass burning techniques – and from giving shale gas and fracking a very wide berth. Nitrous oxide emissions cuts could come from a sea-change in agriculture, turning away from artificial fertilizers, and towards organic practices.
No sign of new those plays in the climate change game yet, though. Unfortunately, the big question is whether anyone, these days, is really watching the climate cards now being dealt. In fact, it seems as if the world's leadership is riveted by a different kind of game – distractedly busy around the economic stagnation crap-shoot. And working up those house debts, hand-over-fist.