Wyrd - OE: that which has become; fate-shaping; destiny-unfolding

Thursday, 29 August 2013

Of monsters, methane and the burdensome sea

It's the ultimate tipping point - the so-called Methane Burp. Gigatons (Gt) of methane are released into the atmosphere by some sudden phase change in the earth's climate system.
Plumes of methane in Arctic Ocean (Westbrook et al, 2009)

With its vastly greater global warming potential - up to 100 times more powerful than CO2, over short timescales - a sudden pulse of methane would accelerate human-caused global warming. It could even cause a cascade of other knock-on effects (Amazon deforestation, collapse of the ice-sheets) so creating a runaway greenhouse effect.

It's that sort of a scenario - with 50Gt of methane gushing from a source in the Arctic over 10-20 years - that was recently modeled by economists in Nature. They put a $60 trillion price tag for the global economy from the consequences of ratcheting upwards man-made climate change. A scary monster, made even more real by describing it in the language our leaders understand most - hard cash.

But the Methane Burp is also complete fantasy - at least according to some recent detractors. Many climate scientists believe the methane locked up in frozen soils, or the curious, icy 'methane-hydrates' under the sea-floor, are a real threat - but only as a slow-burn cooker for the globe's climate. As the planet warms, the natural emissions from these sources will increase, they believe. But not at a rate that will be catastrophic. They struggle to see how anything like as large as 50,000 million tonnes of methane can erupt so quickly from Arctic permafrost, or sub-sea methane hydrates. Such sources have been thought to have been stable in the recent geological past.

Sunday, 2 June 2013

From White to Green - Greenland's Glaciers are History

Article first published as From White to Green - Greenland's Glaciers are History on Technorati.

Greenland ice sheets (Credit: destination arctic circle/ Flickr)
Take a long hard look at Greenland's towering glacial caps - they may well already be history. That's according to a paper published in Nature Climate Change. Scientists have already noticed that the speed at which Greenland's glaciers are rushing into the sea has accelerated. And they have long-feared that, without commitments to curb our greenhouse gas emissions, much of its ice cap will eventually disappear into the sea.

But there is now research to suggest the threshold has already been passed. Previous models made some fairly simple assumptions about how the 2 mile-thick ice block, which is plastered over much of Greenland, will melt. And they gave some hope that the worst of the melting could still be avoided, if we were to pull the plug on our emissions.

Fade to green?

With this new research, however, the physics of Greenland's ice-melting process have been painted out in finer detail. And if the authors are right, the amount of global warming we have stored up, from our emissions so far, may be enough to transform Greenland. The world's biggest island could shift from an icy whiteness to a truly green land.

Ice sheet thickness (km) today (E1) and projected in future (E2/3)
The reason for the change in outlook? The simple realization that as the 2-mile high icy plateaus melt they get considerably lower. And the lower the ice surface, the warmer the air above them gets, pushing the pace of melt even faster – a positive feedback.

Positive feedbacks are the 'loaded dice' of the game of climate crap-shoot we're playing. They push the odds in favor of dangerous consequences, by accelerating the rates of change kicked off by global warming. But how dangerous would it be, if Greenland were to disgorge its entire ice sheet into the oceans, as this study suggests?

Sunday, 3 February 2013

A Book of Kells for the climate - scribe-illustrators needed?

The world of climate science sometimes seems like a swirling sea of numbers. Numbers that come, and numbers that go, like waves breaking silently on the foreshore. There's always another statistic, or table, or figure about to break, ready to erase the brief imprint of the last. But occasionally that sea tosses up a stunningly crafted piece of driftwood - and here's one I found beach-combing the wilder shores of green think-tankery:

This is one of many visual gems to be found in the World Resources Institute's report, 'Navigating the Numbers'. It tried to summarize the state of play for greenhouse gases and climate policy a few years back. I love this picture, because it takes all of those all-often-hurled statistics and beds them into a beautifully-colored context. All of the data is there, of course, showing on how each and every part of our society is contributing to our shocking of the climate.