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

Wednesday, 30 November 2011

Sizing the beast – can climates past foretell climes to come?

It's a tricky beast, this climate change dragon. We only know it is there thanks to the fitful light cast by the flickering torchlight of climate science. Sometimes its shadow looms large; sometimes its shadow shifts and shrinks. But if we're going to gauge the scale of the devastation it could wreak – and equip our dragon-slaying hero with the tools needed – we need to get a better measure of the beast.

Photo credit: Anne-Lise Heinrichs
That metric is what climate scientists refer to as the 'climate sensitivity'. It is a measure of how much the globe's average temperature will rise, if the amount of CO2 in the air were to double. To gain a more accurate tail-to-snout reckoning, researchers often find themselves turning back to ancient lore – and poring over the records of climate change past. By looking at how temperature and CO2 have varied with the ebb and flow of our Ice Age's warm and cold periods, they can get a better idea of how sensitive the world is now – as we face our own catastrophic CO2 gamble.

Many papers, and much painstaking toiling over ancient climatic data, have cast a rough net around the climate's sensitivity. But it is a rather loose net – the IPCC, in 2007, said it could range anywhere from ′2°C to 4.5°C, with a most likely value of about 3°C'. Recent research has done little to tighten that band. Now a study released in Science has proclaimed a much tighter fit to the climate dragon – and controversially, it has even shrunk the beast a little.

Going back to the future

The paper fitted together the climate data puzzle for the last ice age – 21,000 years ago – when ice sheets sat over much of Europe and America. CO2 levels back then were much lower than our fossil-fuel inflated levels – 180 ppm rather than today's 390 ppm. Naturally enough, temperatures then were much colder too. The paper's authors sought to pin down those temperatures by using all the paleoclimate evidence they could find from the Last Glacial Maximum (LGM).

By running various LGM climate models, with different climate sensitivities, they picked out the most likely values – those that matched the LGM temperatures they had already mapped from the paleoclimate data. The sensitivity numbers came back satisfyingly tight – ranging somewhere between 1.4ºC and 2.8ºC of warming for a doubling of CO2. The most likely value was 2.3ºC.

3ºC or 2.3ºC - it's still a dragon

Worryingly, some in the media have taken this lowered sensitivity as requiring a big downgrading of the climate threat. 'Global warming much less serious than thought' trumpeted many a news outlet. It is as if the climate dragon has been shrunk to a climate poodle. But a 2ºC climate sensitivity was enough to shift us from the deep freeze of the LGM to today's relatively balmy conditions. Another 2ºC would take us on a dangerous path, one that could lead to equally dramatic changes. Our current increasing emissions are pulling us firmly along just such a path.

Maybe – if this single paper is right, and there are many scientists who contest it – then the dragon's roar could be notched down a decibel or two. But a dragon it still remains.

Tuesday, 29 November 2011

Arctic scythe laying the ice-sheets low

First published on Earth Times as "Arctic scythe laying the ice-sheets low" 

One of the problems scientists often have is teasing out meaning from noisy and variable real-world data. Sometimes patterns need statistical tests and techniques to coax out any patterns of behavior. But that's not a problem apparent in the latest research to reconstruct the levels of Arctic sea-ice for the last millennium and a half. In a paper published in Nature last week, Arctic scientists have attempted to map out the rise and fall of the North's ice-cap, using more than 1400 years worth of data. And the lead picture from their paper is striking. It shows sea-ice falling off of an unprecedented cliff in the last few decades.

Sea-ice levels have been seen to fall dramatically for much of the last 30 years. But we have only been accurately observing the ice-caps for the last 4 decades of the satellite era. To paint the line of wiggling Arctic sea-ice extent back across the centuries, the team turned to 'proxies' in the region around the Arctic. These are the various parts of the natural world which both roughly track local temperature, and can be accurately dated. All told the team looked at 69 proxies for historical Arctic conditions – from tree rings to ice cores to lake muds.

From hockey-stick to scythe

These proxies were melded to form an indicator of sea-ice level. This was shown to tie-in tightly to sea-ice area seen in the recent satellite data – as well as to the 200 years of direct observations of sea-ice that we do have. The broad narrative of the historical sweep of sea-ice, in the far north, could then be painted out with some confidence. And what stood out from the data was the unprecedented size and speed of the most recent ice-loss.

While global warming often reveals itself in other graphs as a sharp hockey-stick, here we appear to have something more dramatic – a sharply down-pointed scythe. For the authors, that implies something well out of the scope of natural climate cycles; man-made climate change is the only plausible culprit. The story doesn't end there, though. There are margins of error in working out this historical tale by proxy, as is shown by the pink areas in the graph above. Before 600 AD years the level of uncertainty from their proxies meant that the team couldn't draw the sea-ice line back with any confidence.

Other papers, however, using different proxies, have been more confident. It is believed that the Arctic ice-cap was last this small some 6-8,000 years ago. Then the tilt of the Earth's orbit meant the northern half of the planet received more energy from the sun that it does now. But as that tilt changed, the ice-cap regained its size, over the following millennia. Such slow-moving planetary tilts are unlikely to save us today. With our own climate experiment proceeding apace, and likely to melt the last shard of Arctic sea-ice within decades, it seems that we're the only ones who can blunt this particular scythe.

Tuesday, 22 November 2011

Dealing with the rise of the Greenhouse Gas Jokers

Article first published as Dealing with the Rise of the Greenhouse Gas Jokers on Technorati.

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.

Friday, 11 November 2011

Soothsaying and fire-quenching in the Amazon

First published on Earth Times as "Soothsaying the Amazon's fires"

Photo credit: Guido van der Werf [Image © Science/AAAS] 
The last decade has been a tumultuous one for the Amazonian rainforest – the green lung of the planet. On the one side, the hand that wields the ax has been stayed somewhat – with the rates of deforestation last year at their slowest pace in 20 years. On the other, fierce 'once-a-century' droughts have gripped the lush basin – not once, but twice. Some see the lurking shadow of global warming behind such an ill-starred run of searing dry seasons. What is certain is that the planet can ill-afford for this global gobbler of man's CO2 to dry, shrivel and shrink – whether by ax or fire.

But while scientists can't step in to banish these twin threats, they can hold out the promise of foretelling the next gathering drought. That's according to the results of a new study by climate scientists, published in Science today. With such advance warning, those tasked with conserving the Amazon may be able to prevent the droughts worst effects, by putting a damper on their potential for wildfires.

In order to act as modern-day augurs of devastation, the team – led by University of California, Irvine (UCI) – cast their eyes far afield; to the waters of the Pacific and Atlantic oceans. By watching the tremors of temperature here, thousands of miles from the Amazon basin, they were able to pick up subtle signs that predicted droughts – up to five months before they struck.
In years when the temperature of the central Pacific rose by a degree Celsius – and those in the Atlantic rose by a quarter of a degree – several months later, wildfires were seen to bloom across South America's rainforests. The researchers were able to produce models that accurately predicted the devastating fires seen in last year's Amazonian dry season.

''We predicted a massive spike in fires in 2010, and it occurred,'' said James Randerson, one of the paper's authors from UCI.

Because there is a reasonable lead-time for their omen-casting, it gives those on the ground a fighting chance to take action. For example, fire-fighting teams can be placed in known flash points; or controlled burning of conflagration-prone areas can be undertaken – hopefully preventing raging wildfires from taking hold across wider swathes later.

''During the 21st century, there are expectations that drought may intensify, and forests may become even more vulnerable. Understanding in advance whether you're going to have an exceptionally bad year will become critically important for managing them,'' said Randerson.

Given the desperate importance of holding onto those parts of the globe – such as the Amazon forests – that absorb much of our rising CO2 emissions, the need for such climate-oracles has never been greater. But with the bones also speaking loudly of a wider, more globally-ominous future, are we actually listening?

Monday, 7 November 2011

Frozen box of Pandora stirs in Arctic

Article first published as Bugs ready to munch on climate time-bomb on Technorati.

© Photographer: | Agency: Dreamstime.com
Many strands of our climate's future criss-cross in the far north of the planet. The frozen Arctic is one of the quickest warming parts of our globe, so perhaps that shouldn't come as a surprise. Here you will find fast-shrinking ice-caps; once-fabled sea-ice passages that have newly opened; mysterious methane hydrates, buried in cold sea-muds, which one day could release a stupendous global warming belch.

And frozen bugs.

Surprisingly, it is the frozen bugs in the permanently iced soils – or permafrost – of the Arctic that has scientists worried. Those bugs are sitting within a climate time-bomb; some 1,600 billion tons of carbon that's been locked into the icy soils for millennium. It comes from the dead remains of plants that lived in the far north before the last Ice Age. The bugs were locked in place too, as the ice advanced; and for them, that rich organic matter is food, for when the permafrost soils next melt.

And that melting is already starting in places across the Arctic, with more on the cards. So how those newly defrosted bugs respond, on awakening from their slumber, is critical in deciding what happens to the Arctic's massive permafrost carbon store. Which is why scientists from the Lawrence Berkeley National Laboratory have been looking at the gassy effluence of the permafrost microbial community, in a study just published in Nature.

They have found that, when these bugs spring back to life, they start munching on the dead plant remains straight away – producing methane and CO2 in equal measure. Both are important greenhouse gases, but methane has a stronger short-term boost to warming. But the researchers also noticed that the methane production slowed down within a couple of days. It seems that some bugs find the newly produced methane a tasty alternative foodstuff for themselves, and quickly snap it up.

That could, possibly, be good news. If the same story, of only a short-lived methane burst, pans out for the real-world perma-defrost, then the climate implications could be less severe. Methane is twenty times more potent a greenhouse gas than CO2. But the team also found a worrying sign that another greenhouse gas – nitrous oxide – may be a player too. No microbes seem to put this gas on their menu in the tests conducted. So nitrous oxides could be released in higher quantities than previously thought. And this gas packs a punch 300 times more powerful than CO2.

Whatever the greenhouse gas mix the Arctic's microbes chose to gift us, one thing is clear. The only way to avoid putting Arctic bugs in charge of the planet's thermostat is to prevent the triggering of further melt-off in the far north. And that requires mankind to get a grasp on our own gaseous pollution – with a great deal more haste than has been shown, thus far.

Wednesday, 2 November 2011

Just passing through – how China's emissions actually come right back at us

Article first published as Just Passing Through – How China's Emissions Actually Come Right Back At Us on Technorati.

China has become the bad boy of climate change of late. With an economy still roaring loudly, even while the rest of the world meekly whimpers, the country's coal-power stations are dialed-up to max. That has led to a booming of greenhouse gas emissions to complement a booming economy. China in fact overtook the US in the emissions stakes way back in 2007. A recent report even suggests that the gases pumped out per person in China will race past those of the average American by 2017.

No wonder fingers are being aggressively wagged by many in the West. We're off the hook – China is powering the world towards climate chaos. If she won't shoulder her fair share of the burden in the fight against global warming, why should we? Except it's not that simple. Even a casual glance down the store aisles reveals how much of the West's economic goodies come from China. Much of China's growing emissions may simply be to fuel our own material excess.

Now a new study from Stanford has put some numbers behind that suspicion. 'The Supply Chain of CO2 Emissions', published last week in the Proceedings of the National Academy of Sciences, comprehensively tracks carbon emissions – all the way from the oil wells and coal mines right through to the consumers, proudly displaying their latest gadgets and goodies. The principle is that the consumer gets the benefit of these goods – and so holds responsibility for the emissions piled up along the path of their manufacture and transport.

Global carbon flows
The flow of carbon emissions (in millions of tons CO2) from well and mine to consumer. Source: http://www.pnas.org/content/early/2011/10/13/1107409108.abstract

Put those numbers into a picture, as seen above, and it's clear to see that China is just a middleman. The arrows point fingers of blame pretty clearly. The big carbon sources are the coal, oil and gas merchants of the Middle East, Russia and Canada. And the voracious emissions gobblers remain the world's rich club -- the US, Europe and Japan. So the carbon buck can't be passed onto China, or others making our stuff. It's time to stop the blame game. We're all in this together.