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 new paper out yesterday 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 this new research suggests 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?

2-miles of ice, 21-feet of water

Well, how about seas lapping 21-feet higher than they do now? It's fairly obvious that this level of sea-rise would be immensely disruptive; fortunately it is likely to be immensely slow, too. The study showed that Greenland would lose its signature ice-sheets over tens of thousands of years. But the fact is that this research adds another ratchet upwards to the sea-level rises expected by the end of the century.

Even small sea-level rises will bring many more coastal-dwellers within reach of the sea's awesome natural power. Hurricane surges, tidal waves, tsunamis – they will all get an unwelcome destructive boost, as Greenland nudges up its contribution. More than enough to worry about, then. But of course models are just models, not reality. Ice-sheet models are no different. They will be debated and revised, and maybe things will look better, as climate science progresses.

Or maybe worse. And that's the nub of the matter. Climate scientists have been pointing out the potential rocks that could hole the good ship humanity for some time now. They're difficult to spot – things are often a little misty – but the warnings are clear. If we keep on our reckless journey, into climate change's unknown rapids, sooner or later we're going to hit one of those rocks – and sink.

Ten tall-tales from the skeptics – the come-backs to topple them

Photo Credit: WireWizard

First published on EarthTimes as "Ten tall-tales from the climate change skeptics" 


The devil has all of the best songs, so they say. And the climate-change denial camp have certainly banged out their tunes to good effect, over the last few years. It's not hard to see why the clamor of the climate skeptics has won more and more of those thronging in the stalls. But if you're caught out by one of those seductive refrains from the naysayers, what you need is counter-melody to cut them short. So what are the top-ten comebacks to the tall-tales often peddled by the denialist community?


1 Warming isn't really happening, it's all down to the 'urban heat-island effect'
The consensus that the planet is warming didn't just drop off of a graph of dodgily-placed thermometers. Yes, cities and towns are warmer than the countryside, and yes, urban areas have swallowed rural ones over the last century. But climate scientists try to correct for these when working out the globe's average temperature.


And the indicators that temperatures are rising come from a myriad of sources, not just land-based temperature records. Satellites, tree-rings, snow and ice-cores, stalactites and corals – all of these are used to piece together the global temperature record. And they confirm that the recent warming is unprecedented.


2 Global warming stopped years ago; it's yesterday's story..
This is a story which can always be shown to be true – as long as you do some careful cherry-picking of the wildly wiggling graph of global temperatures. The planet's climate, even from year to year, isn't a sedate old tabby by the fire – it's a skittish kitten careering up and down, always on the go. Some years will be colder than others, even as temperatures are rising over the long term.

That's down to shifting oceanic and atmospheric circulations patterns, which can cycle temperatures up-and-down over a number of years. When scientists talk about 'global warming', what they mean is a change in the average atmospheric temperature, across the whole globe – and for enough broad time-frame (10 to 15 years) to even out those wiggles. On that very specific measure, the inexorable rise in global temperatures is just as apparent recently, as it has been in the 1990's, the 1980's and before.




3 Even if the planet is warming, the climate has always changed – why worry?
Geologically, planet earth's climate is always on the go, thanks to plate tectonics, volcanic eruptions, and a wobbly orbit around the sun. But the changes being seen now are not comparable to those seen in the past – they are faster than any previous temperature changes we see in the geological record. And speed kills. The rate of change being seen now may well be too fast for much life on the planet to adapt to, and survive.


4 Carbon dioxide is a boon to the green world, we really need more of it!
CO2 can indeed be seen as a plant food which could boost agricultural yields – and enclosed trials have shown that raising CO2 can help some plants to grow more. But in practices those rises are limited by other factors. Plants need many other nutrients than CO2 to grow. Also, the climatic effects of a warming world are likely to knock-back most plants far more severely than any limited benefit from extra CO2. And don't forget about the seas. CO2 is more of a poison than a food for coral reefs, as it is driving the acidification of the oceans, which is wasting them. Acidification is also threatening oceanic food-chains in unpredictable ways.


5 There's 50 times more water vapor than CO2, and no-one worries about that.
Given that the atmosphere contains 2 to 3% water vapor, and H2O is a greenhouse gas, just like CO2, it comes as no real surprise that water accounts for up to 72% of the greenhouse effect. So why the big deal about CO2? Because, unlike water vapor, CO2 is increasing rapidly in the atmosphere, thanks to our fossil-fuel burning ways. More CO2 means rising temperatures. CO2 is also very persistent – once in the atmosphere, it carries on warming it for thousands of years, unlike extra water vapor, which is cycled out of the airs within days.


6 If the world is warming, why is there more sea-ice around the Antarctic?
Global warming isn't acting everywhere, in the same way, at the same time. Some parts of the world are cooling, or showing higher rainfall. That is why 'climate change' makes more sense as a label than 'global warming'. It is true that much of the interior of the Antarctic has seen such cooling recently. But that doesn't mean the world as a whole isn't warming. And the increase in sea-ice around the most-southerly continent has been linked to greater falls of snow. More snow acts to insulate the sea-ice, helping it to last through the summer.


But with the waters warming, even around the Antarctic, that increased snow could eventually become rain – and the sea-ice would then lose its insulating cover. And looking up to the north pole, a very different picture is seen. Sea-ice volumes there are continuing to plummet, in this, the fastest warming part of the globe.






7 'Climate-gate' proved that climate scientists are part of a global conspiracy
One thing 'Climate-gate' proved for certain is that those opposed to taking action on climate, will go to extreme lengths to further their agenda – including hacking computers and stealing e-mails. The scientists involved, however, have had the basic climate science and methods vindicated numerous times, since those communications were leaked. Did they act in a self-protective and far-from open manner? Almost certainly. But that in no way undermines the picture of a globe threatened by man-made warming.


8 How can the puny efforts of man compare to mighty furnace of the Sun in affecting climate?
Whilst the sun is responsible for the vast majority of energy arriving at the surface, and does go through a regular cycle of rising and falling energy levels, changes in incoming energy are minute. Solar cycles show fluctuations over a period of 10-11 years, which are apparent in the yearly global temperature record. But average those temperature series out, and naturally enough the solar cycles drop away – leaving behind the rising tide of global warming. Longer-term changes in the sun may have had subtle influences on the climate, but given that the last 30 years have seen falling levels of solar activity, but rising temperatures, the flickering of the sun seems unlikely to be part of the global warming story.


9 Even if global warming is happening, we're clever enough to engineer our way out of the problem.
If you're stuck in a self-made hole, the first thing you should do is stop digging – not to dig deeper in a risky attempt to tunnel your way out. The problem of global warming was kicked off by mankind conducting a gigantic experiment in geoengineering – releasing vast amounts of CO2 from fossil fuels. Now that we've realized that our experiment is starting to go hay-wire, the last we should be doing is a blind stab at counter-geoengineering. Attempts to slow down warming that way could backfire badly, especially if all our geoengineering efforts have to be stopped suddenly, because of unforeseen consequences for the delicate global ecosystem. Long-suppressed temperature changes could then wreak real havoc in short shrift.


10 Well it wont affect me..
This is the most scary of all denialists tales. It shows that what they are really interested in is preventing the golden goose of the global economy from being upset. A goose that is laying plenty enough shiny golden eggs for them personally, to distract them from worry about the effects on others. And climate chaos from global warming could leave some in the more developed parts of the world less affected, initially. Projections show that the developing world is more prone to effects from severe weather, drought-induced famine and rising sea-levels.


But the back-wash from the breaking wave of global insecurity, induced by climate change, is sure to hit all countries eventually. And with the worst predicted for the future, do we really want to pass that particular Pandora's box on, for our children and grand-children to open?

When Arctic ice goes, the North wind blows..

"Global warming is now making our winters colder!"

Only the craziest of eco-doom mongerers would be foolish enough to spout such nonsense, surely? The threat from a warming planet may take many guises, but making us colder – that's plainly on the 'wing-nut' side of things, isn't it. But in fact just such a claim is now being made, not by the deep-green fringe of the environmental movement – but by respected climate scientists from Columbia University, Georgia Tech and China's Institute of Atmospheric Physics. And the tale that their research lays out, in the most recent edition of the PNAS, is anything but a madman's babblings.

Patterns all-a-flux on the climate's patchwork quilt 

Instead, their paper coolly describes how the patchwork-quilt climate of the northern hemisphere is quickly unravelling, as the world warms. And for some – including parts of North America, Europe and Asia – the new pattern has plenty of colder winters woven into the fabric. That's something that no-one living there can fail to have noticed, in recent years. Deep snows and freezing temperatures have made themselves unwelcome guests, repeatedly, over the last four winters. But the culprit for all that cold may turn out to be the very thermostat dials being turned up, to keep us snug – all thanks to the global warming being bought on by higher greenhouse gas emissions.

The story begins 30,000 feet up, with the wandering band of winds – the polar jet stream – whistling around the Arctic regions, at up to 250 mph. This high, narrow wind-belt in fact marks the boundary between the cold airs at the North pole, and the warmer moist airs of the temperate zones. The jet stream keeps all that cold where it should be, up north – and the stronger the jet stream is, the more tightly those frigid airs are locked in at the pole. It's when the jet stream weakens and slows, that the cold air has a chance to spill down below the Arctic Circle, bringing harsher winters in its wake.

The sea-ice, the cliff and the snow

The driver for the jet stream, and the wall of winds separating the cold north from the warmer south, arises precisely from that stark contrast in temperatures. The cold dense air at the pole sinks to form high pressure; while the warmer air surrounding it rises, making a ring of low pressure systems. And the frozen sea-ice over the Arctic ocean acts as an anchor,  providing a deep pool of cold that is one of the drivers for a strong jet stream. 

But something has changed of late, and changed dramatically. The Arctic's cap of sea-ice, which was slowly receding thanks to global warming, fell off a cliff in 2007. Sea-ice volumes for the last 5 years have been half, or less, what they were before 2007 – as can be seen in the plummeting graph above. With less sea-ice after each summer's melt, those waters up north are taking longer to freeze over in the autumn.

That's where the team of researchers –looking for reasons for the last few winters of record snowfalls – have turned, in the search for an explanation. ′For the past four winters, for much of the northern US, east Asia and Europe, we had this persistent above-normal snow cover,'  paper co-author Dr Jiping Liu, of Georgia Tech, explained. In order see if there was a connection between less sea-ice for the Arctic, and more snow for us, the team looked afresh at the mounds of sea-ice and snow data from 1979 to 2010. They also ran computer simulations that modeled the climate, with simulated sea-ice being reduced, as has unfolded in the real-world.

Spinning top ready to topple

The conclusions drawn from these two different approaches were the same, according to Dr Liu. More open water at the start of winter means more heat is passed back into the air, when the sea freezes. That heat makes the winter Arctic air mass warmer, and so softens the contrast in air temperatures. That in turn makes the jet stream more weak and wobbly – a bit like a spinning top losing speed, and on the verge of toppling over.

′We think the recent snowy winters could be caused by the retreating Arctic ice altering atmospheric circulation patterns by weakening westerly winds, increasing the amplitude of the jet stream and increasing the amount of moisture in the atmosphere,' he said. ′These pattern changes enhance blocking patterns that favor more frequent movement of cold air masses to middle and lower latitudes, leading to increased heavy snowfall in Europe and the Northeast and Midwest regions of the United States.′

So while the world gets relentlessly warmer – on average, and over a number of years – some of us are getting slaps of rude winter cold, much more often we used to. It's almost as if the planet is pressing out its own desperate S.O.S to the world's big polluters. And the madness, maybe, is not in the planet's contradictory message, but in the perpetrators – addicted to fossil-fueled growth – who continue to ignore it, at their own peril.

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

Article first published as Sizing Up the Beast – Can Climates Past Foretell Climes to Come? on Technorati.

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.

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.

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 7^th 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 18^th 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.

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?