The climate change debate is not being helped by the exaggeration both from alarmists and sceptics. So what do scientists and policy-makers actually believe these days? JOHN McCRONE finds out.
Funny how hearing a scientist say that sea levels are going to rise by "only" a metre each century counts as reassuring news these days.
Global warming is alarming stuff. This year all we nervous types have been watching the record melt of the Arctic sea ice.
Suddenly, up north, things seem to be lurching out of control. The summer pack ice cover is disappearing 50 years ahead of schedule. The extent of this took a big dip in 2007, then another even bigger dive this year to drop below half what it used to be in the 1980s.
Some climate researchers fear it marks a planetary tipping point.
In widely reported comments, Cambridge University ocean physicist Peter Wadhams has said the loss of a white reflective polar cap will allow so much extra ocean warming that it is "the equivalent of about 20 years of additional CO2 being added by man".
Wadhams says it also risks the catastrophic release of methane deposits trapped in the Arctic's permafrost and thawing seabed - a blanket of greenhouse gases to send Earth into a death spiral.
We failed to take action over carbon emissions and now it looks to be too late. Wadhams says it is truly time for panic measures - the science fiction remedies of geoengineering, such as burning sulfur in the stratosphere to create a shielding haze, or exploding an asteroid to make a sunshade of space dust.
Also widely reported is Nasa's James Hansen, the "father of global warming science". Again, Hansen is saying everything is going far faster and far further than predicted as the climate feedback systems begin kicking in.
He worries even the now internationally agreed target to limit warming to 2 degrees Celsius is enough to result in a "disaster scenario".
The world is already seeing out- of-whack weather extremes, Hansen says. Injecting just a bit of extra heat into the climate system is sending it off in all sorts of odd directions.
And if the Greenland and Antarctic ice masses start to go, Hansen says we could see a swamping five metre sea level rise by the end of the century.
So it is against this backdrop of the most dire warnings that it is a relief to hear a somewhat different story from those right at the heart of the world's climate change science and climate change policy. People like Victoria University's Climate Change Research Institute (CCRI) director David Frame.
Speaking at a global warming session during Christchurch's recent IceFest, Frame says yes, something really is happening with the climate, but the public are hearing only the extreme views - either the alarmists or the deniers - while the science itself sits somewhat forgotten in the middle.
"Regrettably a lot of the public opinion is very distanced from the actual views of the expert community and the papers in the literature.
"It tends to be either complete scepticism, it's not happening at all, or if it is, it's a rather weak effect. Or else it's the alarmist end- of-the-world portrayals. And neither of those really accord with the best evidence."
Frame says climate change is still a relatively new issue - it was barely discussed in the mainstream media before ex- United States vice-president Al Gore's 2006 documentary film, An Inconvenient Truth.
So the public has been forced to take sides on a complex subject and decide for themselves what to believe, and naturally opinions have become polarised. Arguing yes it is, no it is not, the emotion drives people to seek out whatever evidence appears to most dramatically support their own case.
This year, for the alarmists, it has been the Arctic sea ice melt. While in reply, the sceptics can point instead to a record winter sea ice gain down off the Antarctic continent. Both camps are shouting "gotcha" and the resulting confusion is paralysing.
But there is also the middle- ground rational insider's view of climate change, the considered picture of the scale of the problem and the ways it might be tackled.
Frame says the balance of the evidence is that our actions are warming the planet in a dangerous fashion. Yet these changes still look relatively "well-behaved", not switching into some runaway mode.
Likewise, the concern over the international response.
Many worry that the climate change jamborees, such as the 17th round of the United Nations Climate Change Conference held in Durban last year, are producing too little action. Even New Zealand appears to have about given up on its own "world best practice" emissions trading scheme (ETS).
However, Frame says this is judging climate politics against the wrong expectations. People want noble, utopian answers for a problem so severe. Everything else has to be dropped to deal with this one issue.
But the reality is countries are going to act only on the basis of pragmatism and self-interest. The good news, says Frame, is this can also work.
Starting with the science, what are the "take homes" of current understanding? Tim Naish, director of Victoria University's Antarctic Research Centre, a colleague of Frame, attempts to tick them off.
First, says Naish, there is no question that CO2 levels are soaring. Naish is a glaciologist by training and co-leads the Andrill ice drilling project in Antarctica, which is measuring atmospheric carbon levels for the past 20 million years.
Naish says graphs of CO2 show the level holding steady for the 10,000 years since the end of the last ice age, then suddenly hooking skyward about 150 years ago following the Industrial Revolution.
The pace is quickening, says Naish. In just the past 40 years, the concentration of CO2 has shot up from 320 parts per million to nearly 400ppm. And oxygen levels are falling to match, he says, because of course the carbon comes largely from the burning of fossil fuels.
These are definites. And the evidence is also that, historically, CO2 levels are tightly coupled with planetary temperature.
"Our world has been a nice, constant, balmy 14'C on average for the past 10,000 years. Why? It's because the thermostat is the greenhouse gas CO2," says Naish.
He says a sobering fact is the Earth has warmed by only 1'C so far - this is the consensus figure of the Intergovernmental Panel on Climate Change (IPCC). And yet the last time CO2 levels stood at 400ppm was three million years ago when the world was two to three degrees warmer.
Naish pauses a moment to let the implication sink in. Clearly there is a lag in the response and CO2 has been allowed to rise so fast that the greenhouse effect is still catching up. Further warming is already locked in by what we have done.
OK, not so reassuring then. Especially as some are saying unless the brakes go on hard, we are looking at CO2 levels of 1000ppm by 2100.
However, Naish says understanding the timings and the nature of the lags, is important to the actual assessment of the risks. The biggest fears are all about things changing abruptly, suddenly spiralling out of control. But the consensus view is the "steady change" predictions are actually holding up.
Frame says the Arctic sea ice is a good example. The IPCC forecast there is in fact broadly on track. For a while there was less melting than modelled, and recently there has been a spurt of catching up. But overall the outcome remains within the range predicted some time back.
Frame offers a rugby-watcher's metaphor.
"A lot of stuff that ends up in the media is about how things are worse off than we thought, or not really happening. The extent of Arctic sea ice is a story like that this year. But any given year is too short to matter.
"I liken it to panicking every time the Springboks get the ball. Connoisseurs of rugby and climate connoisseurs know it's a long game. Just because you turn the ball over, just because something happens this year, doesn't mean it's a trend."
Naish says the confidence researchers now have in their climate modelling is why he feels he can speak with some certainty about his own speciality of sea level rise.
Naish says the sea has already risen 20 centimetres in the past 100 years - 1'C of warming causing this much thermal expansion. But only one metre of further rise is expected this century.
He shows a chart of New Zealand to illustrate what a one metre rise would mean. Only the tiniest red nibbles come out of the coastline. A problem, but not a terminal one. In a city like Christchurch, it would take six metres before the waves arrived in Cathedral Square.
The real danger is if the ice covering land masses like Greenland and West Antarctica melts. About a quarter of the world's fresh water is held in these kilometre-thick ice sheets, enough to raise sea level by 12m if it all goes.
Naish says even with higher temperatures, it would take centuries for these ice sheets to thaw. So the threat of inundation is not really so imminent. But the flipside to that is we have also likely condemned future generations to a long-continuing problem. Because change lags the warming, even if temperatures were stabilised right now says Naish, the one metre rise would be one metre per century for many centuries to come.
Frame says sea level rise is an example of the value of having a good grasp of what to expect.
Some climate activists believe the public needs the shock horror scenarios - Hansen's five metres of inundation by 2100 - to stir it from its apathy and send out the call for urgent action.
"But this kind of talk is paralysing rather than helpful. All you do when you double the stakes is make people hunker down even more," Frame says.
"I think most scientists who get into this are still fighting the old battle of how to raise awareness about climate change. But look, everybody in the world has heard about the problem. Now, how do we deal with it? That requires quite different kinds of information."
Frame says that after sea level rise, the most obvious effects of global warming will be on the world's ability to produce food and the increasing extremes to be expected of the weather.
This year extreme weather became a suddenly more convincing tale, with new models of how Arctic warming is disrupting the circumpolar jetstream in the northern hemisphere.
Rutgers University's Jennifer Francis says a hotter Arctic is causing the encircling jetstream to slow down and throw off larger sideways wobbles - the snaky meanders, like a river slowed by hitting the plains and known as Rossby waves.
So weather systems are getting stuck in one place over countries for much longer than usual. The sideway meanders are also either drawing down a larger polar blast or drawing up more tropical air.
The result explains the general "weirding" of the northern hemisphere weather - the droughts that shrivelled the corn harvest in the US this year or the wash-out summer in the UK.
So Frame says climate change is being experienced first through these localised disturbances, the bigger dries and explosive flooding events, which are taking things in all sorts of contrary directions. But in the longer term, world agriculture is going to have to adapt to more permanent shifts in rain belts and climate patterns.
Australia is expected to have even less rain in the future. In New Zealand too, the South Island between Kaikoura and Picton, the lower east coast of the North Island, and Northland, are all forecast to become much more drought-prone.
However, Frame says New Zealand as a whole is something of a lifeboat so far as global warming goes. Surrounded by a deep and wind-tossed ocean, change here will lag the rest of the planet.
"For simple physical reasons, it just takes more energy to heat a bucket of water than a bucket of rock. And the warming rate is slowest over the bits that have storminess over the ocean."
So our own prediction is for just a degree of warming by 2040 and 2'C by 2090. Eventually New Zealand will catch up of course says Frame, but its position gives it a little more time to adjust. It is refreshing talking to someone who appears to be operating in a world where the basic climate change arguments are settled.
The parameters of the problem have been agreed, the bands of uncertainty quantified, and now the job is to identify the rational political solutions.
Frame's own career path suggests how far, in just a decade or so, the debate has evolved.
An Invercargill lad, Frame started out as an atmospheric researcher at Canterbury University, finding time also to study moral philosophy before he got a high-flying job as a Treasury think-tanker, moving to Wellington to learn about real-life policy making.
From there, Frame went back into science at Oxford University before in 2011 taking over as director at Victoria's CCRI.
It is a breadth of background experience that positions Frame now to have an influential say in what governments actually do. And he says much of the attraction of coming back to New Zealand is that it is a small, nimble democracy likely to be an early adopter of new ways of thinking.
Frame feels generally optimistic because he views past policy disappointments as just part of the world's learning process. Even if first-pass solutions like the ETS agreements fail to stick, people will move on and discover other approaches that work.
But what strikes him is the extent to which climate change seems still entangled in other agendas - the utopian thinking that says more about where we are coming from than where we need to go.
For instance, he says, there is the way green political philosophy has become so hairshirt anti- growth that it has created a partisan split between left and right.
"Thirty years ago, it wasn't obvious that when environmentalism first became an issue - especially because it came up as an issue in the rich world's middle-classes - that it was going to be politically left-wing."
But Frame says global warming fitted so neatly into beliefs about the need for social control and brakes on exploitation that it got seized upon. The threat was talked up to support a particular world view.
And yet Frame argues it seems a simple truth that economic growth itself has only been a force for the good.
"On average, human beings in modern society live almost twice as long as they did. They are happier. They are well fed. There is much less violence.
"There are a whole bunch of changes that have been hugely beneficial for people. So the only question here really is how can we now decouple future growth from carbon?"
Frame says he finds the politics of climate change are weighed down by a colonial guilt as well. For many of the European countries that once used to run empires, fixing global warming is seen as the rich world's responsibility.
Again, it is about social justice and utopian ideals, says Frame - which is fine up until the point where, in international negotiations, people expect other nations to respond the same way.
But he says it is an objective fact that carbon emission levels in the developed economies have levelled right off and it is the emissions from the emerging ones, like China, Brazil and India, that will soon be causing the bulk of the problem.
"There is a misconception that it is all being done by the industrialised north and the developing world is just a passive victim. But under a big 'burn it all' future, three-quarters of the atmospheric stock of carbon will come from the developing world."
So there is no point trying to found climate policy on notions of what is morally right, historically just, or even "people just being nice to each other", says Frame. It has to be recognised that countries are going to be motivated by self- interest as much as the collective good and learn to work with that.
"The idea of coupling climate to aid and development obligations that arise out of colonial history, really doesn't have a very strong resonance with other countries like the US.
"Americans don't perceive themselves as being a colonial power. Their historical narrative is that they were the destroyer of these big European empires. So if you try to hang your hat on an emotional feeling, you'll get a very different answer from them." Climate policies can be effective only if they are focused on tackling the problem at hand, says Frame. Take the plight of low-lying island nations like Tuvalu and the Maldives.
Even a one metre sea level rise will swamp these small countries, removing them from the map. But is the rest of the world really going to change its ways to save them?
"I saw an estimate where it would cost US$30 trillion to 2030 to get the Earth on a 1.5'C warming trajectory. Well, let's say, ballpark, there's 150 million people living in the bottom two metres above sea level. The spend to achieve that would be US$200,000 per person.
"Now the average statistical value of a life across the world - the amount we normally spend on people to keep them alive - is about US$6000. So we'd be spending some 50 times more on this particular initiative than any other initiative.
"So why would we do this? Why would it be rational?"
At a climate summit, the simple mathematics would rule, says Frame. Which means island nations ought to be going into the talks seeking some kind of other rescue deal.
"I think there would be some will for that, but very often negotiators don't know that is the question they should be asking."
Frame says this cold-eyed assessment of how the players are going to act might sound brutal. However, it is the only way robust policy bargains can be struck across a world with so many different viewpoints and circumstances.
This is why Frame is not too concerned by the apparent failure of the Kyoto Protocol ETS agreements - the attempt to put a world price on carbon by charging countries to pollute.
New Zealand is being much criticised for backing even further away from its own ETS commitments this year. To be effective, the New Zealand scheme would have to cost $20 per tonne of emissions, yet it has been so watered down the price sits at around $1 a tonne.
He says it was too much to expect the world to move in the same direction at the same speed. "Each country is going to have to decide what it can do."
He believes the game has now changed to a more pragmatic approach, where individual nations will do deals that may be wrapped in with trade and aid agreements. "Access to markets could be swapped for climate commitments."
It might be piecemeal, but it will create the economic incentives to play the good global citizen by embracing renewable energy programmes, carbon taxes and other climate-friendly policies. The planet should still get there in the end, Frame says.
"Yes, the ETS has been watered down and that's a shame. But it comes down now to what's good second-best policy? What's fair in an unfair world?"
Ice reflects 80 per cent of the sunlight that strikes it back into space, while open ocean absorbs 90 per cent.
In 2012, Arctic sea ice shrank to its smallest recorded extent in recent times, its coverage falling to 3.4 square km.
2007's previous low of 4.2 square km followed an unusual summer of warm southerlies and clear skies. The 2012 melt was without these helpful conditions.
Since the 1980s, the September minimum sea ice extent has been declining by 13 per cent per decade.
Because Arctic sea ice is getting less time to reform each winter, it is thinning rapidly as well.
In Antarctica, sea ice near the Antarctic Peninsula is seeing a decline, but is in fact increasing slightly in other parts.
The Arctic is an ocean surrounded by land which contributes to its warming, while the Antarctic is a continent isolated by encircling wind and ocean currents.
Source: US National Snow and Ice Data Center
- © Fairfax NZ News
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