Part 2 (2/2)

Seidel and her team also found that the expanding equatorial belt has 'potentially important implications for subtropical societies and may lead to profound changes to the global climate system'. They argue that the pole-ward movement of large-scale atmospheric circulation systems such as jet streams and storm tracks 'could result in s.h.i.+fts in precipitation patterns affecting natural ecosystems, agriculture and water resources'. Of particular concern to them are subtropical dry belts that could affect water supplies, agriculture, and ecosystems over vast areas of the Mediterranean, the south-western United States, northern Mexico, southern Australia, southern Africa, and parts of South America.

For wooded tundra, an average of 27 per cent of the ecosystem would remain in place for a warming of 3 degrees in 100 years - or 0.3 degrees per decade, over a century timescale. At that rate, IPCC lead authors Rik Leemans and Bas Eickhout found that 'only 30 per cent of all impacted ecosystems ... and only 17 per cent of all impacted forests' can adapt. If the rate were to exceed 0.4 degrees per decade, all ecosystems would be quickly degraded, opportunistic species would dominate, and the breakdown of biological material would lead to even greater emissions of carbon dioxide. This would, in turn, increase the rate of warming.

With emissions already tracking higher than the worst scenario of the IPCC, we must conclude that 'business as usual' would see the destruction or degradation of most species and most ecosystems by mid-century.

CHAPTER 7.

The Price of Reticence.

Roger Jones is a CSIRO princ.i.p.al research scientist. On 10 December 2007, in Melbourne's Herald Sun, he issued this call for scientists to overcome their aversion to risk taking: Often, scientists do not like to release their results until they are confident of the outcome. Important decisions need to be made now and cannot wait another five to seven years. Scientists will have to leave their comfort zone and communicate their findings on emerging risks, even when scientific confidence in those findings may be low... Sometimes, it is worth taking some risks in the short term to avoid worse risks down the track. We have spent too long being risk-averse about short-term costs and ignored the benefits of avoiding long-term damages.

If only the IPCC would adopt such an att.i.tude. Those turning to the 2007 IPCC reports for an up-to-date, authoritative view on global warming will find little of the real discussion of the events in the Arctic with which we started our story. The 2007 report is the IPCC's strongest call yet for governments, businesses, and communities to act immediately to reduce greenhouse emissions. But it is not enough, because it is based on outdated and incomplete data sets. The IPCC's four-year schedule for producing reports requires a submission deadline for scientific papers that is often two years, or more, before the report's final publication. What happens if there is significant new evidence, or dramatic events that change our understanding of the climate system, in the gap between the science reporting deadline and publication? They don't get a mention, which means that the IPCC report - widely viewed as the climate-change Bible - is behind the times even before it is released, though some new data is presented at forums.

On 28 January, just days before the release of the first of the IPCC's 2007 reports, the science editor of The Observer, Robin McKie, told of a serious disagreement between scientists over the report's contention that Antarctica will be largely unaffected by rising world temperatures: [M]any researchers believe it does not go far enough. In particular, they say it fails to stress that climate change is already having a severe impact on the continent and will continue to do so for the rest of century. At least a quarter of the sea-ice around Antarctica will disappear in that time, say the critics, though this forecast is not mentioned in the study. One expert denounced the [IPCC] report as 'misleading'. Another accused the panel of 'failing to give the right impression' about the impact that rising levels of carbon dioxide will have on Antarctica.

As McKie notes, the IPCC is, necessarily, a careful body.

Its reports involve the synthesis of many hundreds of pieces of research, and cooperation between many authors and contributors, such that only points that are considered indisputable by all of them are included: 'This consensus deflects potential accusations that the body might be exaggerating the threat to the planet. But the critics say it also means its doc.u.ments tend to err too much on the side of caution.'

Under intense pressure from global-warming deniers, the IPCC has adopted some methods that have gone beyond being 'careful' and are now simply conservative.

Fred Pearce, writing in New Scientist on 10 February 2007, tells of an IPCC review process that was 'so rigorous that research deemed controversial, not fully quantified or not yet incorporated into climate models was excluded'. Pearce wrote: 'The benefit - that there is now little room left for sceptics - comes at what many see as a dangerous cost: many legitimate findings have been frozen out.' After interviewing many of the scientists involved, he described the process as 'a complex mixture of scientific rigour and political expediency [that] resulted in many of the scientists' more scary scenarios for climate change - those they constantly discuss among themselves - being left on the cutting room floor'.

The peer-review process for experimental science is conservative, insisting on verifiable, reproducible results. Peer-review can significantly delay the full publication of new findings. When research produces a range of outcomes with differing probabilities or risks, there is a tendency for the general reader, and even policy-makers, to be drawn to the middle position - or even to the low end of the range, which requires less action.

Wider uncertainties in climate science and the vulnerabilities of species to fast rates of temperature change are good examples, because they drive us to consider the worst outcomes - not just the scenarios that have average effects. Some of the high-impact scenarios considered by the IPCC to be 'extreme' are now looking quite likely.

Barrie Pittock says that uncertainties in climate-change science are inevitably large, due to inadequate scientific understanding, and to uncertainties in human agency or behaviour. He says: [Policies] must be based on risk management, that is, on consideration of the probability times the magnitude of any deleterious outcomes for different scenarios of human behaviour. A responsible risk-management approach demands that scientists describe and warn about seemingly extreme or alarming possibilities, for any given scenario of human behaviour (such as greenhouse gas emissions), even if they appear to have a small probability of occurring.

This, he says, is recognised in military planning, and is commonplace in insurance; the lesson for climate policy is that the object of policy advice must be to avoid unacceptable outcomes, not to determine the most apparent, likely, or familiar outcome.

Michael Oppenheimer and three fellow scientists agree, arguing that the emphasis on consensus has put the spotlight on expected outcomes, which then become anch.o.r.ed via numerical estimates in the minds of policy-makers; however, with the general credibility of the science of climate change established, they say it is now equally important that policy-makers understand the more extreme outcomes that consensus may exclude or downplay.

In the case of the Arctic, for example, it is clear that this has not been done. James Hansen laments: For the last decade or longer, as it appeared that climate change may be underway in the Arctic, the question was repeatedly asked: 'Is the change in the Arctic a result of human-made climate forcings?' The scientific response was, if we might paraphrase, 'We are not sure, we are not sure, we are not sure ... Yup, there is climate change due to humans, and it is too late to prevent loss of all.' If this is the best that we can do as a scientific community, perhaps we should be farming or doing something else.

Pittock has described the limitations of the IPCC process: Vested interests harboured by countries heavily reliant on fossil fuels for industry and development, or for export, lead to pressure to remove worst-case estimates; scientists ... tend to focus on 'best estimates', which they consider most likely, rather than worst cases that may be serious but which have only a small probability of occurrence; many scientists prefer to focus on numerical results from models, and are uncomfortable with estimates based on known but presently unquantified mechanisms; and due to the long (four-year) process of several rounds of drafting and peer and government review, an early cut-off date is set for cited publications (often a year before the reports appear).

Inez Fung at the Berkeley Inst.i.tute of the Environment says that for her research to be considered in the 2007 IPCC report, she had to complete it by 2004. 'There is an awful lag in the IPCC process,' she says, also noting that the special report on emission scenarios was published in 2000, and the data it contains were probably collected in 1998. 'The projections in the 2007 IPCC report [using the 2000 emission scenarios] are conservative, and that's scary', she says.

There is a widespread view that the more extreme an outcome, in a range of possibilities, the less likely it is to occur. This can underestimate the role of feedbacks in a nonlinear world, and the evidence suggests that, in many cases, it is precisely the more extreme events that are coming true.

The data surveyed strongly suggests that, in many key areas, the IPCC process has been so deficient as to be an unreliable and, indeed, a misleading basis for policy-making. We need to look to processes that are not dogged by politics, and to a more up-to-date and relevant scientific knowledge base that integrates recent data and findings, expert comment, and the need to account for the most unacceptable, but scientifically conceivable, outcomes. On that basis we can build strategies that will at least give us a real chance to avoid the great dangers manifest in the climate system, of which humanity has become both master and victim.

The primary a.s.sumptions on which climate policy is based need to be interrogated. Take just one example: the most fundamental and widely supported tenet - that 3 degrees represents a reasonable maximum target if we are to avoid dangerous climate change - can no longer be defended. At less than a 1-degree rise, the Arctic sea-ice is headed for rapid disintegration; in all likelihood, triggering the irreversible loss of the Greenland ice sheet, catastrophic sea-level increases, and global warming from the albedo flip. Many species and ecosystems face extinction from the speed of s.h.i.+fting isotherms. Our carbon sinks are losing capacity, the seas are acidifying, and the tropical rainforests are fragile and vulnerable.

We have been lulled into a false sense of security by the stability of the climate during the Holocene period (the geological period that started 11,500 years ago, after the last glacial retreat, and which includes the whole period of human civilisation). Yet the period of ice ages and rapid deglaciations that occurred when the climate whipsawed between two states for millions of years is the usual mode. 'Abrupt change seems to be the norm, not the exception', says Will Steffen, head of the ANU's Fenner School of Environmental Science in Canberra. This is something we do not see, or do not want to see - and that incapacity means that, inevitably, abrupt changes, which our actions are now ensuring will occur, will be all the more devastating for our lack of foresight.

If we could start all over again, surely we'd say that we need to stabilise the climate at an equilibrium temperature that would ensure the continuity of the Arctic ice. This safe level has long since been pa.s.sed. We should have acted rapidly to restore and maintain the Arctic ice cap, with a safe margin for uncertainty and error, as soon as we knew there was a problem. But, given what has happened, what choices do we have now?

PART TWO.

Targets.

'We, the human species, are confronting a planetary emergency - a threat to the survival of our civilisation that is gathering ominous and destructive potential ... the Earth has a fever. And the fever is rising. The experts have told us it is not a pa.s.sing affliction that will heal by itself. We asked for a second opinion. And a third. And a fourth. And the consistent conclusion, restated with increasing alarm, is that something basic is wrong. We are what is wrong, and we must make it right.'

- Al Gore, n.o.bel Peace Prize acceptance speech, 11 December 2007.

CHAPTER 8.

What We Are Doing.

Something is wrong and we must make it right. This section explores the direction in which we must head to do so. How far must human greenhouse-gas emissions be reduced? What is a safe temperature zone? How do we get there?

In answering these questions, our first task is to understand what the greenhouse gases that we are pouring into the air have done, and what they are likely to do in the future.

In November 2006, The New Yorker reported on calculations by Ken Caldiera, from Stanford University, that 'a molecule of carbon dioxide generated by burning fossil fuels will, in the course of its lifetime in the atmosphere, trap a hundred thousand times more heat than was released in producing it'.

The quant.i.ty of carbon dioxide in the atmosphere and its persistence mean that it contributes more to global warming than any other product of human activity. Together with water vapour, methane, nitrous oxide, ozone, and trace gases, it maintains the Earth's greenhouse effect by trapping heat that radiates from the surface and, in doing so, keeps the surface temperature 33 degrees warmer than it would otherwise be.

Humans pour carbon dioxide into the air princ.i.p.ally by processing and burning fossils fuels (coal, gas, oil, and its derivatives), and through the burning and decay of large amounts of organic material (as a result of changing land-use patterns and de-afforestation).

Human activity has increased the level of carbon dioxide in the air by 38 per cent from the 1750 pre-industrial level of 280 parts per million: by 2008, it was at 387 parts per million. According to UNESCO, this is the highest carbon dioxide concentration recorded in the past 600,000 years and, probably, the highest in the past 20 million years. What's more, the rate of increase has been at least ten, and possibly a hundred, times faster than at any other time in the past 400,000 years. So our species is creating energy imbalances in the climate system that are pus.h.i.+ng the rate of change far more rapidly than at any time since modern humans began to walk the planet.

When carbon dioxide is added to the atmosphere, oceans absorb some of it, vegetation (through photosynthesis) absorbs some, and some is trapped in sediments or by chemical reactions with eroding rock. The portion that remains in the atmosphere, however, is so stable and long-lived that it continues to produce its greenhouse effect for hundreds, even thousands, of years. It is generally understood that if we stopped adding carbon dioxide to the air, the carbon cycle would gradually draw down the amount of atmospheric carbon dioxide and, slowly, over time, the temperature would decrease; but this may not happen over the short time relevant to our current predicament.

New research presents a very sobering picture. Ken Caldeira and his Stanford University colleague Damon Matthews have used climate modelling to demonstrate that the portion of carbon dioxide that remains in the air produces a temperature increase that persists for many centuries. In the terms of their study, this means for at least 500 years - which was as far into the future as their model was run.

They showed that current human-related carbon emissions will produce a temperature rise of 0.8 degrees that will persist for more than 500 years. In plain language, the carbon dioxide that we emit will keep the planet heated for many centuries, and the more we emit the higher the temperature over that period will be. The unavoidable bottom line, according to Matthews and Caldeira, is that if we want to stabilise temperatures, we must eliminate all carbon dioxide emissions. They show that 'stabilizing global temperatures at presentday levels [which are 0.8 degrees above the pre-industrial level] required emissions to be reduced to near-zero within a decade [our emphasis].' This is an important result to which we will return later in the story.

Methane quant.i.ties in the atmosphere are also increasing. Since 1750, they have increased by 150 per cent, and about half a billion tonnes of methane are added each year, mostly as a consequence of human activity. When the full impact of methane is accounted for, its heating effect - including the results of its interaction with other gases to form ozone in the lower atmosphere - is at least half that of human carbon dioxide emissions. (At low levels in the atmosphere, ozone contributes to smog and is polluting. This is distinct from its role at levels in the upper atmosphere, where it creates the protective 'ozone layer'.) Drew s.h.i.+ndell of NASA's G.o.ddard Inst.i.tute for s.p.a.ce Studies estimates that methane may account for one-third of all climate warming from well-mixed greenhouse gases since the 1750s (carbon dioxide, methane, nitrous oxide, and halocarbons are known as well-mixed gases because their lifetime in the atmosphere is a decade or more): 'Control of methane emissions turns out to be a more powerful lever to control global warming than would be antic.i.p.ated,' s.h.i.+ndell concludes.

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