It is greatly to Flannery’s credit that, faced with daunting conclusions on this scale he habitually finds grounds for positive thinking and action. That was true of The Weather Makers which ended with a call to arms for household action, still one of the main fronts of climate strategy. In 2006, as the emerging data bean to indicate the dramatic acceleration of the warming trend, his scientific training led him to a pessimistic assessment and into advocacy of nuclear technology as a last line of defence–a not inconsiderable reversal for him, given his long-held green convictions. Even now he seems to be prepared to keep the nuclear option (as in technology, not war, although it is difficult to disentangle the two) on the agenda. But with the publication of Hansen’s paper Flannery’s focus has moved. The critical challenge presented by the paper, and a startlingly new one, is not how to prevent emissions growth, which is the only potentially positive contribution of nuclear technology (and even then, in terms of life-cycle and embedded energy, a matter of continuing controversy). It is how to extract carbon from an already overloaded atmosphere, a task to which nuclear technology can make no contribution. It becomes necessary to turn to other strategies and technologies, some very old, some new, some well understood and tested, others still being proved. Whatever works, is the blunt criterion.

To begin with, Flannery, following Hansen (as he does throughout the lecture) turns to the fuels that are the mainstay of modern economies: coal and oil. There is no doubt coal-fired energy is the single greatest contributing technology to greenhouse gases among all technologies. That is particularly true of electric power stations that burn low-grade brown coal. These are common in the developing world; although Australia, too, to its shame, has its share of them. In this context it is worth remembering that China is reported to be commissioning a new, mid-sized power station, fired by coal, every week. The Flannery/Hansen position is that coal technologies must be phased out, but that this is unlikely to occur at the pace which the new models indicate is required. Weight is therefore given to carbon sequestration as a means to minimise the impacts. Under this proposal no new coal-fired power stations would be built without support from the sequestration technology.

In this, many would argue, Flannery/Hansen have for once allowed wishful thinking to override scientific, or even practical, judgement. There is no proven sequestration project operating anywhere in the world. There are serious challenges facing both CO2 extraction from the coal-firing process and its concentration prior to injection and storage. There are equally serious questions concerning the geological feasibility of storing these emissions for the very long periods of time–far in excess of any social scale we can contemplate–that a coherent climate change policy will require. While not as dangerous to long-term human health as nuclear waste, these stored emissions are nevertheless potentially lethal. Natural leakage of carbon monoxide is known to have been responsible for many deaths. On the timescale of the action required by the Flannery/Hansen position, there is serious doubt that carbon sequestration technology can be developed, tested, proven and safely deployed. It may well be that it cannot be developed at all. 

Oil and gas, the other main fossil fuel culprits, are to be handled by economic instruments, specifically a carbon tax. Weighted against the chief alternative, an emission trading scheme, I agree that a carbon tax is to be preferred. Any emissions trading scheme is complex and expensive to mount, as the EU experience with carbon trading has shown. Special exemptions for exposed industries, such as those now being sought, with flagrant greed and self-interest, by companies associated with the Business Council of Australia, threaten to eviscerate the effectiveness of the proposed trading scheme. A carbon tax, in contrast, is simple and inexpensive to implement. Moreover, it yields a ‘double dividend’, collected tax revenue which can be applied to cushion impacts on the most disadvantaged–the poor and the economically marginalised–and to further the development of renewable technologies. 

Either way, whether economic instruments can lead to material reductions in greenhouse gas levels or not is yet to be seen. Four years of the EU emissions trading operation has not produced unambiguous evidence of reduced emissions in the EU countries trading through it. On the other hand, there is well-documented evidence of financial windfalls gained by companies which were over-allocated emissions permits in the initial handouts and quickly sold them. Carbon offset mechanisms have proved an ecological and regulatory minefield. There is a long way to go before effective trading in greenhouse gases can be said to be in place anywhere in the world. To extend this task to the development and implementation of a truly global emissions trading scheme–the requirement for handling global CO2 levels, since the atmosphere doesn’t recognise national borders–is a formidable challenge to the global community, to say the least of it. 

Renewable energy technologies, particularly wind and solar, are supported under the Flannery/Hansen proposal. In places like Australia, geothermal energy and its associated technologies offer particular promise. There is emerging evidence that, at the household level, wind and solar technologies can be effective. What is would take for these technologies to make an impact on business and industry–by far the greatest users of energy–is not at all clear: the tradeoffs in land use that would require are daunting to contemplate. 

This tripartite approach–carbon sequestration, economic instruments, renewable energy technologies–constitute the main ramparts that Flannery, following Hansen, proposes to build against the tide of increasing greenhouse gas emissions. On the other side of the equation, the extraction of existing CO2 from the atmosphere, Flannery/Hansen offer two strategies. The first centres on the ability of trees to take up and store carbon as they grow. This is hardly a new strategy, but Flannery/Hansen give it new urgency. Their focus is on tropical forests, because it is there that growth is most rapid and the rate of carbon uptake is consequently greatest. The two arms of the strategy are thus the reduction and eventual (but sooner rather than later) halting of tropical deforestation, particularly in Indonesia and Latin America; and the replanting of the vast areas of degraded tropical forests. This strategy doesn’t exclude other forest ecoregions, such as the Taiga: a recent Australian National University study found maximum levels of carbon storage in Australia’s old growth forests, many of which are in temperate (for the time being) zones. But, other things being equal, Flannery/Hansen are pointing out that the best outcomes, in terms of carbon extraction and storage, for a given level of resource expenditure, is a tropical forest strategy. 

Alongside this well-known mechanism, Flannery/Hansen place considerable weight on a relatively new application of a process called pyrolysis. Essentially this technology is a method of burning carbon under controlled conditions to produce charcoal (‘biochar’–see Cornell research). Unless further heated, charcoal, Flannery points out, is inert and stable, and can be buried with impunity; in fact, properly crushed, charcoal is known to improve soil structure and fertility. Flannery paints a picture of a future crop harvest, where a pyrolising unit is being towed behind a harvester to render stubble into charcoal, instead of burning it off. Experiments are said to be under way in large-scale pyrolising, such as that associated with municipal waste-water systems. It is, however, a technology that is still in its early stages, and its scope of application is far from certain. Even its energy budget is yet to be established finally: one needs to be confident that it is, in fact, a technology that reduces, not increases, net emissions before it is widely deployed. 

Both tropical forests and pyrolising strategies are clearly in the right direction. However, if Flannery’s numbers are right, at best they offer limited CO2 capture, relative to the requirement. Even if CO2 production is reduced by the other three strategies, it is not at all evident that together they will effect the closing of the gap between production and capture that a stable global CO2 budget demands; certainly, if Hansen’s projections are correct, not in time.

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