KEY POINTS:
Large advertisements at Brussels airport on Saturday offered flights from there to Vienna or Prague for €19.
That's about $35 for flights to what are not even neighbouring countries. The taxi fare at the other end might cost more.
While such cheap air travel may be great for the cause of European integration, it is not so good from the standpoint of greenhouse gas emissions and climate change.
Emissions from aviation account for only 3 per cent of Europe's overall emissions but they are growing fast and have almost doubled since 1990.
Hence plans put forward by the European Commission to include aviation in Europe's emissions trading scheme (ETS), so that the price of air travel will incorporate, at least to some degree, the cost of its global environmental impact.
Under the commission's proposal, from 2012 not only flights within Europe but those originating or terminating in a European airport will be bound by the cap-and-trade scheme.
So it would include, for example, the Heathrow-Los Angeles or Hong Kong-Frankfurt legs which make up about half of the journey from New Zealand to Europe.
A lot of kerosene has to flow from the bowser before this is a fait accompli.
But the issue illustrates in microcosm the kind of difficulties that arise in dealing with climate change in a globalised but far from united world.
Let's start with the environmental case. That figure of 3 per cent of emissions probably underestimates the impact of aviation on global warming, because it reflects carbon dioxide emissions but not other, indirect effects from emission of oxides of nitrogen, contrails and the effects of cirrus clouds.
The United Nations' intergovernmental panel on climate change has estimated that the total impact from aviation may be twice, or even as much as four times, that of its CO2 emissions alone.
The EC estimates that someone flying from London to New York and back generates the same level of emissions that the average European does heating his home for a year.
The proposal to cap emissions at the average level between 2004 and 2006, it reckons, would save 183 million tonnes of CO2 a year by 2020, a 46 per cent reduction.
To put that in context, New Zealand's total greenhouse gas emissions are running at about 80 million tonnes a year.
Environmentalists say one reason European air fares are so low, and the associated emissions growing so fast, is that under an international convention the aviation fuel used in international flights is not taxed. The same applies to the fuel used in international shipping.
In addition international air fares escape the equivalent of GST.
The case for making polluters pay through a cap-and-trade system, rather than tax or regulation, is that - in principle at least - it achieves the emissions cuts at least cost.
It is accepted that not all - indeed probably not much - of that 183 million tonnes reduction in emissions would be achieved within the aviation sector itself, through airlines investing in more efficient engines or optimising their operations so they haul fewer empty seats around, for example.
What emission trading does is allow the airlines to buy emission reductions achieved, more cheaply than they could, in other sectors covered by the ETS.
Learning a lesson from the first phase of the European ETS, the proposed policy for aviation will give national Governments no discretion in setting the caps for their national carriers, lest they use it to try to get some competitive advantage over those of other member states. The caps on the airlines' permitted emissions will be harmonised across the union.
Likewise the proportion of allowances auctioned, rather than issued free, and the extent to which credits generated outside Europe through the Kyoto Protocol's clean development mechanism, can be used will be based on averages for those parameters through the ETS as a whole.
The EC expects the extra cost from including a carbon price in air fares to be significantly lower than the increases arising from higher world oil prices in recent years.
And it expects including aviation in the ETS to have only a marginal effect on airlines' profitability because they should be able to pass on most or all of the extra cost to customers.
That may be a prematurely sanguine view. After all the rapid growth in the patronage of low-cost carriers suggests that at least some aviation markets are pretty price-elastic. Higher fares should have some impact on demand.
All of this would be of purely academic interest in New Zealand but for two things.
One is that the Government reaffirmed this week that it is heading down the emissions trading path and favours a scheme that is economy-wide, covering all sectors and all the greenhouse gases. That presumably includes aviation.
The second is that the EC's plan includes flights to and from, and not just within, the European Union.
The reason for not confining it to intra-European flights seems to have been political.
Southern European countries worried that it might mean it would be cheaper for holidaymakers from northern Europe to fly to North African destinations rather than their own resorts.
And clearly applying the measure only to European airlines would put them at a competitive disadvantage.
But by moving unilaterally the EU is buying a fight with the United States. Washington has said the EU can do what it likes with its own carriers but extending the measure to non-European airlines is permissible only on the basis of mutual consent of those airlines.
The New Zealand Government is more non-committal, saying it is studying the plan but could have wished for a more consultative approach.
The United Nations body which deals with international aviation matters, the International Civil Aviation Organisation (ICAO), has been discussing the issue of greenhouse gas emissions for years.
Its most senior body, called the assembly, which meets only every three years, endorsed at its last meeting in 2004 the development of an open emissions trading system for international civil aviation and commissioned the development of guidelines to provide guidance for member states on how to incorporate aviation emissions into their emissions trading schemes.
But whether this amounts to a mandate for what the Europeans are now proposing is a moot point.
It would not be surprising if they were frustrated with the ICAO process. The more multilateral the forum, the more ponderous and slow-moving it tends to be.
But in any case the wisdom of buying a fight with the US on the issue is questionable.
At this point in the tormented geopolitics of climate change the focus surely should be building a global consensus for action beyond 2012.
Coaxing the US to take its responsibilities seriously is likely to be more productive than trying to bully it.
The European Parliament and the council, the EU's ultimate decision-making body which represents the member states, have yet to pronounce on the commission's proposal.
Whether the delicate state of climate geopolitics cuts any ice with them remains to be seen.
Europe can justly claim leadership in the climate change issue, but in the end it is only leadership if others follow.
* Brian Fallow visited Brussels under the European Union Visitor Programme.
