Last week's announcement by the Government of a target of a 10-20 per cent reduction in greenhouse gas emissions by 2020 was a big disappointment and continues a disturbing recent trend of bad decisions for the environment.

The 2020 target is important. The world needs to stabilise greenhouse gas emissions at 450 parts per million by 2050 - which will require emission reductions of 80 per cent from developed countries - to avoid runaway global warming.

To get on this path, scientists say developed countries need to reduce emissions by 25 to 40 per cent by 2020. New Zealand is not yet even at the lowest point of that range with our offer last week in Bonn. The overall costs to the economy of reaching the 2050 target will be lower if we start now rather than being forced to make deep cuts later.

The world needs to act boldly and in concert to avoid catastrophic climate change. New Zealand has always prided itself on being an environmental leader. With our target, we are now seen as a laggard.

It may be that Greenpeace's 40 per cent campaign failed to address the complexities of climate change targets enough, but the community support it got certainly gave the Government a mandate to be bold with its decision.

Ten per cent is a desultory starting point that provides the big emerging economies with a further excuse to do nothing. Only if developed countries offer more significant cuts in emissions than ours, will China, India and Brazil make a commitment.

The role played by the Greenhouse Policy Coalition has once again proven decisive. The GPC is a coalition of big energy users and polluters. The activities of Solid Energy, a taxpayer owned SOE, are especially questionable. How can public monies be used to bankroll a campaign designed to protect profits being made from the use of coal - the worst greenhouse fuel - while denying the wider public interest?

The one good bit of news in last week's announcement was that the Government remains committed to an all-sectors, all-gases emissions trading scheme. Agricultural emissions make up 50 per cent of our total, and their growth from 2005 onwards will face a price under the scheme. At least we retain a little international credibility there. This approach will also provide an incentive to explore ways of reducing emissions in the farming sector that could create an economic windfall for New Zealand by selling new reduction technologies abroad.

The assertion by the Prime Minister that New Zealand's policy is moving in step with Australia will be explored at the fifth Australia-New Zealand Climate Change and Business Conference in Melbourne, August 24-26. While both countries are taking low 2020 targets to Copenhagen, at least New Zealand will be forging ahead with an ETS. The Australians are deadlocked on their equivalent.

* Gary Taylor is chairman of the Environmental Defence Society and convener of the fifth Australia-New Zealand Climate Change and Business Conference.