John Key should treat seriously the challenge issued by the Greens' new co-leader to find common ground on climate change. James Shaw sounded genuine in his victory speech on Sunday when he declared himself open to working with National "where there is common cause".
New Zealand soon needs to set itself a new emissions reduction target to take to an international climate conference in Paris in December. The Prime Minister is probably struggling to summon much enthusiasm for the task having attended the non-event in Copenhagen ("a long way to go for a bacon sandwich") in his first year of office. But all Governments had more pressing concerns at that time. Seven years after the financial crisis, the world may be ready to address the climate seriously again.
If so, New Zealand could be embarrassed in Paris. A consultation paper issued by the Government last month was silent on an emission reduction target for the decade 2020-30, unlike the European Union which is aiming to reduce emissions to 40 per cent below 1990 levels by 2030, and the United States which is offering 26-28 per cent below its 2005 emissions by 2025. New Zealand will be expected to at least improve on its current target of 5 per cent below 1990 levels by 2020.
National has always overstated the economic costs of putting a realistic price on greenhouse emissions. If it were to adopt a 10 per cent reduction target, the consultation paper estimates the value of household consumption in 2027 would be lower by 1.5 per cent, or less than $1300 a year. GDP growth could average 2.3 per cent rather than 2.4 per cent a year. The prospect is hardly terrifying, and it is based on a carbon price of $50 a tonne - about eight times its level in emissions trading at present.
The Greens have always argued that the economic costs would be more than made up by the economic opportunities available to early movers on clean technology and adaptations to climate change. It is a possibility National tacitly accepts by investing in efforts to reduce methane emissions from farm stock, source of nearly half of New Zealand's greenhouses gases. It reports promising developments on that front without clear commercial prospects as yet.