Countries like New Zealand must shift to a low-carbon economy or risk being shut out by trade barriers, says a leading voice on climate change.

British economist Lord Nicholas Stern, in Auckland for a University of Auckland lecture series, says that the world is embarking on a "new industrial revolution".

Countries that did not invest in renewable energy and cleaner innovation risked falling behind technologically, or being excluded from trade markets, he said.

"All countries have to embrace [the industrial revolution] ... or countries will be reluctant to trade with them. Ten or 15 years from now, those that produce in dirty ways are likely to face trade barriers."

Lord Stern is the author of the landmark Stern Review, which articulated the cost of stabilising global warming.

In a lecture at the university's business school this week, he said New Zealanders needed to reduce their carbon footprint from nearly 20 tonnes of CO2 equivalent per person to two tonnes by 2050.

He believed that this was achievable with political will and radical changes in technology, particularly in agriculture.

"We know that New Zealand has half of its emissions from agriculture. But the possibilities of technical change in agriculture to move to the low-carbon economy are very strong. New Zealand could lead the world in that sort of change."

He said New Zealand's role was as important as any country's in reducing carbon emissions.

"Most of the countries in the world could argue that they're not making any difference because they're only 1 or 2 per cent [of emissions], or in New Zealand's case even less.

"But this has to be collaborative. Poorer countries could look at the richer countries, like New Zealand, and say 'well if they're not getting on with it, if they're finding it difficult, how can we, so much poorer, be expected to get on with it?'. One country has a big effect on others."

Lord Stern said he was a strong supporter of a price for carbon, but was not in a position to comment on New Zealand's emissions trading scheme.

However, he said, not chargingfor emissions would continue a market failure.

"If we go to have a meal in a restaurant, we expect to pay for the space, for the service that we get, for the food, for the energy, the cooking and the equipment, but we do not pay for the emissions associated with that whole process.

"That's a massive market failure. This market is not signalling scarcity. Some correction is fundamental. So we do need a price for carbon - it can be a tax, or a carbon trade."

The Stern Review, commissioned by the UK Government and published in 2006, said the benefits of strong, early action on climate change outweighed the cost.

The global response to climate change since then had been mixed, Lord Stern said.

The push to reduce emissions suffered two setbacks in the last year - accusations of bias in the science community, and criticisms of the Intergovernmental Panel on Climate Change.

"These have not helped."

But he said climate change science, gathered over 200 years, remained robust, and policy-makers should see the accusations as mostly irrelevant.

Lord Stern's final seminar in his three-part Sir Douglas Robb lecture series is tonight.

His primary reason for being in New Zealand was "to give some good lectures", but he planned to meet Government ministers and business leaders during his trip.