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Dr Jim Salinger composts his food scraps and uses energy-efficient light bulbs, while Dr David Wratt uses public transport and plants trees.

But the personal contributions of the Niwa climate scientists in tackling the issue of global warming go way beyond commitments to reduce their carbon footprints.

For years the pair have devoted huge amounts of time to the work of the Intergovernmental Panel on Climate Change (IPCC) which was this month awarded a Nobel Peace Prize.

The organisation shares the prize with former United States Vice-President Al Gore for his film An Inconvenient Truth, in recognition of their efforts to raise awareness and impetus around the threat of climate change.

While Gore might have got star billing in his attention-grabbing documentary on the frightening implications of human-induced global warming, the platform on which he launched it was thanks to the work of the IPCC scientists.

The IPCC is an international body of scientists and officials who have collaborated to assess the available scientific literature on climate change.

Among them have been about 30 New Zealand researchers who have contributed their expertise to the organisation which was established in 1998 by the World Meteorological Organisation and the United Nations Environment Programme.

Dr David Wratt, leader of Niwa's national climate centre, has been involved virtually from the start and overviews the IPCC process.

Dr Wratt was one of two co-ordinating lead authors for the Australia-New Zealand chapter in the 2001 assessment and is currently the only New Zealander on the 40-member IPCC bureau.

He said Gore had proven a skilled communicator who could "talk the science" in a way people could understand.

"Each report is the size of a telephone directory and even the summaries are quite technical and not that accessible to the public."

Dr Wratt said while Gore had perhaps over-simplified some material and in cases made errors in the detail, the overall scientific picture he presented was correct.

"Scientists have no doubt that carbon dioxide levels have increased and human-related activity is influencing the climate with substantial impacts."

Dr Wratt thought the sharing of the Nobel Peace Prize was "wonderful" and a well-earned reward for hours of unpaid work many scientists had dedicated to the task.

While some of the work was done as part of his salaried job at Niwa, there was still a great deal done in Dr Wratt's private time.

"I have spent a lot of weekends reviewing, but it is a satisfying commitment."

The IPCC assessed scientific literature, examined the arguments and laid out any disputes.

Climate models still differed with a range of predictions and the rate of global warming was open to debate.

Dr Wratt was aware there remained sceptics of the IPCC findings.

"That's been happening a long time - different people have different economic interests. What I get frustrated about is their very selective use of data which they don't properly assess."

The IPCC aimed to get good scientists and experts from around the world so the information was authoritative rather than "from just a small group with a particular road to hoe".

Dr Wratt did not believe the IPCC findings came too late, yet the reduction of greenhouse emissions was a huge challenge and how that was met would determine the impact of climate change.

"I would not like to see people giving up."

Success required international agreement involving China, India the US and Europe.

"Without that and good technology we won't get there but we do have time to do something. Attitudes are changing - they've moved on a lot even in the last year but there is a long way to go."

His colleague Dr Jim Salinger has been studying climate change for 30 years.

Dr Salinger was the lead author for the scientific assessment of climate trends in the 2001 IPCC report and was lead author for climate impacts in the Australia-New Zealand chapter of the fourth assessment.

Back in 1975 a scientific paper of Dr Salinger's was published suggesting the globe was warming up.

"So it has been a long time convincing people."

Dr Salinger said when studying for his doctorate in the 1970s a careful assessment of weather records showed there was measurable warming in New Zealand.

The country had warmed by 1C in the 20th century which was like changing Auckland's climate to that of Cape Reinga's, he said.

"The message is very clear that the climate is warming. We are on a roller-coaster and we must act now."

Dr Salinger said the IPCC process was robust and open, coming up with balanced assessments.

"It is an extremely good way of doing science and a very good demonstration of collaboration and cooperation."

Dr Salinger said the IPCC had worked quietly behind the scenes and deserved recognition, although "we were all surprised" by winning the Nobel Peace Prize.

"We got a note from the IPCC chair [Rajendra Pachauri] saying we were all nobel laureates."

The IPCC was established in 1988 by two United Nations organisations, the World Meteorological Organisation and the United Nations Environment Programme, to evaluate the risk of climate change caused by human activity.

The panel does not undertake research, or monitor climate. One of its key tasks is to publish special reports on the implementation of the UN Framework Convention on Climate Change, a treaty acknowledging the possibility of harmful climate change. Panel reports are drawn from peer reviewed and published scientific literature.