'Nothing off-limits' in climate debate- Rajendra Pachauri

THE UN's climate change chief, Rajendra Pachauri, has acknowledged a 17-year pause in global temperature rises, confirmed recently by Britain's Met Office, but said it would need to last "30 to 40 years at least" to break the long-term global warming trend.

Dr Pachauri, the chairman of the UN's Intergovernmental Panel on Climate Change, said that open discussion about controversial science and politically incorrect views was an essential part of tackling climate change.

In a wide-ranging interview on topics that included this year's record northern summer Arctic ice growth, the US shale-gas revolution, the collapse of renewable energy subsidies across Europe and the faltering European carbon market, Dr Pachauri said no issues should be off-limits for public discussion.

In Melbourne for a 24-hour visit to deliver a lecture for Deakin University, Dr Pachauri said that people had the right to question the science, whatever their motivations.

"People have to question these things and science only thrives on the basis of questioning," Dr Pachauri said.

He said there was "no doubt about it" that it was good for controversial issues to be "thrashed out in the public arena".

Dr Pachauri's views contrast with arguments in Australia that views outside the orthodox position of approved climate scientists should be left unreported.

Unlike in Britain, there has been little publicity in Australia given to recent acknowledgment by peak climate-science bodies in Britain and the US of what has been a 17-year pause in global warming. Britain's Met Office has revised down its forecast for a global temperature rise, predicting no further increase to 2017, which would extend the pause to 21 years.

Dr Pachauri said global average temperatures had plateaued at record levels and that the halt did not disprove global warming.

"The climate is changing because of natural factors and the impact of human actions," Dr Pachauri said.

"If you look at temperatures going back 150 years, there are clearly fluctuations which have occurred largely as a result of natural factors: solar activity, volcanic activity and so on.

"What is quite perceptible is, in the last 50 years, the trend is upwards.

"This is not to say you won't have ups and downs - you will - but what we should be concerned about is the trend, and that is being influenced now to a large extent by human actions."

He said that it would be 30 to 40 years "at least" before it was possible to say that the long-term upward trend in global temperatures had been broken.

"If you look at the last century, records tell you that the increase in average surface temperature has been 0.74C," he said.

"If you have five or 10 years when you don't have the same trend, that doesn't necessarily mean that you are deviating from the trend - you are still around the trend."

Dr Pachauri said the record accumulation of Arctic ice this northern summer - following a record melt last winter - was consistent with the current understanding of climate change.

He said the IPCC had "clearly specified there are going to be extreme precipitation events".

"If in the Arctic, for example, we get a huge amount of snowfall this year, you will get ice formation," Dr Pachauri said.

"That again is something that doesn't deviate from the trend, which time and again has shown that ice cover in the Arctic is shrinking."

Dr Pachauri said the IPCC was yet to finalise its estimates for sea-level rises and the contribution from melting ice sheets.

Commenting on the global energy transformation, Dr Pachauri said renewables faced an uncertain future in Europe, where public subsidies were being wound back and the carbon trading market had slumped.

He said there were many reasons for this, including the global financial crisis.

Dr Pachauri said nuclear energy was a reality that "you can't wish away" and would be dealt with in the upcoming fifth IPCC report.

He said the shale-gas revolution sweeping the US was already having a big impact on that country's carbon dioxide emissions.

"In terms of emissions, gas is certainly less than coal," Dr Pachauri said.

But he added that the importance of gas as a transitional fuel globally would depend on availability and price.

Overall, Dr Pachauri said, "we aren't doing all that well" in global attempts to combat climate change.

"There is a lot of awareness now but a lot of people also talk about these things of a fashion, without necessarily understanding what it represents and what sort of actions we need to take."