UN scientists to say they are '95% sure humans to blame for climate change'

The UN's Intergovernmental Panel on Climate Change will release its fifth assessment report tomorrow. Photo: Reuters/Pawel Kopczynski

Nine years ago, climate change was becoming THE issue. How do I know? My editor sent me on the most extensive foreign trip I've ever done - 50,000 miles, six countries on five continents. Three months of travel and reporting on how our climate was changing and whether man's activities were driving that change.

Now the issue has slipped down almost everyone's list of priorities. And that's not surprising given the near collapse of the banking system and recession.

People are more worried about the size of their electricity bill, rather than whether the electricity comes from a coal-fired power station belching the carbon dioxide that has accelerated global warming or a nice green wind farm.

But tomorrow sees the focus once again on this contentious debate with the United Nations' Intergovernmental Panel on Climate Change (IPPC) publishing a huge report on the science of what's happening to our climate.

The IPCC is a bit apprehensive about its reception because a few years back it had to admit that it had been less than scrupulous in presenting a previous report.

Climate and energy has slipped down the global agenda since the recession. Credit: Reuters/Lucy Nicholson.

But among scientists, there's a real confidence about two "facts".

First, the world is warming - that, they say, is rock solid. And secondly, that our emissions of CO2, from power stations, cars and lots of other sources, are helping to drive increasing temperatures.

Tomorrow the IPCC is widely expected to say that is now 95% certain.

The IPPC say scientists agrees that the world is warning, and that it its warning because of our CO2 emission. Credit: Reuters/Enrique Marcarian

But they will also admit that something unexpected has happened over the last 15 or so years - the trend in average global temperatures has reversed. The trend over that period has been downward.

They can't explain exactly why - though some think it's because the heat has been going into the oceans rather than our atmosphere.

But they know that it's just a blip - and tomorrow's report will almost certainly says it's just part of natural variation and it's happened before in the records.

Middle Rongbuk glacier, Everest photographed in 1968 and again in 2007. Credit: Greenpeace/PA wire

They may well be right, but governments have reportedly been asking the IPCC for more explanation. And that's partly because those who don’t believe man-made climate change is a reality have seized on this "pause" in global warning as evidence that it isn't really happening at all - or is a lot more complicated than we've been told.

The scientists are frustrated. Just at a time when they think scientific certainty is at an all-time high, doubts are creeping in.

Tomorrow's IPCC report will try to dispel those doubts about the basics of climate change and urge the need for governments to act. But on a political level, MPs know that in the next general election, climate change is probably not going to be a decisive issue.

Governments last for five years - planetary changes last a lot longer.