The financial markets are humanity’s only hope in the battle against global warming, the world’s top climate expert declared today as he presented the most overwhelming case ever made that humans are responsible for rapidly increasing the Earth’s temperature.

Rajenda Pachauri, the chairman of the Intergovernmental Panel on Climate Change (IPCC), said his organisation’s latest report provided “unequivocal” evidence that since 1950 the atmosphere and oceans had warmed, and that scientists were now “95 per cent certain” that humans were the “dominant cause”.

These patterns had been replicated across the climate system, as the amount of snow and ice had diminished, the mean global sea level had risen and concentrations of greenhouse gases had increased, he added..

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The report says many of the observed changes are unprecedented in recent millennia and without extreme action to curb greenhouse gas emissions, global warming is likely to exceed 2C by the end of this century. This is the level at which the consequences become even more devastating and which world governments have agreed to try to avoid.

But Dr Pachauri warned that unless a price could be put on carbon emissions that was high enough to force power companies and manufacturers to reduce their fossil-fuel use, there seemed to be little chance of avoiding hugely damaging temperature increases.

“An extremely effective instrument would be to put a price on carbon. It is only through the market that you can get a large enough and rapid enough response,” he said, calling on policymakers around the world “to see what’s required”.

Dr Pachauri said the IPCC was working on “mechanisms” through which the market could be used to reduce carbon emissions. These are likely to be announced in April next year when the IPCC releases the third part of its assessment, which deals with climate change mitigation.

Today’s instalment dealt with the science. The second section, released in March, will cover impact and adaptation.

Dr Pachauri noted that the world had already burned more than half of the one trillion tonnes of carbon permitted if it is to have a reasonable chance of limiting the temperature rise to 2C. Furthermore, rapid industrialisation in the developing world is increasing global emissions so fast that the world is on course to use up its entire carbon budget within 25 years.

The consequences of climate change include rising sea levels, more and hotter heatwaves, and changes to rainfall meaning dry regions get less and wet areas receive more, the report says.

The report’s co-chair, Professor Thomas Stocker, said: “Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions.”

In a clear message to climate change sceptics within the Conservative Party ahead of its conference in Manchester, the International Development Secretary Justine Greening told The Independent that global warming caused by humans “could not be ignored”.

“It is clear to me that we need to see climate change tackled and we need to play our role both nationally and internationally. We cannot keep just consuming more and more and more forever… Can we ignore it? No,” she said.

Professor Kevin Anderson, of Manchester University and the Tyndall Centre for Climate Change, said: “So what are we doing in the UK to help reverse this reckless growth in emissions? Record levels of investment in North Sea oil, tax breaks for shale gas, investment in oil from tar sands and companies preparing to drill beneath the Arctic.”

The IPCC admitted that it was still unclear about the causes for the slowdown in climate change in the past 15 years, but insisted that the long-term trends were beyond doubt and that a decade and a half was far too short a period in which to draw any firm conclusions. The temperature rise has slowed from 0.12C per decade since 1951 to 0.05C per decade in the past 15 years – a point seized upon by climate sceptics to discredit climate science.

Professor Stocker said: “People always pick 1998 but that was a very special year, because a strong El Niño made it unusually hot, and since then there have been a series of medium-sized volcanic eruptions that have cooled the climate.”

The oceans are also thought to have played a large role in the so-called warming hiatus, with the earth’s heat being re-arranged as larger quantities are taken down into the deep ocean.

The report’s 18 headline messages include the finding that the pace of the Earth’s warming has increased rapidly over the past three decades – a period that is “likely” to be the warmest in the past 1,400 years. It says it can state with “high confidence” that ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90 per cent accumulated by the planet between 1971 and 2010.

Qin Dake, the other co-chair of the report, said combating climate change would have severe implications for people’s lifestyles, especially in his home country of China, the world’s most populous nation and its largest carbon emitter.

Speaking through a translator, he said: “If every Chinese has two or three cars like in the US, it will be a disaster for China as well as for the world… This will have a very big impact on the lifestyle of Chinese people.”

What the Scientists Say...

Lord Stern. London School of Economics

The report makes clear that the Earth is warming and the climate is changing, that human activities are primarily responsible, and that without very strong cuts in emissions of greenhouse gases, we face huge risks from global warming of more than 2C by the end of this century compared with the period before the Industrial Revolution. All governments have agreed that it would be dangerous to exceed a threshold of global warming by 2C. Delay is dangerous because greenhouse gases are accumulating in the atmosphere and because we are locking in high-carbon infrastructure and capital.”

Professor Tim Lenton. Chair in climate science at the University of Exeter

“What concerns me most is the growing evidence that frozen parts of the climate system are responding extremely sensitively to global warming – the retreat of Arctic summer sea-ice is unprecedented and the rate of ice loss from both the Greenland and Antarctic ice sheets has increased five-fold in just the last two decades.”

Professor Corinne Le Quéré. Director of the Tyndall Centre for Climate Change Research

“This is not just another report, this is the scientific consensus reached by hundreds of scientists after careful consideration of all the available evidence. The human influence on climate change is clear and dominant. The atmosphere and oceans are warming, the snow cover is shrinking, the Arctic sea-ice is melting, sea level is rising, the oceans are acidifying, and some extreme events have increased. CO2 emissions from burning fossil fuels need to substantial decrease to limit climate change.”

Professor Bob Watson. Tyndall Centre for Climate Change Research and the University of East Anglia

“The latest IPCC report strengthens its earlier conclusions that most of the observed warming since 1950 has been caused by human activities, and future changes are inevitable. Also, many of the other changes observed in the climate system, such as the rate of loss of Arctic sea-ice, melting of mountain glaciers and the Greenland ice-sheet are unprecedented. Without immediate reductions in global emissions of greenhouse gases, the world will not be able to achieve the political target of limiting the increase in global mean surface temperatures to 2C, but rather we are likely to see an increase of 3-5C. Time to act is running out if we are to take the threat of human-induced climate change seriously.”

... and the sceptics

Professor Judith Curry, The Georgia Institute of Technology in Atlanta

“Well, IPCC has thrown down the gauntlet – if the pause continues beyond 15 years (well it already has), they are toast.”

Myron Ebell , the right-wing think tank the US Competitive Enterprise Institute

“Global warming, although it may become a problem some decades in the future, is not a crisis and is highly unlikely to become a crisis. We should be worried that the alarmist establishment continues using junk science to promote disastrous policies that will make the world much poorer.”