Previous criticism suggested large parts of IPCC reports were compiled with input from organisations such as WWF and Greenpeace

Report said CO2 has reached levels unprecedented in at least 80,000 years

Critics say this shows carbon dioxide isn't as damaging as was claimed

This is despite more greenhouse gases being pumped into atmosphere

UN scientists said today they are '95 per cent' certain that climate change is man made, but still could not explain why the world has barely got any hotter in the last 15 years.

The United Nations’ Intergovernmental Panel on Climate Change (IPCC) said that sea levels have risen by 19cm since 1901 and are expected to rise a further 26-82cm by the end of the century.

It added that concentrations of CO2 and other greenhouse gases in the atmosphere have increased to levels that are unprecedented in at least 800,000 years.

But the landmark report conceded that world temperatures have barely risen in the past 15 years, despite growing amounts of greenhouse gases being pumped into the atmosphere.

The IPPC reported revealed that it is 'extremely likely' that human activity is the dominant cause for global warming. It claims a rise in temperature in the Northern Hemisphere (right) will cause snow cover to decrease by 25 per cent by the end of the 21st century. But the report failed to conclusively explain why the rise in global average surface temperatures had largely 'paused' over the past two decades (left)

The high latitudes and the equatorial Pacific Ocean are likely to experience an increase in annual mean precipitation by the end of this century (right). In many midlatitudeand subtropical dry regions, mean precipitation will likely decrease from the 1986-2005 period (left)

KEY FINDINGS OF THE IPCC REPORT World temperatures have barely risen in the past 15 years. Temperature rises have dropped from 0.12°C per decade since 1951 to just 0.05°C per decade since 1998. The slowdown is great enough to be termed a ‘pause’ or ‘hiatus’ by scientists. But over the long term, from 1951, climate models have matched what has happened to global temperatures, the report said. The report said it is ‘extremely likely’ – with at least 95 per cent certainty – that humans are the main cause of rising temperatures since the 1950s. Each of the past three decades have been successively warmer than any preceding decade since 1850. Sea levels have risen by 19cm on average since 1901, with the rate of increase higher than in the previous two millennia. Concentrations of the greenhouse gases carbon dioxide, methane and nitrous oxide have increased to levels unprecedented for at least 800,000 years. Carbon dioxide is 40 per cent above pre-industrial levels, mainly due to burning fossil fuels and changes to land such as deforestation. Around 30 per cent of the carbon dioxide emitted has been absorbed by the oceans, which has the effect of making them more acidic. Continued emissions of greenhouse gases will cause further warming and changes ranging from melting ice sheets to sea level rises. Temperatures look set to rise more than 2C above pre-industrial levels without ambitious action to reduce emissions. Sea levels are expected to rise by between 26cm (10 inches) and 82cm (32 inches) by the end of the century. Climate change will also affect rainfall, with extreme rainstorms expected to get more intense and more frequent by the end of the century. Most aspects of climate change will persist for many centuries even if emissions of carbon dioxide are stopped. Advertisement

Temperature rises have dropped from 0.12°C per decade since 1951 to just 0.05°C per decade since 1998.

This slowdown has been seized upon by climate sceptics who claim carbon dioxide is not as damaging as has been suggested.

IPCC scientists, however, believe the pause is temporary and a return to 'substantial warming' is expected in coming decades.

The report only made a brief mention of the issue, stressing that short-term records are sensitive to natural variability.

In the briefing this morning, Thomas Stocker, co-chair of working group, said that the current warming hiatus could not be predicted because ‘there are not sufficient observations of the uptake of heat, particularly into the deep ocean.’

‘Likewise, we have insufficient data to establish a relationship between the causes of the warming,’ he added.

As expected, the IPCC raised its projections of the rise in sea levels to 26-82cm by the end of the century. The previous report predicted a rise of 18-59cm.

Storms will become more intense and frequent, and the oceans will become more acidic, the report predicted.

Mr Stocker added: ‘Heatwaves are very likely to occur more frequently and last longer. As the Earth warms, we expect to see currently wet regions receiving more rainfall, and dry regions receiving less, although there will be exceptions’.

Using four scenarios with different emissions controls, the report projected that global average temperatures would rise by 0.3°C to 4.8°C by the end of the century.

Only the two lower scenarios, which were based on significant cuts in CO2 emissions, came in below the 2°C limit that countries have set as their target in the climate talks to avoid the worst impacts of warming.

The report added that global warming will cause the circulatio n of warm and cold water in the Atlantic to weaken by 11 to 54 per cent by the end of the century.

This could have a big impact on Britain, causing cooling of about 1°C and disrupting weather patterns.

Some scientists have warned that the cooling would hide the impacts of global warming on the UK, and cause even more unpredictable and extreme weather patterns.

But there are concerns about the computer models used to calculate the data.

Professor Peter Wadhams, professor of Ocean Physics at the University of Cambridge, said: 'There are serious deficiencies in the modelling. The assessment makes extensive use of the UK Met Office model which does not take account at all of the feedback due to emissions from thawing permafrost.

'Nor is the possibility of a major methane emission from melting offshore permafrost on Arctic shelves mentioned, even though this has been projected as capable of adding 0.6°C to global warming.'

CO2 concentrations haveincreased by 40 per cent since pre-industrial times, primarily from fossil fuel emissions, claims the IPCC. The ocean has absorbed about 30 per cent of the emittedanthropogenic carbon dioxide, causing ocean acidification

Ocean acidification is determined by a decreases in pH. The pH of ocean surface water has decreased by 0.1 since the beginning of the industrial era, according to the report

WHAT IS THE IPCC AND WHY DOES THE REPORT MATTER? WHAT IS THE IPCC?

A scientific body with 195 member countries. The panel was established by the U.N. in 1988 to assess the causes and impacts of climate change. Since then, it has released four assessments, each stating the human link to global warming with more certainty than the previous one. The IPCC doesn't conduct its own research, but appoints hundreds of experts to review and summarise the latest scientific studies on climate change. It is headed by Rajendra Pachauri, a scientist from India.



WHAT IS THE REPORT FOR?

The report forms the scientific basis for U.N. negotiations aimed at curbing global warming. It will be a reference point for governments as they negotiate a new global climate agreement, which is supposed to be adopted by 2015 and to take effect in 2020.



WHY HAS THE IPCC COME UNDER CRITICISM?

It has been argued that the IPCC process is so time-consuming and laborious that by the time the assessments are published they are already out of date. A series of errors embarrassed the authors of the 2007 assessment, including the incorrect statement that the glaciers in the Himalayas would disappear by 2035. There has also been criticism about the IPCC's lack of openness. Advertisement

The IPCC report – the first in six years – was compiled with the help of over 800 scientists inciting more than 9,000 scientific studies. It will be used to inform government policy around the world.

Officials from 195 countries have spent this week behind closed doors in Stockholm, Sweden with UN scientists, hammering out a 30-page summary document which was released this morning.

The IPCC’s last major report was criticised for a string of errors – including the since-withdrawn claim that Himalayan glaciers would vanish within 25 years.

The group has also come under fire by sceptic Donna Laframboise whose analysis of previous IPCC reports revealed that two-thirds of their contents had been compiled with input from non peer-reviewed journals and organisations such as WWF and Greenpeace.

The latest report said it is ‘extremely likely’ – with at least 95 per cent certainty – that the burning of fossil fuels and other human activities are the main cause of rising temperatures since the 1950s.

That level of certainty is up from 90 per cent in the last report in 2007, and 66 per cent in 2001.

Controversially, several governments have called for the references to the 'pause' in climate to be amended or even removed from the report.

Germany has asked for the passage to be deleted, saying a timespan of 10 to 15 years is misleading in the context of climate change, which takes its toll over longer periods. Belgium objects to using 1998 as a starting year for the statistics, as it was exceptionally warm.

Climate scientists say such pauses in warming occur regularly throughout history and can last for up to 20 years – but cannot be predicted.

John Shepherd, professor of Ocean and Earth Science at the University of Southampton said: 'The recent slow-down in warming is interesting, but it may still be just a wiggle, maybe caused by a natural cycle in the ocean. If so we should expect more rapid warming in a few years time.

'There is no reason whatever to suppose that the slow-down is permanent: these things have happened before (e.g. 1950 to 1970), and no-one ever claimed that climate models could predict all these decadal wiggles.'

The IPCC added that much of the ‘missing’ heat is being stored deep beneath the sea, preventing it from contributing to temperatures at surface level.

Volcanic eruptions and changes in the sun’s activity are also thought to have contributed to the slow-down.

Scientists claim that global average sea levels will continue to rise during the 21st century under all temperature scenarios presented in the report. They say it will 'very likely' exceed that observed during 1971-2010 due to increased ocean warming and loss of mass from glaciers and ice sheets

During the longest period calculated (1901-2012), almost the entire globe experienced surface warming. The report said that warming of the climate system is 'unequivocal'. However, the report conceded that world temperatures have barely risen in the past 15 years

New forecasts: Intergovernmental Panel on Climate Change chief Dr Rajendra Pachauri

'It is predicted, from simple physics, that the more humanity increases the quantities of greenhouse gases in the atmosphere, the warmer the Earth will become,' said Professor David MacKay, chief scientific advisor to the Department of Energy and Climate Change.

'The far-reaching consequences of this warming are becoming understood, although some uncertainties remain.

'The most significant uncertainty, however, is how much carbon humanity will choose to put into the atmosphere in the future. It is the total sum of all our carbon emissions that will determine the impacts. We need to take action now, to maximise our chances of being faced with impacts that we, and our children, can deal with.'

Dr Ed Hawkins, a Reading University climate scientist, added that the current 'pause' in global surface temperatures certainly does not mean climate change has stopped.

He said surface temperatures have continued to rise more slowly than before, but other measures, such as rises in sea levels and melting snow and ice, show the climate has continued to change during this period.