Humans are the main reason for climate change – but the scientists behind landmark report STILL can’t explain why the world’s barely got any hotter in the last 15 years

Ellie Zolfagharifard — Daily Mail Sept 27, 2013

Humans are the main reason for climate change – but the scientists behind a landmark report published today still can’t explain why the world has barely got any hotter in the last 15 years.

The United Nations’ Intergovernmental Panel on Climate Change revealed this morning that it is ‘extremely likely’ that human activity is the dominant cause for global warming observed since the 1950s.

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. Click to enlarge

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

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.

However, the IPCC made only 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.

But critics argue this shows carbon dioxide is not as damaging as had been claimed. Indeed, the report admitted that computer models of climate change were too pessimistic.

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.

At this point, emissions keep rising mainly due to rapid growth in China and other emerging economies.

They say rich countries should take the lead on emissions cuts because they’ve pumped carbon into the atmosphere for longer.Climate activists said the report should spur governments to action. However, some scientists insist the slow-down is temporary – and warn that global warming remains a pressing threat.

The report added that global warming will cause the circulation of warm and cold water in the Atlantic to weaken by 20 to 44 per cent by the end of the century.This will have a big impact on Britain, causing cooling of about 1.8F (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.

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 report has given the strongest warning yet that climate change is man-made and will cause more heatwaves, droughts and floods unless governments take action.

The 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.

The IPCC, led by Rajendra Pachauri, will also give new estimates of the effect of global warming on sea levels, glaciers and ice sheets.

But its explanation of why the rise in global average surface temperatures has ‘paused’ is the most contentious passage.

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.

Controversially, several governments have called for the references to the slowdown 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. 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.

However, the report acknowledged that some of the computer programmes used to predict changes to the climate over-estimated the effect of carbon dioxide.

Ed Hawkins, a climate expert from Reading University’s department of meteorology, said: ‘The current “pause” in global surface temperatures certainly does not mean climate change has stopped.

‘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.

‘Greenhouse gases are continuing to build up in the atmosphere and are warming the climate, but we believe temporary factors such as small volcanic eruptions and a decline in solar activity, alongside extra heat being absorbed into the deep ocean, are acting to temporarily cool the climate.

‘When these temporary factors subside, we should see a return to warming.’

The IPCC report also said that the world has already burned through half the amount of fossil fuel that will bring about dangerous levels of climate change, and that many of the changes that have already occurred to the atmosphere, land and sea are ‘unusual or unprecedented on time-scales of decades to millennia’.

Two more IPCC reports will be issued shortly, covering the impact of the changing climate and how to limit the damage, ahead of treaty talks in Paris in 2015.

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