Scientists deliver a bleak vision of a future in which storms are more frequent and the sea has risen by up to 82cm, as they say they are more certain than ever that mankind drives global warming.
The Intergovernmental Panel on Climate Change (IPCC) said it was extremely confident, with 95 per cent certainty, that the dominant cause of climate change is human activity, as it released its latest scientific report.
Michel Jarraud, secretary general of the World Meteorological Organisation, said: “This report confirms, and you’ll hear a lot more about it, with even more certainty than in the past, that it is extremely likely that the changes in our climate system for the past half a century are due to human influence.
Human influence on climate change is clear. Thomas Stocker, IPCC
“And it should serve for yet another wake-up call that our activities today will have a profound impact on society, not only for us, but for many generations to come.”
These assessments are important because they form the scientific basis of UN negotiations on a new climate deal.
Thomas Stocker, co-chair of the IPCC report’s working group, said: “Human influence on climate change is clear.”
The new deal is supposed to have been agreed upon by world governments by the end of 2015, but it is unclear if they will agree to emissions cuts that scientists say are needed to prevent the worst impacts of climate change.
The report, the first since 2007, upgraded estimates for the impact of climate change.
It raised estimates for sea-level rise by the end of the century from an 18 to 59 centimetre increase to a 26 to 82 centimetre increase. This compares with a 19-centimetre increase over the last century.
Using four scenarios that adopted different levels of global emissions, the report projected that global average temperatures would rise by 0.3 to 4.8 degrees celsius by the year 2100.
Science Editor Tom Clarke traveled to the Arctic to sea the impact of climate change first hand - find out what he discovered here.
The report also predicted extremes of heat, saying: “It is virtually certain that there will be more frequent hot and fewer cold temperature extremes over most land areas on daily and seasonal timescales as global mean temperatures increase.
“It is very likely that heat waves will occur with a higher frequency and duration.”
Storms will become more fierce and frequent, the report also warns.
“Extreme precipitation events over most of the mid-latitude land masses and over wet tropical regions will very likely become more intense and more frequent by the end of this century, as global mean surface temperature increases,” it said.
Estimates of the reduction in sea ice levels vary from 43 per cent by the end of the 21st century to 94 per cent.
The sea is also estimated across 95 per cent of the world’s oceans, and will also “acidify”, caused by increased levels of carbon dioxide being absorbed by oceans.
Governments should learn from the mistakes of the global financial crisis… and listen to the experts before it is too late. Tim Gore, Oxfam
The report also reveals the impact that climate change has had up until 2012. It says the period from 1983 to 2012 was the warmest 30-year period in the last 1,400 years.
Carbon dioxide, methane and nitrous oxide have increased to “unprecedented levels”, the report says, adding that carbon dioxide concentrations have increased by 40 per cent since pre-industrial times.
The report has been welcomed by campaign groups, who say it is further evidence of the harmful impact humanity is having on the earth.
Tim Gore, of Oxfam, said: “The latest climate science affirms what small-scale farmers around the world are telling us: seasons are changing, weather is increasingly extreme and unpredictable, making it tougher to feed their families.
“This report also tells us it is possible to avoid the very worst impacts of climate change and the goal of ensuring everyone has enough to eat is still attainable.
“Governments should learn from the mistakes of the global financial crisis, where warning signs were ignored, and listen to the experts before it is too late.”
Wendel Trio, director of the Climate Action Network Europe, said the debate about the responsibility for climate change was now over.
“Scientists are more certain than ever that humans are causing climate change but, fortunately, equally certain that we still have the time and means to fix it.”
Climate Change Secretary Ed Davey also welcomed the report, saying: “Without urgent action to cut greenhouse gas emissions, this warming will continue, with potentially dangerous impacts upon our societies and economy.
“This strengthens the case for international leaders to work for an ambitious, legally binding global agreement in 2015 to cut carbon emissions.”
Reaching such an agreement will hinge on the attitude of China and other emerging economies, who are the drivers of rising carbon emissions.
However, Dr Bjorn Lomborg argued that the report was proff that “alarmist” scenarios are not being played out.
“Since 1980, the average of all climate models have overestimated actual temperature increases by 71 to 159 per cent.
“This does not mean that there is not some global warming, but it likely means that temperature rises will be lower than originally expected. That fact makes alarmist scenarios ever more implausible.”