Post date: Sep 27, 2013 12:7:29 PM
Leading climate scientists say they are more certain than ever mankind is the main culprit for global warming and warn the impact of greenhouse gas emissions will linger for centuries.
STOCKHOLM, SWEDEN (SEPTEMBER 27, 2013) (REUTERS) - Leading climate scientists said on Friday (September 27) they were more certain than ever mankind was the main culprit for global warming and warned the impact of greenhouse gas emissions would linger for centuries.
A report by the Intergovernmental Panel on Climate Change (IPCC) played down the fact temperatures have risen more slowly in the past 15 years and said there were substantial natural variations that masked a long-term warming trend.It said the Earth was set for further warming and more heatwaves, floods, droughts and rising sea levels as greenhouse gases built up in the atmosphere. The oceans would become more acidic in a threat to some marine life.
In a video message to a news conference to present the report, United Nations(UN) Secretary General Ban Ki-moon called for action.
"This new report will be essential for governments as they work to finalise an ambitious legal agreement on climate change in 2015," he said.
Governments have promised to agree a UN deal by the end of 2015 to restrict emissions.
"It is extremely likely that human influence has been the dominant cause of observed warming since the mid-20th century," according to the summary issued after a weeklong meeting in Stockholm and meant to guide policymakers in shifting towards greener energies from fossil fuels.
"Extremely likely" means a probability of at least 95 percent, up from 90 percent in the panel's last report in 2007 and 66 percent in 2001.
"Since the 1950s, many of the observed changes are unprecedented - over decades to millennia. The atmosphere and oceans have warmed, the amounts of snow and ice have diminished, sea level has risen and the concentrations of greenhouse gases have increased, so this I think is a succinct summary of what we are doing to the system that really determines the climate of this planet," IPCC Chairman Rajendra Pachauri told the news conference.
The report, compiled from the work of hundreds of scientists, will face extra scrutiny this year after its 2007 report included an error that exaggerated the rate of melting of Himalayan glaciers. An outside review had later found the mistake did not affect its main conclusions.
Sceptics who challenge evidence for man-made climate change and question the need for urgent action have become emboldened by the fact that temperatures have risen more slowly recently despite rising greenhouse gas emissions.
The IPCC reiterated from the 2007 report that a warming trend is "unequivocal" and some effects would last far beyond the lifetimes of the current generation.
"The warming in the climate system is unequivocal, a conclusion that has been drawn in the fourth assessment report, now based on many more multiple lines of independent evidence from all climate system components - that is from the atmosphere, the ocean, the ice and the land," Working Group I co-chair that authors the paper Thomas Stocker said.
"One of the eighteen key messages that the 110 governments that were present in this room for four days have adopted in consensus: Human influence on the climate system is clear," he added.
The report said temperatures were likely to rise by between 0.3 and 4.8 degrees Celsius (0.5 to 8.6 Fahrenheit) by the late 21st century. The low end of the range would only be achieved if governments sharply cut greenhouse gas emissions.
It also said world sea levels could rise by between 26 and 82 cm (10 to 32 inches) by the late 21st century, driven up by melting ice and an expansion of water as it warms, a threat to coastal cities from Shanghai to San Francisco.
As the news conference came to an end, around 100 protesters gathered outside the venue shouting for action.