Scientists are more certain than ever that the planet is warming and that humans are to blame.
That’s the finding of a new report by the Intergovernmental Panel on Climate Change (IPCC). The assessment will help inform policy makers and the public as they consider what action to take on climate change.
One hundred and ten governments adopted the scientific consensus that, “It is extremely likely that human influence has been the dominant cause of observed warming since the mid-20th century.”
Wake-up call
At a news conference in Stockholm Friday, World Meteorological Organization Secretary General Michael Jarraud underscored the importance of the finding.
“It should serve as 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,” Jarraud said.
Greenland and Antarctic ice sheets have been losing mass and glaciers continue to shrink, the report says, calling the decrease in Arctic sea ice, “unprecedented.” The report notes the mean rate of sea level rise since the mid-19th century is higher than at any time in the previous 2,000 years.
The international panel also probed the connection between extreme weather events and climate, says Brenda Ekwurzel, senior climate scientist with the Union of Concerned Scientists, who has worked with the panel's authors.
“This is a lot of cutting edge research, and the most we can say is that extreme events dealing with coastal flooding and extreme heat, [we have] very high confidence with these events being linked to climate change,” Ekwurzel said.
Climate change deniers have tried to dismiss the science, citing a 15-year slowdown in atmospheric warming. That was downplayed in the report, which called it a natural phenomenon that masks on-going warming. The report reiterates the 2007 assessment that the warming trend is “unequivocal,” according to Ekwurzel.
“The 5th Assessment report has really notched up the confidence level, that greater than 95 percent confidence of the likelihood that the warming that happened on this planet between 1951 and 2010, more than half of it is due to human activities,” she said.
Those human activities include the burning of fossil fuels in factories, buildings and cars, which emit heat-trapping gasses.
Moving forward
Past IPCC reports have set the stage for world agreements like the Kyoto Protocol, the 1997 climate treaty signed and ratified by 192 nations that expired in 2012. The United Nation’s top climate official says the new IPCC report will help move climate talks forward.
“That policy response will have to end up in a global agreement that is going to be legally based and applicable to all countries and will be adopted in 2015. And for that, governments are already working,” Christiana Figueres said.
While the Intergovernmental Panel on Climate Change is sometimes criticized as appearing to be too conservative in its predictions, Figueres says this report is right on the mark.
“Everything that we thought about climate change has been underestimated, that we will have much faster and much more intense effects from the growing concentration of greenhouse gases in the atmosphere," she said. "So it’s a very sobering message that calls for a more invigorated and accelerated policy response to address that.”
Government leaders and climate experts will get an opportunity to do that at the next round of climate negotiations in Warsaw, Poland in November.
Friday’s IPCC report will be followed next year by reports on the impact of climate change and what can be done about it.
