Global warming: why is IPCC report so certain about the influence of humans? | Dana Nuccitelli

100 percent of the global warming over the past 60 years is human-caused, according to the IPCC's latest reportThe fifth Intergovernmental Panel on Climate Change (IPCC) report states with 95 percent confidence that humans are the main cause of the current global warming. Many media outlets have reported that this is an increase from the 90 percent certainty in the fourth IPCC report, but actually the change is much more significant than that. In fact, if you look closely, the IPCC says that humans have most likely caused all of the global warming over the past 60 years. Spot the DifferencesHere is the relevant statement from the fourth IPCC report in 2007:"Most of the observed increase in global average temperatures since the mid-20th century is very likely [90 percent confidence] due to the observed increase in anthropogenic greenhouse gas concentrationsNow here is the statement from the fifth IPCC report:"It is extremely likely [95 percent confidence] that human influence on climate caused more than half of the observed increase in global average surface temperature from 1951−2010."Did you spot the differences? The 2007 IPCC statement focused on human greenhouse gas emissions, while the 2013 statement pertains to all human influences on the climate. This includes the cooling effect from human aerosol emissions (pollutants that scatter sunlight). Cooling from human aerosol emissions offsets about one-third of the warming from human greenhouse gas emissions. The new IPCC s...
Source: Guardian Unlimited Science - Category: Science Authors: Tags: theguardian.com Blogposts Intergovernmental Panel on Climate Change (IPCC) Climate change scepticism Environment Source Type: news