how do we know humans are the main cause for global warming
100 percent of the global warming over the past 60 years is human-caused, according to the IPCC's latest report. The IPCC is 95 percent confident that humans are the main cause of the current global warming. Photograph: Jianan Yu/Reuters The 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.