Scientific understanding of the cause of global warming has been increasing. In its fourth assessment (AR4 2007) the Intergovernmental Panel on Climate Change (IPCC) reported that scientists were more than 90% certain that most of global warming was being caused by increasing concentrations of greenhouse gases produced by human activities (anthropogenic).[6][7][8] In 2010 that finding was recognized by the national science academies of all major industrialized nations.[9][b]