Scientific understanding of global warming is increasing.The Intergovernmental Panel on Climate Change reported in 2014 that scientists were more than 95% certain that most of global warming is caused by increasing concentrations of greenhouse gases and other human activities.Climate model projections summarized in the report indicated that during the 21st century the global surface temperature is likely to rise a further 0.3 To 1.7 for their highest.These findings have been recognized by the national science academies of the major industrialized nations.