The report by the Intergovernmental Panel on Climate Change (IPCC), due for release on Feb. 2 in Paris, draws on research by 2,500 scientists from more than 130 countries and has taken six years to compile.
"There are a lot of signs and evidence in this report which clearly establish not only the fact that climate change is taking place, but also that it really is human activity that is influencing that change," R.K. Pachauri, the IPCC chairman, told Reuters.
"I hope this report will shock people, governments into taking more serious action as you really can't get a more authentic and a more credible piece of scientific work. So I hope this will be taken for what it's worth."
The IPCC will say it is at least 90 percent sure than human activities, led by the burning of fossil fuels, are to blame for global warming over the past 50 years, sources say.
The new report is likely to foresee a rise in temperatures of 2 to 4.5 Celcius (3.6-8.1 Fahrenheit) this century, with about 3 Celcius (5.4F) most likely.