"Unless there is unprecedented global cooperation to bring down emissions, no country would be left unaffected. Governments everywhere have to act," Xinhua quoted Hague as saying, following the UN Intergovernmental Panel on Climate Change (IPCC) published its second report "Climate Impacts, Adaptation and Vulnerability" on Monday.
"A two degree increase in the world's temperature would be dangerous, and four degrees would be catastrophic," he said, citing research findings from the IPCC report.
The results of a failure to take action will be widespread, with serious consequences for human health, global food, resource security and economic prosperity, warned David King, the foreign secretary's special representative for climate change.
The representative added that only by working together to secure an international agreement to successfully lower carbon emissions can we hope to meet the climate challenge.
The IPCC report is the second volume of the latest comprehensive assessment of the science of climate change since the last publication of such a report in 2007.