Global warming__ A. is controversial. While international regulations include the UN Framework Convention on Climate Change (UNFCCC) and the Kyoto Protocols, not all countries have agreed on the best way to solve it. B. can be easily addressed by countries, without incurring any economic costs. C. is measured by a specific figure for an acceptable concentration of greenhouse gases that was set by the Intergovernmental Panel on Climate Change (IPCC). D. is addressed by the Kyoto Protocols which has the same restrictions for all countries, including developing countries