This report investigates the environmental system on the climate change of The 21st Conference (COP21) founded by the Paris Treaty, colonial change and its associated global warming effects. It analyzes the data on energy security and investigates the environmental sustainability. The report is divided into three subtopics, the first subtopic analyzes scientific evidence of temperature tested at 2 ° C in IPCC AR5 using the current emission path worldwide. The second subtopic presents the decarbonisation of the G7 countries to be contracted for the current climate policy position. The third subtopic investigates the reduction of the climate emission stages on COP21 and to find the decarbonisation by 2070. The subject of the report is Environment System and Climate Change, and the document type is a research report.