Abstract: Highlights of the IPCC Working Group I (WGI) Fifth Assessment Report (AR5) are the essence refined from the researches in the field of climate change physical science in the past seven years. More than half of the observed increase in global average surface temperature since the 1950s was caused by the human influence. Nighty-three percent of the energy resulting from the anthropogenic CO₂ emissions since 1971 is stored in the ocean. Besides, ocean has absorbed about 30% of the emitted anthropogenic CO₂, causing the decrease in pH of ocean surface by 0.1, etc. Based on the CMIP5 models, it is projected that global warming will continue. Relative to 1986-2005, the global mean surface temperature by the end of the 21st century will increase by 0.3~4.8℃. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions. Controlling the warming caused by anthropogenic CO₂ emissions alone with a probability of >66% to less than 2℃ since the period 1861-1880, will require cumulative CO₂ emissions from all anthropogenic sources to stay between 0 and about 1000 Gt C since that period.

Key words: climate change, greenhouse gas, IPCC AR5, WGI