Carbon emissions and energy use
Carbon emissions related to energy use directly influence global climate change, and their reduction will obviously play a vital role in limiting atmospheric warming to no more than 2°C and even 1.5°C above pre-industrial levels. From 1971 to 2014, global carbon emissions multiplied by 1.32 times along with the growth of energy consumption. High-income countries accounted for more than half of the global emissions during 1990–2004, but upper-middle-income countries surpassed them due to the rapidly growing energy consumption. Of global incremental carbon emissions, 69.31% came from upper-middle-income countries, 16.52% from lower-middle-income countries, 11.74% from high-income countries, and 0.30% from low-income countries. The decomposition results show that population growth and GDP per capita served as the major driving factors to the growth of carbon emissions, while energy intensity caused the decline in carbon emissions. However, the effect of carbon intensity was positive, which means high carbon content of the energy structure. The increments derived from population growth, GDP per capita growth, and carbon intensity attained 5,740.69 MtC, 15,810.70 MtC, and 210.80 MtC, respectively. The reductions owning to energy intensity and population share were 9,646.13 MtC and 617.68 MtC, respectively. Therefore, decarbonization of energy system and decoupling of energy use and economic development becomes crucial.