The findings of the 2018 Intergovernmental Panel on Climate Change special report imply that we need to reduce global emissions of carbon dioxide within 12 years to where they were 41 years ago, to avoid a 1.5 °C increase in average Earth surface temperature. Global emissions and concentrations are still rising, however, so temperatures continue to go up.
Our estimates show that emissions from fossil-fuel combustion and cement manufacture in 2017 surpassed 10 gigatonnes of carbon (see go.nature.com/2teyafi). Population growth is partly responsible. In 1977, when the global population was 4.23 billion, emissions per capita were 1.19 tonnes of carbon per person. By 2017, this had increased to 1.34 tonnes (the global population that year was 7.55 billion). So, decreasing total emissions to the 1977 figure will mean returning per capita emissions to those recorded for 1955.
Growth in industrialization and population distributions also increase carbon emissions. Emissions are still high from countries such as the United States, Japan and Germany, which industrialized early. Top emitters now also include China, India, Iran, Brazil and South Africa. The distribution within countries is also changing as urbanization and transportation increase (see go.nature.com/2hwpia3).
We need to make drastic changes in carbon emissions, soon. This means widespread global cooperation and unprecedented commitment.
Nature 565, 567 (2019)