Trends in global temperature are an important indicator of the magnitude of climate change and its possible impacts. Global annual near surface temperature has been rising steadily since the end of the 19th century. The rate of increase has been particularly high since the 1970s at about 0.2°C per decade. In this period, global temperature has risen faster than in any other 50-year period over at least 2000 years, with the past six years (2015–2020) being the warmest on record. All temperature datasets used here and the IPPC AR6 report place the year 2020 as one of the three warmest years on record, with anomaly ranges between 1.23°C and 1.31°C above pre-industrial levels. Anthropogenic activities, particularly greenhouse gas (GHG) emissions, are largely responsible for this warming.
To prevent serious environmental, economic and societal impacts of climate change, all signatories to the United Nations Framework Convention on Climate Change (UNFCCC) committed in the 2015 Paris Agreement to limiting global temperature increase to well below 2°C above pre-industrial levels by 2050 and to pursuing efforts to limit the increase to 1.5°C. The observed warming up to now already amounts to more than half of the maximum 2°C increase that would be compatible with the Paris Agreement.
Climate modelling has been used to estimate future climate change for different emissions scenarios and socio-economic pathways underlaying these scenarios (Shared Socioeconomic Pathways, SSP). Without significant efforts to curtail emissions, the increase in global temperature will continue rapidly, and even accelerate.
Global temperatures are projected to increase by 2.1-3.5°C above pre-industrial levels under SSP2-4.5 and by 3.3-5.7°C under SSP5-8.5 by the end of the 21st century. The only scenarios with a chance to stay within the limits established by the Paris Agreements are SSP1-1.9 with projected warming of 1.0–1.8°C and SSP1-2.6 with ranges between 1.3 to 2.4°C till the end of the 21st century compared to pre-industrial levels. These scenarios assume a drastic reduction in emissions in the coming decades and the decline of CO2 emissions to zero and subsequently negative net emissions around the year 2050 (scenario SSP1-1.9) or around 2080 (scenario SSP1-2.6).