It is very likely that 2017 will be one of the three hottest years on record, with many high-impact events including catastrophic hurricanes and floods, debilitating heatwaves and drought. Long-term indicators of climate change such as increasing carbon dioxide (CO2) concentrations, sea level rise and ocean acidification continue unabated. Arctic sea ice coverage remains below average and previously stable Antarctic sea ice extent was at or near a record low.
The World Meteorological Organization’s provisional Statement on the State of the Climate says the average global temperature from January to September 2017 was approximately 1.1°C above the pre-industrial era. As a result of a powerful El Niño, 2016 is likely to remain the warmest year on record, with 2017 and 2015 being second and/or third. 2013-2017 is set to be the warmest five-year period on record.
The WMO statement - which covers January to September - was released on the opening day of the United Nations climate change conference in Bonn (https://cop23.unfccc.int/). It includes information submitted by a wide range of UN agencies on human, socio-economic and environmental impacts as part of a drive to provide a more comprehensive, UN-wide policy brief for decision makers on the interplay between weather, climate and water and the UN global goals. [Source: WMO Press Release, 6 November 2017. https://public.wmo.int/en/media/press-release/2017-set-be-top-three-hottest-years-record-breaking-extreme-weather]
According to the WMO’s Greenhouse Gas Bulletin, concentrations of CO2 in the atmosphere surged at a record-breaking speed in 2016 to the highest level in 800,000 years. The abrupt changes in the atmosphere witnessed in the past 70 years are without precedent.
Globally averaged concentrations of CO2 reached 403.3 parts per million in 2016, up from 400.00 ppm in 2015 because of a combination of human activities and a strong El Niño event. Concentrations of CO2 are now 145% of pre-industrial (before 1750) levels, according to the Greenhouse Gas Bulletin. The report notes that rapidly increasing atmospheric levels of CO2 and other greenhouse gases have the potential to initiate unprecedented changes in climate systems, leading to severe ecological and economic disruptions. [Source: WMO Press Release, 30 October 2017. https://public.wmo.int/en/media/press-release/greenhouse-gas-concentrations-surge-new-record]