Record atmospheric greenhouse gas concentrations and associated accumulated heat have propelled the planet into uncharted territory, with far-reaching repercussions for current and future generations, according to the World Meteorological Organization (WMO).
The past seven years are on track to be the seven warmest on record, according to the provisional WMO State of the Global Climate 2021 report, based on data for the first nine months of 2021. A temporary cooling “La Niña” event early in the year means that 2021 is expected to be “only” the fifth to seventh warmest year on record. But this does not negate or reverse the long-term trend of rising temperatures.
Global sea level rise accelerated since 2013 to a new high n 2021, with continued ocean warming and ocean acidification.
The report combines input from multiple United Nations agencies, national meteorological and hydrological services and scientific experts. It highlights impacts on food security and population displacement, harming crucial ecosystems and undermining progress towards the Sustainable Development Goals.
“The provisional WMO State of the Global Climate 2021 report draws from the latest scientific evidence to show how our planet is changing before our eyes. From the ocean depths to mountain tops, from melting glaciers to relentless extreme weather events, ecosystems and communities around the globe are being devastated. COP26 must be a turning point for people and planet,” said United Nations Secretary-General António Guterres.
The provisional State of the Climate 2021 report is released at the start of the UN Climate Change negotiations, COP26, in Glasgow. It provides a snapshot of climate indicators such as greenhouse gas concentrations, temperatures, extreme weather, sea level, ocean warming and ocean acidification, glacier retreat and ice melt, as well as socio-economic impacts.
It is one of the flagship scientific reports which will inform negotiations and which will be showcased at the Science pavilion hosted by WMO, the Intergovernmental Panel on Climate Change and the UK Met Office. During COP26, WMO will launch the Water and Climate Coalition to coordinate water and climate action, and the Systematic Observations Financing Facility to improve weather and climate observations and forecasts which are vital to climate change adaptation.
In 2020, greenhouse gas concentrations reached new highs. Levels of carbon dioxide (CO2) were 413.2 parts per million (ppm), methane (CH4) at 1889 parts per billion (ppb)) and nitrous oxide (N2O) at 333.2 ppb, respectively, 149 percent, 262 percent and 123 percent of pre-industrial (1750) levels. The increase has continued in 2021.
The global mean temperature for 2021 (based on data from January to September) was about 1.09°C above the 1850-1900 average. Currently, the six datasets used by WMO in the analysis place 2021 as the sixth or seventh warmest year on record globally. But the ranking may change at the end of the year.
It is nevertheless likely that 2021 will be between the 5th and 7th warmest year on record and that 2015 to 2021 will be the seven warmest years on record.
2021 is less warm than recent years due to the influence of a moderate La Niña at the start of the year. La Niña has a temporary cooling effect on the global mean temperature and influences regional weather and climate. The imprint of La Niña was clearly seen in the tropical Pacific in 2021.
The last significant La Niña event was in 2011. 2021 is around 0.18°C to 0.26 °C warmer than 2011.
As the 2020-21 La Niña has waned, monthly global temperatures have increased. The year 2016, which started during a strong El Niño, remains the warmest year on record in most of the data sets surveyed.