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The Copernicus Climate Change Service (C3S), implemented by the European Centre for Medium-Range Weather Forecasts on behalf of the European Commission with funding from the EU, routinely publishes monthly climate bulletins reporting on the changes observed in global surface air temperature, sea ice cover and hydrological variables. All the reported findings are based on computer-generated analyses using billions of measurements from satellites, ships, aircraft and weather stations around the world.

Surface air temperature anomaly for September 2021 relative to the September average for the period 1991-2020. Data source: ERA5. Credit: Copernicus Climate Change Service/ECMWF.

September 2021 surface air temperature:

  • September 2021 was one of the four warmest Septembers globally, along with those of 2020, 2019 and 2016
  • September 2021 is estimated to be the second warmest of these months, after September 2020, but only limited significance can be attached to rankings as the four warmest years differ in global-average temperature by less than 0.08ºC
  • Europe had near-record warmth in places, but was cooler than average in the east, and close to average overall
  • Regions where temperatures were much above average include central South America, north-western Africa and southern and eastern China

September 2021 sea ice:

  • In September, the monthly average sea ice extent reached its annual minimum for 2021 in the Arctic and its annual maximum in the Antarctic.
  • Arctic sea ice extent was 8% below average, ranking 12th lowest in the 43-year satellite data record and fourth highest value since 2007, well above the very low extents of 2012, 2019 and 2020.
  • On a regional scale, sea ice extent reached a record minimum in the Greenland Sea but a 15-year high in the Beaufort-Chukchi Sea sector.
  • Antarctic sea ice extent was slightly below average, after six consecutive months of above average values.
  • Sea ice concentrations were above average around the Antarctic Peninsula and in the northern Weddell Sea and below average in the two adjacent ocean sectors.

Maps and quoted data values for temperature are from ECMWF Copernicus Climate Change Service’s ERA5 dataset. Area averages for temperature over the European region are for land only with the following longitude/latitude bounds: 25W-40E, 34N-72N.

Maps and quoted data values for sea ice are drawn from a combination of information from ERA5, as well as from the EUMETSAT OSI SAF Sea Ice Index v2.1, Sea Ice Concentration CDR/ICDR v2 and fast-track data provided upon request by OSI SAF. 

C3S has followed the recommendation of the World Meteorological Organisation (WMO) to use the most recent 30-year period for calculating climatological averages and changed to the reference period of 1991-2020 for its C3S Climate Bulletins covering January 2021 onward. Figures and graphics for both the new and previous period (1981-2010) are provided for transparency.

More information about climate variables in September and climate updates of previous months as well as high-resolution graphics can be downloaded here:

https://climate.copernicus.eu/monthly-climate-bulletins

More information about the C3S data set and how it is compiled can be found here:

https://climate.copernicus.eu/climate-bulletin-about-data-and-analysis

More information on the switch of the reference period, can be found here:

https://climate.copernicus.eu/new-decade-reference-period-change-climate-data

Answers to frequently asked questions regarding temperature monitoring can be found here:

https://climate.copernicus.eu/temperature-qas

Notes:

Copernicus is a component of the European Union’s space programme, with funding by the EU, and is its flagship Earth observation programme, which operates through six thematic services: Atmosphere, Marine, Land, Climate Change, Security and Emergency. It delivers freely accessible operational data and services providing users with reliable and up-to-date information related to our planet and its environment. The programme is coordinated and managed by the European Commission and implemented in partnership with the Member States, the European Space Agency (ESA), the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), the European Centre for Medium-Range Weather Forecasts (ECMWF), EU Agencies and Mercator Océan, amongst others.

ECMWF operates two services from the EU’s Copernicus Earth observation programme: the Copernicus Atmosphere Monitoring Service (CAMS) and the Copernicus Climate Change Service (C3S). They also contribute to the Copernicus Emergency Management Service (CEMS), which is implemented by the EU Joint Research Council (JRC). The European Centre for Medium-Range Weather Forecasts (ECMWF) is an independent intergovernmental organisation supported by 34 states. It is both a research institute and a 24/7 operational service, producing and disseminating numerical weather predictions to its Member States. This data is fully available to the national meteorological services in the Member States. The supercomputer facility (and associated data archive) at ECMWF is one of the largest of its type in Europe and Member States can use 25% of its capacity for their own purposes.

ECMWF has expanded its location across its Member States for some activities. In addition to an HQ in the UK and Computing Centre in Italy, new offices with a focus on activities conducted in partnership with the EU, such as Copernicus, are in Bonn, Germany as of Summer 2021.


The Copernicus Atmosphere Monitoring Service website can be found at http://atmosphere.copernicus.eu/

The Copernicus Climate Change Service website can be found at https://climate.copernicus.eu/

More information on Copernicus: www.copernicus.eu

The ECMWF website can be found at https://www.ecmwf.int/