January
Strategy and machine learning roadmap launched
Our ten-year Strategy for the period 2021 to 2030 came into force, with an emphasis on providing ever-more skilful forecasts to Member and Co-operating States and users around the world. It was accompanied by a machine learning roadmap setting out our plans to integrate machine learning into numerical weather prediction (NWP) and climate services to improve predictions and their use in many areas of the workflow.
CO2 monitoring project to deliver prototype system
A European programme to build a monitoring and verification support capability for global emissions of carbon dioxide (CO2 ) related to human activities got under way. The ECMWF-coordinated Copernicus CO2 (CoCO2) project will deliver the prototype for a new European anthropogenic CO2 emissions monitoring and verification support capacity which will be implemented as part of the EU’s Copernicus programme. The project went on to hold its first General Assembly in November.
ECMWF science presented at AMS Annual Meeting
With international conferences continuing to take place virtually due to the COVID-19 pandemic, our scientists took the opportunity to hear from colleagues and present ECMWF research and plans at the Annual Meeting of the American Meteorological Society (AMS).
Emergency bulletins support humanitarian work in Mozambique
ECMWF helped to produce emergency bulletins to the UK Foreign Commonwealth and Development Office in response to flooding in Mozambique caused by tropical cyclone Eloise. We provided meteorological guidance about the cyclone itself and streamflow forecasts from the Global Flood Awareness System (GloFAS), run on behalf of the EU Copernicus Emergency Management Service (CEMS). The bulletins were produced with the Universities of Reading and Bristol, HR Wallingford and Fathom and enabled the deployment of aid resources to the affected areas.

February
Workshops explore cloud technologies
Participants at our ‘Weather and climate in the cloud’ workshop shared experiences and plans for using cloud technologies to improve services for users. Two more workshops in May and November provided an opportunity for Member and Co-operating States of EUMETSAT and ECMWF to review achievements in the pilot phase of the European Weather Cloud project and look ahead to a future operational phase.
March
Destination Earth and digital twin plans presented
We held the first of our science and technology seminars presenting the European Commission’s planned Destination Earth programme from the perspectives of ECMWF, ESA and EUMETSAT. Two more followed in April and May. These seminars gave participants a preview of how digital twins of the Earth will make it possible to interactively explore various natural processes and human activities.
April
European State of the Climate published
The EU-funded Copernicus Climate Change Service (C3S) implemented by ECMWF published a comprehensive overview of the 2020 European climate, including a focus on the Arctic and a summary of global conditions. The report confirmed 2020 was the warmest year on record for Europe. Winter temperatures were particularly notable, 3.4°C higher than the 1981–2010 average and 1.4°C higher than the second-warmest winter on record.
Atmospheric composition forecasts added to data store
The Copernicus Atmosphere Monitoring Service (CAMS) run by ECMWF made it easier to access its atmospheric composition global forecasts by making them available in the CAMS Atmosphere Data Store (ADS). Archived past data and past forecasts are also available in the store, where they can be downloaded in one standard format, so that scientists, businesses and policymakers can access atmospheric data for research or decision-making.
MAELSTROM project to prepare for machine learning applications
A three-year project to help prepare the weather and climate community for large-scale machine learning applications began, funded under the EuroHPC Joint Undertaking and coordinated by ECMWF. The ‘Machine learning for scalable meteorology and climate’ project (MAELSTROM) puts an emphasis on co-design to allow feedbacks between application, software, and hardware developments.
May
Single precision and higher vertical resolution in IFS upgrade
An upgrade of ECMWF’s Integrated Forecasting System (IFS) to Cycle 47r2 introduced single precision for high-resolution and ensemble forecasts, freeing up computing power for other improvements. One such improvement was an increase in the vertical resolution of ensemble forecasts, which enhanced many aspects of forecast skill across different time ranges.
Summer coding challenges begin
The coding period for the fourth ECMWF Summer of Weather Code (ESoWC) ran from May to August. Nine developer teams worked on projects at the intersection of machine learning, web development, visualisation, data compression and open data exploration and showcased their results at a final presentation day in September.
Extratropical cyclone database updated
Updates to ECMWF’s extratropical cyclone database products brought improvements to the visualisations and behind-the-scenes changes to the software. Developed in collaboration with the UK Met Office, the extratropical cyclone database products have been available from ECMWF for more than a decade. They provide forecasters with familiar synoptic-style charts, showing fronts and low-pressure (cyclonic) weather systems that can be associated with hazardous conditions such as strong winds, snow and rain.
Scientists share results at EGU General Assembly
Our scientists made a strong contribution to the European Geosciences Union (EGU) General Assembly, with virtual presentations touching on many aspects of weather prediction as well as work done by the EU Copernicus services on climate change and atmospheric composition run by ECMWF.
June
First phase of data centre project completed
A handover agreement between the Italian authorities and ECMWF marked the end of Phase 1 of the data centre project. Responsibility for managing the centre and ownership of certain equipment such as the chillers and dry coolers were transferred to ECMWF. We also had the opportunity to show Italian Prime Minister Mario Draghi around the facility and explain its importance for the delivery of services to our Member States.
User meeting looks at weather in extraordinary circumstances
Our second fully virtual Using ECMWF’s Forecasts (UEF) event attracted 228 people from 53 countries to discuss and provide feedback on ECMWF products and services. The theme of ‘Weather in extraordinary circumstances’ encompassed topics such as the impacts of COVID-19 on forecasting and other extraordinary events that impact forecasting, modelling, users and the public. New elements this year included a full day focused on the EU’s Copernicus services linked to ECMWF, five-minute ‘lightning talks’ on a variety of topics, and a Science and Art event.

Saildrone data to help understand the Gulf Stream
ECMWF joined a new partnership with Saildrone, the University of Rhode Island and Google to use data from the highly turbulent Gulf Stream to improve the understanding of ocean processes in the region. In December, three Saildrone uncrewed surface vehicles set off on a six-month mission to gain observations.

July
Intense rainfall leads to devastating floods in Europe
July saw very heavy rainfall in western central Europe in a region with soils close to saturation. This led to severe floods in several countries, with the most heavily impacted including Germany, Belgium, Luxembourg, and the Netherlands. ECMWF high-resolution forecasts predicted the broad location and intensity of the rain three days in advance. Flood forecasts were issued by the European Flood Awareness System (EFAS), part of CEMS.
Copernicus contracts renewed
ECMWF signed an agreement with the European Commission to continue implementing the Copernicus Climate Change Service (C3S) and Copernicus Atmosphere Monitoring Service (CAMS) for the next seven years. We will also continue as the computational centre for the hydrological forecasting activities of the Copernicus Emergency Management Service (CEMS) until 2027.
New forum and virtual assistant help users
We opened a Forecast User Forum for users to comment on topics related to weather and forecasting, join conversations and provide feedback to ECMWF. It complements existing forecast user pages such as the Forecast User Guide and Severe Event Catalogue and provides a space where users of our forecasts can interact with other users and ECMWF experts. We also launched a virtual assistant – the knowledge duck – in the C3S Climate Data Store to help users make the most of the information and support services available.
August
Europe experiences warmest summer on record
The Mediterranean region experienced extreme temperatures with a heatwave moving from east to west during August. At the beginning of the month, severe wildfires hit Greece and Turkey. On 11 August, a provisional European temperature record of 48.8°C was set in Syracuse in Sicily. Later the heatwave continued to the Iberian Peninsula, with temperatures of 46.9°C in Cordoba on 14 August. The ECMWF Extreme Forecast Index (EFI) showed a consistently strong signal for the extreme temperatures up to a week ahead.
Atos user acceptance testing begins
User acceptance testing began on the Atos supercomputers in Bologna and was continuing at the end of the year.
CAMS and C3S data in IPCC climate assessment report
CAMS and C3S data and products were used extensively in the Intergovernmental Panel on Climate Change (IPCC) Working Group 1 contribution to the Sixth Assessment Report. Several CAMS datasets were used, and ERA5 was cited more than 200 times. ERA5 is the latest climate reanalysis produced by ECMWF, providing hourly data on many atmospheric, land-surface and sea-state parameters together with estimates of uncertainty.
September
WMO fellow to develop Climate Data Store application for Africa
ECMWF welcomed a meteorologist from the National Department of Meteorology, Cameroon, to work on a Climate Data Store application for Africa as part of a one-year World Meteorological Organization (WMO) Fellowship. The Fellowship is part of a long-standing WMO scheme to provide specialised training placements to develop capacity in least-developed and developing countries.
Annual Seminar focuses on Earth system observations
Thirty-seven experts set out the latest thinking on Earth system observations at ECMWF’s Annual Seminar. Our flagship educational event was held online and attracted 520 attendees.
Workshop considers exascale computing in NWP
Experts from national weather centres, academia and industry came together online for our biennial event on the use of high-performance computing in meteorology. With more than 50 talks on the theme ‘Towards Exascale Computing in Numerical Weather Prediction’, the workshop attracted 313 participants from 43 countries.

NextGEMS project begins
A new, four-year EU-funded project to contribute to developing a new generation of Earth system models began, with 26 partners involved and ECMWF as co-coordinator. The NextGEMS project aims to develop models that will help fill gaps in our understanding of how the Earth system works and how the world’s climate will change over the next three decades.
ECMWF becomes a multi-site organisation
Following opening ceremonies at our new offices in Bonn, Germany, and our data centre in Bologna, Italy, ECMWF officially became a multi-site organisation. The headquarters remain in the UK, while the focus in Bonn is on work conducted in partnership with the EU and the Bologna data centre houses the new Atos Bull Sequana high-performance computing facility.

ERA5-Land reanalysis dataset extended
C3S made the back-extension period of its high-resolution ERA5-Land reanalysis dataset available through the Climate Data Store. This subset of ERA5-Land covers the period 1950–1980 and is designed to improve the knowledge of land evolution from the last seven decades. The ERA5-Land dataset is the first of its kind, providing global, hourly, historic and high-resolution land-focused information for a more accurate representation of water and energy cycles.
October
OpenCharts catalogue extended
New products added to our OpenCharts Catalogue included parameters such as lightning and visibility. The new products and most of the existing ones also benefited from increased time steps, moving from 12–24 hours down to 3–6 hours, in line with our normal forecasting processes. Ensemble-based products in OpenCharts were also enhanced, providing more detailed information for users, such as probabilities for additional variables and weather types.
Improved moist physics and use of satellite observations
A second forecasting system upgrade in 2021, Cycle 47r3, improved the representation of moist physics in the model and increased satellite observation usage in cloudy regions in data assimilation. The developments are a culmination of work spanning several years and are part of a long-term development of the moist physics in the IFS in preparation for the transition to higher horizontal resolutions (3–5 km) in future operations. Separately, the CAMS global forecasting system was also upgraded to use IFS Cycle 47r3 and began operationally assimilating NO2 observations from ESA’s Sentinel-5P satellite.
Antarctic ozone hole large and long-lived
CAMS scientists monitoring the ozone hole over the south pole reported that it was one of the deepest in CAMS or C3S records. The hole closed in December, ending another of the longest lasting Antarctic ozone hole seasons on record. 2021 was marked by very cold temperatures in the stratosphere and a very stable polar vortex, which contributed to the duration of the hole.
November
ECMWF attends COP26 Climate Change Conference
At the United Nations Climate Change Conference of the Parties (COP26), ECMWF showed how data and services from the EU’s Copernicus Earth observation programme can support countries in meeting the goals of the Paris Agreement and the UN Framework Convention on Climate Change. Staff spoke on topics including a future anthropogenic CO2 emissions monitoring and verification support capacity and the importance and use of reanalysis and essential climate variables data held by C3S.
Partnership to support EIB adaptation strategies
The European Investment Bank (EIB) and ECMWF signed a Memorandum of Understanding setting out a framework for cooperation on the enhanced use of Copernicus Earth observation data. The partnership will see the two parties work together to enable Copernicus climate and atmosphere data to support EIB activities as the EU’s Climate Bank.
December
Georgia becomes ECMWF Co-operating State
A Co-operation Agreement between ECMWF and Georgia came into force on 1 December, granting Georgia full access to ECMWF real-time products, archive data and software tools, and ECMWF training facilities.
New site approved for ECMWF headquarters
Our Council of Member States approved an offer from the UK Government to transfer the ECMWF headquarters from Shinfield Park near Reading to a new site on the campus of the University of Reading, planned to be ready in 2026.
CONFESS project hosts General Assembly
The EU-funded CONFESS project coordinated by ECMWF hosted its first General Assembly. Over 70 online participants from Europe and beyond heard about the objectives and progress of the project, which is contributing to the development of the next C3S reanalysis, ERA6, and of C3S seasonal forecast products.
ECMWF to develop digital twins for Destination Earth
Following approval from our Council, we officially became part of the EU’s ambitious Destination Earth initiative to create a digital twin – an interactive computer simulation – of our planet. ECMWF, ESA and EUMETSAT are the three organisations entrusted by the EU to achieve this unprecedented endeavour for weather, climate and computing sciences.

OpenIFS turns ten
Our OpenIFS initiative marked its tenth anniversary. OpenIFS began in 2011 to provide supported versions of the operational IFS for research, education and training in NWP and meteorology by Member and Co-operating States and academic institutes. Licences are now held by 90 institutions.
2021 fifth-warmest year on record
Globally 2021 was the fifth-warmest year on record, according to findings released by C3S. The annual average temperature was 0.3°C above the 1991–2020 reference period, and 1.1–1.2°C above the pre-industrial level of 1850–1900.