OBSERVER: Five Copernicus apps transforming climate and atmosphere insights
sonia
From assessing heat and cold stress to exploring historical climate data and future projections or mapping methane plumes and monitoring major aerosol events, a range of user-friendly digital tools from Copernicus is delivering climate and air-quality intelligence to users worldwide. Building on data from the Copernicus Climate Change Service (C3S) and the Copernicus Atmosphere Monitoring Service (CAMS), these applications translate complex Earth Observation information into interactive maps, time series, and thematic indicators. In this Observer, we present five flagship C3S and CAMS apps which show how open data is being transformed into accessible tools, supporting understanding, risk assessment, and decision-making across sectors and regions.
Thermal Trace: monitoring heat and cold stress
Developed by C3S, Thermal Trace is a web application designed to help users assess heat and cold stress conditions in near real time (~5-day latency). It responds to the growing need for health-relevant information as extreme temperature events become more frequent and severe.
The app draws on more than 80 years of climate data from ERA5, the C3S fifth-generation reanalysis of the global climate from 1940 to the present. At its core is the Universal Thermal Climate Index (UTCI), a “feels-like” temperature which integrates air temperature, humidity, wind, and thermal radiation. Understanding how heat stress is measured requires looking into the complex interplay of environmental factors which affect the human body. By reflecting the body’s physiological response to environmental conditions rather than just temperature, UTCI provides a more meaningful indicator of risk than air temperature alone.
Thermal Trace allows users to explore indicators of cold stress or heat stress. Once they choose an indicator, users can select daily, monthly, seasonal, or annual periods, specify specific locations or custom regions, and switch between maps, time series, and downloadable tables, with a step-by-step video tutorial available for those new to the application. Alongside maxima and minima, it includes practical metrics such as the number of heat-stress days, tropical nights and cold-stress days.
Designed for event reconstruction and trend analysis rather than real-time alerts, Thermal Trace enables journalists, planners, and public-health professionals to benchmark recent extremes against historical patterns and better understand evolving thermal risks. The data used in the application can also be downloaded from the Copernicus Climate Data Store (CDS).
For example, users can revisit the conditions from the 2003 European heatwave, one of the most severe extreme-temperature events recorded in Europe, and explore monthly UTCI maxima over Western Europe, highlighting the widespread and persistent conditions corresponding to heat stress during the event.
ERA Explorer: delving into 85 years of global climate data
While Thermal Trace focuses on human thermal comfort, ERA Explorer provides a broader view of long-term climate conditions worldwide. Built on the ERA5 reanalysis dataset, this application makes decades of global climate data easy to explore to both specialists and non-specialists.
Users can click anywhere on the map or search for a specific location to view climatological averages for key variables such as temperature, precipitation, and wind. The base layer can be switched between 30-year average temperature or precipitation, revealing the warmest, coldest, wettest, and driest regions of the planet, as well as large-scale patterns such as the tropical rain belt.
Monthly breakdowns, animated wind fields, and long-term time series add further depth. All displayed data can be downloaded in CSV format, while advanced users can access Python notebooks to reproduce or adapt the underlying analyses. An in-app guide takes new users through the main features.
Powered by cloud-optimised data storage, ERA Explorer calculates statistics in just a few seconds from decades of hourly data, delivering rapid insights while keeping the full scientific dataset openly accessible through the CDS.
C3S Atlas: interactive climate projections and reproducible insights
For users seeking to explore future climate change trends alongside historical data, the Copernicus Interactive Climate Atlas (C3S Atlas) delivers global climate projections from the Coupled Model Intercomparison Project (CMIP), an international scientific programme which brings together climate models from research centres worldwide to produce standardised projections of past and future climate conditions, as well as ERA5 reanalysis and regional downscaled datasets. Since its launch in 2024, it has become a central tool for examining climate projections, observations, and reanalysis data at global and regional scales.
Key variables include mean temperature, accumulated precipitation, and extreme heat days. Regional time series are among the most popular products, complemented by long-term climatological averages and change maps across different periods and global warming levels.
Data can be downloaded directly in different formats, supporting both the communication of results to non-specialist audiences as well as in-depth scientific analysis. A recent addition, the C3S Atlas User Tools, improves transparency and reproducibility through Jupyter notebooks and an open GitHub repository, allowing users to recreate indices and visualisations.
With extensive guidance, a helpful video tutorial, and built-in support, the C3S Atlas serves policymakers, researchers, journalists, and educators seeking authoritative and accessible climate intelligence.
Methane Hotspot Explorer: tracking major methane plumes from space
Turning to atmospheric composition, the Methane Hotspot Explorer from CAMS focuses on methane, a short-lived greenhouse gas contributing to near-term warming. The app visualises large methane emission plumes detected using satellite observations from the TROPOMI instrument aboard the Copernicus Sentinel-5P satellite.
The Explorer uses machine-learning techniques to identify these emission plumes. These are displayed on a dynamic global map with estimated upwind source locations and indicative source categories such as coal, oil, gas, or solid waste, based on emission inventories.
While the kilometre-scale resolution does not allow individual facilities to be pinpointed, the tool shows where major emission events are occurring worldwide. Recent upgrades now provide detailed plume shape visualisations, illustrating how atmospheric conditions influence the spread and transport of methane. By transforming satellite data into an accessible monitoring platform, the Methane Hotspot Explorer supports greater transparency of a crucial driver of climate change.
Aerosol Alerts: early warnings for major air pollution events
The CAMS Aerosol Alerts service provides daily, forward-looking insights into major aerosol events affecting air quality worldwide. Launched in 2024, the free tool delivers forecasts up to three days in advance, helping users anticipate aerosol episodes linked to dust storms, wildfire smoke, and severe pollution outbreaks.
Built on ECMWF’s Integrated Forecasting System, the service evaluates aerosol optical depth and surface concentrations of particulate matter with diameters of 10 and 2.5 micrometres against reference levels and predefined thresholds. When anomalies exceed these limits, the system triggers high, very high or extreme alerts.
The interactive homepage features a global map displaying multiple aerosol species simultaneously, including dust, sea salt, sulphate, organic matter, and black carbon, alongside animated wind patterns showing atmospheric transport. Users can customise views, compare forecasts with satellite observations, explore 2D or 3D perspectives, and review forecast performance by region and season.
A personalised notification system allows users to define areas of interest and receive automated email alerts, helping public authorities, health professionals, and individuals to better respond to air pollution events.
Powering the apps: cloud-ready data and a growing ecosystem
Behind these applications lies a data infrastructure built around the Climate Data Store and Atmosphere Data Store. These platforms provide free and open access to large collections of quality-assured climate and atmospheric datasets, spanning reanalysis, observations, projections, and near-real-time forecasts.
The integration of Analysis Ready, Cloud Optimised (ARCO) datasets is enabling interactive analysis and visualisation directly in the cloud, allowing apps to deliver rapid insight directly from the underlying data stores without heavy data transfers.
To showcase this expanding ecosystem, Copernicus has launched a dedicated Data Stores Applications Catalogue with a selection of interactive tools featuring data from C3S, CAMS, and the Copernicus Emergency Management Service (CEMS). The repository brings together a wide selection of Copernicus-enabled tools and provides access to new apps built on Copernicus data.
Together, these digital tools illustrate how open and FAIR (Findable, Accessible, Interoperable, and Reusable) environmental data can be transformed into accessible, user-friendly, tools and services, strengthening transparency, supporting decision-making, and bringing climate and air-quality intelligence closer to society.
