Choosing Climate Data for Adaptation Projects: A Guide to Free Public Sources.

As extreme weather events become more frequent and new regulations, such as the European CSRD or the French National Climate Change Adaptation Plan, come into force, an increasing number of companies must develop adaptation strategies. Standards and methodologies like ISO 14090, BPIfrance’s "Diag Adaptation", Canada’s PVIEC protocol, the OCARA method, and many others exist... but they all share the same starting point: accessing reliable, localized climate projections.

Regardless of the company or methodology, the adaptation process almost always begins with the same question: What do I need to adapt to?

To address this need, several public and free climate data sources have been established. However, for companies just beginning their adaptation journey, navigating these options can be challenging. In this article, we provide an overview of the main public climate data sources, IPCC Atlas, Copernicus Climate Data Store, DRIAS and ESGF, and compare them to our own service, ClimateVision.

Tool	DRIAS	IPCC Atlas	Climate Data Store	ESGF	ClimateVision
Data Generation	CMIP5	CMIP5 & CMIP6	CMIP5 & CMIP6	All	CMIP6
Coverage	France	Global	Europe/Global	Global	Global
Spatial Resolution	~8 km	Regional	Variable (>10 km)	Variable (>10 km)	Up to 4.5 km
Ready-to-Use Data	Yes	No	No (with exceptions)	No	Yes
Indicators	General	General	Some sectoral indicators	No	Sectoral & industrial indicators
Ease of Use	Low usability	Very simple	Complex	Very complex	Very simple
Analysis/Visualization Tools	No	Yes	Yes (for some topics)	No	Yes
Scientific Support	Limited docs	No	Docs & training	No	Docs, training & access to climatologists

The IPCC Interactive Atlas: A Global, User-Friendly but Highly Aggregated Source

The IPCC Interactive Atlas is one of the major innovations developed as part of the IPCC’s 6th Assessment Report. Its purpose is to make climate projections based on the models used in this report (CMIP6) accessible to a broad audience. Projections from previous generations (CMIP5 and Cordex) and historical data are also available.

Screenshot of the IPCC Atlas: Average temperature (SSP5-8.5 scenario, end of the century)

The Atlas allows users to visualize climate data in just a few clicks, based on different emissions scenarios (SSPs or RCPs) and warming levels. It covers the entire globe but with coarse spatial resolution: results are only available at the scale of large regions, such as continents or major river basins.

Around 20 indicators are provided, but the data is generally not bias-corrected. The indicators are generic and do not include extreme values analysis. Combined with their low resolution, this makes the IPCC Atlas a powerful awareness-raising tool, but one that is less suitable for local or industrial studies.

Copernicus Climate Data Store: Europe’s Open Climate Data Library

The Copernicus Climate Data Store (CDS), operated by the European Earth Observation program, provides free access to a wide range of climate datasets, including projections based on the IPCC’s 5th and 6th Assessment Reports. However, most of these projections are not bias corrected. As a result, users must perform bias correction before use, a complex process requiring specialized expertise.

That said, Copernicus offers extensive resources, including tools, tutorials and even free training programs, to support users.

The CDS also provides ready-to-use indicators for some specific sectors, such as energy and agriculture. Geographic coverage varies, ranging from European to global, with spatial resolutions from tens of kilometers to regional scales.

Finally, it’s worth noting that with over 250,000 registered users and around 500,000 daily queries, the Climate Data Store is sometimes a victim of its own success. Download times can be very slow, especially during peak usage.

ESGF: The Expert-Level Reference Tool

The Earth System Grid Federation (ESGF) is an international collaboration designed to provide infrastructure for sharing Earth system science data. Used by climatologists worldwide, it hosts virtually all existing climate projections.

However, the ESGF's data access is highly complex and unintuitive. Simply downloading a projection dataset requires datailled uderstanding of the system, fluency in the technical language of climate science (including abbreviations and data conventions) and the use of programming languages.

Most datasets are raw and require extensive preprocessing before use. This means users must have both climatology expertise and significant computational resources to effectively leverage the platform.

DRIAS Portal: The "French Exception" of Climate Data

Finally, let’s introduce what is arguably France’s most widely used climate data source: the DRIAS portal, developed by a scientific consortium including Météo-France, IPSL, and CERFACS. It provides high-resolution, ready-to-use climate projections, a rarity in the field.

The projections are bias-corrected and can be used directly, though the methodologies applied do not support multivariate indicator calculations. The platform is relatively straightforward to use but its design and ergonomics seem borrowed from the early days of the internet. Although DRIAS offers some educational resources, users are largely left to fend for themselves, which can lead to misuse or misinterpretation of the data.

DRIAS is a benchmark source for public organizations and private actors in France. However, its scope and methodologies inherently limit the coverage to metropolitan France. Overseas territories are only partially covered, and the platform cannot support comprehensive risk assessments or adaptation strategies for companies with international supply chains or production sites.

DRIAS is a generalist service. While it provides pre-calculated indicators, these are unlikely to meet the needs of specific projects, particularly those requiring data on extreme weather events. Finally, DRIAS relies entirely on models and scenarios from the IPCC’s 5th Assessment Report (CMIP5 and RCP), which risk becoming obsolete as they are replaced by CMIP6 and the newer SSP scenarios.

Which Free Climate Data Source for Which Use Case?

Each of these sources has limitations that make them more or less suitable depending on the objective:

• The IPCC Atlas is the ideal tool for rapid awareness-raising, as its built-in visualization features allow users to communicate climate changes without additional effort.

• DRIAS is an essential source in the French context when the required information remains general for example, in local climate action plans (PCAET) or initial climate risk screenings.

• ESGF and the Copernicus Climate Data Store enable the calculation of advanced, sector-specific indicators, but they require significant expertise.

This categorization highlights a key challenge: the need for expertise grows exponentially as users move from awareness-raising to the detailed studies required for adaptation planning.

Using pre-processed climate data, such as those available through DRIAS, typically requires 1–2 days of work for an experienced user. Using ESGF or CDS data can take weeks of efforts and demands highly specialized technical and scientific skills. In practice, few companies have the in-house capacity to conduct such studies.

To prevent adaptation efforts from stalling at this stage, Callendar developed ClimateVision. This solution provides access to advanced indicators, for example, updating technical design standards, in just a few hours and without requiring specialized expertise. While ClimateVision is a paid service, it is ultimately more cost-effective than the human resources needed to conduct an equivalent study using free data sources.

Use Case: Navigating Climate Risk Assessments for a Global Energy Company

When a global energy company sets out to conduct a climate risk assessment aligned with local adaptation frameworks, such as France’s TRACC, the EU’s CSRD or other national climate plans, it quickly encounters a fragmented landscape of data sources, each with distinct strengths and limitations.

For French sites, DRIAS offers the most straightforward solution, providing TRACC-aligned indicators that can be accessed through free tools. Processing data for a limited number of sites typically requires a few days to two weeks, to produce dashboards, reports or analyses.

However, DRIAS is limited to France, leaving companies with international operations to seek other sources for sites outside the country.

Relying on a patchwork of national databases risks creating inconsistencies in metrics and methodologies, ultimately failing to deliver a global perspective or actionable insights.

The Copernicus Climate Data Store provides a valuable resource, particularly as it offers sector-specific datasets tailored to energy-related projects. Yet, their coverage remains confined to Europe. It may be technically feasible to replicate the methodology for sites in Asia or the Americas using other projections, available from Copernicus or the ESGF, but this requires specialized expertise that most companies lack. If outsourced to a consulting firm, the project could easily cost tens of thousands of euros and extend timelines by several months, making it impractical for companies needing rapid or cost-effective solutions.

In such cases, ClimateVision emerges as a pragmatic alternative. It enables near-instantaneous assessments of all global assets, applying uniform methodologies across all locations. Beyond standard indicators, it also provides sector-specific metrics tailored to operational needs with ready-to-use datasets and interactive vizualisation tools. Additionally, Callendar provides support from climatologists to ensure the results are properly interpreted and actionable.

While free sources, like DRIAS and the Copernicus Climate Data Store, remain invaluable in some situations, ClimateVision offers a scalable, efficient solution for companies that require global coverage, technical precision and rapid execution. In those cases, using ClimateVision proves faster, more reliable but also more cost-effective than free data sources in practice.

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