From Licensing to Open Access: Designing a Sustainable Transition in Operational Weather Data
This paper documents the European Centre for Medium-Range Weather Forecasts' (ECMWF) successful transition from a restricted licensing model to open access under CC BY 4.0 by October 2025, demonstrating through an iterative, tiered service approach that operational sustainability and open data obligations can be reconciled while maintaining high retention of former paying clients and significantly increasing global data access.
Original paper licensed under CC BY 4.0 (http://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Imagine the European Centre for Medium-Range Weather Forecasts (ECMWF) as a massive, high-tech bakery that bakes the world's most accurate weather forecasts. For decades, this bakery operated on a "ticket" system. If you wanted a fresh loaf of bread (the weather data), you had to buy a specific license. You could eat the bread, but you weren't allowed to sell slices of it to your neighbors or show them exactly how the bakery made it.
This system worked, but it was getting complicated. The European Union started saying, "Publicly funded bread should be free for everyone to take home." The bakery faced a tough choice: if they gave the bread away for free, how would they pay for the ovens, the flour, and the bakers?
This paper tells the story of how ECMWF solved this puzzle between 2020 and 2025 by switching to a "Freemium" model (a mix of free and paid services). Here is how they did it, explained simply:
1. The New Strategy: The "Free Sample" vs. The "VIP Delivery"
Instead of charging for the bread itself, ECMWF decided to give the bread away for free to everyone, but they kept charging for the delivery service.
- The Free Tier (Open Access): Everyone can now download the weather data for free, just like walking into a bakery and taking a fresh loaf off the shelf. The data is open to anyone, anywhere, with no legal restrictions on how they use it.
- The Paid Tier (Service Agreements): If you are a busy restaurant owner (a business or government agency) who needs the bread delivered to your door before anyone else, needs it delivered at a specific time, or needs a driver who speaks your language and guarantees the bread won't get cold, you pay for that service.
The Analogy: Think of it like a newspaper. The news itself is free to read online (Open Data). But if you want the paper delivered to your doorstep every morning at 6:00 AM with a guarantee that it arrives on time, you pay a subscription fee (Service Agreement).
2. How They Planned the Switch (The "Slow Cook" Method)
ECMWF didn't flip a switch and give everything away overnight. That would have been too risky. Instead, they used a "Yearly Tasting" approach:
- Step 1: They set a goal to reduce their income from selling "tickets" by a small amount each year.
- Step 2: They took that saved money and used it to make the "free bread" slightly better (adding more ingredients or making the loaf bigger).
- Step 3: They watched to see if people stopped paying for delivery.
- Step 4: They repeated this every year until, in October 2025, the "ticket" price for the data itself hit zero.
The Result: They were worried that everyone would stop paying for delivery once the bread was free. But they were wrong. Most people (over 93%) kept paying for the delivery service because they needed the reliability and speed that only the paid service could guarantee.
3. The "Cloud Mirrors" (The Delivery Network)
One big problem was that the bakery couldn't physically deliver free bread to every single person in the world; the delivery trucks would break down.
To solve this, ECMWF partnered with giant digital warehouses (Amazon AWS, Microsoft Azure, and Google). These partners built "mirrors" of the bakery's data on their own servers.
- The Bakery's Role: They make the bread.
- The Mirrors' Role: They handle the heavy lifting of shipping the free bread to millions of people.
- The Payoff: This meant the free data exploded in popularity. In fact, more people are downloading the free data from these mirrors than the bakery's own servers could ever handle on their own.
4. The "AI Loaf" (A New Challenge)
Recently, the bakery started baking a new type of bread using Artificial Intelligence (AI). This AI bread is even faster to make and is also given away for free.
- The Concern: If the AI bread is free and high-quality, will people still pay for the delivery of the regular bread?
- The Reality: So far, people are still paying for the delivery because they need the reliability and support that comes with the paid service, even if the "ingredients" (the data) are free. However, the bakery knows they need to keep watching this closely.
5. What They Learned (The Takeaway)
The paper concludes with a few simple lessons for other organizations trying to do the same thing:
- Don't fear the free: Giving the core product away for free didn't kill the business; it actually made the paid delivery service more valuable.
- People pay for convenience, not just the product: Users were willing to pay for speed, reliability, and support, even when the raw data was free.
- You don't have to give away everything: The free data is high quality, but the paid data is "premium" (faster, more detailed, guaranteed). This balance is key.
- Self-service is essential: You can't have a help desk for millions of free users. You need tools that let people help themselves.
In short: ECMWF proved that you can give away your most valuable public data for free to help the world, while still keeping your lights on by charging for the premium service of delivering that data quickly and reliably. They didn't have to choose between being open and being sustainable; they found a way to do both.
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