Science flourishes when data are shared freely, enabling verification, replication and innovation. In climate science, where I work, the stakes of open data sharing are nothing less than the future of our planet. Yet it is precisely in this field that access to fundamental data sets is often withheld or limited by gate-keeping national agencies, which often cite security, privacy or commercial concerns.

These restrictions have huge consequences. Climate models are a crucial tool for projecting future warming and informing global policies, and must be validated using observational data. The same is true of reanalysis data sets, which combine models and previously gathered data to understand climate patterns. Without access to relevant observational data, these models and analyses can propagate flaws, leading to misguided policies or ineffective mitigation strategies. There is an urgent need to enact policies that ensure all relevant climate data are shared for the benefit of everyone.

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Good intentions are already there. The World Meteorological Organization has made efforts to support data sharing through initiatives such as Resolution 60 on the free exchange of meteorological information, adopted in 2019, and the 2022 Unified Data Policy, which aims to standardize practices among its 193 member states and territories. Yet progress has been slow, with certain national agencies still reluctant to release their data. However, most of the reasons given are spurious, and many of the proposed barriers can be surmounted.

Take national security. Climate data can involve sensitive sites, such as military bases or ships, but most of the obtained data pose minimal or no security risks. In cases with legitimate concerns, simple measures, including censoring the sites’ coordinates, can deal with such issues effectively.

Most weather stations are on public property, such as state facilities, parks and educational institutions. But where this is not the case, privacy considerations can arise because localized data sets might reveal private landowners or properties. But such challenges are not unique to climate science: fields such as health research encounter them, too, and navigate them using anonymization methods that climate scientists could easily adapt and adopt.

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When commercial confidentiality is cited as a reason for not sharing data sets, it is often because maintaining observational networks and curating the data comes with costs that are usually borne by state-run institutions. Some governments argue that making the data freely available undermines those institutions’ financial viability.

But these arguments don’t take into account that environmental data gathered using state funding ought eventually to yield benefits to the public, something that is best ensured by the broadest possible access. Free access is also prudent economically: it stimulates innovation in the private sector, enabling businesses and entrepreneurs to develop new technologies, services and applications.