The ocean and the climate: why measuring heat exchange between the sea and the atmosphere matters

When we talk about climate change, we tend to think about the atmosphere: temperatures, emissions, greenhouse gases. But there is an equally decisive actor that receives far less attention: the ocean. The exchange of heat between the ocean and the atmosphere is one of the most important physical mechanisms for understanding how the Earth’s climate is regulated. And it is precisely the subject of the project Zenithal Blue Technologies has been working on since 2025: the CCI Ocean Surface Heat Flux, funded by the European Space Agency.

An idea that was born in 2018

The idea for this project was co-developed with the Institut de Ciències del Mar in Barcelona in 2018. The central question was whether it was possible to combine salinity and temperature measurements from satellite to measure variations in heat content in the upper layer of the ocean, and from there to better understand the physical processes of exchange between the two fluids: the ocean and the atmosphere.

In 2024 we submitted the proposal to ESA. In 2025 we were told we had won it. We have now been working on it for a year, and it has proven to be a very compelling project.

Why these exchanges matter so much

Since my university days I have been convinced that the interrelationships between heat exchanges between the atmosphere and the ocean — occurring at different times, at different scales and in different places — are behind many of the extreme climate events we are experiencing. And also behind the long-term scaling of climate variation: heatwaves, droughts, changes in the water cycle.

These phenomena represent very serious threats to a large part of the world’s population, even though we still do not seem to be placing enough emphasis on understanding their long-term consequences.

What makes this project special is that, for the first time, satellites are being used to systematically observe these exchanges at the ocean surface. It is a new use of already existing data, applied to a question that has gone without a sufficiently precise answer for decades.

The value of finding new uses for existing data

Much of what we do at Zenithal Blue is exactly this: discovering new uses for satellite data that is already available. A new satellite is not always needed to advance knowledge. Sometimes the answer lies in data we already have, waiting to be read in a different way.

At the same time, when we identify gaps in available information that cannot be resolved with current satellites, those gaps become the seed for the next generation of Earth observation missions. This is how the cycle works: exploit what exists, identify what is missing, propose what comes next.

The ocean as a climate regulation system

The ocean is not a passive backdrop against which things happen. It is an active system that absorbs, stores and redistributes heat on a global scale. Understanding how it does this — with what intensity, in which areas, and in response to what conditions — is fundamental to improving climate models and to better anticipating what lies ahead.

This is the kind of scientific question that, back in my university days, already struck me as essential. Being able to work on it now, with the resources and independence we have at Zenithal Blue, is precisely the kind of research that makes building this company worthwhile.