Maria Sand and her team at CICERO have just delivered news that could reshape how the world scales up hydrogen as a climate solution: the science is solid enough now to actually guide real policy and business decisions.
Hydrogen is set to play a starring role in decarbonizing heavy industry, long-distance transport, and energy storage—sectors where simply switching to electricity remains stubbornly difficult. But there's a catch that researchers have been racing to quantify. Hydrogen isn't a greenhouse gas itself, yet when it leaks into the atmosphere (and it does leak at every stage of the value chain), it doesn't simply vanish. Instead, it chemically reacts in ways that boost other warming agents: methane, ozone, and stratospheric water vapor. For years, this indirect warming effect was poorly understood, making it hard for policymakers to know whether scaling up hydrogen would actually deliver the climate benefits everyone hoped for.
The review, published in Nature Reviews Earth & Environment and led by Sand with contributions from institutions across the United States, United Kingdom, France, and Norway, settles a critical question: hydrogen has a global warming potential approximately 12 times that of CO2 over a 100-year timeframe. More importantly, those estimates are now converging and robust enough to be trusted. "Hydrogen has largely been considered environmentally benign," Sand notes. "But as the science evolves and it is acknowledged that hydrogen has a global warming potential, including hydrogen's climate impacts in assessments and climate accounting frameworks is key as hydrogen deployment scales up."
What makes this finding urgent rather than merely academic is the acceleration happening right now. Governments and companies worldwide are betting on hydrogen as a cornerstone of their net-zero strategies. Without solid climate accounting, those bets could backfire—a hydrogen economy built on leaky infrastructure might solve one climate problem while accidentally creating another. The research team, which includes collaborators from Spark Climate Solutions, the Environmental Defense Fund, the Laboratoire des Sciences du Climat et de l'Environnement in France, Cambridge, Edinburgh, GFDL, and UC Irvine, has done the work to prevent that scenario.
The conclusion is clear: hydrogen absolutely can support decarbonization, but only if losses to the atmosphere stay minimal. That means every link in the chain—production, compression, transport, storage, and use—needs to be engineered for tightness and monitored carefully. It's not a showstopper; it's a design specification.
The review also flags what researchers still need to figure out: better measurement of hydrogen emissions across the entire supply chain, deeper understanding of how soil naturally removes hydrogen from the atmosphere, and more detailed representation of hydrogen chemistry in climate models. The HYway project, led by CICERO, is already working on these gaps. That ongoing research will sharpen estimates further, turning what are already robust metrics into even more precise tools for building a hydrogen economy that actually delivers on its climate promise.
The age of treating hydrogen as a silver-bullet solution with no tradeoffs is over. The age of managing it strategically and scaling it responsibly has begun.