As the world works towards deploying a cleaner energy future, governments and industry are investing in building a hydrogen economy to replace high greenhouse gas emitting energy sources in critical hard to decarbonize sectors. But as we prepare to deploy hydrogen at scale, we must ensure that our standards and policies are rooted in the latest science. Otherwise, we risk undermining the very climate benefits we seek.
At the recent World Hydrogen Summit in Rotterdam, our organization engaged with hydrogen industry leaders to discuss how we can collaboratively ensure the climate benefits of hydrogen are fully realized. Conversations at the summit showed growing recognition of the need to quantify and reduce hydrogen emissions as they undercut the climate benefits being sought. The scientific consensus underlying this understanding is based on published research spanning decades, but there has been resistance in utilizing this work, particularly around how (and why) to incorporate this science into standards and emissions accounting.
The stakes are high. Clean hydrogen could play a critical role in the global energy transition — but only if its climate benefits are maximized. Failure to utilize what we know could leave us with a problem that has to be addressed moving forward, wasting capital and an opportunity to maximize hydrogen’s benefits.
Hydrogen’s indirect warming effect is well-established
Hydrogen’s warming impact is well documented in scientific literature, even if underrecognized in policy. Unlike carbon dioxide or methane, hydrogen does not trap heat directly. Instead, when it escapes into the atmosphere, it affects other gases — extending the lifetime of methane, increasing ozone near the Earth’s surface, and boosting water vapor in the stratosphere. All three are greenhouse gases contributing to global warming. It is worth noting that these indirect impact pathways are not novel — methane has very similar indirect impact pathways that are included in the calculation of its warming impact. Hydrogen’s indirect effect has been known since the 1970s and is cited in three assessment reports by The Intergovernmental Panel on Climate Change. Yet it’s largely absent from the climate frameworks used to evaluate hydrogen’s climate benefits for no apparent reason other than that it is inconvenient.
Scientists at the Environmental Defense Fund and other institutions began raising this issue in 2022. The International Energy Agency, European Commission, UK government, dozens of climate scientists and some leading companies, all acknowledge the need to consider hydrogen’s climate impacts fully. The International Partnership for Hydrogen and Fuel Cells in the Economy has clearly stated that “it is important to take into consideration these potential additional hydrogen emissions into the atmosphere when assessing the GHG reduction potential from hydrogen systems and undertake efforts to minimize them.” Yet many current emissions accounting systems remain outdated and incomplete.
Our accounting tools are stuck in the past
Under the United Nations Framework Convention on Climate Change’s emissions framework — established over 30 years ago during the Kyoto Protocol era — only a fixed set of “Kyoto Gases” are tracked using a metric called Global Warming Potential over 100 years (GWP100). Hydrogen’s climate impact wasn’t fully understood at the time, and it wasn’t included. In addition, GWP100 is an essential but incomplete metric, because the 100-year timeframe does not reflect the value of near-term climate action in achieving policy objectives of climate neutrality by 2050.
The science is clear: hydrogen is about 37 times more potent than carbon dioxide pound for pound over 20 years, and 12 times over 100 years.[i] Hydrogen emissions matter. Recent studies show that each 1% of hydrogen emitted can reduce hydrogen systems’ climate benefits by about 3% in the near term, and by roughly 1.5% over the long term.[ii] It is now up to decisionmakers — governments, regulators and standards bodies like ISO to reflect that science in policy and accounting.
We can do better with hydrogen
Some argue that hydrogen emissions from industry are too small to worry about now. That misses the bigger picture. As global use expands, emissions from transport, storage and use can be expected to grow unless taken into account now. If we don’t act proactively, we could see a repeat of the methane story: underestimated, underregulated and increasingly costly to address.
Practical, science-based tools already exist to account for and manage hydrogen’s climate impacts. Updating our analytics to include hydrogen’s long and near term warming effects gives us a fuller, more accurate picture of hydrogen’s true climate benefits.
Standards must lead, not lag
It’s not every day that experts from over 15 countries come together to write a new global emissions standard. With the first international standard for hydrogen under development ahead of COP30, we have a rare opportunity to define what clean hydrogen truly means. But without incorporating hydrogen’s warming effects — along with accurately accounting for its carbon dioxide and methane emissions — we risk codifying poor practices.
While the ISO process has made important strides toward global harmonization, the current draft is a missed opportunity. It doesn’t reflect the scientific consensus on hydrogen’s warming impact and doesn’t allow its emissions to be factored in. It also lacks input from climate scientists, despite the important input from its mostly industry-based contributors.
This is not about finger-pointing, it’s about ensuring success. We need a forward-looking framework that reflects both the science and the scale of what is at stake.
Let’s not miss the forest for the trees
This represents more than a technical detail about one gas. It’s a test of whether our climate frameworks are based on the latest science or reflect an out-of-date understanding. We are building a new energy economy — one that must be resilient, transparent and genuinely climate aligned.
The good news? We already have the knowledge. We have the tools. And we have a community of scientists, industry leaders, and policymakers ready to act. Let’s seize this moment to build a hydrogen standard that is truly clean — not just in name, but in reality.
[i] Sand, M., Skeie, R.B., Sandstad, M. et al. A multi-model assessment of the Global Warming Potential of hydrogen. Commun Earth Environ 4, 203 (2023). https://doi.org/10.1038/s43247-023-00857-8
[ii] Hauglustaine, D., Paulot, F., Collins, W. et al. Climate benefit of a future hydrogen economy. Commun Earth Environ 3, 295 (2022). https://doi.org/10.1038/s43247-022-00626-z
Warwick, N. J., Archibald, A. T., Griffiths, P. T., Keeble, J., O’Connor, F. M., Pyle, J. A., and Shine, K. P.: Atmospheric composition and climate impacts of a future hydrogen economy, Atmos. Chem. Phys., 23, 13451–13467, https://doi.org/10.5194/acp-23-13451-2023, 2023
Ocko, I. B. and Hamburg, S. P.: Climate consequences of hydrogen emissions, Atmos. Chem. Phys., 22, 9349–9368, https://doi.org/10.5194/acp-22-9349-2022, 2022
Sun, T., E. Shrestha, S.P. Hamburg, R. Kupers, and I.B. Ocko 2024: Climate impacts of hydrogen and methane emissions can considerably reduce the climate benefits across key hydrogen use cases and timescales. Environmental Science & Technology. https://pubs.acs.org/doi/10.1021/acs.est.3c09030
