When the snow fades from Mount Fuji, it is hard not to notice how quickly the world is changing. For the first time in more than a century, Japan’s iconic peak went snow-free well into November 2024. The latest and most delayed first snowfall on record since observations began in the 1890s. Unusually warm autumn temperatures kept the mountain bare until early winter.
I have sailed through the years when LNG became the new badge of responsibility and pride for few who got an opportunity to sail on them. From the sea, watching trade turn cleaner and more complex, LNG looked like progress with no black smoke, no soot, and quieter stacks. Most of these ships are dual-fuel vessels, designed to run mainly on gas but able to switch to heavy or marine gas oil when required. For many shipowners and regulators, this flexibility made LNG the perfect compromise, a bridge fuel until something truly green arrived.
But every bridge has a cost, and this one leaks.
The reality is simple. LNG solved one problem and exposed another. Its numbers should be treated for what they are, engineering data, not moral evidence. When you trace LNG’s full journey from wellhead to wake, or from cradle to grave, the clean story blurs. Methane losses, liquefaction energy, and shipboard slip erode much of the promised benefit. The more I have read and seen, the more it feels that LNG’s climate advantage depends on where you stop counting.
The inconvenient chemistry
Methane (CH₄) is a quiet and powerful gas. Chemically simple, but far more potent than carbon dioxide when it comes to trapping heat in the atmosphere. Over a 20-year period, methane warms the planet about eighty times more than CO₂. Over a 100-year period, that effect drops to roughly thirty times.
These numbers come from what scientists call Global Warming Potential, or GWP. It is a way of comparing how much heat a gas traps in the atmosphere compared with carbon dioxide, and for how long. The shorter measure, GWP-20, shows the impact over twenty years, while GWP-100 spreads it across a century. The shorter horizon matters more for near-term warming.
This is not a matter of opinion but of physics. The Intergovernmental Panel on Climate Change lists both values, and both are correct. Policymakers often prefer the hundred-year version because it looks gentler on paper, but anyone at sea knows that the next twenty years decide the weather we sail in.
What the real world is showing us
Numbers written in reports are one thing, numbers measured on ships are another. Methane slip is turning out to be higher than many official figures suggest. Methane slip is the portion of the fuel that passes through the engine without burning completely and is released into the atmosphere through the exhaust.
A recent international study known as the FUMES campaign measured the exhaust plumes from eighteen LNG-fueled ships operating under normal sea conditions. The researchers found an average methane slip of about 6.4 percent. Most of these ships were fitted with low-pressure dual-fuel engines, the kind commonly used in today’s LNG carriers and new merchant vessels.
That number is almost double what most regulatory models still assume. It also changes with how the engines are run. Slip rises at low load and falls at sea, but some gas always escapes unburned. What looks clean at the funnel is not always clean when you count the molecules leaving the exhaust.
These are not estimates or theories. They are measured values. And measurement remains the only language the atmosphere understands.
The upstream story nobody likes to talk about
The discussion about LNG often ends at the ship’s funnel, but the story starts much earlier. Methane can escape at almost every stage before the gas even reaches a vessel. Leaks occur during drilling, from wellheads, along gathering pipelines, and at compressor and liquefaction plants. Each small loss adds up and decides whether LNG is truly cleaner or only looks that way.
The lEA’s Methane Tracker shows that the amount of methane escaping from oil and gas operations around the world is far greater than what many companies report. In some production regions, the methane intensity of gas is over one hundred times higher than in others. Gas from countries such as Norway and the Netherlands is among the cleanest, while gas from older or poorly maintained fields in parts of Russia and Central Asia leaks much more.
This means the phrase “LNG is cleaner” is not automatically true. It depends on where the gas comes from, how it is handled, and whether the losses are measured or merely assumed.
The hidden energy cost
Turning natural gas into liquid is not a simple or free process. The gas has to be cooled to around -160°C to become liquid. That takes a large amount of power. Modern liquefaction plants consume about 7–15% of the feed gas just to run their own systems, and they require roughly 300 kWh of electricity for every tonne of LNG produced. This adds a new layer of carbon dioxide to the total footprint even before the fuel leaves the terminal.
The energy loss does not stop there. During transport, a small amount of the cargo evaporates naturally each day. This is known as boil-off gas. Even with advanced reliquefaction systems, most LNG carriers still lose about 0.1–0.15% of their cargo every day. Some of this gas is burned as fuel, and some escapes as methane.
These numbers are not minor details. They are part of the physics of moving gas across oceans. The ship may run smoothly, but the real efficiency loss begins long before the first engine start.
What the studies actually say
Independent studies show that LNG’s full climate impact is often higher than early reports suggested. When researchers calculate the entire chain ie. from gas extraction and liquefaction to transport and combustion, the results depend heavily on how much methane leakage they assume and on which time frame they use.
Recent research from Cornell University found that when methane losses and shipping energy are fully included, LNG can produce a 33% higher climate impact than coal over a 20-year period. On a 100-year basis the numbers look better, but that is because the short-term effect of methane is averaged out across a century. Many industry assessments still use the longer time frame, which softens the problem on paper.
This is not about who is right or wrong. It is about what assumptions are used. The atmosphere does not read policy documents or spreadsheets. It only reacts to what is actually released.
A new light from Japan
Not all the news is bad. Engineers in Japan have shown that technology can cut methane slip far more than anyone expected a few years ago. In 2025, Mitsui O.S.K. Lines (MOL) together with Yanmar Power Solutions and Kanadevia Corporation tested a new methane oxidation catalyst to reduce unburned methane from dual-fuel engines.
Supported by Japan’s Green Innovation Fund, the project reported a 98% methane slip reduction during sea trials on the LNG-fueled bulk carrier Reimei, following earlier ClassNK-verified land trials that achieved 93.8% at full load.The system combines exhaust-gas recirculation with a catalytic process that converts methane into carbon dioxide and water before release.
If these results hold across fleets and over time, it will be an important milestone, but still one step in a larger equation. The atmosphere measures fleets, not trials.
Why LNG still sails
Shipowners choose LNG because it works today. It lowers visible carbon dioxide at the stack by about 20–25%, meets sulphur rules, and fits into existing dual-fuel engines. Bunkering networks are expanding.
Regulations such as the IMO measures and the FuelEU Maritime framework also treat LNG favourably because they focus on carbon dioxide at the exhaust, not on methane across the supply chain. That gives LNG a policy advantage even when its full impact is uncertain.
It is not a perfect fuel, but it is a practical one. The industry moves on what can be delivered, not on what is still in design.
Do we need LNG at all?
The answer changes with the point of view.
From a mariner’s view, LNG is a workable fuel. It burns cleanly, keeps the machinery compliant, and fits within the systems already on board.
From a climate observer’s view, LNG is a temporary fix. If methane leaks and slip stay high, its total warming can exceed the fuel it replaced. The numbers, not the labels, decide whether it helps or harms.
From a layman’s view, LNG looks cleaner because the smoke is gone. But what leaves the exhaust unseen can matter more than what is visible. The difference lies between what we see and what the science measures.
What needs to happen next
- Measure, don’t assume. Regulations must adopt real-world data for slip and leakage.
- Price the full chain. Use GWP₂₀ where short-term impact matters.
- Avoid locking in infrastructure that will last beyond its usefulness.
- Scale technologies like MOL’s catalyst fast, and fund methane detection across the fleet.
- Push for green methanol, ammonia, hydrogen. The direction is known; the discipline to move faster is what matters.
From the bridge
LNG was never a bad idea. It was the best option available at a certain time. It made ships cleaner to the eye and easier to regulate. But the sea has no patience for half measures. It reacts to what we release, not what we intend.
Methane that escapes will keep warming the planet no matter how clean the funnel looks. Technology can reduce the losses, but it cannot erase them. The numbers will always tell the truth, even when the stories around them change.
From the bridge, the lesson is simple. Count everything, measure honestly, and never mistake appearance for progress.
And yet, seasons still change. When winter returns, Mount Fuji takes back its snow, white and calm above the bay. It reminds us that renewal follows correction. If we learn from what we measure and act with honesty, the sea, the air, and the mountains can find their balance again.
Shipping does not need slogans. It needs accurate data, transparent reporting, and the discipline to act on both. The direction is known, the discipline to move faster is what matters. LNG was sold as a bridge to a cleaner future.
The real transition will come from what we measure, not from what we market.
References
- Intergovernmental Panel on Climate Change (IPCC), Sixth Assessment Report (AR6), Working Group I: The Physical Science Basis, 2021.
- International Council on Clean Transportation (ICCT), FUMES Study: Field measurements of methane slip from LNG-fueled ships, 2024.
- International Energy Agency (IEA), Methane Tracker 2025, Paris: IEA, 2025.
- IEAGHG, CO₂ Emissions from Liquefied Natural Gas Production, Technical Report 2023/02, 2023.
- Cornell University, R. Howarth, Assessment of greenhouse gas emissions from LNG exports, Cornell University, 2023.
- Mitsui O.S.K. Lines (MOL), “MOL achieves 98% methane slip reduction using catalyst system on Reimei”, Press Release, May 2025.
- ClassNK, Statement of Fact on methane oxidation catalyst performance, Tokyo, 2025.
- FuelEU Maritime Regulation (EU) 2023/1805, Official Journal of the European Union, 2023.
- International Maritime Organization (IMO), 2023 IMO Strategy on Reduction of GHG Emissions from Ships and 2024 LCA Guidelines, London, IMO.
- Wärtsilä Corporation, Boil-off gas management and reliquefaction systems for LNG carriers, Technical Brochure, 2024.
- MAN Energy Solutions, ME-GI Dual Fuel Engine: Operating Experience and Methane Slip Data, Technical Paper, 2024.
- WinGD, X-DF2.0 with Variable Compression Ratio: Methane Slip Reduction Results, Technical Release, 2024.
Note
All figures and statements in this article are drawn from verified 2023–2025 industry and scientific sources, including the Intergovernmental Panel on Climate Change (AR6), International Council on Clean Transportation (FUMES campaign, 2024), International Energy Agency (Methane Tracker, 2025), IEAGHG (2023/02), and published data from Mitsui O.S.K. Lines and ClassNK (2025). Methane Global Warming Potential (GWP) values reflect IPCC AR6 metrics for both 20-year and 100-year horizons. The Mount Fuji snowfall reference is based on Japan Meteorological Agency records confirming the latest first snow in over 130 years during November 2024.
Leave a Reply