Note: This blog post was revised on 12/12/2025. The first version of this post used an incomplete LNG tanker list and included some non-LNG liquefied gas carriers in emission estimates. The analysis and data files have now been corrected using a refined LNG vessel list.

The LNG industry claims it’s better for the environment than other fossil fuels, but is that true?

SkyTruth set out to make data about the Liquified Natural Gas (LNG) supply chain publicly accessible and to track the industry’s rapid growth. LNG has been touted as the clean alternative to other energy sources, and we aim to put that claim to the test. 

Natural gas has long been greenwashed as a clean alternative to other fossil fuels because it produces fewer greenhouse gases (GHG) when burned. However, natural gas comes with a host of other emissions. Cooling and compressing the fuel into liquid form requires huge amounts of energy, while transporting it around the world in massive tankers adds CO₂ from powering ship engines. On top of that, many LNG facilities leak methane — a greenhouse gas far more potent than CO₂ at trapping heat in the atmosphere.

Beyond greenhouse gases, LNG expansion also poses serious risks to the ocean ecosystems these tankers pass through. Whale strikes are estimated to kill more than 30,000 whales each year. And noise pollution disrupts their ability to communicate. Both are  likely to increase as more large vessels take to the sea. In the Sea of Cortez, for example, which is home to 39% of the world’s marine mammal species and serves as a breeding ground for many whales, including endangered species, new terminal proposals have drawn heavy condemnation for the harm that increased tanker traffic could bring to this sensitive ecosystem.

Offshore LNG is a complex industry, with many factors contributing to its environmental impact, but we are beginning to tackle some of the most pressing questions. In this post, we will explore some key aspects of the LNG supply chain that impact the environment, including

• The expansion of LNG infrastructure over time
• Atmosphere warming GHG emissions from transport and methane leaks
• Tanker traffic through sensitive marine ecosystems

LNG Infrastructure

Our goal is to gain a deeper understanding of the offshore production and movement of natural gas, and how it affects the environment. In order to do so, we first set out to inventory all LNG infrastructure worldwide. We gathered LNG terminal locations from Global Energy Monitor’s Global Gas Infrastructure Tracker (GGIT), identified likely LNG infrastructure as a subset of Global Fishing Watch’s (GFW) infrastructure data, identified operating locations of FLNGs (Floating Liquid Natural Gas), and created a catalog of 842 natural gas vessels, 799 of which were operating in 2024. This number has nearly doubled since over the last decade. The number of active LNG terminals, based on the GGIT terminal list, has grown rapidly since the 1970s.

Methane

Like all greenhouse gases, methane is invisible. However, CarbonMapper and the International Methane Emission Observatory (IMEO) can spot it from space using satellite-based short-wave infrared sensors. From their methane plume data, we can see instances of LNG infrastructure leaking or venting methane. 

The SkyTruth table below – which uses information from GGIT, CMAP, and IMEO – shows the number of methane plumes detected and their average emission rates at several terminals. Because satellite coverage is not consistent across all sites, these facilities should not be assumed to be the worst emitters — they are simply the ones where plumes were observed. Many more leaks likely went undetected.

Transport emissions

The University of California, Santa Barbara’s Environmental Markets Lab (emLab) developed GHG emissions data from 2015 onward in partnership with Global Fishing Watch for vessels based on type, size, speed, and distance traveled using vessel metadata and AIS location, among other factors. We calculated annual CO₂ emissions for our list of 893 LNG tankers. Then, we split the results by country, calculated as the segment emission that leaves or arrives in that country’s EEZ (segments are counted twice for international travel).

The number of active LNG tankers, as well as the associated CO₂ emissions, climbed quickly over the last decade. In addition to the power used to move the gigantic vessels, LNG tankers use auxiliary engines to cool and liquify the product for transport, which is a major contributor to the vessel’s overall emissions. In 2024 alone, LNG tankers produced at least 50 million metric tons of CO₂. This accounted for roughly 4% of maritime CO₂ emissions, and this figure is rapidly increasing year over year, more than doubling since 2015, with the US driving much of that growth.

Tankers traveling through sensitive ecosystems can also be detrimental. Vessel strikes are a threat to large whale species. With the rapid growth of LNG transport, the potential for LNG spills increases. In some cases, LNG tanker corridors cut directly through Marine Protected Areas (MPAs), zones meant to safeguard habitats and marine life, with some MPAs experiencing hundreds of kilometers of LNG vessel travel each day. 

A few examples from 2024 highlight this issue:

• The OSPAR Commission’s Southern North Sea MPA (WDPAID=555624872) protects marine ecosystems in the Northeast Atlantic.
• The Marine Musandam Reserve (WDPAID=555760584) is a recently established protected area, which also hosts rich biodiversity, but because of its location in the oil and gas rich northern tip of the Arabian Peninsula, vessel traffic is a significant concern.

What’s Next?

We’re currently developing a method to better understand vessel voyages from one anchorage to another and their associated emissions. However, not all anchorages are the terminus of a voyage; sometimes they are just a common place for a vessel to wait for berths. Ultimately we are working to better understand the full paths of voyages to identify the amount of time tankers spend at sea, which vessels frequent which terminals, monitor LNG trade partners, and track the emissions of other vessels that service LNG infrastructure (support vessels, construction ships, tugboats, etc.). 

One ongoing application of these voyage analyses focuses on incorporating emissions from liquefied petroleum gas (LPG) transport into our broader LNG emissions estimates. Roughly 60% of LPG is produced from natural gas processing, while the remaining 40% comes from oil refining, and the LPG fleet consists of over 1,000 tankers. Separating emissions from LNG- versus oil-linked LPG transport is challenging, but by identifying LPG terminals (as locations where vessels anchor for extended periods to load or unload) and cross-referencing nearby oil and gas facilities, we can classify many LPG sites as LNG-related. From these terminals, we estimate voyage emissions for vessels operating in the LNG supply chain.

This work is ongoing, and as our methods improve, the resulting data can help researchers, policymakers, and advocates hold the industry accountable, evaluate its true environmental footprint, and push for more sustainable energy transitions.

Special thanks to OceanMind for constructive conversations that helped us refine our approach.

Download the data