Shell announced that it has signed a five-year contract with PetroChina to supply the Chinese company with carbon-neutral liquefied natural gas (LNG) cargos.

Many businesses, particularly those in the fossil fuel industry, are using carbon offsets to compensate for emissions that they are unable to reduce in their operations.

The two companies will “cooperate to offset life-cycle carbon dioxide equivalent (CO2e) emissions generated across the LNG value chain, using high-quality carbon credits from nature-based projects” for each cargo delivered under the agreement, according to Shell.

Offset projects based on nature, such as reforestation, protect, transform, or restore land, allowing nature to add oxygen and absorb carbon dioxide emissions.

Shell made the announcement as PetroChina received its first carbon-neutral LNG cargo at China’s Dalian port.

“This first term deal is an important step in scaling up the market for carbon-neutral LNG, and we are extremely grateful to our valued partner PetroChina for their collaboration in enabling this industry milestone,” said Steve Hill, Executive Vice President Shell Energy, in a press release.

Shell stated that the offsets would come from its own portfolio of emission-reduction projects in nature.

Many environmental groups are dubious of the use of carbon offsets, warning that the capacity to pay for emission reductions elsewhere may extend the use of fossil fuels, which are largely blamed for climate change.

The 2015 Paris Agreement on Climate Change intends to limit temperature rises to 1.5 degrees Celsius beyond pre-industrial levels, which scientists predict will necessitate transitioning the world into a net zero economy by 2050.