Liquefied natural gas (LNG), often touted as a cleaner alternative to coal, has a greenhouse gas footprint 33% larger than coal when factoring in its entire production and shipping process, according to a new Cornell study. The findings challenge the perception of LNG as a “bridge fuel” to cleaner energy.

The work challenges the industry line that sending liquefied natural gas around the globe is a cleaner alternative.

Rising LNG exports are expected from the U.S. to China, India, and other emerging economies, as well as global shipping growth and LNG bunkering.

Greenhouse gas emissions, such as carbon dioxide and methane, are released into the atmosphere, while a greenhouse gas footprint indicates the impact of these emissions on the environment.