The Sulphur Institute filed a brief this week in the U.S. Court of Appeals for the District of Columbia opposing the California-led effort to phase out gas- and diesel-powered vehicles.

Sulfur is a fundamental crop nutrient and indispensable to U.S. agriculture, according to the institute.

Regulations that target internal-combustion engines while promoting battery-powered vehicles will paradoxically reduce the supply of sulfur but increase the demand for it, the institute argues.

If there is a sulfur shortage, the U.S. will have to import it, according to the institute. China is the world’s largest sulfur producer, followed by the U.S., Russia and Saudi Arabia.

The institute represents 60 companies, including Boise-based J.R. Simplot, that make, transport or use sulfur-related products.

The institute is one of dozens of trade groups, environmental organizations and businesses that have filed amicus briefs in a lawsuit over whether California can ban new gas- and diesel-powered vehicles.

California’s drive toward zero-emission vehicles has prompted several lawsuits against the Environmental Protection Agency, which must approve California’s laws.

The suits have been merged into one case led by 17 states that oppose California’s mandates and fear they will dictate the auto market for the entire country.

California will ban new gas- and diesel-powered cars, pickups and SUVs in 2035 and is considering applying the ban to all new trucks in 2040.

Washington automatically follows California and is one of 20 states that have intervened to support the EPA.

The Sulphur Institute, which uses an alternative spelling of sulfur, highlighted an issue that it asserts the EPA has paid too little attention.

Sulfur occurs naturally and goes into making many products, such as chemicals, paints and “most importantly, fertilizers,” according to the institute’s amicus brief.

Almost two-thirds of the global supply went to make fertilizer in 2019, according to the institute. Sulfur can be mined, but 80% of world production comes from refining fossil fuels.

In August, United Kingdom researchers at University College London warned of a “potential sulfuric acid crisis” as the unintended consequence of ridding the economy of fossil fuels.

In a paper published in the journal of the Royal Geographic Society, the researchers agreed the world needs to eliminate fossil fuels to restrict climate change. “Yet a problem looms, which is largely unnoticed,” they wrote.

Sulfur seems plentiful and cheap because it’s extracted by refineries. But, they wrote, “as the world decarbonizes over the next three decades, the supplies of sulfur will drop, just when the material is needed most.”

Intensive agriculture, electric motors and lithium batteries will increase the demand for sulfur, according to researchers. Food costs could rise, especially if “green tech” outbids fertilizer makers, they said.

The world theoretically has an almost limitless supply of sulfur in geological deposits. But old techniques to melt and bring to the surface sulfur produced a large amount of contaminated wastewater and “should be unacceptable now,” researchers said.

Sulfur mining, primarily in Texas and Louisiana, ended in the U.S. two decades ago. Nevertheless, sulfuric acid is the most-produced chemical in the U.S., according to the U.S. Geological Survey.

Sulfuric acid consumption is one of the best indicators of a nation’s development, the USGS stated.