California Senators Dianne Feinstein and Alex Padilla are calling on 13 major ocean carriers to help alleviate the global food shortage by acquiring more containers for agricultural exports.

In a letter sent Wednesday, the senators urged company CEOs to ensure the products, “especially perishables, expeditiously get to export markets worldwide during this important season.” They referenced a letter that six agricultural associations sent to the Biden administration last week.

Three out of four containers are returning to Asia empty, leading to a significant backlog of products, according to the farm groups, which urged the heads of agriculture, transportation and the Economic Council to negotiate a deal with the carriers to restore services.

The letter ran through a long list of impacts to the industry. The almond inventory, for one, has more than doubled from a year ago, while walnut producers have lost up to $700 million from shipping issues. Supply chain challenges cost dairy exporters $1.5 billion last year.

Not restoring services means the “cash flow will be nearly eliminated” and “we will lose farmers, farms, acreage and market share as a result,” according to the groups. “We cannot emphasize this enough: The viability of our industry, the rural and disadvantaged communities that depend on it, and the global competitiveness of our nation are at stake.”