Create seaweed farms for livestock feed.
Methane production goes down.
Livestock are larger and healthier.
The farms turn seawater and carbon dioxide into oxygen.
On average, according to Google, a head of cattle eats 27 pounds of food daily. If 1.5 billion cows eat .27 pounds each, that is 405 million pounds of seaweed per day. That must lower the sea level something, even if it is negligible.
If you add 2% seaweed to chili, does it reduce the methane production?