The recent research suggests that lab-grown meat may not be better than conventional meat (at least for beef) because a part of cows emissions are methane related that dissipates fast while majority of emissions for lab grown meat is CO2 that stays in the atmosphere for long.
From https://www.frontiersin.org/articles/10.3389/fsufs.2019.0000...
>We conclude that cultured meat is not prima facie climatically superior to cattle; its relative impact instead depends on the availability of decarbonized energy generation and the specific production systems that are realized.