While geologic hydrogen may offer some emissions advantages compared to other hydrogen production methods, large uncertainties remain regarding its environmental impact and scalability. More research is critically needed to evaluate if geologic hydrogen can be a major climate-friendly energy solution, or if efforts are better focused on other decarbonization strategies that are farther along in development. There are open questions around how much methane or hydrogen leaks could diminish any climate benefits, as well as whether geologic hydrogen can realistically be produced at scale by 2050 when deep emissions cuts are essential. I recommend caution in promoting geologic hydrogen until further studies provide more definitive answers.