So instead of methane that will stay ~10 year (GWP of 2.8-3.4) in the atmosphere, you release C02 (GWP of 1) that will stay ~10k year. So short term (for ~10year) you reduce warming by ~3.5, if your look long term (10k years) you increase warming by 285x by doing that.
CH4 + 2 O2 → CO2 + 2 H2O
Not sure I will call that a win for the climate. (and this energy could be put to better use than burning it on crypto)