Oh yes, I've heard of this. Fears among climatologists are that if temperatures increase even moderately above minimum predictions these methane hydrates will start melting and releasing methane directly into the atmosphere. If this happens, they exacerbate the warming problem. Methane is a better greenhouse gas than co2, meaning it's more dangerous. Many scientists are afraid that if the ices start melting, it will create a feedback warming loop that will release even more methane. The scenario they fear leads to a mean average temperature above that of just co2 warming. Some have even speculated it's possible to trigger a runaway loop that leads to a Venus situation. While those are still speculations, overall it shows that releasing captured methane is a very bad idea. It is utterly irresponsible to consider mining these materials and putting more greenhouse gases into the air.