Methane hydrate, colloquially called "fire ice," was a popular alternative energy explored in the late 1990s and 2000s, consisting of methane trapped within ice. As natural gas reserves gradually diminished, methane hydrate was found to be up to ten times more numerous than remaining recoverable natural gas and more uniformly distributed across the globe. Although a sizable research and extraction industry boomed, it crashed by the end of the 2000s due to a number of factors.
There were three main drawbacks that led to the decline of research into methane hydrate. First, the burning of methane hydrate would excessively contribute to global climate change, with potency as a greenhouse gas several times that of carbon dioxide. Second, the extraction of methane hydrate proved exceptionally difficult and costly, leaving it as a last resort should the world's supply of natural gas run out. Finally, enough natural gas remained in known reserved before its replacement came in the form of fusion power by the 2020s, with fusion's place solidified by the peak oil crisis.