God has covenanted that He will not destroy the earth by water again. But He is saying that He will judge the world by fire. Everything will explode with a roar of judgment. The elements will melt away...so, Peter exhorts, this should change the way we live! Why are we living for things when every thing will one day be dissolved? Peter exhorts us to live holy & godly lives, looking for the new heavens and the new earth!