The poem serves to highlight the way that nature itself will in the end triumph over man if man insists on destroying themselves. The poem highlights the fact that nature doesn't care if man disappears, the war and idiocy of mankind obviously can kill and maim parts of nature but nature itself will eventually triumph regardless of man's greatest efforts. And so this also highlights one of the themes of the story which is the conflict between man and nature and man's inherent inferiority in the conflict.
Something like a nuclear weapon which obviously caused the destruction in the story is an incredibly powerful weapon, one that is feared and thankfully used only twice. Yet with all of its power and terror, it too would eventually submit to nature's inexorable power.