Glaciers have been melting for 15,000+ years. They melt relatively faster when they get smaller. Champaign, Illinois used to be under a mile of ice. Even if humans had zero impact on the climate the idea that the climate would stay the same indefinitely is absolute lunacy.
The good old 'of course there is climate change. There has always been climate change." argument.
No one has ever argued that, without humans, the climate would stay the same indefinitely..
My understanding is we are currently in a great ice age. Within this ice age there are long periods of relative cooling with glacial expansion and long periods of relative warming with gradual glacial retreating.
During our industrial age, humans began influencing this process in a couple ways. Burning high sulfur coal, besides polluting the air and water, also caused global cooling. This was a concern at one time, but proved to be transient and was dealt with via regulation.
The bigger problem has the dumping of vast amounts of carbon dioxide into the atmosphere.by burning fossil fulls. As we all should know, CO2 is the primary long term green house gas. This has effectively triggered an acceleration of natural glacial retreating.
Every grade school kid should know this.