We should TRY to prevent Climate Change no matter what the cause is. Deniers often focus on the wrong question.

If we stop polluting the air, IT MIGHT STOP GLOBAL WARMING...
If we take no action, we are guaranteed to fail. 

Climate Change Deniers often switch the discussion to what he cause is... man made or natural... but that does not really matter... That's just a "Red Herring" to distract attention to the real question. "What should we do?"

Climate Change Deniers are often paid by the Fossil Fuel Industry to write articles that recommend we continue burning oil, gas and coal... Protecting Profits.