It matters because it changes how we would try to stop it. If it's caused by something we're doing, we could just change what we're doing. If it's natural, then

It matters because it changes how we would try to stop it. If it's caused by something we're doing, we could just change what we're doing. If it's natural, then we need to find a way to alter nature. That gets into terraforming, which we really don't know how to do, and it'd probably be safer to to learn to live with the climate change rather than trying to stop it.