Does it even matter if it was warmer in the past? Right here, right now, we can prove that human efforts have changed the temperature of the planet. Right here, right now, we can see the effects of that change. Increased frequency of storms, increased intensity of storms, shifting of seasons, decline in animal populations, etc. Being a "skeptic" just because you can't prove that it's currently warmer than it was 200 years ago is pointless