RE: Of Late
Maybe you should try reading up on global warming instead of assuming things. Scientists have never said that there hasn't been points in our history where the Earth has heated up -- infact, quite the opposite. They acknowledge there has been warming periods.
Furthermore, most of those warming periods are followed by ice ages.
Scientists believe that we are in a warming period now, the problem is that we're speeding up that natural process and it's happening much faster than it should.
Even if it was natural, warming of the Earth causes massive changes. Species die out, new species appear. Diseases spread faster. Coastlines shrink. And so on... regardless of how things have been in the past, forced global warming by our emissions will result in a drastically different world.