global warming hype?

Recently the History Channel has been showing several programs on the earth's climatic history. Supposedly the earth experienced an extremely warm period immediately after its first ice age ended. The earth was supposedly 10 degrees hotter (C or F is never specified while the size of C degree is bigger than an F degree so it makes a difference) then than it is now about 250 million years ago.

Then the earth cooled off and then had a period that was 20 degrees hotter than it is today.

But, did geologists and paleontologists and climatologists know about these intensely warm periods before global warming became such a large political issue today? Did they know about them but didn't pay much attention to them? Did they learn about them by re-interpreting data that they already had? Or are they just speculating in order to add to today's global warming hype?