Strange we walk on the same planet as Shakespeare and I've heard he lived in a world that was 10 degrees cooler than our world.
That sounds extreme. I'm guessing you mean fahrenheit, but that would be about 6 degrees celsius. The worse case scenarios for global warming over the next century are only 3-4 degrees over 20th century averages.
The below graph is from Wikipedia, and shows estimates from different studies. The most extreme estimate would be about 1.5 degrees warmer than Shakespeare's day.