To add a little more confusion on the subject - let me paraphrase an article published Saturday in the rather liberal slanted Los Angeles Times.
"Eastern Sahara Apparently Once Lush"
"A 3,200 hundred year interlude of tropical rains once transformed the eastern Sahara into a verdant savanna where seminomadic people thrived amid elephants, cattle and more than 30 species of fish, according to German researchers.
After collecting more than 500 radiocarbon dates at 150 sites in qn area larger than western Europe, University of Cologne researchers found that the sudden climate change 10,500 years ago coaxed thousands of people to move into the now desolate desert."
It goes on to comment additionally, but I think this is but another bit of evidence that our earth's climate has changed constantly through time and we may be seeing something similar occuring now, with a tiny, tiny bit of help from human hands.