Can't say I agree with the preceding response that there is no such thing a global warming. The sun came over the horizon this morning and the earth began to warm up in my part of the world the moment that happened. Oh, yes, and it affected the flowers, too. They started to unfold and to open their cute little faces towards those rays of sun.
Now, if the former writer was talking about long-term global warming, then we have that, too. The world is apparently markedly colder now than it was a 12,00 years ago when the Vikings settled in Greenland. They stayed around 300 years, then either left or died out when the place grew colder. The world's temperature rises and falls in cycles. The sun's emanations (e.g. its 11-year sunspot cycle is one example) are the main cause, apparently.
However, to think that humankind's turning savannas into dust bowls, and jungle clad areas into deserts, does not affect the earth's climate is to know little about the way the earth was millenia ago. Did you know that elephants and lions roamed North Africa before human beings turned it into the Northern Sahara? What is now desert sand was the wheat belt for Ancient Rome.
Of course, there is global warming caused by human beings.