ACCER asks:Why do people want to believe humans are at fault?

I believe that Humans are having an impact, It's difficult to say we are not. But, That being said I do believe that the planet has it's own cycles and the warming and cooling of the earth is a natural occurrence, It may be that we are merely speeding it along by some of our practices.
Parts of the middle east, I.E Iraq and Pakistan were once very fertile places 4-5 thousand years ago and changed over time...long before Humans started producing toxins and greenhouse gases.
There is evidence that the Sahara was a very lively and fertile region tens of thousands of years ago. Paintings in caves show Giraffes and Gazelles were they do not exist today, In the American southwest the Anasazi lived where there is now desert. They were mainly farmers with squash and corn were there main foodstuffs. These plants require a lot of water to grow.
Change is enevitable on our planet, we may just be speeding it along.