we are contributing to the global warming ,
but you do have to take into account the slight change in earths orbit,the sun moving closer to becoming a super nova(albiet several million years away)
but as the sun grows and intensify it will get hotter.
we had the dinosaurs and they were wiped out by the ice age,the earth has got steadily warmer since the end of this age.
the earth is millions of years old,we the humans a in the mere thousands,with the tech revolution in the hundreds.
and we are vain enough to think we are the major cause of everything.
it is just a case of we cant see the trees for the forest