"Here's 1.2 mil. We want you to tell us that it is possible that global warming is being caused by the sun"
The Sun causes all warming, there is no other source of energy for us. (And no, things that originally came from the sun don't count...)
But, if you want to know if it is possible that the Sun could cause what is called "Anthropomorphic global warming", then yes of course it could. It is already known to do so. The berden of proof is on the other side, to prove that it is -not- caused by changes in the sun !