A recent review finds that over 97% of scientists believe that human activity is contributing to climate change. That is a very solid consensus of scientific opinion.
This, of course, does not mean that the consensus must be correct, but (along with other data) it makes it unreasonable to claim that there is no consensus, or that there is significant scientific controversy on this topic. In fact, the 97% figure exactly matches prior surveys. Many scientific organizations have also officially endorsed this consensus.
One of the common methods of deniers is to pretend as if there is a raging scientific controversy when in fact there is a solid consensus. Creationists, for example are constantly trying to portray evolution as a “theory in crisis,” when in fact it is doing quite well, thank you.
The study employed an interesting methods. They reviewed 12,000 peer-reviewed published papers on topics relevant to climate change. They then tabulated, for those papers in which the researchers expressed a clear opinion about climate change, whether or not they supported the conclusion of anthropogenic global warming. In over 97% of cases they did.