No-one is debating whether it's happening. Plenty are unconvinced WHY it's happening, and the extent to which it is man-made vs natural. Unfortunately such debate is widely ridiculed or suppressed, usually by journalists who have no clue. But ask any geologist with expertise in the subject, when the glaciers started melting. It was about 1850. Way before man-made CO2 could possibly have had anything to do with it. Is that common knowledge? No. Moreover, the climate-nazi's don't want you to know it, in case more people become skeptical.
There is a consensus on anthropogenic CO2 being a major driver (it's not the only driver, even if these experts are right) but there are plenty of people who are skeptical of the extent to which it's a driver, or the projected impact, or indeed whether man-made CO2 has anything to do with it at all.
Rather amusingly, one such person is Jeremy Corbyn's brother!
http://www.weatheraction.com/
He's a bit of a crank, but there are thousands of scientists who never get any air time who are somewhat skeptical.