The AGW hypothesis may or may not reflect actual reality. That's the problem with an unfalsifiable hypothesis.
The AGW hypothesis is not unfalsifiable. People with no understanding of science often make that claim. A couple decades of significant cooling (0.05C per decade or so compared to the warming trend of 0.18C/decade warming since 1970. ) while CO2 levels continued to climb would probably be enough to do that.
The problem for people who like to lie about science is that the science of AGW is very basic and well understood. To pretend it's not going to happen you have to imagine something that could stop it. And so far nobody has been able to invent something that can stop it short of a catastrophic breakdown in global atmospheric and oceanic circulation. Be my guest. Find something that can prevent CO2 from increasing temperatures and prove it. In 1906, Arhennius calculated the climate sensitivity to a doubling of CO2 when including water vapor feedback was 2.1C. Current estimates are between 2C and 4.5C. Go ahead, find a way to make the climate sensitivity negative and show that it works.