It is a well accepted scientific fact that the Earth has warmed by 0.9 degrees C since the mid 1800s. And the Earth is still warming. There is no question about that. The question is how much are humans causing the current warming?
According to NASA, the average temperature of our Moon is ~260K, or -13C, whereas the average temperature of the Earth is 288K or 15C or ~60F. Why is Earth 28-30C warmer than the Moon, which gets the same identical amount of sunlight per square meter? The answer is greenhouse gases. The recognized greenhouse gases are H2O, CO2, Ozone (O3), Methane (CH4), and NOx (Oxides of Nitrogen). Of these, H2O is by far the largest contributor. H2O can be higher than 6% of the air in places like the Gulf of Mexico, and close to zero at the poles in winter. 3% would be a good average planet wide, which is 30,000 parts per million. CO2 has recently risen from ~280 parts per million in 1850 to currently ~400 parts per million and still rising, for an increase of 120 parts per million. Adding the two together, we have gone from 30,280 to 30,400 ppm. Is this enough of an increase to cause an increase in our greenhouse warming of 30C to 30.9C?
I personally don't think so.
There are natural causes for global warming that have nothing to do with CO2. We had a "Little Ice Age" of unusually cold weather from 1250 to 1850. We are currently warming up from that, which again, has nothing to do with CO2. And our most recent warm interglacial prior to our Holocene was known as the "Eemian", which was much warmer than today. The Eemian warming likewise had nothing to do with CO2.
In short, our planet is definitely warming up, and CO2 is definitely also going up. But to say that one is causing the other when there are other possibilities will require more proof of the association, in my humble opinion.