"but can't claim to be applying the scientific method by ignoring fundamental facts like CO2 is a greenhouse gas"

But you can't argue that science has nothing to do with quantifying information.
Such as CO2 is a small part of the entire atmosphere. That CO2 is not a strong greenhouse gas.
That the measured rate of change in CO2 gas is small- regardless of what is causing the change.

That the rate of change of CO2 in the atmosphere do not exactly relate to the amount of CO2 humans emit into the atmosphere- it's not even close or in the ballpark.

And the only way one can argue that it is somewhere near
this rate is because there is no exact means of measuring the CO2 emitted by human activity. Or other stupid arguments,
Let me prove this.
In regards to human emission of CO2, what causes more CO2 emission? Fossil fuels or changes due to farming de-forestation or other factors?

Now, in regards to Fossil fuels, we have a fairly accurate measure- because coal mining and oil production are economically important, therefore the have been measured and records have been kept.

Much of the argument has to do with fossil fuel use. And fossil fuel production has increase at a much faster rate than Global CO2 levels.
The only way this can be ignored, is to talk about other types of human CO2 emission, or to suggest the CO2 emitted by humans is being hidden in some way- neither are very scientific, there are much more a kin to a child trying explain the mud tracks leading to his shoes, as not being caused by him tracking in the dirt.

So, this science, hasn't even accurately measured the amount of CO2 in the atmosphere. Nor has it measured accurately how much CO2 is added to the atmosphere or removed from the atmosphere by "natural causes" each year. And by accurate I mean to a scale of what human activity is said said to be responsible, i.e, within a accuracy
of +/- 1 billion tonnes.
In other words, assuming countries would be open in terms of reporting CO2 emission, we could know within a few million tonnes of accuracy, how much CO2 emission were caused by burning CO2 globally.
That would pretty simple to do.
But an uninhabited chunk of ocean of say 100,000,000 sq km, is not known within a billion tonnes how much it absorbs or emits from life processes.
How much does cold sinking ocean water absorbs per year?
How much does warming tropical oceans emit per year?
Yeah, we know in terms of 100 billion give or take a few ten billions. But is there any real reason this can't be known more precisely? Assuming we were vaguely curious.

And finally you can't argue that CO2 is not needed for life to exist on this planet.
That higher CO2 level will result in more plant growth.
That some people are concerned about future food supply and that higher level of CO2 would be helpful in regards to allowing more food to be grown.

Or that life has existed on this planet for hundreds of millions of years, that global temperature have changed by far more than 10 C, and that CO2 levels have been more than 10 times there current levels.
Or that in the millions of years of this planet, major volcanic events have occurred which have produced more CO2 than Humans have, and have produced more CO2 in a shorter periods than Humans have done or are capable of doing.
And if you want to limit it to only centuries in the past, we have had major volcanic events [very minor relative to planetary history] which altered our global climate far more than we have or are capable of doing- though as result of dust particles not from CO2.