Its not science.

The hypothesis

"Human action is causing our observation of the measurement of temperature to increase"

Is not testifiable. We don't have 2 planets, 1 with humans and 1 without. So we can never test this theory.

If we can never test it, we can never prove them wrong, and they can never prove it true.

It will always stay in the middle gray area.

All they can do is make observations without controlability.

It is absolutely required to have controlability in a system to attribute causality.

Therefore, that hypothesis is not a scientific hypothesis. Maybe its in the field of statistics or history. But not science.

Now the green house gas effect is real, humans do burn hydrocarbons which release co2 in the atmosphere.

But you can't extrapolate those 2 ideas to a system with billions of other variables and assume nothing changes, or even assume our models can accurately predict environments it has never faced.