Re: In what universe is this hard science?
"Very few things are absolutely (dis)provable in science: hypothesis are put forward, tested and evidence accumulated."
No, it is fundamental that any hypothesis that cannot be tested (i.e. cannot in principle be disproved) cannot itself be scientific. It can be many other useful things, and (as in the present case) it can offer the challenge of working out the test that will make it scientific, but unless there is a way to test it, it's not a scientific hypothesis.
To say the moon is made of green cheese is not scientific unless there is a way of checking that it isn't. Once there is a way, then the hypothesis that the moon is made of green cheese is a valid part of science. (In case the incautious should be tempted to believe in lunar cheesism, I must add that that ship has sailed. The hypothesis happens to be wrong. But it's not just wrong, it's scientifically wrong).
One thing that we know about past climate is that all the ice core and deep-sea sediment data suggest rather strongly that changes tend to occur in steps. That is, it rather looks as if the total climate system response tends to be quite highly non-linear. Wise people don't mess with systems like that, especially when the system in question happens to be an important part of their own life-support. (Bits of that argument may not be completely scientific yet, but the common sense involved is undeniable).