Somewhere, in my feeble brain, I seem to have heard this before, many times.
We are 15-20 thousand years into the interregnum of the current ice age, 7 thousand years into “civilization” and no one can tell what the average temperature should be. No one can tell how deep the ice will be on Manhattan in 25 thousand years. No one can tell how the ice ages began 2-3 million years ago. But, they are certain it is going to be too hot twenty years from now.