Well since the Sun puts out about 400,000,000,000,000,000,000,000,000 Watts of measurable energy per second, I just wonder.
I'd guess they are full of shit.
The Carbon cycle is NEVER in balance, why do you think we have the extremes recorded in the sediment.
Oh well, we are all doomed anyway, as soon as Oil, Coal, LPG, etc... is gone.
All plastic, food delivery and other things we take for granted right now will be gone.