Sure the sun is in the equation. That's what causes the warming lol. I mean, we make gases that trap it. There's a loose theory about the sun's expansion warming the Earth and the habitable zone moving, but there's no hard data for that yet.
Peer-reviewed is an issue for you? So what would you have in its place? What method could scientists use to corroborate and verify the results of rival scientists? Already, this method of acquiring knowledge is the most strictly conservative in their approach.
To even submit a research paper for grants, you need to speak to five different science specialists - a panel, and tell them what you want to do. If your paper smells even remotely like shit, they'll toss it on you and tell you to go back and try again.
You do your paper, at least 1,000 is the minimum sample size (number of people tested). Then you have to prove it twice, submit it to others for testing, see if they can repeat the results, then you submit it back to the panel, then they put it out for the greater scientific community to test and see if they can repeat the same results.
Depending on the experiment, it can take several years, to complete. Mental health studies are even harder as the experiments typically span 7 to 14 years at minimum so developmental change can be noted.
Sure, there can be some hacks who get put on the panel. But this is the best we've got.
Could you offer a better solution?