Energy conservation has been known about for a long time.
It's all it takes to understand global temperature on climate scales, absenting the onset of an ice age. And that is not likely to happen at present, owing to unprecedentedly high summer temperatures over the whole Arctic. You need to make it through a whole not-completely melted taiga summer to set it up, and that's not likely.
Melting permafrost can change the current situation quite the other way.
Detailed predictions of weather patterns in 100 years from now are hard, but it's very very likely it'll be warmer than it is now.