I haven’t read”Footfall” but I’ll give it a go...thank you!!
“Lucifer’s Hammer” is a great book, only a little dated. The astronauts arguing over global warming and global cooling is incredibly prescient.
I’d also add “Fallen Angels” by Niven and Pournelle. An ice age has started, and environmentalists have taken over the government, requiring energy rationing and banning genetically engineered foods, everyone has ethanol vehicles, while the space station struggles to hang on, when two air scoop pilots fall to Earth ...