The phrase "to miss the heat" means to long for or feel nostalgic about a past time or situation that was exciting, intense, or lively. Full definition
As of 2013, was there any climate scientist left who still thought there was a significant amount of missing heat? (judithcurry.com)
Well, I'll miss the green trees and the flowers in bloom, but I will not miss the heat! (theartyologist.com)
Similarly, I don't need to calculate the exact amount of thermal expansion based on hypothetical missing heat when there is no obvious acceleration of sea level rise. (blog.hotwhopper.com)