What would cause a cooling in the thermosphere?
With anthropogenic activities there has been an increase in global carbon emissions. The concentration of CO2 in the thermosphere has therefore increased. When the CO2 atoms are energised in the thermosphere by collisions with other atoms and molecules, their energy is radiated as heat before it can transfer its energy by other means such as another collision. Over time this manifests itself as an overall cooling and contraction of the thermosphere.
