Methods of disaggregating data to smaller units?
From a statistical point of view this is impossible if one doesn't have any data at the fine-grained level. Any statistical inference must be based on a sample from which specific patterns can be observed.
If there is no data at the fine-grained level, any calculation is based on assumptions. For example one may assume that a variable is proportional to population (linear relation). But why not assume that the variable is a polynomial function of the temperature? Or that it is related to the prevalence of a particular gene? The main issue is that without any data there's no way to test any of these assumptions, so no there can be not reliable conclusion.