I recently came across this article outlining the use of our advancements in oil and gas drilling to implement "district heating" (or geothermal heating for our buildings/cities as a whole) by pumping water underground to be heated by the mantle, then pumped back up to the surface. I like the premise and it sounds great, but what are the effects? This seems like alcohol expanding our capillaries, we feel warmer but as a whole are getting colder as heat is lost more rapidly on the surface.
If accomplished globally would there be a significant decrease in the temperature of the mantle?
Would areas of high use cool the mantle there, forcing a deeper crust at those locations? Or is the amount of energy used so minuscule in comparison there'd be no discernible difference? What about after a millennia of use?
Hopefully helpful diagram for reference? Maybe redundant in this SE, I just joined so lmk
I know I asked a few questions, but those all stem from the title "How would district heating affect the temperature of the earth's mantle/core?"