What would happen if a vacant lot if it was left alone for 25 years

It would just sit there
Probs get vandalised
Maybe bought from the owner to do something with

Something like that maybe...
That is if your talking about a lot of land

If it’s near any plants the plants would grow on the walls and maybe depending on the weather the roof would probably in bad condition and cause leaks so the floors or walls may rot idk

Carbon dioxide and methane are both greenhouse gases. Greenhouse gases hold the earth's heat in the greenhouse effect. Too much of these gases is causing global warming. Carbon dioxide (CO2) and Methane (CH4) are transparent to visible light energy but somewhat opaque to thermal or infrared radiation or energy.