Imagine pollution increasing in the atmosphere over thousands of years
predict how the surface of the earth might change

Well typical acid rain, that is today's acid rain, takes only a few hours to form from over-pollution and has a Ph of about 4.0. So taking that into consideration as well as the already dampening atmosphere, id say we could be looking at the largest Acid storm the world has ever seen. it would wipe out all natural habitats in vicinity which would kill off millions of species and only leave a wasteland in its wake. Insect might be the only survivors of that war. A war on mankind declared by mankind's ignorance.