When non renewable resources are used, sooner or later the principal consequence could be simply depletion, but sometimes others end being more prominent as it happens today with the completely unsustainable rate of carbon dioxide emissions leading to air pollution.
Every civilization needs energy although it's obvious that having the technology for using renewable, clean energy only non intelligent species would be polluting its own environment and waiting for the critical consequences of interacting with the atmosphere in geologic proportions.
It happens in the same way with nuclear energy because it produces an insane risk, both personal and toward the environment, in the order of thousand years at exclusion zones as it happens in the present time at Chernobyl. That disaster would seem an important example for learning, either way it was not enough for some entities.
Carbon is the other big player in the non renewable chart, intensely used in the past and also today with a great percentage of the world production of electricity being a carbon sub-product, leaving another footprint in terms of overall air contamination and climate change due to the greenhouse effect, affecting quality of life in cities principally. So, any electricity consumption couldn't be free of environmental implications; it should account with potential contamination and more climate instability.
Non renewable resources like carbon and fossil fuel require a laborious extraction mechanism. During centuries, to work in a coal mine was one of the most intensive works. While fossil fuel extraction relies on partially automated systems, the resource is exhausted day after day creating risks of more environmental aggressions (fracking, explosives, assaults of natural areas with hazards to diversity and heritage for new generations, ...), with even a worse scenario if nobody takes responsibility and acts accordingly. Simply with the Sun's energy it's enough for thousands of species like ours.
Non renewable means that the environment cannot produce more after using the resource. This concept could create incorrect assumptions since fossil fuel is renewable after millions of years and the Sun's energy will inexorably fade even later, so it's not renewable at all!
The point is nonetheless clear to understand: non renewable at a certain exhaustion ratio.