Answer:
The effects would be pretty negative.
Step-by-step explanation:
Because as population increase, there would be an increase of demands or needs. As a result, resources would decrease such as wood, freshwater, animals (since some animals have already gone extinct). As for the environment, yes there would be some people trying to change the environment but people with big money, own big companies and because of that, there would be a problem. These big companies don't really care about the environment only the cash itself. So, they would pollute the water, and due to the dirty water, aqua animals will die. In addition, when the population increase, people would litter, I know that there are laws in it, but there's still trash on the ocean and the ground. Therefore, population can effect the resource and environment by increase the demands of needs and the environment slowly diminishing.
Also, if the population decrease, the effect will still be negative towards the environment but there would be a hope for change or action for change. The resources might increase because we won't need to cut down many trees, overfish or overhunt, and etc.