Let's start with what is our environment?  Our environment is the external forces that affect human survival and its economic activity. External forces can be our weather, our climate, air, water, soil, and living things such as plants and animals that have an impact on us. What you are looking for is situations that have occurred that are unethical in nature that have harmed our environment. 

If you need a little help to figure out what a harmful situation is, here is a link to a massive environmental disaster that occurred in the 1970's to help you understand what I'm looking for. This article is about the Love Canal Disaster  https://archive.epa.gov/epa/aboutepa/love-canal-tragedy.html

Let's start with what is our environment?  Our environment is the external forces that affect human survival and its economic activity. External forces can be our weather, our climate, air, water, soil, and living things such as plants and animals that have an impact on us. What you are looking for is situations that have occurred that are unethical in nature that have harmed our environment. 

• Global climate change-both natural forces and human activities are influencing the global climate.The green house effect that allow incoming solar radiation to pass through the earths atmosphere but prevents much of the outgoing infrared radiation from escaping into outer space is a natural process and the emission of the green house gases are a results of human activities which create green house effect.Human activities have altered the chemical composition of the atmosphere which results to climate change from emission from cars,power plants and other human inventions which has results to rise in global warmth over the past century.This has resulted to changes in regional climate and productivity of agricultural land.Degradation from human induced climate change should not be tolerated by the international community so as to protect our environment for future generation.
• Worldwide loss of biodiversity,forests and wetlands-Current rates of extinction are much greater right now except at periods of cataclysmic destruction.Rates of extinction have increased dramatically as human numbers an technological power have increased.This is because there have been nonnative species introduction,habitat destruction and hunting or other acts of deliberate extermination. Habitat destruction is caused by land development ,by degradation caused by pollution or vegetative removal and erosion and by fragmentation of ecosystem.We have a duty to protect biodiversity as humans.
• long-rage transport of toxic substance-which is a threat to human health and ecosystem.Chemicals like Persistent organic pollution(POP) which are toxic to humans and animals do not degrade easily in the environment and might even travel long distance,bio-accumulate and change from solid to gaseous phase before being redeposited in the environment. This toxic substance cause variety of genetic,reproductive and behavioral abnormalities in wildlife and humans.
• decline of coastal ocean quality-due to urbanization and aquatic pollution it creates is threatening the fresh water supply from overuse,expanding population and pollution.Human are endangering the marine food supplies by over-exploiting fish stocks.About 50% of land on Earth has been irreversibly transformed or degraded by human action even forests are disappearing at a high rate.