Whole countries, even entire continents must participate. Of course, this is easier said than done. But, for example, electric and solar-powered cars are a reality. We need to put them into more widespread use. This would greatly reduce the amount of pollutants, such an carbon monoxide, which are released into the air every day.
Recycling is another step that can be easily taken.
If everyone recycled only a portion of the wastes they disgarded, we would consume less resources, and dump less waste into our landfills. Recycling is easy to do, it just takes a little time and effort, which is why most people choose not to. Recycling your newspapers, aluminum cans, plastic bottles, etcetera is a good start. Most people just think it is too much of a hassle and would rather not go out of their way. It has become too easy to use, use, use, and waste, waste, waste with no regard to the consequences to our environment.