Photosynthetic organisms use sunlight to provide the energy necessary to combine carbon dioxide and water to form organic molecules and ATP. Those same photosynthetic organism also use cellular respiration to breakdown those organic molecules whenever there is an energy demand greater than what can be provided by photosynthesis or in the absence of light.
Pollution adds heat to the air. for example: gas and smoke from cars and trucks etc. climate change will be affected because the heat will cause the weather and atmosphere around to get hotter. clearing pollution will keep the air cleaner.