All of those questions you asked are certainly causing problems. I'm not sure that pollution would affect climate as much as it's the cause of increased disease in the world. Deforestation is probably the most direct way of altering a climate. Just look at aerial photos of the borders between places like Haiti and the Dominican Republic. Or North and South Korea. One side has no trees left and the other side is lush. When the Roman armies invaded Africa, they made the Sahara desert much larger by cutting down all of the trees to build their camps at night. There is also direct evidence that planting trees can shrink desert zones.