When oils (fossil fuels) are burned, they release an extremely large amount of carbon dioxide into our air. Carbon Dioxide is a Greenhouse gas which means it traps heat into our air which can be linked to Global Warming.
When large areas of land are cut down (deforestation) then it means Carbon Dioxide is released into our air which can also get trapped and cause Global Warming because it is a Greenhouse gas.
Another thing - As Carbon Dioxide is a Greenhouse gas - Greenhouse gases can lead to a large amount of respiratory diseases and pollution (smog) in areas where deforestation can happen or where fossil fuels are burned and used.
