Does pollution harm the environment? Lock yourself in your garage while your car is idling and see whether it harms you.
And even if all the emissions don't actually warm the planet, they still pollute. Note the blanket of smog that hangs over our cities during the summer. While our politicians and scientists argue themselves breathless, the white shirts we wear to work will be stained yellow by the air. So breathe it in while it lasts - fresh air will be passing into the history books before anything is actually done.