Dear Mr. Knoop,
I personally think that humans are causing drastic speeding up of the Earth's natural heating and cooling cycle. I believe that this will cause a problem if now but in the distant future.
Also, heating Earth is causing the polar icecaps to melt, which then cause flooding and rising of water levels. The rising water levels can put certain cities in danger, and destroy communities with floods.
I also think that the levels of pollution, which are extremely high, are causing many people to fall ill when otherwise they might be fine.
I think that humans are causing drastic changes on Earth and that we should change our ways so to reach a better world for us and our posterity to live in. If we try hard enough and stick to it we can save the Earth from any further damage. After all, Earth is all we've got.
Rebecca C.