Answer:
CO2 - Otherwise called carbon dioxide effects our climate in many different ways. The way it works is that basically certain 'greenhouse gases' can't escape from our atmosphere because they get trapped. CO2 is what plants need to create oxygen etc. But when there is too much CO2 being admitted into our environment from burning fossil fuels, cars etc, and we are cutting down trees for paper - it is imbalanced and now it has started to catch up with us. a.k.a global warming. Because these gases are trapped in our atmosphere, they have more time to collect heat from our atmosphere and the sun - thus making our climate increase in heat. This then triggers ice caps to melt and floods to occur and then one day we will face a world with no more fresh water and many extinct animals who cannot survive in warm climates.
Carbon Dioxide would indirectly effect us by increasing global warming, melting the polar ice caps and flooding the world!
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Global warming is a fraud and a fallacy. Look up John Coleman (He's the founder of the Weather Channel and a top notch meteorologist.) on google, and he'll debunk the entire global warming myth in a single post. Look up his videos on youtube and he'll thoroughly explain why global warming is a myth and how it's become so popular today. As John Coleman once wrote about global warming, " It is the greatest scam in history."