I'll just hardly jump into the subject because everyone knows about it.
Many studies have shown that in a few years compared to millions of years the environmential temperature will increase and the climate will change. There where it rains today it will be dry and at some other place will flood the city with rain. Some important animals will die out for instance bees. Then we have to find an other solution for pollinating our plants. The sea level will rise because of the global warming and some places will get flood because of this. We have to stop emiting so much CO2 or find a solution for that.