I learned in my Biology class that if humans added enough Co2 into the air, then we could create global warming. However, since satellite data and weather balloon data indicate that over the whole earth, global tempatures are staying the same, then that means that we are just not polluting enough to make a significant difference in the temature. If we added a whole lot more pollution, then perhaps we might change the global tempature a degree, but as it is, humans are just too small in a big world to make a difference. By the way, all the data you see showing melting ice caps, etc., is correct, however, it is misleading. The Artic is melting, but Antartica is cooling. The tempatures constantly change eveywhere, but when you add it all up, and average it out, the tempature is the same since the 1990's. And a steady global tempature is unusual, anyway. During the middle ages, the earth was warmer than now, and that was clearly little, if at all, affected by man. Also, it is true that the land is warming, but if you add the cooling that is taking place at sea, then you see that the tempature is the same. That is what I learned in my Biology class.