Pigeon English, no michael was right; without the greenhouse effect Earth’s surface temperature would be much colder on average. Water vapour is a major greenhouse gas, and it helps keep us warm. But the additional greenhouse gases, mainly carbon dioxide and methane are increasing the greenhouse effect too much. Earth can regulate its atmosphere’s water vapour content, but plant growth is too slow to keep up with human combustion of fossil fuels, because we are burning countless millions of years of organic deposits in just a couple of centuries. Apart from which our toxic system keeps cutting down forests because they don’t make a damn profit.