Question

what causes Global warming ? is it really the people?

Answer 1

While it isn't really a true biology question.. I'm going to answer anyway...

Yes, it could be siad that 'global warming' is caused by people. Climate change is a process that does occur naturally and has occured many mnay times in the past. Humans have simpily accelerated this processes. We know that increased greenhouse gasses causes an increase in global temperatures and we know that the increased greenhouse gasses in the atmosphere are from humans (through tracers, the CO2 in the air is the same CO2 from buring coal etc.).

Answer 2

Global warming mainly in the present is increasing due to man kind. But it was not so in the past, vehicle fumes, Volcanic eruptions , emission of CFC gases are the major reasons at present.CO2 and SO2 are the main gases involved,And the radiation from the sun directly comes to the earth due to the destruction of Ozone layer which reflect the excess heat and radiation in the earth but due to the huge amount of CO2 in the atmosphere acts as a layer of absorbing and directed to the earth surface and this also reflected further and further by CO2 layer and increases the Global warming

Answer 3

Hmmm you've got that all a little bit tangled Thurunusanu. Or perhaps it is the way I'm reading it...

Nonetheless, I'll try to clarify. Firstly the greenhouse effect, short wave radiation comes from the sun and hits the Earth's surface, from here it becomes long wave radiation in the form of heat (IR). This heat moves away from the Earths surface but some of it is reflected back by the greenhouse gasses in our atmosphere, retaining some of the Earths warmth in much the same way a blanket does to you at night. As we have both said, this is a natural process to that keeps the Earth warm and us alive. Humans have been adding to the greenhouse gasses in the atmosphere at a much greater rate that has been previously seen and so 'the blanket is getting a little too thick' and the earth is getting warmer than before.

The major gasses contributing to the greenhouse effect are:
water vapor, 36–70%
carbon dioxide, 9–26%
methane, 4–9%
ozone, 3–7%
But there are many many greenhouse gasses (GHG's), those are just the major players. The main GHG's that we are releasing are CO2, CH4, N2O, CFCs and SO2.

The ozone layer is another matter in itself. The ozone layer reflects UV light (very high frequency light) which is damaging to .. well molecules in general - so life. The release of CFC's depletes this ozone layer and allows a greater proportion of UV light into the atmosphere (basically burning stuff, If you stand in the sun for more than 10mins in the very south of Western Australia you will get bad sun burn, no joke). The depletion of the ozone layer is not global warming, while it does contribute to it (maybe) the interactions are complex and not entirely known.