[Iowa_Flames_Fan]

Originally Posted by White Doors

Remember the ozone layer? More energy from the sun is making it through now because of depleted ozone. This is causing skin cancer etc. The ozone is now replenishing itself however, but I wonder why the correlation between ozone depletion and the earth warming is never mentioned? (at least that I have seen)

This is just wrong. In fact, Ozone is a greenhouse gas. It's also a naturally-occurring one and a beneficial one as long as it's in the stratosphere, but less ozone won't mean more warming. The depletion of the ozone layer just affects what kinds of radiation reach us on the planet surface. A serious environmental problem, but a different one. Here's the link: http://www.eia.doe.gov/cneaf/alterna...ent/chap2.html

Ozone is a beneficial GHG in the stratosphere and a harmful pollutant in the troposphere. Ozone survives anywhere from a few hours to a few days in the upper troposphere and for only an hour in the stratosphere [38] (see Appendix B for a discussion of ozone's stability). Thinning the stratospheric ozone layer increases the amount of harmful UV-C radiation reaching the Earth's surface. This will not only increase UV-induced diseases, but also aid the production of ozone in the troposphere. It is beneficial when ozone stays in the stratosphere because ozone shields the Earth's surface from harmful ultraviolet rays of the Sun. Because of its oxidizing power, ozone is hazardous to health. Therefore, ozone is classified as a criteria pollutant in the troposphere. Throughout the atmosphere, however, ozone acts as a greenhouse gas.

Originally Posted by White Doors

When humans emit 0.014% of the total GHG's in the atmosphere I find it very difficult to believe that Global warming is human caused.

I can't find this stat anywhere. Does it include the emissions that result from deforestation and changes in land usage? Hard to know, since you don't provide a source. However, the term GHG's is probably misleading in this context. If there weren't some GHG's there would be no greenhouse effect, and therefore no life on earth. The greenhouse effect, within certain limits, is a good thing. But it's a delicate balance. What matters is not the percentage of GHG's that are anthropogenic. What matters is the EFFECT that those anthropogenic GHGs have on the climate. This from the Pew Center for Climate Change:

The current state of knowledge regarding 20th century temperature changes is clear. Temperatures, at least in the northern hemisphere, of recent decades are likely warmer than at any point during at least the previous millennium, and the probability that some as yet unidentified factor other than GHGs can account for this warming is low. Thus, despite the long-term natural variability of the climate system, current scientific evidence indicates there is a significant human influence on current climate trends. This human influence is projected to grow increasingly strong in future decades as human emissions of GHGs continue to alter the composition of the atmosphere.

(download the pdf here: http://www.pewclimate.org/global-war...act_sheets.cfm

As I've said before, the jury is no longer out on this one. It's time to start looking at energy alternatives, and in a big way. At this point the only practical option is probably nuclear energy, but we have to start somewhere. Fossil fuels are not going to be a viable alternative in the future.