>>890167So how do we know, beyond a shadow of a doubt, that human activity is causing the global warming we've detected over the past century? Goddamn everything:
1. No combination of natural forcings could be warming the climate over the past 100 years. If anything, we should be slightly cooling.
2. If you measure the change in radioactive isotopes of the air, there is now a greater percentage of fossil carbon than natural carbon (fossil fuel sources have heavier isotopes.)
3. The isotope measurement is corroborated by proxies measured from corals.
4. The structure of the atmosphere is changing: the tropopause is rising, and the troposphere is expanding. Meanwhile, the stratosphere is cooling. All of these would happen due to increased greenhouse gas emissions, and they wouldn't happen due to some kind of solar forcing.
5. The days are not getting hot as fast as nights, which indicates that increased fossil fuels are the cause. If it was something to do with the Sun, it would be the opposite.
6. Ocean acidification.
5/?
