What, then, is the evidence that it is or isn't?
As for the general trend that many who would consider themselves "green" take, which *is* that global warming is caused by people, it may just be that this is a very intuitive leap given that the current world population and impact that this population appears to have on the immediate environment (deforestation, pollution, etc.). With this in mind, it isn't hard to imagine that the trend of global warming (which appears to be a reality) has anthropogenic origins if only in part.
So the question then, is global warming natural, anthropogenic, or both? If both, to what extent either way?
Consider the following argument:
- Global CO2 emissions have increased greatly in the last few hundred years and are strongly correlated to human industrial advances.
- We know that CO2 is a by-product of the use of fossil fuels. Fossil fuels dominate our energy production.
- CO2 has the effect of trapping radiative energy from the Sun, which gets reflected back to the surface of the planet.
- The global mean temperatures are in a rising trend when observational data is analyzed.
- Since CO2 is created through human activity, it can be concluded that human activity is at least a partial cause of global warming.
What weaknesses exist in the premises that lead to the conclusion?