Anthropogenic global warming (AGW) is *not* a theory. A scientific theory is a conceptual framework that is developed to unify and explain the totality of observations made regarding a natural phenomenon.
By definition, AGW is not a theory. It is, rather, a hypothesis. A hypothesis is a supposition made on the basis of an observation or group of observations, and it is informed by theory. In this case, AGW is a hypothesis formulated on the facts that 1) carbon dioxide has a broad absorbance/emittance band within the infrared portion of the electromagnetic spectrum (in other words, it fluoresces in the infrared); 2) that heat is a result of infrared radiation; and 3) that human industrial processes are reintroducing carbon dioxide into the air that has been sequestered underground for thousands or millions of years.
A hypothesis is testable; scientific experiments are designed around devising a test that either supports the hypothesis, or shows that the hypothesis is incorrect (or that the null hypothesis is correct). If a hypothesis is not supported by the experimental evidence, then the assumptions used to formulate the hypothesis should be revised.
In the case of AGW, although experimental observations have not really supported the hypothesis, the assumptions underlying the hypothesis have not been appropriately revised.
Hman-caused. Of course