The simple answer is because there is no general climate theory.
As usual the proper answer is complicated. It is a very good question because it speaks directly to a major issue in the public and scientific debate about climate. It was the subject of my recent speech for the Friends of Science in Calgary. The topic was “Recent Theoretical and Observational Evidence for a Cooling Atmosphere.” This was not my choice because it is too esoteric for a general audience. I spoke to the issue, but in the much broader context of the significance of the new evidence and current cooling. It helps understand how proponents of global warming due to human CO2 hypothesis are able to move the goalposts so easily from global warming to climate change to climate chaos and climate catastrophe.
History records Alexander von Humboldt as the last ‘universal’ person. Significantly, he died in 1859, the same year Darwin’s “On the Origin of Species” was published. A renaissance person is one with extensive knowledge in many areas – a diverse scholar. A universal person is one who knows essentially everything there is to know. Von Humboldt knew all the physics, chemistry, biology and other disciplines of his time. He traveled to and was knowledgeable about all the continents except Antarctica.