Greg Tomlinson and I have been discussing in comments a blog post from last April:
Global warming XIII – The Carbon Dioxide Control Knob . I think that his comments and my replies will be informative to our readers, who aren’t likely to notice items from six months ago. Therefore, I’m going to create new blog posts each of which contains a comment and a reply with titles The Carbon Dioxide Control Knob I, II, III, and so on.
Here’s the first:
You give no arguments as to what makes CO2 a primary “control knob” for the earth’s temperature, except for saying that this is what “knowledgeable people” believe. Well, the knowledgeable people I know realize this “climate change” fraud for what it is worth.
I’m afraid that the “knowledgeable people” you know have misinformed you.
Here’s how climate scientists and other researchers know that carbon dioxide is a key “control knob” for the Earth’s temperature. They have known this since Svante Arrhenius published research on the greenhouse effect in the 1890s. Svante_Arrhenius and the Greenhouse effect.
The greenhouse effect is not a new phenomenon caused by human fossil fuel use. It is a natural effect, and is the reason why the Earth’s average surface temperature is about 60 F instead of 20 F, which is what it would be if there were no water vapor or carbon dioxide in the atmosphere.
The basic idea is this: The flow of energy into the Earth must balance for the temperature to be stable. The flow in comes from the Sun. The flow out comes from the Earth and appears in the far infrared. The atmosphere is transparent to most of the Sun’s radiation, which is in the visible and near infrared. But the atmosphere absorbs and re-emits substantial parts of the Earth’s upward flowing far infrared radiation. Water vapor and carbon dioxide absorb upward moving far infrared radiation and re-emit it in all directions. This reduces the amount flowing to space. Therefore, the Earth’s temperature must increase to increase the amount of upward flowing radiation leaving its surface until the flow outward equals the flow inward from the Sun. To increase its radiation, the Earth’s surface temperature must increase. That is, the globe must warm.
Natural fluctuations in the amounts of water vapor and carbon dioxide in the atmosphere produce fluctuations in the Earth’s surface temperature, as when there have been massive volcanic eruptions.
Thus actual knowledgeable people, and not your “knowledgeable people” know from fundamental principles, the 1st Law of Thermodynamics, and the detailed properties of water and carbon dioxide, that carbon dioxide is a key “control knob.”