The (surface of the) earth is warmer than if it was just heated by the sun, because it is heated by two sources: the sun and the atmosphere. [This is the inappropriately named ‘greenhouse effect’]. More atmosphere, more ‘greenhouse effect’. For the details, read the papers.Commenter, this in no way wins you a £5 voucher. A ‘Fermi explanation’ has to be a complete chain of reasoning from cause (or evidence) to effect. Approximations are OK, so are gross assumptions, so long as they are reasonable assumptions, but every link of the logical chain has to be visible. Your comment is wholly useless in this respect. It doesn’t explain the relation between carbon emissions and ‘atmosphere’, nor the relation between ‘atmosphere’ and temperature, nor the relation between temperature and ‘damage’ or ‘harm to planet’. So, no prize, sorry.
On ‘read the article’, about a year ago I got tired of reading stuff about ‘scientific consensus’ and tried to work the whole thing out for myself. It was surprisingly hard. Wikipedia articles like this are a useful overview, but they remind me of those science books I read avidly at the age of 8, how telephones work, how air brakes work, how jet engines work. A useful ‘pictorial overview’, but without depth of explanation. This article is much better, but fails for two crucial reasons. First, it is mathematical. Although the mathematics is not very difficult, there are many people to whom this kind of reasoning is impenetrable. A verbal, or pictorial explanation (or a combination of those modes of explanation) is needed to explain the underlying reasoning, without the maths. The second fault is far worse, because it fails to connect the variable representing the amount of atmosphere, with the industrial process. It neatly explains in a quantitative way how increases in epsilon correspond to changes in equilibrium temperature. But it doesn’t explain how emissions in carbon dioxide are related to epsilon*. Which is what we wanted to know. How much is my stash of incandescent bulbs likely to increase the equilibrium temperature of the earth? Don’t know, and I am keeping the stash for now.
*To be fair, the article does state this implicitly, in the bit where it says “The radiative forcing for doubling carbon dioxide is 3.71 W m−2”. But it doesn’t explain where that figure comes from, nor does the article http://en.wikipedia.org/wiki/Radiative_forcing it links to. And it only gives figures for carbon dioxide emissions. As I mentioned in the previous post, carbon dioxide is not the only greenhouse gas.