If I understood Lubos correctly, the observational data says that increased temperature is correlated with increased outgoing radiation. This is not at all inconsistent with the greenhouse effect: for example if you had an actual greenhouse and you ran a space heater you'd find more radiation leaking out than if you hadn't heated it. This is because the greenhouse is not entirely opaque to infrared: it still diffuses out, like light through frosted glass, or like light from the center of the sun to its surface. The Earth's greenhouse is not complete. Of course, to make this demonstration I had to use a device: the space heater, whereas in real life the Sun's radiation is measured as relatively constant, as compared to the degree of the heating.<p>The wildcard is in the heat capacity of the varying components of the earth, and convective heat transfer between them. While the greenhouse effect is likely to work in the steady state (e.g. as confirmed by much of planetary science) over the short term temperature increases may be driven more by openings in cloud cover than the residual planetary greenhouse effect. Cloud cover, being a function of water vapor, also a greenhouse gas, will increase reflection and cut heating to the surface, while simultaneously reducing infrared outgoing radiation. However, since CO2 doesn't form clouds, it will have the primary effect of cutting outgoing radiation.