Eindelijk empirisch bewijs voor menselijke broeikashypothese?

The empirical evidence that humans are causing global warming
When presented with the overwhelming evidence that the planet is warming, many people react by asking "but how can we be sure that we’re causing the warming?" It turns out that the observed global warming has a distinct human fingerprint on it.

In climatology, as in any other science, establishing causation is more complicated than merely establishing an effect. However, there are a number of lines of evidence that have helped to convince climate scientists that the current global warming can be attributed to human greenhouse gas emissions (in particular CO2). Here are just some of them:

The first four pieces of evidence show that humans are raising CO2 levels:

1. Humans are currently emitting around 30 billion tonnes of CO2 into the atmosphere.
2. Oxygen levels are falling as if carbon is being burned to create carbon dioxide.
3. Fossil carbon is building up in the atmosphere. (We know this because the two types of carbon have different chemical properties.)
4. Corals show that fossil carbon has recently risen sharply.

Another two observations show that CO2 is trapping more heat:

5. Satellites measure less heat escaping to space at the precise wavelengths which CO2 absorbs.
6. Surface measurements find this heat is returning to Earth to warm the surface.

The last four indicators show that the observed pattern of warming is consistent with what is predicted to occur during greenhouse warming:

7. An increased greenhouse effect would make nights warm faster than days, and this is what has been observed.
8. If the warming is due to solar activity, then the upper atmosphere (the stratosphere) should warm along with the rest of the atmosphere. But if the warming is due to the greenhouse effect, the stratosphere should cool because of the heat being trapped in the lower atmosphere (the troposphere). Satellite measurements show that the stratosphere is cooling.
9. This combination of a warming troposphere and cooling stratosphere should cause the tropopause, which separates them, to rise. This has also been observed.
10. It was predicted that the ionosphere would shrink, and it is indeed shrinking.

Often one hears claims that the attribution of climate change is based on modeling, and that nobody can really know its causes. But here we have a series of empirical observations, all of which point to the conclusion that humans are causing the planet to warm.

Re 1: There is little doubt about the contribution of anthropogenic CO2 emissions. But our understanding of the natural CO2 cycles is insufficient to estimate the size of its contribution. We don't know, for instance, the size of CO2 outgassing from the deep sea into the atmosphere and the return flux (order of magnitude: 100 – 150 GtC/y). The statement as such bears no relevance to an expected enhanced greenhouse effect by CO2. It is only suggestive, circumstantial evidence.

Re2: Agreed. It would be surprising if this CO2 was not present. But see comment under 1 and its conclusion: The statement as such bears no relevance to an expected enhanced greenhouse effect by CO2. It is only suggestive, circumstantial evidence.

Re 3: Of course, fossil fuel burning will use oxygen from the atmosphere. But again: The statement as such bears no relevance to an expected enhanced greenhouse effect by CO2. It is only suggestive, circumstantial evidence.

Re 4: This is to be expected as under 2. But again: The statement as such bears no relevance to an expected enhanced greenhouse effect by CO2. It is only suggestive, circumstantial evidence.

Intermediate general conclusion: Wight's reasoning is so far exclusively based on circumstantial evidence. Not a single proof is presented that CO2 can affect the natural greenhouse effect. But we have to take a closer look at his additional arguments.

Re 5: This observation is incorrect. Satellite measurements have shown that more total radiation energy has been transported into space.

Re 6: It is, of course, to be expected that with increasing CO2 in the atmosphere, more radiation from it contributes to downward radiation at its specific wavelength. But that is no proof that it contributes to additional warming because the authors who claim such an effect, are insufficiently aware of physical forces other than radiation, which remove heat from the atmosphere (e.g., evaporation and forced convection).

Re 8. This has nothing to do with the greenhouse effect in the troposphere. CO2 is a gas that goes higher up in the atmosphere than water vapour. Consequently, it facilitates the radiation out into space.

Re 9: The altitude of the tropopause differs depending on latitude. It is low at the poles and high at the equator. It is determined by the vertical convection. When it rises, it is a sign of warming at the surface – not that this warming is caused by CO2.

Re 10: The underlying reference states: 'The increase in global surface air temperature during the 20th century has been attributed mainly to the increasing atmospheric concentrations of greenhouse gases.' It states that it is 'attributed' to greenhouse gasses of which water is the most important one – not that CO2 is the cause.

Conclusion
The AGW hypothesis is still exclusively based on the fact that CO2 is absorbing and emitting infrared radiation in a narrow band and the expectation that this will enhance the greenhouse effect.

Point 5 is not correct. The outgoing radiation increased by 2.6 per cent or 6 W/m^2.

Points 6 to 10 can be explained today without attributing an enhanced greenhouse effect to CO2.