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This is a scientific article. Or at least I pretend it is because it did not yet go through peer review.

Summary of the summary:
It’s impossible to know from observation how much of the actual warming can be attributed to CO₂ or to other parameters.
So far, only model calculations provide more or less plausible estimates of its contribution to the observed 1 °C rise: it lies between 25 and 30% (according to some other calculations it could even be only ~10%).

Summary for the general, but educated public:
Climate change is mostly revealed by the evolution of the temperature at the surface of the globe. Over the past 150 years or so it rose by about 1 °C. But, in parallel, the global sea level also rose, as well as the declination of the Earth’s magnetic field changed in a steady way, and, of course, the atmospheric CO₂ concentration increased by 43%, from 280 to 400 ppm, in line with industrialization. Temperature correlates weakly with each and all of these parameters without it being possible to distinguish their individual contributions. Linked with solar input and oceanic circulations, other short- to mid-term oscillations, unrelated with long term climate evolution, overcast and blur the observations. Using rates of changes (the velocity at which a parameter changes over time) it is not possible to find any valid correlation. Temperature and sea level show a high variability while CO₂ and magnetic field declination have a quite monotonous pattern.

Therefore, any tentative to correlate and quantify the temperature evolution with the CO₂ atmospheric concentration remains inconclusive.

With a simple model calculation using radiative forcing and the known feedbacks, the CO₂ contribution is estimated to be 27% (or even less than 10% if using latest, still unchecked, estimates for primary radiative forcing). This means that other, yet not identified and quantified  causes are at play for the remaining 73% (or 90%).

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