But theories behind AGW, and the results and projections derived from them, are yet weak from a scientific point of view.
You are completely wrong about global warming theory. I am not a climate scientist, but I recently took a course in global warming science from a prominent and respected climate scientist, Dr. Kerry Emmanuel, in an online course that covered the same material as in the MIT undergraduate course in global warming science which he teaches. Global warming theory does not depend upon adjustable parameteres and computer simulations. It rests upon simple measurable physical phenomena.
1. Energy comes to the Earth from the sun, mainly in the the visible spectrum of electromagnetic radiation.
2. A portion of this is reflected away, while the remainder is absorbed.
3. All bodies re-radiate energy away, depending upon their temperature. At the temperature of the Earth's surface, this is in the longwave infrared spectrum.
4. Greenhouse gases in the atmosphere absorb the longwave radiation coming up from the surface, and re-radiate it in all directions. The amount of energy re-radiated back downward is observable and measurable, as is the energy that escapes from the top of the atmosphere.
5. The amount of greenhouse gases in the atmosphere is increasing, at a rate consistent with the amount of those gases being released by fossil fuel burning and other human activities, and the Earth being able to absorb a fraction of them.
6. The difference between the amount of solar energy absorbed and the net longwave energy radiated from the Earth is the amount by which the Earth is gaining energy, resulting in warming.
No complex computer simulations needed, in fact no computers needed. Over a century ago, a generation before the invention of computers, the Swedish scientist Svante Arrhenius calculated by hand the amount of warming that would result from a doubling of CO2 in the atmosphere at about 4 degrees Celsius, a number which falls within the range of modern computer-assisted calculations.