We can have opinions about what to do with scientific facts. But unless you’re an experienced scientist working in the field, the average lay person really is in no position to have an opinion on the scientific facts themselves. This seems to be a popular misconception here in the US by the lay public about their own qualifications to make judgments on highly complex technical matters.
“ The strain of anti-intellectualism has been a constant thread winding its way through our political and cultural life, nurtured by the false notion that democracy means that my ignorance is just as good as your knowledge.”
-Isaac Asimov
Not at all. There is unanimous consensus of every single scientific organization on the entire planet on this issue. As far as individual scientists, there are always a few kooks and charlatans around. You can find individual “scientists” who hold eccentric positions on everything from a flat earth to creationism/intelligent design. That doesn’t make it science.
The person with a science background can look at the predictions and see if they have come to pass.
They can also evaluate the criteria upon which the predictions are based.
In the case of AGW, the only thing that really matters, is the climates sensitivity to added CO2.
For over a century, Science has been working on the issue, not just CO2 but the entire greenhouse effect.
It was noted in the nineteenth century that Earth was warmer than it should be.
Later the number was refined down to 33°C, the temperature of Earth would be -18°C if the atmosphere
were completely transparent, but is at +15°C.
Some like the GISS say this is really just a thought experiment, but let's go through the exercise.
NASA GISS: Science Briefs: Taking the Measure of the Greenhouse Effect
The size of the greenhouse effect is often estimated as being the difference between the actual global surface temperature
and the temperature the planet would be without any atmospheric absorption, but with exactly the same planetary albedo,
around 33°C. This is more of a "thought experiment" than an observable state, but it is a useful baseline.
In actuality the surface emits about 150 Watts per square meter (W/m2) more than goes out to space.
We find that water vapor is the dominant substance — responsible for about 50% of the absorption, with clouds responsible for about 25%
— and CO2 responsible for 20% of the effect.
So CO2 is responsible for 20% of the 150 W/m2 of imbalance that keeps our planet livable.
CO2's forcing is measured in doubling s or halving the levels.
Past studies have used a CO2 level of 1.5 ppm as a near zero measurement.
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Figure 5(a)presents TOA spectra with current atmospheric conditions but using five different CO2 concentrations: 0, 1.5, 389, 2 × 389 and 32 × 389 ppmv.
This works out to ~8 halving steps to get to near 1 ppm from the historic level of 280 ppm.
So ancient CO2 has added 8 fully equalized doubling steps equal to 20% of 33°C.
Now we can try out their thought experiment.
33°C X .2=6.6°C, 6.6°C/8=.825°C per doubling step.
Now comes the question, of why modern climate scientist expect the next doubling step of CO2
to have a fully equalized value of ~ 3°C, when all earlier doubling steps only had a .825°C doubling value?