Originally Posted by
Through
Carbon dioxide comprises approximately 0.52% of our atmosphere. A very small amount.
Carbon dioxide in the atmosphere does indeed absorb and re-emit a small amount of infra red radiation.
Infra red radiation is a very tiny part of the electromagnetic spectrum.
In any mathematics, small X small X small = very, very small.
Carbon dioxide does have a tendency to warm the planet. However, the effect is very small and is overwhelmed by other factors. Not only that, but every addition of carbon dioxide to the atmosphere makes a decreasing contribution to warming.
Spitting in the ocean causes sea level rise in a similar way that additions to a minor component of the atmosphere causes warming.
Advancement of scientific knowledge works in the following way. An interesting phenomenon is noticed. Important factors are identified and the thought process generates potential theories concerning how the phenomenon works. Once a suitable candidate theory is identified, evidence needs to be collected to test the theory. Three possible outcomes arise:
a) the evidence agrees with expectations and the theory is accepted (even "proven" theories can be disproved at a later date when a greater understanding is achieved)
b) the evidence seems to be close to expectations, but does not quite prove the theory
c) the evidence is widely different from the expected outcomes.
In some cases, theories are completely abandoned, because no modification of the theory is found that gives a better result.
In other cases, theories are modified and retested and sometimes this results in the development of a better theory.
Even accepted theories are update and improved from time to time.
So, how is the evidence collected?
If experiments can be devised and run in a laboratory, then generally all of the relevant factors can be adequately controlled and the evidence can be collected in the most controlled fashion.
However, some phenomena occur on a scale that is just too large to fit into a laboratory.
Sadly, we can not yet construct a hard copy of the planet and its atmosphere to run the necessary experiments in the most controlled way possible and neither can we control any of the factors affecting our climate. It's a good job we can't do that, can you imagine if the Met Office contacted everyone in the UK to say that they were excluding rain from our weather system for a year long study?
This means that we have to collect evidence from the real system, over which we have no control.
This evidence can be used in different ways. For example, we can carry out comparisons of one factor against another or we can apply statistics to the input data and investigate the output. Alternatively, we can construct models and run simulations.
The problem with such simulations or models is that sometimes there is just too much data to process.
This is the kind of thing that our Met Office tries to do. They have built up some expertise in forecasting our weather, but how often do you hear the complaint that they are just not good enough or words to that effect. Now that's just the weather over a small area and it achieves a certain accuracy for later today, a bit less accuracy for tomorrow, less for the rest of the week and so on.
Now consider the climate over the whole planet and you'll start to see the scale of the problem.
More on the General Circulation Models that Hadley Centre and others use later, but for now consider that in the lab. a small amount of warming can be measured by subjecting carbon dioxide to a narrow band of radiation and yet for the most part of the planet's history, carbon dioxide moved in the opposite direction to temperature or temperature changed while carbon dioxide did not, or carbon dioxide changed while temperature did not.