The scientists agreed that the world is in a process of global warming and that it’s true that humankind has contributed to it. The debate centers principally on the magnitude of the man-made global warming.
Some says that man-made global warming is insignificant, others says that it has a cascade (or multiplier) effect that result in a significant contribution of man to global warming, and the lesser support that man-made global warming is huge and, in consequence, humans can (and should) do something to revert it.
So, how could scientist reach such diverse conclusions? The answer to this question comes from the models that scientists use.
The former group, which affirms that man-made global warming is insignificant, bases its research in static and simple models that include water vapor as a greenhouse gas.
“Water vapor, responsible for 95% of Earth's greenhouse effect, is 99.999% natural (some argue, 100%). Even if we wanted to, we can do nothing to change this.
Anthropogenic (man-made) CO2 contributions cause only about 0.117% of Earth's greenhouse effect, (factoring in water vapor). This is insignificant!
Adding up all anthropogenic greenhouse sources, the total human contribution to the greenhouse effect is around 0.28% (factoring in water vapor).”(4.)
With these facts is difficult to think that man can affect climate in any way; beware, this is a conclusion that can’t be made easily.
There are models that challenge this first hypothesis saying that there is a cascade effect that, even if the initial effect of human actions over climate is insignificant, the resulting man-made global warming is significant. This is what is called the “positive feedback loop” which states that man emissions of greenhouse gases warms climate a bit, this extra warming increases water vapor emissions that in turn warms the climate a bit more, and so on, ending in a significant effect over climate.
There are other models that challenge this last statement saying that there’s a “negative feedback loop” based on clouds reactions to climate changes.
“Pete wrote:
The argument put forward by anthropogenic global warming theorists is that the increase in man-made greenhouse gasses is warming the earth, and the additional water vapor caused by the warming is enhancing the greenhouse effect even further.
[Response by John]
Yes I am aware of this argument. It is called a positive feedback loop. However this theory is not proven and one MIT study showed we may actually experience a negative feedback loop. Certain types of clouds actually act to cool the Earth's surface. Climatologist Richard Lindzen used satellites to measure the expanse of clouds in accordance with surface temperature. He discovered that as surface temperatures increase, the types of clouds that warm the Earth actually decrease.”(5.)
As it is explained in this discussion, nor one theory, neither the other, is proven, these are hypothesis that expand the initial scenario.
Finally, there are models that just ignore the effect of water vapor over the warming process. This omission results in an over weighted contribution of man-made emission of CO2. This omission is not yet clearly justified, so the reasonable conclusion is that it’s due to a hidden agenda by the authors.
Resuming, the scientific debate is centered over the magnitude of the man-made global warming and there are three basic positions:
Man-made global warming is insignificant because water vapors (95% of greenhouse gasses and almost 100% natural) overwhelm in effect any other greenhouse gas emission. So global warming is over us principally due to natural causes and there’s nothing we can do about it, just get prepared.
Man-made emissions (principally CO2) have a cascade (multiplier) effect over the water vapor emissions that, even if the former are insignificant in the beginning, the final aggregate emission of greenhouse gasses has a significant effect over climate.
Man-made emissions play a significant role by itself and are the principal cause of global warming.
These three lines of thought can be challenged as it was explained earlier. Lets see a serious analysis of this issue and how relative and speculative is the debate at this moment.
“The major radiatively active components of the atmosphere are water vapor and so-called layer clouds. The latter contribute to cooling by reflecting sunlight that otherwise would be absorbed by the surface, and contribute to heating by absorbing and re-emitting infrared radiation (essentially the greenhouse mechanism).
Recent observational studies show that these effects almost balance, but that the cooling effect is somewhat more important. From the point of view of global change, however, it is crucial to note that this small difference is about five times larger than the radiative effect anticipated from a doubling of atmospheric carbon dioxide (CO2), and that the individual components of the difference are orders of magnitude larger. In existing climate models about one third of the predicted warming due to increasing CO2 arises because of the predicted cloud changes. These predictions, however, are highly speculative because none of the models include interactive cloud physics.
The treatment of layer clouds is a more difficult problem at the moment, and demands a combination of expertise in large scale dynamics, cloud dynamics, and cloud physics. Comparable cloud covers exist under a wide variety of climate conditions, and thus, no obvious parameterization suggests itself. Careful studies of the dynamic and thermodynamic conditions that lead to the formation of layer clouds are crucial. We note that better treatment of layer clouds will, among other things, require better prediction of atmospheric water vapor content, which requires better representations of convection.”(6.)
From this analysis is almost obvious that omitting water vapor of the analysis is an error that couldn’t be accepted anymore.
So finally there are only two central ideas that should be the starting point in the analysis (this doesn’t mean that the other variables, ideas or scenarios should be omitted from the analysis) and these two ideas gives a very clear message:
Global Warming is over us, and there’s nothing we can do to stop it.
If it’s accepted that there’s a dominating positive feedback loop, then maybe humankind, with a great effort, can only mitigate a bit the effects of global warming but definitely can’t stop it, global warming is over us and everyone will feel its effects.
