I've never used Venus as a model for climate change on Earth.
I've used it when a post seemed to be denying the very existence of the greenhouse effect, so as to show that there are places where it can be shown to have happened.
I don't include you in that group; but I have also used it by way of emphasis when a post seemed to be implying that the greenhouse effect was only one of several possible solutions, and hence was no more likely than any other. With respect, I have got that impression from your posts at times.
I have also referred to it in the occasional discussion about runaway greenhouse effects, but have been careful to point out that that is not predicted for Earth under current scenarios.
The atmosphere of Mars is 96% CO2 and yet the average surface temperature is about -50°C.Clearly global warming isn't a issue for the average Martian.
I think you confuse people denying the existence of greenhouse effect with people who are trying to tell you that the earth's climate is quite different from "more CO2 = more heat".
If it was that simple, there wouldn't be ups and downs, it would be parallel lines on a graph.
The earth has been warmer before and that was without our help or even the amount of CO2 we have now so unless you include ALL of the factors (and I doubt anyone has done that), you can't come to a certain conclusion.
And again, some people say "so what do we do? take the risk?". Well what risk? As far as I know a warmer planet is actually nicer (and I'm not talking about being able tu sunbathe in summer).
Water vapour is more of a greenhouse gas than CO2 because it has a much wider infra red absorption spectra. Probably 90% of all greenhouse gas activity is by either clouds or water vapour drifting around in the air. The rest is CO2, Oxygen (yes that's also a greenhouse gas), Ozone, Methane, etc
It doesn't work like a net, that's a fundamental misconception.
Atmospheric CO2 already filters out virtually all the infra red radiation in its absorption range coming up from the surface of the earth. It does this within a few meters, to a few kilometres of the surface, depending on the wavelength. Adding more CO2 would only marginally shorten this distance.
Also, no greenhouse gas truly 'traps' heat. It just delays its escape into space. If the sun were to suddenly go out, the earth would become a complete snowball in very short order.
There are implications for the human race and civilisation as we know it shouldtenperatures rise. Land that is currently productive to agriculture could become unuseable but new areas could become productive. At higher temperatures the equatorial zone may become uninhabitable forcing people to displace to different latitudes which would increase pressure on resources and space.
Evolution will continue and everyhing on earth will adapt to the changes or die out and be replaced by new species. Obviously that is a doomsday type scenario as far as civilisation is concerned and as you cantell from my posts I am not currently in the agw camp. I do not deny that we could be responsible for changes but I am as yet uncovinced by the argument largely because the same processes have been occurring for billions of years.
Sorry I don't quite understand the several possible solutions bit. Do you mean that there are several possible explanations other than the greenhouse effect for potentially rising temperatures? If so then why not? We know the greenhouse effect is real and may well explain potential climate changes. However it may only be part of a very complex system that we are only just beginning to understand. You asked in another post where does all the heat go? I don't know but alterations of cloud cover will have some influence in reflecting heat back into space. It's possible that there are other mechanisms for extra heat to be lost to space.
The extra CO2 may trap more heat but it makes up such a miniscule fraction of our atmosphere that the extra heat retained as a result may be insignificant.
Got no problem with any of that. The "net" was a bad analogy and I shouldn't have used it. Your other comments mirror those that I have made before.
I think this perfectly sums up where my thinking is at the moment, can I plagierise it please?
AGW or not, we still need a sustainable energy source as natural resources decline. I think we should be building enough nuclear power stations right now, 50 of them if that's what's required. And stop messing around with ridiculous things such as wind turbines and the like.
I agree, but we've got 300 years of coal reserves. If these eco-idiots have there way, we'll be getting brownouts and blackouts like some crappy 3rd world country in a few years.