Raff, the UK has little room for additional hydro. Wind and solar are unreliables. And the people who don't want nuclear are on your side, not ours. If you want to make a difference, you need to be on environmentalist sites trying to persuade rabid greenies that if they're so worried about AGW they need to accept nuclear. We haven't even got replacements for the entire fleet bar one that are due to close in the next ten years. If we don't we'll actually be in the worst of both worlds. Either we'll run drastically short of capacity or (more likely) we'll run ever older and aged stations, raising the chance of what the greens are scared of.

Or are you too scared of your own side to stand up to their lack of commitment to your favourite catastrophe? Are we more pallatable in opposition than your own buddies?

Martin A, it's worth doing, if for no other reason that when you get lots of different answers, people can see how much of a dart board it all is. And that's all before they fiddle with the data.

Tiny, believe it or not, the UK is not the whole world. Also I omitted energy efficiency, perhaps the most important consideration for energy supply.

Martin, I'm intrigued that geronimo and now also you admit that temperatures could rise 4C and that we essentially don't know how likely that is. I've never seen such an admission from a skeptic before. Do others here agree now? Maybe you, like geronimo think that a 4C rise is no big deal, but it is an encouraging shift all the same, even if you still think that we should do nothing about it.

Geronimo, how could 4C not be hugely disruptive? It is an average of course so higher latitudes would warm more than the equator. It would have good and bad effects, weather patterns worldwide would change, some areas becoming drier (maybe bcoming deserts), some wetter (maybe deserts becoming fertile), farming practices would have to change, all ecosystems would be hugely disrupted. And if you think the migration into Europe or the US now is a concern, just wait until swathes of the world (maybe Spain, Italy, the Levant, north Africa), become uninhabitable or others (coastal cities) submerged. Sure, other areas might become more suitable but someone already owns them and they are not likely to give them up to migrants without a fight. Irrigation? Well rich countries might, but poor ones can't now and won't be able to in the future either - those rich countries are no more likely to pay in the future than people like those here who begrudge the poor just 0.25% ($100bn mentioned earlier) of rich world GDP now.

You pick your battles. At the moment none of us can prove what effect CO2 has. Nic Lewis' work is evidence that the science is not settled. The best we can hope for is that the foot is eased off the gas pedal. We can't expect the world to erupt into scepticism overnight and say 'it's ok folks, it was all a misunderstanding.' Not least because none of us can prove what effect CO2 has.

I'll try to spell out why saying "nobody has a clue" is very far from saying "I concede that xxx could happen".

So you think we don't have a clue what effect all that extra CO2 has on the atmosphere but I'll be disappointed if you don't nevertheless claim that, whatever effect the CO2 has, it is definitely not a 4C (or any other number) rise in temperature. I'll look forward to the mental gymnastics.

Raff, we can't prove that we won't be wiped out by a massive pandemic in the next 12 months either but none of us are planning to hide under the bed with a face mask, tinned food and a shotgun in the near future. There are all sorts of worst cases that MAY happen but we can't live like we think it's going to happen unless the evidence is better than climate science has come up with.

"Martin, I'm intrigued that geronimo and now also you admit that temperatures could rise 4C and that we essentially don't know how likely that is. I've never seen such an admission from a skeptic before. Do others here agree now? Maybe you, like geronimo think that a 4C rise is no big deal, but it is an encouraging shift all the same, even if you still think that we should do nothing about it."

Thank you Raff, I conceded it could rise to 4C, or if you want 6C, because I don't have a clue what the temperature will be in 2100 - just like the IPCC. Conceding something COULD be true isn't the same as believing it IS true. I was going to say, "But I guess you know that", but I am dealing with someone who believes that that exacerbating current known problems and spending money on future unknown problems is a reasonable course of action, so maybe you don't know it.

Why am I unconcerned?

We are set to double the CO2 in the atmosphere the current rate in 80 years time when the temperature will rise by 1.2C other things being equal, (i.e. I don't know that for sure because I don't believe in the simple CO2 --->temperature rise in a coupled non-linear complex system), but let's say, for instance, over the next 50 years it CO2 doubles because of the acceleration of the BRICS emissions. It will take another 2-3 centuries for the temperatures through feedbacks to get us to "X" C (choose your own numbers) other things being equal. I'm assuming this increase in temperature will be non-linear, but not a step-function. So our descendants will see a gradual increase in temperature over a period of, say, 250 years.

That is approximately 300years from today. Now cast your mind back to 1715, no electricity, no motor cars, no television, no radio, no aeroplanes, no man on the moon, no satellites no mobile phones, no internet, no... I hope you're getting the picture. A lot can happen in 300 years to a coupled non-linear chaotic system like human society. And in this case it's always for the good.

The IMF has calculated that if we carry on with business as usual until 2100 the average person on the planet will be 10-70 times more well off than today.

That's why I'm not concerned about how humans will cope, they will, especially if they're wealthier. Humans, even in primitive times, inhabited the Earth from the Arctic circle to the Kalahari desert, I'm sure they'll cope with a temperature rise of 4C over a period of 300 years, especially if they're an order of magnitude, or more, richer every 85 years. Taking the conservative IMF figures the average person will be 1000 times wealthier than today 300 years from now if human society progress continues as it has done since the industrial revolution.

And to put the icing on the cake, "other things" are not equal. We don't know what's going to happen, nor can we forecast it, no matter how many MIPS the birds' entrails have, they're still birds entrails.

Nice one, Martin A.

Martin, you missed your true vocation. You show how to combine the deceptive PR skills of the financial services "industry" with the essential dishonesty of a climate science skeptic.

There is no reason to doubt these projections

That is your primary deception. No climate scientist would ever say that of the probabilities plotted in a sensitivity pdf.

You, in your roles as junk bond salesman, might say that of your fake "pdf". Not a pdf? Of course, as the area under the graph should sum to 1; yours sums to thousands unless it really claims the possibility of £3999 or any other value not listed is zero (in which case it is even more dishonest). But admitting this presentational error (or ruse), your secondary deception is in equating decreased probability with increased gain. To be comparable with a climate pdf, you'd have shown the reverse. Here's the new predicted return on £1000 invested, with probabilities:

greater than £1000 : 0.1
£1000 to £900 : 0.4
£900 to £700 : 0.25
£700 to £500 : 0.1
less than £500 : 0.15

The numbers have no basis in anything. You could create your own, hundreds of different ones to reflect the fact that you don't have a clue. Or you could take your cluelessness at face value and have a flat distribution:

greater than, equal to or less than £1000 : 1.0

That is both obviously correct, as it contains no information, and at the same time a fairly stupid choice. But it seems to be what you think.

I'll try to spell out why saying "nobody has a clue" is very far from saying "I concede that xxx could happen".

With your preferred, flat, clueless distribution, it is obvious that all values above and below £1000 are equally probable and so this explicitly admits that "xxx", whatever value that is, could happen.

Whatever distribution you chose, as you don't have a clue, you'd have to include long negative tails. And the long tail risk of heavy loss would now be clearly shown, as it is in my numbers. So the investment manager now saying "I'm intrigued you now admit that we could lose most or even all of the money" is now not such an easy thing to shrug off.

So I'm not disappointed with your effort although it is less mental gymnastics than self delusion. You seemingly don't even know what "I don't have a clue" means as a probability distribution.

Raff, for a while there I thought I was dealing with someone who might have a clue. Good luck for the future.