Back from a weekend in the West Country, several commenters and a couple of bits and pieces need a quick summary.

It was a mistake to suggest the term ‘quantum’ might be useful; it simply isn’t accurate enough, and permits people to obfuscate about quantum mechanics rather than deal with the issues. Given that the old man is likely to be lost in technical discussions of quark strangeness and charm, or s-matrix interactions, it’s probably best avoided. Mistakes happen. Still in search of suitable metaphors to describe to non-scientists what is happening with the climate, the current thought runs with hillwalking.

If you go for a walk in the hills, it is useful to know what sort of a climb you are going to face. Most walks involve a gentle ascent, followed by a steeper section, followed by a levelling off near the summit. On the journey to the summit, there are some lesser inclines and the odd descent, but the overall journey is uphill. Some people still claim that recent warming is a natural phenomenon which is going to change soon enough. As ‘evidence’, they cite 1998 as the warmest year on record (note, 2005 may or may not have been as warm or warmer), and point to the ‘slope’ of the temperature trend: ‘look; it’s levelling off; we are near the summit; no problem!’

This is not what the Global Climate Models persistently tell us. It also doesn’t fit with the physics of the atmosphere. We are past the lower level of the ascent, and are now climbing an increasingly steep slope. It looks like the slope is going to get steeper still (the rate of temperature increase is still accelerating). So it will be a while before we reach the upper slopes and can expect a levelling off.

What is in question is how far up the slope we are, how far we have to go, and how much extra hill there will be to climb once we reach the upper levels (we are collectively adding to the height of the summit by adding wmGHGs to the atmosphere). How far up we are depends on how much extra we add to the top whilst we are on the journey.

At the moment, we are adding to the height of the hill at a faster rate than ever before, but we can’t see this because we are still on the climb. We may be a quarter of the way up, maybe a third or half-way. ‘Alarmists’ are saying that we have to stop adding to the height of the hill, or we’ll get altitude sickness before we reach the summit and won’t make it; the hill will become too high to climb. Most scientists seem to think that, if we stop adding so much to the top, we’ll reach a more gentle slope and ease ourselves to the summit, but it’ll take it out of us. We should be somewhere between a third and half-way to the top.

It is easier to know where we are on the hill if we have a good map, with proper contours, produced by careful triangulation and measurement. If we go up the hill armed with a sketch drawn on the back of an envelope by a man in the pub, we’ll be less well placed to understand how much more of the journey still lies ahead of us. Global Climate Models are supposed to function as detailed maps, but some people claim they are no better than back-of-envelope sketches. It is probably fair to suggest that they show the slopes reasonable well, but not all of the details ahead; in this sense, they are probably a bit better than a sketch, but their reliability is a matter of uncertainty to us. But the details matter less than the overall slope and the final height.

And then there are those who point out that, if the slope we are on gets too steep, it will be so unstable that we are at risk of causing an avalanche or landslide, putting ourselves at extreme risk and permanently changing the nature of the hill.

BACK to the irony, on the radio this morning, the old man hears a reference to now former prime minister Mr Blair, saying that the floods which now beset the UK (a month’s rainfall in a day), are a prime example of why we must combat climate change. Score one to the old man. We respond best to threats which we experience directly; we can ignore mother saying; ‘Don’t put your hand there, its hot’, but we’ll learn when we’re standing crying because we got burned and she says; ‘there, you see, it is hot; you should keep away.’

So, how grown up can we be? Can we work out for ourselves whether or not to stick our hands in the fire, or will we have to wait for someone to say ‘I told you so…’ The old man’s experience of human nature suggests a miserable prognosis in this respect. Was it Hegel? ‘What we learn most often from history is that we never learn from history’. Great,that’s really cheered us all up. More later.

Be loved.