"10 per cent of Alpine glaciers melted in 2003"

A snowHead

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Don't blame the Americans for lack of progress on AGW. Some of the biggest proponents of the theory (that's badly worded, but it gets the message across), are NASA, NOAA and MIT (as well as many other US universities). A recent MIT study broadly agreed with the Hadley Centre's studies that the warming trend could be about the same as the middle IPCC estimate/projection, call it what you will. (I can go and dig out some URLS is requested, but have a limited time at the moment).

Here is how I see the current state of the debate:

CO2 (amongst other gases, all occuring naturally, many who's levels in the atmosphere are directly and indirectly affected by man) is a greenhouse gas in that it's presence in the atmosphere causes warming. This leads to one of the following:

1) No effect. A position taken by those on the fringes, or outside the fringes of the scientific debate.

2) Negligible effect. This is increasingly the stance taken by the "sceptics" - e.g. it's within the natural cycles of the climate.

2) Little effect. As espoused by some governments and some figures such as Bjorn Loomborg(sp?) who say that yes it's happening but there's worse.

3) A noticebale effect (1 degree Celcius). The lower limit of the IPCC's estimates/projections.

4) A large, catastrophic effect (5 degrees Celcius). People like Dr David King and various environmental organisations. The upper end of the IPCC estimates/projections.

The general opinion of the scientific community (inc. the IPCC) reckon that, taking as much of the feedback mechanisms within the climate (positive and negative) as is currently possible, and various political predictions (whether business as usual or reduction etc. in ghg production is a political decision) is that the change will be between 3 & 4 (those set the limits). The MIT & Hadley Centre studies tend to suggest the middle of the range - which is reasonable intuitively if you assume that the various feedback loops have varying effects and probabilities of importance. This is around the 3degree mark over a period of time (I can't remember what it is, sorry).

That these feedback mechanisms are not fully understood means more research is needed, but 1-5 degrees is the generally accepted range by the climate research community. Note that this is where the varyability lies as the amount of ghg's produced and their direct affect is easily calculated from the energy generated around the world.

It needs to be remembered that whatever's done now ghg-wise, it'll have no effect until the latter half of the century, at the earliest.

Now, how "catastrophic" or "manageable", etc. this change is and what "sensible" measures constitute, is also open for debate. For example, what would cause the displacement of 135million people from Bangladesh? Would it be considered a catastrophe? Would it be considered worse than current terrorist threats? Could it lead to increased conflict anyway?

That's how I read the situation, anyway.

Anyway, snowHeads is much more fun if you do.

skanky, I think that's a pretty fair summary. There's quite a range of 'respectable' opinion in this field.

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The range depends what you term as 'respectable'. With research teams at NASA (I think), NOAA, The Hadley Centre and MIT tending toward the mid-range, I think that in my unqualified readings around it, I'll err on the side of edging towards that herd.

I used to have some mates who work(ed) the the Hadley Centre, I wish I was still in touch with them. Their opinions would be worth knowing. Confused

Then you can post your own questions or snow reports...

skanky, I'm a bit to the sceptical side of the spectrum (as I'm sure you've gathered). I'd like to explain why. I have a little bit of background in atmospheric physics. I used to be involved in the design of multispectral (including infra-red) scanners on board earth observation satellites. The mass, volume and power consumption of these instruments had to be kept to a minimum, which meant that we were constantly looking to strike engineering compromises between these factors and the accuracy of the instruments. The question arose as to how much these compromises mattered, given that the radiation detected by a "perfect" space-borne sensor is only an approximation of what is radiated from the bit of the earth's surface that it's pointed at. Understanding how much of an approximation required modelling all kinds of effects, one of them being absorption by "greenhouse" gases. Now, the biggest absorber in the infra-red by far is water vapour. Burning fossil fuels adds to the water vapour in the atmosphere, but only by a tiny proportion, because there's so much of it about already. So, although human activity is responsible for quite a high and growing proportion of atmospheric CO2, that's only a minor greenhouse gas. The overall human contribution to greenhouse absorption is much less than the scary figures that are quoted on CO2 emissions would imply (it would seem to me).

All my study was done when environmentalists worried themselves much more about "nuclear winter" than global warming. I wasn't involved in calculating anything to do with that anyway. It's possible (though I think unlikely) that there have been major improvements in the understanding of atmospheric processes since then. I've looked into this in a desultory fashion recently, but I can't find anything that contradicts what I've just said in scientifically convincing terms. I'd like to think I'm open to persuasion.

After all it is free

The nuclear winter side of things is a bit of a tangent. We're as likely to see a nuclear conflict these days (probably), and it'll (probably) have a cooling effect. It is however the result of doing something diffierent to what we do today (e.g. stop keeping the bombs at home).

The CO2 is effective because, though it is minor in terms of being a ghg relative to the physical properties of other gases, the system was in a certain amount of equalibrium (the CO2 especially), and so a (relatively) sudden, large increase has ceryain (relatively easily calculable) results. The other ghgs can come into play via the various feedback mechanisms: would a slight temperature change result in more or less water vapour in the atmosphere and would this create a positive feedback loop? Would the same hold true for cloud cover? levels of methane, etc.? How does it affect the CO2 cycle itself?

This why the variability of prediction is so high (4 degrees). This is the area where the climate researchers are trying to narrow the gap down.

Help!!

"10 per cent of Alpine glaciers melted in 2003"

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