Don,

As a first stop, you could try the following link; it contains a brief review of the book.

http://jebin08.blogspot.com/2007/03/six-caveats-about-six-degrees.html

This next link discusses the book from various perspectives and has the added facility for you to ask specific questions on issues that concern you.

http://www.realclimate.org/index.php/archives/2007/11/six-degrees/

At the end of the day, OLO is an opinion forum and while posters may mean well, they may also be wrong, particularly where complex science is involved.

I find it more beneficial to go to primary or recognised secondary sources for technical or scientific information.

I'm normally one of the more enthusiastic global-warming alarmists here, but I'll briefly pause to point out this sweetly optimistic article in the UK's Independent (thanks Crikey for the link):

http://news.independent.co.uk/sci_tech/article3223603.ece

Global warming is an excess of solar energy. Earth receives an enormous flow of solar energy, and radiates the same amount to space, either reflected or as thermal re-radiation. Raised greenhouse gas levels temporarily trap some thermal energy, sufficiently to raise surface temperatures until equilibrium is restored by increased surface-level thermal radiation.

Previous historical warm periods like the Medieval Warm Period and the 1930s were driven not by greenhouse gases but by marginally higher solar radiation. Likewise the Little Ice Age was caused by decreased solar radiation (the relative absence of sunspots is known astronomically as the Maunder Minimum).

Solar observations show an 11-year cycle of sunspot activity, but no-one has really explained a mechanism driving the cycle, nor have satisfactory theories been developed to explain longer-term variations where sunspots simply don't appear for a while. Solar radiation and sunspot activity last peaked around 2000 and has been on its cyclical decline since then; it was expected to pick up again this year but so far, it has not.

If it doesn't, a new solar quiet period might last some decades, effectively saving us from ourselves and giving us a grace period for harmlessly weaning ourselves off fossil fuels as supplies decline.

If solar activity does pick up as expected, just a few months behind schedule, and we don't deal with emissions soon enough to forestall a 2-degree warming, we're toast.

In the interests of further playing devil's advocate, I'll give Baron Lawson a nod and admit that the economic costs of adaptation to a gradual warming may be modest given the inherent adaptability of humankind.

However (batting for my own side again), other species may not be quite so nimble, and I would not be prepared to bet on a gradual and orderly warming against the looming threat of large-scale positive-feedback tipping points and a thorough disruption to rainfall patterns and agriculture.

I thank those who have pointed out sites that might be useful to me. I will read them and add them to the fifty or so I already have in my system. I am not a 'denier'; I repeat that I find the use of that term a Holocaust-type smear, and add that its use I see as patronising. I am, nonetheless at least an agnostic. Xoddam's post above indicates the kind of uncertainty that there is about AGW. I find it odd that people are so sure that AGW is true, and that we must do X or Y in order to be 'saved'. The tenor of a lot of this stuff is religious, not scientific. The IPCC's own estimate of global warming over the 20th century is 0.6ºC plus or minus 0.2º. On the evidence, that is well within known variation over the last 10,000 years, the period in which human beings have lived in settlements. The IPCC's estimate for global warming over this century is not a great deal higher. The global climate models on which the scary predictions appear not to be based on evidence of AGW, but on the conviction that it is true. Finally, no one has come up with a satisfying account of why carbon dioxide causes global warming, and the long-term links (over 1m years) see the rise in carbon dioxide concentrations occurring after the warming, not before it (perhaps because warmer oceans will release CO2, while colder oceans absorb it).
Altogether, my present position is that it is possible that the earth is warming, but if it is the rise is not unprecedented in human terms, and is unlikely to have been caused by the burning of fossil fuels, and will not lead to the flooding of Florida or anywhere else. But I'm not sure, and if powerful evidence comes to the fore that suggests otherwise, I will take it seriously. Until it does, I would regard carbon taxes and caps as bad public policy.
.

I need to add a further comment. It seems to me that AGW is becoming the Great Distractor. We need to deal with water, energy and population limits for obvious and good reasons, not because they will lead to a reduction of greenhouse gases and thus save us from becoming toast. The scary stuff can be so powerful that people feel that there is nothing they can do, whereas there is a lot we can do to manage our water, think more creatively about energy (for the long haul, especially), and recognise that many of our problems come from an over-abundant human population.

AGW seems to me to get in the way of our doing so.

Don, there are some that think climate change or global warming is a kerfuffle … akin to a conspiracy theory concocted by,

• all the countries of the world from differing ideologies and now meeting in Indonesia,
• big business, including energy suppliers and insurance companies,
• religious bodies with differing philosophies, including Islam and the Catholic Church,
• international academies of science, economics and research institutions
• military generals of the "super-powers", including the USA
• 1000’s of scientists world-wide from varying disciplines and areas of expertise.

Personally, I don’t think that all the above are a bunch of loonies hoodwinked by and of themselves or conspiring together to play a big con on us plebs for their own ends. However, some people obviously do (or bury their heads in the sand).

I think all of the above they take their respective roles and vocations in life seriously. If they are worried about the causes and consequences of global warming, so am I.

I therefore expect our leaders (church, state, business and science) to take the necessary steps to adapt and to mitigate – to lead in the face of the “scary stuff”. Otherwise, we will have anarchy.

We are told it can be done, and we have a certain amount of time to do it – so why not?

And you are right, we do need to address water, energy and population concerns – it really is about sustainable development of the environment, the planet – whether you believe in human caused global warming or not.

Sorry Don but there are grave errors in your post.

> The IPCC's estimate for global warming over this century is not
> a great deal higher [than the 20th century's 0.6 +/- 0.2 degrees].

This year's IPCC report originally carried warnings of long-term positive feedback mechanisms. Only short-term temperature feedbacks such as water vapour were included in the final version.

> The global climate models on which the scary predictions appear not to be
> based on evidence of AGW, but on the conviction that it is true.

That's mildly slanderous. Climate models are based on physics, not on conviction.

> Finally, no one has come up with a satisfying account of why
> carbon dioxide causes global warming,

Don, this is bullsh-t.

Greenhouse gases have been studied for 150 years and are *perfectly* understood. Atmospheric CO2 and other greenhouse gases cause the earth to retain energy that would otherwise escape to space. More greenhouse gases, more energy retained. All else being equal, this *is* global warming.

Uncertainties in climate science exist (eg. we don't know for sure what the sun will do, or how rainfall will change, and it's hard to predict how much CO2 the ocean can absorb), but the role of atmospheric carbon dioxide is solid, incontrovertible physics that you can test in the lab.

> and the long-term links (over 1m years) see the rise in carbon
> dioxide concentrations occurring after the warming, not before it

Correction: carbon dioxide concentrations *began* to rise after temperatures did. The temperature rises were triggered by marginally-increased solar radiation according to Milankovitch cycles (regular perturbations in Earth's orbit), but temperature increases were far greater and persisted longer than the additional solar radiation can account for. Greenhouse gases do.

> (perhaps because warmer oceans will release CO2, while colder oceans absorb it).

Along with changes in biospheric consumption and emissions, and other greenhouse gases, yes.

This is solid evidence for long-term positive temperature feedbacks -- as avoided in IPCC reports so far.

Industrial consumption of fossil fuels wasn't part of the picture before.

It is now.