Climate models incorporating CO2 levels give hindsight matches better than modelling that doesn't. It is reasonable, just on this basis, to expect that CO2 should impact on foresight projections.

John's basic premise, that modelling, per se, does not and can not give meaningful information on anything, let alone climate science, is a baseless assertion which the example of the hydrogen atom refutes. An algorithm, developed in hindsight i.e. using experimental results,and which revolved around integers, was found to apply well. Nobody knew why. Niels Bohr used this mathematical modelling as as a pointer to help him formulate his precise physical and mathematical theory of atomic structure. Whether the algorithm was developed from curve-fitting to experimental data or simply divined, is irrelevant. It was useful.

John's quixotic tilt at established science is his right, but his position that CO2 has no impact because it is not a greenhouse gas and that modelling incorporating greenhouse gas information has a poor track-record will take a courageous defense in proper scientific fora.

Meanwhile, my advice to laymen on OLO is to accept the scientific consensus on AGW or, if your predjudices can not allow you to go that far, accept that it MAY be right. Then apply rational thought and come up with how we should respond to it. All roads will lead you to the same conclusion.

i will ignore lici-erase implicite threat
in the yes minester mould..'coragous'

and focus on his her other quote
""a baseless assertion
which the example of the hydrogen atom refutes.""

which is studying affect
to find prime 'cause?

not assume cause
to have affect?
[ignoring all the other causes..plus the latest addendumb
in todays news..of the ozone hole over the antarctic..growing bigger..CAUSe.of the extreemly cold winter downunder..!

sems a cold spell preceeds a warming event
to wit this larger OZONE hole allows in more heat
so this summer will be hotter..

[if other affects..;modifiers like cloud cover..
dont mitigate the knockon affect..of the bigger ozone depletion..?]

noting the role of ozone
depletion..is green house gasses
ie
nitrous oxide..methane..cfc's...
and least of all c02

HOW MANY ARE IN THE MODELING?

i can keep asking till we get a reply

""Whether the algorithm was developed from curve-fitting
to experimental data or simply divined,..is irrelevant.""

if trying to find cause
NOT changable various MULTIPLE affects

""It was useful.""

so is fear
and ignorance

when your after new taxes
or grants and subsidies..
to do the research..that pays best

not that which..is most needed
or most usefull

how much more usefull
to find alternatives

or
make useless models?

Ammonite likes to argue from authority and says:
"I prefer actual established scientific organisations rather than those devoted to a single aim."

You mean like www.globalchange.gov?

And:
"But to do nothing - which I believe from your posts, is what you are arguing, is absurd."

To do something based on ignorance and misinformation is surely even more absurd.

Your NASA reference states:
"In its recently released Fourth Assessment Report, the Intergovernmental Panel on Climate Change, a group of 1,300 independent scientific experts from countries all over the world under the auspices of the United Nations, concluded there's a more than 90 percent probability that human activities over the past 250 years have warmed our planet."

This suggests some sort of statistical process has been conducted leading to the "90 percent certainty" figure. This is not the case. The figure is based solely on what the 1300 scientists (or some sub-set of them) felt about the situation. If you tried to market a pharmaceutical on this basis you would be in serious trouble with the law.

tomw says:
"The evidence presented for human caused global warming is now sufficiently credible to act on."

What evidence are we talking about here? Modeling evidence? Or perhaps the number of True Believers.

And:

"I treat global warming as a certainty"

You are welcome to do so. I am merely pointing ou that there is no scientific basis for that conclusion.

Precisely, John

The link to http://www.globalchange.gov/publications/reports/scientific-assessments/us-impacts/key-findings was supplied by NASA.

Not a "higher authority" so much as credible ones.

Like this:

" Trees are taking up a similar amount of carbon, but whether this will continue is much less certain, as the recent forest damage illustrates.

Carbon dioxide is an essential part of the cycle of life on Earth, but geologic history suggests that too much can cause the climate to warm sharply. With enough time, the chemical cycles operating on the planet have a tendency to bury excess carbon.

In the 19th century, humans discovered the usefulness of some forms of buried carbon — coal, oil and natural gas — as a source of energy, and have been perturbing the natural order ever since. About 10 billion tons of carbon are pouring into the atmosphere every year from the combustion of fossil fuels and the destruction of forests.

The concentration of the gas in the atmosphere has jumped 40 percent since the Industrial Revolution, and scientists fear it could double or even triple this century, with profound consequences.

While all types of plants absorb carbon dioxide, known as CO2, most of them return it to the atmosphere quickly because their vegetation decays, burns or is eaten. Every year, during the Northern Hemisphere growing season, plants and other organisms inhale some 120 billion tons of carbon from the atmosphere, then exhale nearly the same amount as they decay in the winter.

It is mainly trees that have the ability to lock carbon into long-term storage, and they do so by making wood or transferring carbon into the soil. The wood may stand for centuries inside a living tree, and it is slow to decay even when the tree dies.

But the carbon in wood is vulnerable to rapid release. If a forest burns down, for instance, much of the carbon stored in it will re-enter the atmosphere. "

http://www.nytimes.com/2011/10/01/science/earth/01forest.html?tntemail0=y&_r=1&emc=tnt&pagewanted=all

Cont'd

Cont'd

Or from Australia's own:

" But what about forecasting Australia’s future energy needs for, say, 2050? Despite the uncertainty in such a task, every government and major energy company in the world is involved in forecasting the future of energy for one simple reason: infrastructure.
Big investments need reliable projections

The Munmorah Power Station is still going strong.

Most energy infrastructure has a 25-50 year lifespan. Our largest power stations are built with a 40 year lifespan in mind, but that can be extended to 50 years with the help of refurbishments.

One example is the Munmorah Power Station on the New South Wales Central Coast. It’s still operating despite being commissioned 42 years ago.

Given the multi-billion-dollar cost of such infrastructure, government and energy companies need to know what needs to be in place as society changes and populations shift.

And, when you have to make payments on a multi-billion-dollar loan for the next 30 years, you want to know that what you’re building will be relevant to energy use demands of the next 25-50 years....

... Consider a proposal for a large-scale solar plant. As energy modellers, here are some of the questions we’d need to be able to answer:

What is the future wholesale price of electricity?
How will the cost of solar energy and its competitors improve over time?
What’s the best location for the project, given the location of the existing grid connection points and the variation in sunlight across the country?
How does a carbon price and other policies change the above factors?

By answering these questions we can then guide and inform investment decisions made by government and industry. "

http://theconversation.edu.au/beyond-the-crystal-ball-why-energy-modelling-is-more-than-a-guessing-game-3509

Big business needs climate modelling just as much as any other organisation, government, private or NFP in order to make the best decisions for their/our future.

Luciferase says:
"John's basic premise, that modelling, per se, does not and can not give meaningful information on anything, let alone climate science, is a baseless assertion".

That is not my basic premise and at no time did I imply that it was. I am not a nihilist; I am a working scientist with experience in numerical fluid dynamical modeling.

My basic premise is that computer models, as the numerical encapsulation of a number of hypotheses, must be tested against real world data just like any other scientific hypotheses. The scientific method should not be abandoned because a model was run on a very fast computer and thousands of man-hours went into its development. All models, climate models or otherwise, must be rigorously tested against real world observations, not just once against cherry-picked data, but time and time again so that their strengths and weaknesses can be evaluated and understood. The results of such testing should be made publicly available and not squirreled away in case future funding is jeopardised.

I was lucky to find in the Ensemble Project. The climate models used there failed to hindcast observational data with regard to the geographical distribution of warming and cooling (http://www.scienceheresy.com/2011_03/hindcasting/index.html). If better models which didn't fail in this way had been avaiable I feel sure that the Ensemble Project would have used them.

It appears that the rules which apply to the rest of science are being waived when it comes to climate models. As a physicist I find that deplorable. Computers should be used to enhance science, not displace it.

Neither did a I say that CO2 was not a greenhouse gas. I said that Arrehnius only showed that it was an infra-red absorber. Whether that implies that it warms the earth by trapping radiation is not yet settled. That is why we are having this discussion.