IPCC

I have little confidence in the IPCC process. and have not quoted it. Rajendra Pachauri, the current president of the IPCC, should be sacked for allowing in the claim that the Himalayan glaciers would be gone by 2035. Use little more than high school physics I was able to demonstrate that this was a wildly improbable claim.

I have not quoted the IPCC in this piece.

CLIMATE MODELS

I have even less confidence in climate models than in the IPCC process. I have made no use of the results of climate models in my piece either.

TOM TIDDLER

Dit gaan goed, dankie.

I said basic physics suggests a significant impact as a result of adding CO2. The planet is a complicated place. It may not conform to theory in the sense that that there may be negative feedbacks that limit the effects of the added CO2.

You have put your finger on what ought to be the crux of the debate.

Given that there is a greenhouse effect what will be the impact of adding to one of the greenhouse gases, CO2?

In trying to answer this question we face the following difficulties:

--The effects could appear over a period of decades. The Earth is a big place and responds slowly.

--There is some natural variability in climate anyway. We are trying to detect an additional effect over and above natural variability.

You can think of it as trying to detect a weak signal against a noisy background. We want to detect the weak signal before it becomes strong.

EVIDENCE FOR THE EXISTENCE OF THE SIGNAL
To me the most convincing evidence of the existence of the “signal” is events around the Northern polar regions. This is the region that is most likely to be affected by global warming. What we see is a diminishing polar icecap and the spread of vegetation northwards.

NB This is not the only evidence

In fact, if the Earth does heat up there will be winners and losers. The big winners will be Russia, Canada and the countries of Northern Europe. The northern states of the US – especially Alaska – will benefit but the more southerly states may become unliveable.

My feeling is that Australia will be a net loser simply because of the latitudes we occupy.

I have not mentioned rising sea levels. The usual estimate is about 20 cm for this century. However glaciers in Greenland and other far Northern regions do seem to be moving faster than expected. Perhaps we should prepare for rises of around a metre.

POLICY IMPLICATIONS

I have focused on the science, not on the policy implications. Australia should not attempt to make a show of combating climate change on its own merely so that Rudd / Gillard / Brown can strut the world stage wrapped in their own self-righteousness. In this matter we need to be a follower, not a leader.

Most of the policy responses so far such as putting photo-voltaics on rooftops have been looney tunes stuff. They will cost a lot of money and have limited if any impact on emissions.

THE GREENS

The Greens and their self-righteousness are part of the problem, not part of the solution.

What I find interesting is that the most fervent Greenies are the most ignorant of basic physics. It is something they share with many posters here. About one on five can give a coherent explanation of the greenhouse effect they purport to believe in so fervently.

And now to work

Again, clear and succinct - thanks Steven.

To Don Aitkin: the Youtube link also showed a presentation by a lawyer and an economist. In fact, the whole presentation was premised on "uncertainty and risk" (aversion). My point (to counter your assertion) was that much of the work done by 'climate' scientists is in fact based on observation, data collection and its analysis - not just models. It would also be wrong to suggest models can't or shouldn't be used to "explain" things, they obviously are.

Moreover, there are far too many people Don, that take "the science is settled" meme out of the context in which it applies. Science is NEVER settled (if it was many of us would be out of a job) and those that regurgitate the meme are either distorting the meaning in which it is said, or are extremely disingenuous in their criticism of it.

Steven - generally a good and sensible summary article , and response to the discussion here, thanks. However there are a couple of places where I think the case is stronger than you make.

First, the allegations that scientists fudged data that (otherwise) disproved their hypothesis have been examined by three committees, including one of distinguished independent scientists, and found wanting. The scientists' remarks were made in a context in which denialists were (and are) trying by any nefarious means to discredit them. The "remove the decline" remark referred to a minor part of the data that were covered by other observations, not to overall global warming/cooling. No published work was affected by the alleged misbehaviour. See my summary at http://betternature.wordpress.com/2010/04/19/climate-science-exonerated/, with other links .

The hysterical disinformation campaign about "climategate" has had its intended effect - to distract the world from the real science, which continues to be very concerning. Those who disbelieve the committees' conclusions are merely indulging in a grand conspiracy theory - that no scientist can be trusted.

Second, there are very sensible arguments that Australia can cut its greenhouse emissions for little cost to the economy, by eliminating highly wasteful practices that actually waste money as well as energy. See http://betternature.wordpress.com/2009/11/02/cut-emissions-and-boost-economy/ .

Unfortunately the Government is giving such efforts a bad name by picking some of the worst possibilities for window dressing. It doesn't want to actually reduce emissions because that would upset its coal industry sponsors. Regarding the Greens, Christine Milne has some very sensible proposals.

Re SM: “ … It really is very basic physics. Most of the effects I’ve described can be reproduced in the lab and are as a matter of routine.”
When? Where? Arrhenius never could or did. It is a theory that has yet to be verified and my own regressions fail to confirm the theory, as there is zilch statistically significant evidence of a correlation between changes in atmospheric co2 and changes in temperature at Mauna Loa, Pt Barrow, and Cape Grim, all pristine locations far from towns and airports, which is why they were selected for measuring CO2. If the theory is valid, it should be confirmed at these locations but it is not, far from it.
Then you said: “We are trying to detect an additional effect over and above natural variability.

You can think of it as trying to detect a weak signal against a noisy background. We want to detect the weak signal before it becomes strong”.

My regressions find a huge signal from changes in [H2O] that largely arise from in situ (not TOA) daytime solar radiation that cannot be attributed to human influence – as Piet Tans (MLSO) puts it: ““global annual evaporation equals ~500,000 billion metric tons. Compare that to fossil CO2 emissions of ~8.5 billion ton C/year”. Evaporation and precipitation (i.e. [H2O]) are not feedbacks but prime movers.
SM added: “the most convincing evidence of the existence of the “signal” is events around the Northern polar regions. This is the region that is most likely to be affected by global warming. What we see is a diminishing polar icecap and the spread of vegetation northwards”.
There is no Arctic warming in the Arctic in terms of rising land temperatures. What we did see (until recently) is warmer incoming ocean currents depending on the phases of the NOA PDO and ENSO cycles, none of which can be plausibly attributed to the global monotonic (i.e. non-cyclical) increases in [CO2].

Bonmot: “My point (to counter [Don Aitkin’s] assertion) was that much of the work done by 'climate' scientists is in fact based on observation, data collection and its analysis…” There is an amazing absence of actual data in AR4, and no sign of regression results. Hegerl, Allen, Karoly, Tett, Stott et al. (all involved in WG1 Chap 9) show no sign they are aware of spurious correlations and multi-collinearity and of tests thereof, they never report R2 or t-stats. They ignore almost all natural sources of climate change other than TOA solar irradiance and volcanic eruptions, and their “data” on sulphate aerosols appear to be fictitious, as they cite no sources other than their models, where SO2 is at whatever level is needed to validate their CO2 effects on temperature. Thus if dT is less than they expect from d[CO2], then that is the measure of d[SO2]. If that is not circular what would be?

Not only that, very successful efforts almost everywhere except China (emissions up by 27% from 2000 to 2006) and India have greatly reduced emissions of SO2, eg. by 60% from the 1980 level in UK, (33% in USA 1983-2002), where the legal clean air limit is 100 ppb (cf CO2 actual 390 ppm). The result is a reduction in the cooling effect of [SO2], which raises the apparent warming from [CO2], but that will taper off as [SO2] is further reduced and [CO2] increases at only 0.41% p.a. My regressions take [SO2] into effect, but I see you are not interested.