Should global warming be completely disproved, for many years after everyone has stopped talking about it Andrew Glickson will still be producing articles "proving" that really it is all happening.

The articles won't be tailored to the audience, such as make even the slightest concession to its known scepticism, or aim at making a particular point. Nope, the articles will start from the point of view that its all proven.

Even for those who agree with the orthodoxy much of what he writes is a collection of wild-eyed assertions. I was under the distinct impression that scientists have had a lot of trouble making past CO2 levels fit with known ancient climactic conditions, under the existing theory.

In any case, it has been tacitly accepted by the global warming side (by the non-extremists) that past changes in climate have a lot to do with changes in solar magnetic activity, at least over the holocene, with the important caveat that the link is supposed to breakdown sometime in the 1980s.

Then there is the problem is that the mechanism for the switch between galacial and intergalacial conditions is still very controversial. The orthodoxy is Milankovitch cycles but that has taken a battering of late.

In the face of all that, and I've only touched the surface of the problems with the theory, Glickson could be at least a little humble. He could have added in a few maybes or perhapses but nope, he powers straight in..

Perhaps he could move into the same building on campus that houses the academics still insisting that socialism was never really given a chance.

All very interesting and Andrew Glikson rightly draws attention to Arctic amplification but in doing so makes no mention of the role salient and increasing role of methane in that process. Shakhova et al (2010) report that as a result of melting offshore clathrates of central east Siberia and onshore permafrost in that region, methane is currently entering the atmosphere at an accelerating rate, currently 1.1 million tones (7 teragrams) per annum.

As a result, methane concentration in the Arctic now averages 1.85 ppm compared to pre-1750 level of 0.7ppm. Further, until recently it was thought that seabed clathrates below 300m were stable. However recent studies show that off Svbalbad, instability is noted at 400m. This not only confirmss ocean warming but a significant increase in the volume of clathrates exposed to melting and the potential of methane emitted to cause sudden climate change.

One would expect that such emissions could result in massive loss of oxygen, particularly in the oceans but also in the atmosphere as methane oxidized to CO2 Hypoxic conditions of this magnitude may cause large extinction of fauna, especially water breathing animals. Some have suggested that we are already witnessing the start of an extinction event and that Shakhova may well be describing the precursor to a sudden, massive release of methane occurring over decades rather than centuries. This has occurred before as described by Carozza et al (2011).

The effect of such an event on average global temperature would be significant, as would its effect on stability of the Greenland Ice Sheet. This could well result in decadal doubling of ice loss postulated by Hansen et al (2011) producing a sea level rise of 5m before the end of this century. The implications of such an occurrence are catastrophic for coastal areas where most of the worlds great cities are located. They are highly vulnerable because they can not be defended against inundation caused by such sudden rise in sea level.

The second omission by Andrew Glikson is that he makes no mention of the fact that previous thermal maxima have been initiated by the earths changing orbital paramaters exposing the northern hemisphere land mass and polar ice to increased solar radiation. Over centuries, possibly millennia, this produced ocean warming and higher atmospheric temperatures resulting in release of methane producing sudden climate change.

Decline of those effects has always a much slower process. It resulted from slow reversal of orbital parameters producing cooler atmospheric and ocean temperatures, permitting the latter to absorb and reduce CO2 concentration of 280 ppm by upwards of 100 ppm producing ice age conditions.

Changing orbital parameters are not causative factors in the present global warming which has been relatively rapid since 1980 and continues to accelerate. Indeed, during this period solar activity has been relatively quiescent. Moreover the earths orbit around the sun has become almost circular and the tilt of its axis continues to move away from the 25.1 maximum, is now at 23.45 degrees and continuing to decline. This movement reduces the level of solar radiation reaching higher latitudes.

Present global warming has been accompanied by rapid increase in the concentration of atmospheric CO2, from 280ppm to the current 390ppm as a result of human activity. There will be no mitigating reversal of orbital parameters and on-going refusal of humans to either stop or reduce their emission of greenhouse gases raises the specter of future runaway global warming, uncontrollable by human action or present technology.

In summary, what we have started we can neither control nor stop, unlike previous global warming events which were self-regulated by natural events. We are fast approaching irreversible tipping points which Hansen predicts will have dire consequences. - and Hansen has been proven right on too many occasions to ignore.

Agnostic of Mittagong

Um, re your post, I dunno if anyone's told you this but you did know that the concentration of methane in the atmopshere has been stable for the past decade or so? See the link
http://www.esrl.noaa.gov/gmd/aggi/ and look down the page.
NOAA is the National Oceanic and Atmospheric Administration.

Methane concentrations have picked up a bit in the past few years but, as you can see, there were flattening out well before 2000. Present figures are far below projections made for them in the IPCC 2000 report. The 2007 IPCC report contains a detailed discussion of the failure of methane to perform as expected which ads up to scientists not knowing why methane concentrations are doing what they are doing.

You also mention orbital cycles. Milenkovitch cycles have been under fire of late. Although they are still orthodoxy, as I pointed out in the earlier post you don't want to cite them as if they are established fact.

Methane emissions have dropped/flattened mostly because the Russian oil (and drilling) industry has become more professional- less leaky pipes and so on . So far there is little sign of a runaway methane, positive feedback, loop - if there was it would be well and truly be all over for red rover. The worst mass extinction of all time the Permo-Triassic Extinction (252 million years ago ) was provably a runaway positive feed back loop, methane, green house - about 90% of all life died.

Negative feed back loops ; famine, disease, war and pestilence will provably greatly reduce civilization and thus CO2 emissions, long before methane could become a problem.

Examination of proxies, according to Andrew, “demonstrate abrupt changes between climate states over periods as short as a few centuries, decades and even few years”

Obviously these have nothing to do with human emissions, which have only been alleged to be capable of affecting climate over the last 160 years.

I say “alleged” because there is no scientific basis for the assertion that human emissions have any measurable effect on climate.

The best estimate of the proportion of human emissions to the CO2 in the natural cycle is that human emissions contribute about five per cent. As the variation in the natural CO2 cycle is 10% the human emissions have no significance. They form part of the natural cycle, and blend in with it.

The best comment which could be made on this article is that it has about the same relevance to science, as human emissions have to climate, namely, negligible.

You might be best to look for a new field of endeavour, Andrew. You will make no difference in the field of science.