I think that we can safely hold the premise that since the beginning of the Industrial Revolution that more CO2 has gone into the atmosphere. Combined with deforestation, and bulk use of fossil fuels we can expect that there has been change in the earth's atmosphere.

There were probably nah sayers in relation to man's impact on the ozone layer by relatively small amounts of CFCs. If there were nah sayers in relation to the ozone layer, they have been proven to be terribly wrong.

I read the supplied background notes in relation to Dr Glikson, and believe that arguments that he is a Climate Scientist; and so, has a vested interest, are meaningless statements. Dr Glikson would appear to be involved in quite a spectrum of related subject areas to make his opinion quite a weighty one.
Dr Glikson talks about time scales in relation to millions of years, not 700 hundred years or 10-12 years.

Although Andrew's statistics about the production of CO2 seem impressive, what he does not tell you is that they amount to 2 per cent or so of natural flows. That is, the human addition is tiny. No one disputes this.

But CO2 concentrations in the atmosphere have been going up. Quite right, so to make the 2 per cent flow account for that increase, scientists have pushed and shoved the computer models to point of claiming that about half the human increase disappears somewhere (the mystery sink we hear about) and the rest hangs around in the atmosphere for decades.

Sounds bizaare but its the only way to make the 2 per cent figure match the increases we can see.

A distinquished academic in Norway, a Tom Segalstad, has been telling anyone who would listen for years that before the global warming story took hold, the time CO2 hung around in the atmosphere had been measured (by tracking fall out in the atmosphere among other methods) at 5-7 years. From memory he can point to more than 30 refereed papers confirming this - all published before the global warming crowd came to town.

I have been unable to find any refutation, or even mention, of this material in the global warming literature. Perhaps Andrew would care to step up to the plate, and point out where the problem is in the refereed literature?

With unusual lucidity for a scientist Dr Glikson provides a compelling warning of the risks associated with a business as usual approach to continued emission of CO2. In so doing he invites attention not only to rising atmospheric CO2 concentration but, importantly, the affect of all greenhouse gases (CO2-e).

It has been argued that radiative forcing of greenhouse gases other than CO2 are negated by the effect of aerosol emissions and land use. This, it is argued, justifies placing emphasis on anthropomorphic CO2 emissions and action to limit it to no more than 450 ppm, in a bid to limit temperature increase to 2C by 2100.

The problem with this emphasis is that it ignores the effect of increased temperature on feebacks, particularly those causing further emission of greenhouse gases such as melting of clathrates and permafrost in polar regions.

This leads to under estimating the effects of rising CO2 on temperature and raises the questions: why is emphasis not placed on concentration of CO2-e and are we further along the road to catastrophic climates change than we think?

What Dr Glikson makes abundantly clear is that the speed with which we are polluting the atmosphere is unprecedented, uncontrolled and likely to result in unstoppable climate change threatening environment if not our ability to survive. A timely warning!

Adams, Maslin and Thomas in a 1999 publication in Progress in Geography postulate that there is a 100 000 year oscillation between glaciation and warmer periods. They suggest the cause is interaction between Northern Hemisphere ice sheets, ocean and atmosphere. One hypothesis is the oscillation acts independantly of any forcings, the other is that orbital oscillations may trigger initial warmings that lead to C02 increses and all the then feedbacks leading to more warmings until overflows disrupt the ocean conveyor which transfer warm water between different latitudes. When the conveyor switches off ice forms and the albedo effect leads to cooling and ice sheets reform. Alley has shown both warming and sudden cooling can occur in less than a decade. The question is are we in this type of global warming upswing, if so will changing human c02 emission change anything

Global warming causes more snow and cooling. So say the warmists when they are having problems explaining weather patterns. They also usually say that more CO2 causes ocean acidification. But now we have Andrew Glikson saying the opposite, quote ‘further release of CO2 from the oceans ..... warms the oceans and induces ocean acidification’. Wow!

Andrew doesn’t overuse the words ‘tipping points’ but they are a clear implication from the words he does use, in particular the implied extinction of plant and animal species due to increasing temperatures. What parts of the planet have the greatest biological diversity? The wet tropics of course, and that diversity decreases towards the poles. He implies that it was the cooling of the late Eocene that allowed the survival of large mammals and he is previously on record as talking about extinctions in the earlier,very warm PETM. But he doesn’t mention that three new families of mammals appeared during that brief, 170,000 year long period of high CO2 and high temperature and, that later periods of warming and cooling in the Eocene coincided with increasing and decreasing diversity respectively. Indeed research (R Erwin and others) concludes that over the last half billion years rates of evolutionary innovation and diversification are higher in high-energy climates than in low energy climates.

Another alleged dangerous tipping point is claimed to be the release of CO2 and methane from melting permafrost. But the area of permafrost at the end of the Pleistocene was much greater than the area of permafrost now. What were the effects of methane release when that melted? Summer melting of the Arctic sea ice is commonly touted as a tipping point. The latest research from the Max Planck institute published only last month concludes that that fear is unfounded. And what would an alarmist contribution be without quoting Jim Hanson /NASA/GISS and their prognostications for polar temperatures. No matter that NASA doesn’t have recording stations in that part of the world; and no matter that many previous rapid short term temperature fluctuations in polar regions are well-documented.

Ant, the ozone hole is growing again, & new research is suggesting that CFCs had nothing to do with it, in the first place.

WE really should insist that all these theories have to mature for at least a generation, say 50 years minimum, before we take them seriously.