Geoff Davies - actually the case for global warming is not based on physics at all but depends on an assumption - a big one. The direct warming effects of CO2 are quite limited - no-one disagrees with this - due to a saturation effect (has to do with the absorbtion bands in the gas). But the computer models say that the warming (maybe 0.6 degrees C for a doubling in concentrations) will feedback on the atmospheric system. Most importantly they assume that the relative humidity of the atmosphere will remain the same. RH means water vapour and to keep the same RH at higher temperatues means more water vapour, which is the major greenhouse gas - forget the rest - hence a lot more warming. There is some evidence that the assumption is wrong, but the climate modellers are no simply too committed to their models to admit the error..

It’s amazing that such a mishmash article is published in “on line opinion”. A capable person like James Fairbairn can’t lack the ability to investigate historical and current situation in a more holistic way instead of picking winning arguments. It can’t be due to stupidity or lack of understanding; it can only be a refusal to see things that would challenge his beliefs. On Line Opinion is degrading it self by publishing such nonsense. James hasn’t notice that when the planet was warming in the past the temperature rose first then carbon concentration followed, while the present situation is opposite, the carbon concentration in the atmosphere is leading and causing the temperature to go up. This is extremely dangerous and, James, you should try and understand this for the sake of today’s children

Tena - That's the first I've heard that "while the present situation is opposite, the carbon concentration in the atmosphere is leading and causing the temperature to go up", while I normally disregard link references as you can always find something you like or dislike on line - could you refer me to the source, (is there some proof, at last!), if possible, of this information?

Wonderful news .. we have some factual evidence at last, thanks Tena.

You say it's very dangerous - why is that? Do you think we can't stand an increase in temperature, like people on the tropics live with?

Do you think say Hobart will be unendurable if temperature goes up a little in winter? Or summer?

Are you worried because humans have never endured temperature changes before?

I accept the climate changes, but do not accept its dangerous, because we'll adapt, as we always have.

Geoff - what physics are you citing? The Sun is an energy source that constitutes 99.86% of our solar system's mass, and which is almost entirely the reason we have life on this planet. It gives us our seasons and is the driving force of climate and the weather system. The solar cycle has an enormous and direct impact on Earth's temperatures (A prolonged period of minimal solar activity in the 17th century caused Europe's little ice age) and yet AGW-philes refuse to count this as significant, instead putting the blame on a gas that amounts to less than 0.04 percent of our atmosphere while water vapour (the REAL greenhouse gas) is almost 10 times greater in volume and is responsible for up to 90% of the greenhouse effect we thankfully experience. Is that enough 'physics' for you?

Tena - are you familiar with the relationship between cause and effect? If, in the past, global temperatures rose and CAUSED the C02 to increase, what has happened for the CO2 to be now the CAUSE of rising temperatures? If you can back up your claim, it is simply proof that correlation can be misinterpreted as being CAUSE rather than EFFECT. Unfortunately you can't have it both ways without a damn good explanation!

Collin, you are correct, Solar cycles (and sun spots, and cosmic rays, and magnetic flux, and volcanoes, and Earth's tilt, etc, etc) do play a role (suggest you distinguish between weather and climate though).

But when you say;

"A prolonged period of minimal solar activity in the 17th century caused Europe's little ice age"

then, you've lost me.

Europe's little ice age caused by minimal solar activity - sheesh!

If you want to pretend to be a "climate scientist", I suggest you refrain from parroting 'denialosphere' white-noise and complete an appropriate course at university, starting with (but not limited to) the radiative transfer properties of ALL the GHG's, including water vapour.

Oh, you are obviously not familiar with climate dynamics either. High CO2 levels can precede global warming AND stem from global warming, depending on the drivers.

Q&A - one thing I can do very well, regardless of my level of scientific knowledge, is research and read.

I did distinguish between climate and weather - I mentioned them both in the same sentence. Did you want more detail to show I knew the difference? They are different, but inarguably inextricably inseparable. We cannot have one without the other.

As for the linkage between the Maunder Minimum and "little ice age", while it cannot be proven (as with any hypothesis, it can only be disproved - same as AGW) it, nonetheless a solid hypothesis (or theory, depending on one's perspective). How else do you explain the little ice age?

Was I pretending to be a climate scientist? Are you? Who are you, anyway? does it matter? lol

FYI your statement "High CO2 levels can precede global warming AND stem from global warming, depending on the drivers." is incorrect.

it should read: "High CO2 levels can precede global warming AND <follow> global warming, depending on the drivers."

Therein lies the heart of the debate ... knowing the difference between cause and effect. As it stands, we do not know! We merely have a hypothesis (or theory) that is yet to be disproved.