Geoff Davies,"Three million yrs ago,when the earth was 2-3c hotter,sea levels were 15-35m higher."During this period CO2 levels were roughly 300 ppm[Much the same as today].Well during the Ordivician period of 450 million yrs ago CO2 levels were 4500ppm and average world temps were the same as today of deg 12C average.During the Cambrian period CO2 levels reached 7000ppm and average temps deg 22C.Jurassic period CO2 2900ppm and average temps deg 20C.Carboniferpous period,300ppm CO2 and average temps 12C.Where is the consistancy?

C02 levels do not proportionately reflect the median rise in world temps.Therefore there must be other more salient influences,outside of your CO2 scenarios,which affect median global temperatures.Please explain.

Funny how the onus is now on the skeptics to prove GW is crap when no true scientific evidence exists for it happening. Sounds like the evolution debate all over again, When people quote what the temperature was millions of years ago it shows how desperate the scaremongers are to brainwash the gullible. Seems like they have succeeded when reading many of the alarmist posts.

It would be impertinently impetuous and stupid for a layperson like me to argue with an expert in the field as professor DavieS is. I'm however a sceptic. It might well be scientifically true that human “greenhouse emissions are the cause of the present warming”. But in my opinion the real scientific question is whether these negative HUMAN actions can TRUMP the positive NATURAL FORCES of the Universe that determine the intra and inter relations of the planets and the sun in their state of equilibrium. It’s this AXIOMATIC QUESTION that the supporters of climate change, like Davies, must answer first.

There has been ample evidence that in Roman and medieval times the earth was warmer. Davies himself admits that there have been “fluctuations in the amount of heat received from the sun (due to the slow gyrations of the earth in its orbit around the sun”). It seems however that natural forces triggered their own stabilizers of cooling periods and the earth once again found its viable natural balance and was not threatened with extinction. Further, Nigel Lawson, the former editor of the Spectator and Chancellor of the Exchequer, poses the up till now unassailable question that has not been answered by the climate “gloomies”.: “Is it really plausible that there is an ideal average world temperature…from which a small departure in either direction would spell disaster?” I rest on the oars of my skepticism.

http://avant-gardestrategies.typepad.com

I think GY in his earlier article described Don Aitken as a GW 'agnostic' - I don't see an ardent denialist here just someone who questions and examines the presiding orthodoxy. Nothing wrong in that - if scientists/academics don't question and test theories they are not doing their jobs properly and we should all be worried.

Let's be honest - how are we to chart our way through the various conflicting scientific opinions and material available on this issue. Most agree GW is apon us, there is disagreement on the part humans have played. Actually let's be more honest, even the scientists cannot agree. Science is evidence-based but data can be interpreted in many ways which suggests that the data is inconclusive and drawn from many sources.

Even a non-scientist can see that man does indeed have a detrimental impact on his environment largely due to an almost religious adherence to an archaic and defunct enconomic system. I have yet to see many scientists argue against sustainability as a desirable and worthy objective.

This is probably where we should aim our efforts. The spin off will be postive regardless of whether future scientific 'evidence' conclusively confirms AGW over natural GW.

The other issue is how do we plan for GW (AGW or otherwise)? The future is how we prepare and plan for climate change - rising sea levels, displacement of large numbers of people, drastic changes in climate etal. These are the issues that should consume us rather than the never ending debate over who is right or wrong about AGW.

Dear RenegadeScience,

The effect of immigration to Australia on the global environment problem is simple.

The overwhelming proportion of the immigrants who come here do so to increase their standard of living. In doing so they will pollute more and generate more global warming gases than they would have done if they had remained in their original countries. Like most posters, I would like to see all the world live at our standard, but this is physically impossible, as the resources do not exist, and if they did, the pollution would be unbelievable. The most practical thing to do for those who are obsessed with closing the gap in living standards between the first and third worlds is to advocate a reduction in our living standard, and you would know how such advocacy would be received. I wouldn't worry too much, because I am sure that peak oil will do the job here in short order. Unfortunately it will cause a corresponding or even larger reduction elsewhere, so the gap will only increase. Nothing will be done to contain to contain the explosion in third world population, which will eventually have to be dealt with by the usual four horsemen.

There is no observational evidence for carbon emissions causing alarmist global warming. AGW is just a mind virus that operates as a literal top down mindset that would blind any effort to find anything. .... i.e. it is mind over matter rather than the much more demanding mind out of matter.

One of my concerns about AGW information, relates to the obvious promotion of `scientism', which is a belief held by many scientists that knowledge not acquired by professional scientists is knowledge not worth having. i.e. "Scientism is an affront to free people everywhere as it denies the right of the public to judge the work of science, even where this work is funded from taxpayer's money. It is a formula that holds scientists above criticism, and unaccountable to anyone but their own peers. It is an anti-democratic view of the world ....."

My other chief concern relates to the role of the media when it comes to examining science. The ABC, our national broadcaster, has proven itself to be truly disgraceful when they see themselves as a powerful priest class. Isn't this how thought police operate or is it simply inflated, cheap, self serving, bias? The media need to understand that there is nothing wrong with passionate debate but ongoing DEBATE is what there needs to be.