I, for one, don't agree that the Gore film is based on sound science. The underlying (but unsaid) premise behind the Gore story of the last two decades or so, is that ours is a self-contained climate and an autonomous Earth - travelling in an empty Universe. Hence, any bad climatic outcome he identifies MUST be our fault (starting with the 1988 heatwave/drought around Washington DC) . I can't proffer up a sworn statement from Sun or planets, of course, but there is abundant correlatory evidence that the major driver of climate at relevant time scales is inertial and electromagnetic - and of external origin. (I am not here referring to IPCC's "straw man" of total solar irradiance. TSI only varies by fractions of a percent.) Mr Gore is doubtless sincere in his belief in the benign and stable climate of a pre-industrial Arcadia - and we can get it back if we 'do the right thing/ about fossil fuels. I think he is mistaken.

Good on you - Fosbog - but I don't think that you're going to convince anyone, in the face of Gore's finely organised film, and the support it gets from scientists. Also there's the Intergovernmental Panel on Climate Change - hardly a bunch of radicals - in fact it represents quite conservative views of scientists of many governments.

My only argument with Brian Bahnisch is that he's advising us to do the "decent and moral thing ... and decease forthwith..."
I'm not ready to give up yet in the effort to act against climate change. I reckon he means "desist"

As far as I'm concerned people like Fosbog and journos like the ABC's Michael Duffy, who are into denying human agency, are either ostriches or in the pay of oil/coal companies like ExxonMobil, which is spending millions on groups and pseudo-scientists to act as mouthpieces in challenging the scientific consensus, and trying to confuse the rest of us(see the Guardian Weekly, 29th Sept., for details). Hopefully these people may one day go on trial for crimes against humanity.

I don't agree Kang,

Ice-Cores are at best dubious. For one, it assumes a continuous buildup of ice over large time frames. This means that ice is added and ever growing. Taking this further, it must be agreed that at a time there was no ice at all.

What we do know (scientifically) is that the biosphere changes. Even in recorded history the fertile middle-east regions and the north African coast have become less hospitable to crops preferred by human. Northern England and Scotland were heavily were heavily forested 8000 years ago. Ice Ages have come and gone, as well as exteded heated periods. Evolotution of species depends upon periodic change.

Simply stating that "I don't remember it being this hot in October" isn't scientific. Much of the debate on climate change revolves around perceptions and emotions.

The Carbon argument is similar to the ice argument except reversed. In order to lay down carbon deposits in the form of oil or coal, there must have been a time where the carbon was in the biosphere in greater abundance than is the case now. More Carbon equals more life. Less Carbon is less life (as seen through periodic Ice Ages). Excess Carbon, however, is absorbed by oceans or creates the famous Green House Blanket.

Are humans responsible? Probably Not.

Do humans contribute to a naturally occuring cycle? Perhaps.

The best thing about Gore's film is that it will help Australia work through denial and get onto solutions.

Scientific denial has all but evaporated. Most citizens are smart enough to read the obvious. Some political denial is still there, being held in place by coal interests (in the main) but is on very shaky ground.

Most Australian people and institutions have shifted, or are shifting, to solutions. Even some big corporations.

We should not let vested interests and a handful of perverse sceptics cloud public perception using quasi-science to distort the truth. Just listen to the seerious professionals and let's get on with doing what we need to do.

Much scepticism is based on a misplaced fear that we have to go back to the dark ages. Nothing could be further from the truth. We can live comfortably on about a quarter of our present (wasteful) energy consumption.

Smart new technology will help also, but it's mainly a change of mindset that is called for.

Nothing to fear, guys. In fact, future society stands to be much more healthy and enjoyable. I'm looking forward to it.

Fosbob, Narcissist and Gecko sound like the 3 wise monkeys. No doubt in earlier times you would have been the panel disputing plate tectonics. Earlier still perhaps the denialists of evolution or a round earth.

Anybody over 30 years of age who hasn't noticed the strange weather conditions we've experienced in recent years and the shortening of winters obviously hasn't left their house. Gore said himself that the correlation between CO2 and temperature was complex. I myself believe that the earths complex ecosystem is failing at a snowballing rate. The damage we are doing to the environment is being accelerated by factors our scientists still don't fully understand.

All of the predictions related to Global Warming are appearing far ahead of estimates. This means that the point of no return and the transformation of this world into a burning greenhouse hell not unlike Venus will soon be upon us if we don't get serious about elimiating fossil fuel usage. On Venus where rivers of lead wind through dead valleys the atmospheric pressure alone would crush a man to death. This is our sister planet. A sulphurous dead planet in every other way identical to our World.

The ice caps are melting and the Greenland ice sheet is cracking up. It's time we woke up and forced politicians to stop pandering to the rich fat cat oil barons and instead listen to the scientists.

While pro-growth interests dominate all major political parties the threat of climate change will be ignored. What government would stop the doze and develop vandalism of bushland or productive farmland for reasons other than to give their own interests a commercial advantage? What government would stop low lying development threatened by sea level rise when it is so profitable? What government would consider cutting immigration or the baby bonus when this would only stop the house price spiral and the huge stresses on water supply and other infrastructure?

The alleged scaremongering and misrepresentation by Al Gore on climate change does not even approach the “Australia is doomed without huge population growth.” scaremongering and misrepresentation from pro-growth interests.

So Gore's movie gets scientific support? I would have expected big Al
got the support before he made the movie.It's all a propaganda war with impartial analysis long forgotten.Funding can best be raised by headlines,and headlines best generated by extreme/scary pickings from selectively winnowed statistics and poor analogies.
The average Arctic temperatures on record for the 1930s were higher than 2005/06 but we are shuffling a stacked deck of stats going back only 27 years probably to make sure the alarmists get their ammunition.

Other say that the movie is Misleading, Exagerrated Speculative and Wrong.

Have a look at http://www.cei.org , and the On Point piece. Even if this document is also only half right it sort of pulls the rug from under the Goreaphiles.

After all Gore has has other fish to fry in promoting this, in the same way Mike Rann is seeking the President of the ALP job and therefore currying favour with the greenies by stumping up his AGW credentials.

The climate is still a chaotic system and with chaotic systems doing nothing has the same probability of an adverse outcome than doing something. For the CSIRO to say they can predict with some certainty what is going to happen in 50 years time is just nonsense.

But when they cant model either the effect clouds and the sun properly then it is a delusion bordering on fraud.

All I can say to those who maintain that nothing is wrong with global climate and no action is needed - be prepared to face up to the victims in years to come.

Be prepared to face the drought stricken farmers, the innundated Bangladeshis, hurricane-stricken victims in the tropics, those hundreds of thousands stricken with the spread of tropical diseases, Pacific peoples whose islands are submerged.

When you see grieving parents whose children have died from these causes, it is no longer possible to glibly assert the problem is not real.

Climate sceptics are like German people 50 years ago who subconsciously knew about the holocaust, but denied it was happening. The weren't strickly being ammoral, they were just in a state of chronic denial because the issue was too big for them to psychologically handle.

For those people who suffer (or will suffer) from climate change events, this issue is not an academic plaything, it is real stuff. Life and death stuff. The numbers of environmental refugees in the world are climbing on an annual basis.

Be prepared to look all these people fair and square in the eye and say there is no problem.

Gore has an unstated and very significant agenda item - he will be running for U.S. President in 2008 and he needs to change the American political agenda away from terrorists and security to environmental disaster. Gore's political party, the Democrats, are viewed as the party more likely to address environmental issues than the Republicans.

An Inconvenient Truth is a movie that everyone should see. This movie will have more influence than any other in history.

There is a book called 1001 movies you must see. This is the 1 movie you must see.

The presentation is first class. It is both straightforward and insightful. It captures the attention of those with little interest in science. It provides plenty of information for those who want the facts laid out. I thought I thoroughly knew this issue, and found there was much more I needed to know.

I encourage everyone to see this movie. I believe it is still playing in all major cinemas. You'll be very glad you did.

Sure go ahead and see it.Then follow it up with a read of the CEI On Point criticism of it. Then sure, draw your own conclusions.

Despite what people like Latimer say, there is another side that puts it in better perspective.

Does that mean that I deny that Co2 may be warming the atmoshpere No.
Do I believe that Co2 is the sole cause of current warming. No it isnt, and neither do the real scientists involved

"The average Arctic temperatures on record for the 1930s were higher than 2005/06"

With these words Carbonari demonstrates a frequently used ploy of sceptics: Realclimate soundly debunked this argument in December 2004 ( http://www.realclimate.org/index.php?p=22 ), yet this and many other debunked sceptic arguments get resurrected from their coffins like vampires in bad horror flicks.

Who cares if there are other contributing factors or not. Humanity is addingthe feather that breaks the camels back in that case. There are so many ways in which we can totally screw up this planet. Globaldimming could trigger an ice-age. The ice cap melt could suddenly escalate when it reaches a certain point as it seems to be doing now and our coastlines will disapear. Hurricanes could increase to the point where we are all living in bunkers during the storm season. The hole in the Ozone layer is now as large as it was in 2000 despite the reduction in CFC gases being released. Maybe this is a side effect of global warming we didn't foresee. The environment is delicate. It goes through all kinds of changes and ofcourse we can influence those changes. It's the butterfly effect. Every action has consequences.We can't dump billions of tons of CO2 and micro-particle nasties from coal burning waste then expect nothing to happen.

Most scientists worldwide now believe that 'we' are causing global warming.The rest are government yes men.

Quite aside for the science of climate change, I'm bothered by many things that have been said on this forum. Kang has suggested that climate change sceptics be tried for crimes against humanity and Gecko has compared them to Germans who sat on their hands in the face of the holocaust. From my experience, this kind of emotive nonsense isn't unsual from the hardcore left. Name calling isn't going to convince any sceptic of the reality of climate change; it only serves to dumb down the debate.

I haven't seen Al Gore's film so I am reluctant to criticise the substance of it. With respect to the climate change theory in general, there is one key issue I've yet to hear addressed. Numerous reputable sources have determined that the relationship between CO2 concentrations in the atmosphere and temperature is logarithmic. That is, each additional amount of CO2 added to the atmopshere has a smaller effect that than the previous addition. Given that C02 levels have already increased significantly, the effect of further increases in C02 levels will not be significant. As some other posters have pointed out, the unusual solar activity of recent decades would also have a significant effect upon global temperatures, some scientists determining that it has had a greater effect than the increase in CO2 levels. Reassuringly, there is evidence to suggest that this solar activity is decreasing and may in fact lead to global cooling in coming decades.

In short, the extent to which the earth's temperature is increasing has been overstated. The causal relationship between C02 levels and global temperature has been exaggerated. And the doom and gloom predictions are entirely unlikely to come to pass.

Fester, if Carbonari is cherry-picking, so is Gore. Ironically, the dramatic scene where he climbs up a graph of projected CO2 growth even involves a real-life cherry picker. One example - Gore claims that because of global warming the snows of Mount Kilimanjaro are melting. In fact, they've always melted, but would appear to be disappearing because of decreased precipitation, meaning less snow is replaced each year, but not because it has got any warmer in the vicinity. This process has been apparently going on for all of the 20th Century.

Gore also invents a few facts, such as Tuvalu and Kirribati sinking and causing the residents to migrate to New Zealand.

BTW, I checked out the Real Climate report. I'm not sure exactly what it's supposed to have "debunked". It confirms that Arctic temperatures were higher in the 30s than now, and suggests that this is to do with changes in wind direction, but now it is to do with carbon dioxide forcing. Perhaps, but the changes observed are still within natural variability as far as temperature goes, so where does that leave the dire predictions that Gore makes for the Arctic?

One should also bear in mind with Real Climate that it has been one of the strongest supporters of the Mann et al. "Hockey Stick" graph which purported to show, using some proxies, that things had never been hotter in the last 1,000 years than at the latter end of the 20th century. The graph has since been discredited as the result of faulty mathematics. The role of Real Climate in the controversy was also criticised. Mann, who came up with the "Hockey Stick" is one of the people behind Real Climate.

That's it! I am sick of people bashing the hockey stick! The hockey stick has NOT been discredited. Those who attempt to discredit the model (eg:McIntyre and McKitrick (2003)) do so along these lines: We fed random numbers into the computer program, and produced a resulting hockey stick graph.

However, these people do not understand the mathematical concpet of statistical regression analysis. Indeed as was reported by Rutherford et all (2004):

"It should be noted that some falsely reported putative errors in the Mann et al.(1998)
proxy data claimed by are an artifact of (b) their misunderstanding of the methodology used by Mann et al. (1998) to calculate PC series of proxy networks over progressively longer time intervals".

I'll try to make this simple. In Mann (1998), they selected a statistical quantity called a Principal Component. They help you tell if quantity is statistically relevant. For the hockey stick, they used PCs to summarise the data of North American tree rings (which give an indication of the temperature). The point of contention was that the PC's used for this data set "select" for the hockey stick shape. Hence the claim that random data makes a hockey stick.

This is not true. Bascially, MM(2003) reached their conclusion only after excluding a certain data set. This is not statisically correct. The critism of MM(2003) is not methodological, but about which data sets should have been included. Even so, the hockey stick has been independantly verified by many different authors. The yearly of decade temperatures predicted are not accurate, but the general trend is accepted, by the US goevernment of all skeptics

The science is far from complete. But the ignorance on this topic drives my to tears.

The cei report was discredited by a group of leading scientists last week:
http://environment.guardian.co.uk/climatechange/story/0,,1876538,00.html

and here is the background on CEI:
http://www.sourcewatch.org/index.php?title=CEI

It drives me to tears too ChrisC, whoever you are. Check out the results of the Wegman committee report before you go telling others how to get the yolk out of their mathematical eggs. You can download it from http://energycommerce.house.gov/108/home/07142006_Wegman_Report.pdf#search=%22wegman%20report%22. Wegman is from George Mason University and is as I understand it President of the American Statistical Association. You can find his biog here: http://www.galaxy.gmu.edu/stats/faculty/wegman.resume2.htm.

The Hockey stick is as shonky as Enron's accounts, and when in this case the auditor actually blows the whistle the fraudsters still carry-on as though nothing has happened. And just as with Enron people should have known the accounts were fraudulent from commonsense, so too with the Hockey Stick, because it purports to show that there was no Medieval Warm Period, nor a Little Ice Age, which we know from objective evidence, including human observation, to be incorrect.

And gusi, perhaps you could point to which parts of the CEI report have been discredited, or are you saying that everything that the CEI author says from the moment he gets up in the morning until the moment he goes to bed is wrong?

Has anyone tried going along to an old-persons home and asking the residents what the weather was like when they were young? I come from a family of long livers, and so consquently have had the chance to talk to people who grew up in the late 1800's. We've had extreme weather conditions forever and a day. Storms, droughts (the Murray stopped flowing back in the early 1900's), hail, floods. The main difference now - plenty of mass-media coverage. Is global warming happening - perhaps. Should we try to curb excessive use of resources - of course. Should we panic - cant see the point.

Have you noticed that when a record weather event occurs it is always never the worst in history. Funny that - goes to show we are still not experiencing the most extreme conditions, even within recorded history. Eg it might be getting warmer in October this year, but go back merely to 2000 and we had heavy coats on for new years eve - IT WAS FREEZING! The drought we are having in Australia now - the worst in 100 years. That means 100 years ago we had a worse one. Was that caused by climate change too? Or simply natural weather patterns.

You know... in all this debate, it occurs to me that nobody is questioning the fact that this warming is taking place, the central arguments relate to whether it has been influenced by people, and whether reducing carbon emissions can do any good.

Putting the blame game aside, perhaps we should be doing more to prepare? I know that there is the push to reduce carbon emissions, but can't we treat that as a separate treatment, and in the meantime, start shoring up coastal towns, and start doing whatever we can to protect areas that are the likeliest to experience adverse weather changes? If we're agreed that this is at least happening, regardless of cause, then shouldn't we perhaps at least agree we should be doing something?

GrahamY, the Wegman paper is not without its critics, as you will see here http://www.realclimate.org/index.php/archives/2006/07/the-missing-piece-at-the-wegman-hearing/#more-328

We could go on endlessly debating the merits of the science, but increasingly there's not much to debate. Climate change skeptics are increasingly shrill, for example Wegman says that "authors in the area of paleoclimate studies are closely connected and thus ‘independent studies’ may not be as independent as they might appear on the surface." This is typical of the sort of cheap shot you use when you don't have any evidence. I'd be surprised if all paleoclimatologists weren't "closely connected", this is the way science works.

Arctic ice is decreasing, glaciers and snowfields are retreating worldwide. Antarctica remains a great unknown, but global climate change is real.

WAKE UP !!

The real points are:

Is humanity responsible for climate change? Don't know.

Does it matter if humanity is responsible for climate change? No.

Is there climate change? Possibly in the next 2 - 3 lifetimes.

If so, should we do something about it? Only if we want our grandchildren to survive.

Is there anything else we should be concerned about? Err... yes.
1. Uncontrolled wasting of resources by a capitalist system that is unsustainable ! (What happens when the oil/gas/coal runs out?)
2. Pollution of the planet on an unprecendented scale as a result of item 1.
3. Deteroiration & destruction planet's ecosystems (and all species) as a result of items 1 & 2.

How's that for starters ??

GrahamY

If the realclimate article wasn't clear enough then try this report on Arctic climate over the past century: ( http://www.nersc.no/AICSEX/rep218.pdf ). The authors show Arctic warming of the 1930s confined to a small area and probably due to natural variability, whereas warming at the end of the century was widespread and unlikely to be due to natural variability. To give an analogy, it is like arguing that average sea levels are lower today because they were higher at one location twenty years ago. To show trends above local and short term variability requires widespread measurements over a long time.

As for doubting that Tuvalu an Kiribati are threatened by rising sea levels, you might wonder why the doubts are not more vigorously pursued by sceptics. Sea encroachment in Tuvalu is made worse by population growth, but this fact is largely ignored by the sceptics: Showing that population growth can be environmentally destructive hardly serves the interests of growth proponents. The sea level data however is clear ( http://www.bom.gov.au/fwo/IDO60101/IDO60101.200608.pdf ), the trend since the early 1990s being an average rise of about 6 mm per year. As an aside, if you look at the sea level graph on page 25 of the report you will note that the rising trend is small compared to the amplitude of the natural oscillations, leaving the data ripe for cherry picking sceptics, though the longer a trend continues the harder it becomes to find cherries.

Further to Johnj's comment, here is a Scientific American article which supports Mann's study and claims that the conclusions were the same when Wegman's criticisms were addressed ( http://www.sciam.com/article.cfm?chanID=sa006&articleID=000D5C47-C124-1509-805C83414B7FFDB0 ). The article also commented that the National Research Council of the National Academy of Sciences conducted an independent review and revision of Mann's study and came to the same conclusions.

Unfortunately, scepticism of global warming seems to be mutating to a politically driven process of public deception by recycling debunked arguments and iron curtain style attempts to suppress the freedom of scientists to report their findings.

I can't believe there is even a discussion here on whether global warming is "real" or not. Denialists are so dumb they don't even know why they are denialists. If they were all taking money from ExonMobil, I'd have more respect for them. Instead, they function from a sedimented, wholly-ideological refusal to look critically upon the way we live our lives and cost of the enormous expansion of human activity upon the planet. Don't think. Don't be skeptical. Just go shopping.

Sorry it took me so long to get here, but I'm not a regular and hence had to sign up. Also I work outside during the day (in the weather!)

First, thanks to ChristinaMac for picking up the mistake in the text. I put it down to ageing synapses, but that doesn't excuse the two other people who read it prior to posting. It's fixed now.

Generally I am happier for people with a science background to deal with the doubters and denialists. Thankfully there are some here. Actually John Quiggin declared the debate over on 4 January this year (http://johnquiggin.com/index.php/archives/2006/01/04/the-end-of-the-global-warming-debate/) and I always believe what Quiggin says! I feel we spend a lot of time and energy on arguing the toss when there are urgent things to discuss.

I posted some additional comments (I was up against the word limit) over at my usual patch at Larvatus Prodeo (http://larvatusprodeo.net/2006/10/05/facing-the-knowns-and-unknowns-of-climate-change/). You're welcome to comment there.

I'll have to leave it there tonight. I hope to come back tomorrow night, if they don't close these things off.

The globe is warming by 0.17 degrees Celsius/decade. I have heard James Hansen talk about a global temperature increase of 2 degree Celsius by 2050. Utterly impossible – the measured trend of temperature increase over the past twenty five years simply cannot support such a conjecture. Do the math yourself.

Sea level has risen by 2-3mm per year for the past 150 years and shows no signs of accelerating. Again, do the math yourself. Multiply by 100 – double it for uncertainty – and you get 600mm or 2 ft sea level rise over this century. This is pretty much consistent with the
IPCC.

James Hansen attributes some of the recent global warming to solar influences. Another influence is the Pacific Decadal Oscillation (PDO) – multi decadal patterns of persistent El Nino (warm phase) or La Nina (cool phase) conditions.

It is true that Arctic temperatures in the 30’s and 40’s were as high as today. Real Climate dismisses this by saying that a trend cannot be determined on the basis of the limited data set. Real Climate ignores the tree ring and ice core data tracing the cycle back for 400 years.

Al Gore is a liar. He says that 2005 was the warmest year on record. The highest temperature on record is 1998 according to NASA sources. The simple truth is that the global temperature trend is declining as would reasonably be anticipated in a cool phase of the PDO.

I am a scientist – I argue that the measured scientific data should be at the centre of the scientific debate rather than marginalised by imaginative climate scenarios.

A cool phase of the PDO brings with it a persistent La Nina pattern over several decades. This means that Australia will have warmer winters, many more storms and cyclones and much more summer rainfall over the next few decades. In the context of our horrendous and long lasting drought – this is a brave but testable hypothesis.

Sorry Indigo, but I'm confused.

I scratched around on the NASA website, and only found one reference to 1998 being the hottest year on record:
http://eospso.gsfc.nasa.gov/eos_observ/1_2_99/p38.html
This post was made in 1999, so obviously they did not have temperature data for 6 years in the future. It does say however, that the 90's were the hottest decade on record.

I did however find a NASA webpage that labeled 2005 as:
"The year 2005 was likely the hottest year in more than a century. According to a study by the NASA Goddard Institute for Space Studies (GISS) examining temperatures around the world, 2005 was either the warmest or tied for the warmest ever recorded. According to the GISS team, global warming is now 0.6°C (about 1°F) over the past 30 years, and 0.8°C (about 1.4°F) over the past 100 years."

http://visibleearth.nasa.gov/view_rec.php?id=17438

I'm sorry, but your claim that NASA has rebuked Al Gore seems spurious. Perhaps I'm missing something here? Perhaps, as a scientist, you should know to quote sources when providing raw data (or citing it). Could you possibly source your claims please?

I will ask similar question of you on your claims about the arctic temperatures. Such claims seem at odds with the direct measurements of:
http://arctic.atmos.uiuc.edu/

Regarding your claims about sea level change. I'm an engineer and a mathematician. My friend and I sat down and did some maths, and attempted to estimate the sea level rise if the Greenland (2.85 million km3) ice cap melted using data off wikipedia. We used a thin shell approximation. Our answer was in the ball park of the accepted answer of 7.2m sea level rise. I fail to see how your criticsim of a constant sea level rise would hold, since the loss of the the Greenland ice cap is accelerating. In 1996, Greenland lost about 96km3 , in 2006, this was estimated at 239km3. See (once again from NASA)
http://www.jpl.nasa.gov/news/news-print.cfm?release=2006-023

Sorry to doubt the claims of a fellow scientist, but they don't seem to stack up, and you haven't provided imperical evidence

I did a quick check via google and came to the same conclusion ChrisC. According to NASA http://www.nasa.gov/vision/earth/environment/2005_warmest.html the hottest years since the 1890s are (in order) 2005, 1998, 2002, 2003 and 2004. I'm not a scientist, but that looks like a warming trend to me....

I'm a little dubious about the Greenland ice cap. According to this article http://www.newscientist.com/article.ns?id=dn4864 it could take 1000 years for the ice cap to melt, but once started the process may be irreversible. Confirms a rise of 7 metres, but gives us plenty of warning on a sea-level rise.

Johnj

You comment about the Greenland ice sheet taking 1000 years to melt. Estimates like that are based on computer simulations. Sceptics are usually quite critical of computer modelling, but all the sceptics commenting on ice sheets accept without question the accuracy computer models in this application. This is surprising, because computer models predicting increased polar snowfall and 1000 year melt times for ice sheets dont seem to match the observations.

http://www.commondreams.org/views06/0217-22.htm

http://www.livescience.com/environment/060810_antarctic_precip.html

There is an extraordinary amount of cherry-picking and outright misrepresentation and misdirection coming from all sides on this debate. The question isn't whether CO2 has an effect on global temperatures, but to what extent, and what should be done about it. People are labelled "skeptics" or "denialists" merely for questioning figures and projections. These terms have no useful meaning, unless you believe in the completely non-scientific idea that we ought to just embrace the IPCC projections, or at least those IPCC projections that a particular lobby wants us to accept.

To deal with a couple of points raised above. Fester claims that the paper he cites shows that the Arctic warming of the 30s was limited to a "small area". Wrong. It says that it occurred above latitutde 60 degrees. The study he cites, while acknowledging difficulties with early century temperature measurements, draws on Eurasian based thermometers to say that the heat extended further down in the 90s, than in the 30s. This hardly negates Carbonari's point.

Fester also cites a BOM report to prove that Tuvalua and Kiribati are sinking below the oceans. The Gore claim was that the islanders had been forced to evacuate to New Zealand, and is completely false. Sea level is rising in the area, but how much due to global warming is conjecture. Kiribati is experiencing sea level increases of 6 mm per year, but Fiji only 2.7 mm. Obviously there's fair bit of movement in the earth's crust around this area.

As for support for Mann et al. The links provided by Fester hardly amount to a ringing endorsement. They say that the NRC finds the Mann et al results "plausible". They don't appear to rebut the fact that the algorithms Mann used result in it graphing even random numbers as a hockey stick. And they contradict the scientific consensus of the Medieval warm period, as well as the Little Ice Age.

I find the criticism of Wegman for not being a climate scientist whimsical, particularly when someone can quote John Quiggin as an expert, when he's not even a scientist at all!

A worthwhile perspective on the scientific debate on climate change can be found here. http://sciencepolicy.colorado.edu/prometheus/archives/climate_change/000641reflections_on_the_c.html

"Interestingly enough, the response from Steve McIntyre is completely in agreement with RealClimate contributors Stefan Rahmsdorf and William Connelley that the "hockey stick" debate is pretty much irrelevant to the scientific question of whether or not greenhouse gases will affect the future climate."

So can we all please forget about the "hockey stick" and get on with the policy changes that are needed.

GrahamY, I was being tongue in cheek when I said I always accept what Quiggin says, although I find he's more often right than wrong. I don't characterise him either as a scientist or a non-scientist. It depends on how you regard economics as a field. I would say, however, that he has an impressive grasp of mathematics.

Also a distinction could be made between 'denialists' and 'sceptics' about AGW. One can be either or both as long as one supports one’s position.

Fashion is not the right word, but I'm also aware that certain paradigms can be firmly established only to be overturned later. Hansen has been to the fore in warning about ice-sheet melting and sea-level rise, departing from IPCC 1. He keeps saying that he hopes he is wrong. We should too, but he's also passionate about following the science. For example, in 1989 he refused to give Gore images of increased drought generated by their computer models because he didn't at that time sufficiently trust the model's estimate of precipitation.

There were one or two things that I thought Gore may have gotten wrong in the film, Pacific Islanders having to flee to New Zealand being one of them, but to dwell on them in the review would have been picky and given the wrong impression.

I can't see why indigo considered it appropriate to brand Gore a 'liar', even if he had been wrong about 2005 being the hottest year. It would have been more scientific to consider other explanations, like being incorrectly informed. To be honest an unjustified accusation like that reflects on the reliability of the author and the ability to respond to evidence in an unemotional way. Nevertheless indigo did raise some issues which I hope to comment about in due course.

Forget about the "Hockey Stick"? What you should realise Johnj is that the "Medieval Warm Period", the "Little Ice Age" and attacking the "Hockey Stick" form a Holy Trinity for denialists. Do a search and you will realise that almost every denialist website is on a quest to "prove" the first two to be global events and the third to be a fraud. It is sad to see what probably started as scepticism degenerate into a quasi-religious fanaticism.

Ultimately, observations are all that matter. What you want things to be is irrelevant.

Indigo mentioned that Hansen had spoken of 2C temperature increase by 2050. I’m not sure whether that is so. I understood his expectation was for 3C by 2100 on a ‘business as usual’ basis. This is based on the forcing implied in doubling CO2 which is estimated to be 4 watts/m2. He sees the equilibrium sea level response to 3C as 25 metres (80 feet), plus or minus 10 metres. This will not happen by 2100, but he sees it as happening in centuries rather than millennia, reminding us that the about 14,000 years ago sea levels rose 20m in 400 years, or 5m per century.

He outlines his reasoning in the editorial essay in <i>Climate Change</i> last year (http://www.columbia.edu/~jeh1/hansen_slippery.pdf).

How much warming should be considered ‘dangerous’ in part subjective. Many scientists seem to think 2C will be OK. Hansen and his associates would like to see it limited to 1C. As I understand it this would mean slamming on the brakes rapidly because 1C is almost certain in the next 50 years from forcings already in the system.

Their reasoning may be found in a 2005 paper. Go to the abstract at http://pubs.giss.nasa.gov/abstracts/submitted/Hansen_etal_1.html and download the large pdf file from there.

I suspect that 2C would not be impossible when you consider, as Flannery tells us, that China and India are building 1400 coal-powered power stations in the 2000-3030 period. That’s one every 8 days. Hansen says that we should be building no conventional coal power stations after 2012 in the developed countries and after 2022 in the developing countries. He’s assuming that geosequestration of CO2 will work. From 2025 we should be bull-dozing conventional coal-fired power stations.

If you have good downloading facilities (ie broadband) I’d recommend the slides for his National Academy of Sciences lecture:

http://www.columbia.edu/~jeh1/nas_24april2006.pdf

It has some wonderful maps showing the implications of sea-level rises in some of the main population centres. I’d also recommend the following slide of climate forcings (a variant of one of the 50 slides in the NAS lecture):

http://www.realclimate.org/images/forcing_1750-2000-toppanel.jpg

When I wrote "that China and India are building 1400 coal-powered power stations in the 2000-3030 period" there was a typo, and now I've waited my 22 hours I can correct it. It should have read 2000-2030 of course.

Brian, you've touched on the really important issue here - it doesn't matter what people like Gore spruik about global warming, CO2 is going to continue to be pumped into the atmosphere because the rest of the world, not unreasonably, wants a standard of living like our own.

So for me the proper question is not "how do we stop it", but "how do we live with it." And further - what is the best application of the resources (including time and money) that we have now.

You need to manage the situation while leveraging your current position to introduce workable strategies. Kyoto isn't a solution. It was ad hoc and was never going to achieve anything, ignoring the future CO2 emitters. Some form of carbon tax, which replaced other indirect taxes, could work well in countries like Australia, without constraining economic growth, although there would be potential substitution issues with imports of energy intensive products from overseas countries.

GrahamY, the importance of Kyoto, in my view, was not in what it could achieve in reducing CO2, but what it represented as process of international cooperation. Paul Monk, who was one of the first who got me reading about climate change when this article (http://www.austhink.org/monk/global_cooling.htm) was published in the AFR a few years ago under the title 'Cold comfort for the clever creature' saw the challenge presented by climate change as developing new ways of thinking.

Looking back, he was probably too concerned about cooling rather than warming, and too focused on single cataclysmic events causing abrupt climate change rather than the interactive effects of lesser events to do with ice melting in the Arctic, melting in Greenland, bits falling off the Antarctic peninsula, methane burps in Siberia, drying and burning of the Amazon rainforest, melting of glaciers in the Swiss Alps and the eastern section of the Himalayas, increased severity of cyclones/hurricanes/typhoons and unusual weather events all around the world. (I disagree with Country Gal further up the thread. New weather records are being set, at an unusual rate, I’m told.) Each of them a worry, but an even bigger worry within the total earth system, making it difficult to identify a single tipping point.

But most of all Monk, I felt at the time, missed the point that we are going to have to find new ways of relating to each other, a level of international cooperation that goes far beyond anything we’ve achieved.

Yesterday we heard about a new report on the effects of sea-level rise in the Pacific (http://www.news.com.au/story/0,23599,20548131-2,00.html). The report suggests that the sea might rise by 50cm by 2070 and points out that with a metre rise a 2002 calculation would see 2.3 million climate refugees from south and South-East Asia. Apparently since 2001, ”citizens of Fiji, Tonga, Kiribati and Tuvalu have been able to enter New Zealand as environmental refugees displaced by climate change.” Tim Costello’s commentary is here:

http://www.news.com.au/couriermail/story/0,23739,20546197-27197,00.html

So maybe an apology is due to Al Gore who said something of the kind in his film.

GrahamY

What was carbonari's point re Arctic temperatures in the 1930s? What is the significance of comparing warming of a small part of the globe with the global warming since the 1990s? Is this part of the misrepresentation of facts by denialists with the purpose of misleading the general public and slandering climate scientists?

Scepticism is an essential part of science, but there is nothing sceptical about making a misleading comparison of Arctic warming of the 1930s and the global warming of today.

Brian, there is no apology due to Gore - he said something that was straight-out incorrect, which he should have known was incorrect, and that's about as close to a lie as you can get without actually telling one.

What you've done with sea levels is cherry-pick the first study that comes along. The IPCC doesn't predict 50 cm by 2070, so what makes you think this new study is any better than the studies that disagree with the IPCC on the downside? Confirmation bias runs riot in this debate.

And Fester, I see you've now shifted your accusation beyond the scope of the study that you cited. It didn't say the 1930s Arctic warming was a "small part of the globe", it said it affected everything over latitutde 60. Check out a globe - that's a huge area. What it said was that the 90s warming came further down into Eurasia. But that doesn't mean that the whole world has warmed by anything near as much as the Arctic. In fact, the Antarctic has got colder.

All of which leads me to wonder why some of the commentators on this thread have such a desire to believe in catostrophic global warming and dismiss, in the case of Fester in fairly vitriolic terms (I'm apparently a "slanderer"), any reasonable criticism.

The Arctic is not a huge area. It is less than 7% of the area of the Earth's surface.

GrahanY, what exactly did Gore say that was incorrect? I saw the film twice and the second time I took some notes because people had claimed that he was wrong. In all the points I checked it turned out that they were wrong, ie. that they had incorrectly quoted him.

I thought a few of his statements were a bit misleading, but I can't say that it was his intention to mislead.

On sea level rise, the article I linked to was a news story about a report entitled "Australia Responds: Helping Our Neighbours Fight Climate Change" prepared by the CSIRO for a roundtable of NGOs. Distribution is the responsibility of the roundtable and I have not been able to find it, or even where it is available.

I doubt whether it would have any original research in it about sea levels. The security analysis done by Alan Dupont and Graeme Pearman "Heating up the Planet: Climate Change and Security" (http://www.lowyinstitute.org/Publication.asp?pid=391) gives the range as 15cm to 95cm by 2100. The lower figure is an extrapolation of current rates from the last century. The higher figure is based on "plausible forecasts" and they give several citations.

I started to worry about sea level after reading this article by James Hansen (pdf):

http://pubs.giss.nasa.gov/docs/2003/2003_Hansen.pdf

The IPCC report assumed that Greenland and Antarctica would be pretty stable and that the sea would rise a bit from other glacial melting and thermal expansion. The NASA GISS mob started to worry about the effect of moulins (see page 8 of this paper - http://pubs.giss.nasa.gov/docs/2004/2004_Hansen1.pdf) in ice-sheet beak-down and other aspects that my brain is too tired to recall at the moment. No-one has observed a major ice-sheet decay and disintegrate. Hansen talks about the time scales in various places including here (pdf):

http://www.columbia.edu/~jeh1/hansen_slippery.pdf

It will be interesting what the next IPCC report says about it. I thought the Gore film explained very well the latest thinking on ice-sheet decay.

Recent information about Greenland from gravitational mass measurements seem to bear out the concerns. I posted about this at Larvatus Prodeo where you will find a some further links:

http://larvatusprodeo.net/2006/08/23/greenland-%e2%80%93-will-it-become-a-green-land/

There are some very interesting images in Hansen’s recent NAS lecture (large pdf):

http://www.columbia.edu/~jeh1/nas_24april2006.pdf

Antarctica is interesting because snow was meant to increase, taking water out of the sea. This hasn’t happened yet but possibly it is still to come which would slow down the rising waters, for a time at least.