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Scientists improve reliability of global warming projections

30 May, 2013

Australian scientists have narrowed the predicted range of global warming through groundbreaking new research.

Scientists from the University of Melbourne and Victoria University have generated what they say are more reliable projections of global warming estimates at 2100.

The paper, led by Dr Roger Bodman from Victoria University with Professors David Karoly and Peter Rayner from the University of Melbourne and published in Nature Climate Change, found exceeding 6 degrees warming was now unlikely while exceeding 2 degrees is very likely for business-as-usual emissions.

This was achieved through a new method combining observations of carbon dioxide and global temperature variations with simple climate model simulations to project future global warming.

Dr Bodman said while continuing to narrow the range even further was possible, significant uncertainty in warming predictions would always remain due to the complexity of climate change drivers.

"This study ultimately shows why waiting for certainty will fail as a strategy," he said.

"Some uncertainty will always remain, meaning that we need to manage the risks of warming with the knowledge we have."

The study found 63 per cent of uncertainty in projected warming was due to single sources – such as climate sensitivity, followed by future behaviour of the carbon cycle and the cooling effect of aerosols – while 37 per cent of uncertainty came from the combination of these sources.

"This means that if any single uncertainty is reduced – even the most important, climate sensitivity – significant uncertainty will remain," Dr Bodman said.

Professor Karoly said the study reinforced the importance of strong action on climate change.

"Our results reconfirm the need for urgent and substantial reductions in greenhouse gas emissions if the world is to avoid exceeding the global warming target of 2 degrees needed to minimise dangerous climate change," he said.

Dr Bodman is Postgraduate Research Fellow at Victoria University’s Centre for Strategic Economic Studies. Professor Karoly and Professor Rayner are from the University of Melbourne’s School of Earth Sciences and the ARC Centre of Excellence for Climate System Science.

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Bruce | Friday, May 31, 2013, 4:41 PM
These days it regularly snows in the mountains west of Sydney. This year for the first time we had snow at Barrington Tops west of Taree. Next year they say it might snow at Toowoomba. What's next Cairns? Darwin? Where's the global warming here folks? Our Climate is definitely getting colder!
Toscamaster | Friday, May 31, 2013, 7:10 PM
Anyone who believes any of David Karoly's prognostications on climate science needs to contact me. I have a beautiful block of land with a sea view located at Alice Springs to sell to you for a prime price.
Alan Swales | Saturday, June 1, 2013, 9:28 AM
I was an Automatic Control Designer. I understand that the level of CO2 in the atmosphere is what drives the "Photosynthesis" Natural Automatic Control process to convert CO2 to Oxygen. This "ERROR SIGNAL" has risen markedly because the forests have been decimated and it takes a larger error signal to get effective Oxygen Production from a smaller production plant.
Ken Goldsmith | Saturday, June 1, 2013, 9:39 PM
"Professor Karoly said the study reinforced the importance of strong action on climate change." Not to me, it don't! To me it shows these pr---s KNOW they don't have a clue! Their computer models don't even model the effects of water vapour, which is both much more prevalent and has a much higher green house potential (GHP) than CO2.
Geoff Thomas | Monday, June 3, 2013, 7:40 AM
In this summer just past, there were highest temperature records broken all over Australia, a good indication that climate change is probably happening, and with the snow reported above showing the increased variability in the climate as predicted. All the personal attacks on scientists and pretence that water vapour is not included is just denial. Each time new research finds more certainty we get the same old untruths trotted out as if they had validity.
Ken Goldsmith | Monday, June 3, 2013, 8:57 AM
Geoff, my info tends to be a bit dated, but I read an article earlier this year that said water vapour was still not modeled because it is "too hard" to model. This past summer did have high temperatures recorded, but in Sydney, we had 3 days very hot, the rest was below average. This morning's news is that CFCs were responsible for the little bit of "global warming" that did occur. What that proves to me, is that science still does not know what caused it. In any case, "warming" stopped about 2 decades ago. The CO2/AGW climate change scam is based on CO2 induced "global warming", if we don't got global warming, we need to look for the source of climate change somewhere else.
Ken Goldsmith | Monday, June 3, 2013, 9:05 AM
Sorry for double post. Geoff, I meant to say, I am waiting to see the results of any model that does include water vapour, if you know of one, please post link/s. I think it is such a basic, stupid omission, if anyone does produce such a model, AND the results agree with CO@/AGW, we will hear no end of it, but as I say, AFAIK, it's not been done. Yet.
Geoff Thomas | Tuesday, June 4, 2013, 9:22 AM
Ken, whilst i understand that you think water vapour should be modelled, a bit of study of the green house effect would have told you why it is not appropriate to 'model' water vapour, - basically although water vapour is responsible for 95% of greenhouse warming, it is not a driver, it is only a multiplier, because the amount of water vapour in the air depends mainly on the temperature and how much water vapour is in the air already, - ie at a certain temperature the air will only contain up to a certain amount of water vapour, - if the temperature drops, the amount will decrease, the extra will rain out. Carbon dioxide, however is a driver, it raises the temperature by stopping the re-radiation of infra red (heat) radiation from the sun warmed earth. Once the air is warmed, it can hold moisture, and as that moisture is a potent greenhouse gas, the air will get warmer still, - water vapour is twice to three times stronger in it's greenhouse effect as carbon dioxide, but it is very variable, - at night, with no sun, the earth, and the air above it, cools, so the water vapour content will fall, reducing the greenhouse effect, so allowing even more cooling, whereas the carbon dioxide keeps on working day and night. If all the carbon dioxide were removed from the atmosphere, the water vapour in the atmosphere would decrease every night, so increase less the next day and before long the average temperature on earth would drop by 30 degrees C. Similiarly, the more carbon dioxide in the atmosphere the more heat will be saved of a night so the water vapour will be more, and gradually that extra heat will increase the land temperature then the sea and ice temperatures, hence the disappearance/retreat of many glaciers and the reduction of Polar ice etc. if the increase is maintained you would get to a situation like Venus, where the atmosphere is over 96% carbon dioxide and the surface temperature is 462 degrees C. Venus probably had an ocean once, but after it was all evaporated, that water in the atmosphere would have been photo-disassociated and the hydrogen lost to outer space. So back to the modelling, as water vapour is not a driver but is driven, and all sorts of day to day events can change it's temperature, - night, mountains, storm systems, vegetation and such, it is hard to 'model' So the driver, carbon dioxide, a percentage of which remains in the atmosphere for thousands of years therefore can be modelled, with the warming effect of the carbon dioxide then allowing the greater warming from the water vapour, which is built into the model. The carbon dioxide warms, the water vapour increases and then magnifies the warming. Hope that helps, Geoff.
Ken Goldsmith | Tuesday, June 4, 2013, 12:24 PM
Thanks Geoff. Who wrote "and pretence that water vapour is not included is just denial."? 95% of the cause of greenhouse warming, is not a driver? Man's 3% of the "new" CO2 that goes into the atmosphere, (ie 97% is natural) IS THE driver? "carbon dioxide, a percentage of which remains in the atmosphere for thousands of years" Just days ago, I read (in reports of the new CFC/AGW theory)that CO2 turns over in the atmosphere every 3 or 4 years. Weather/Climate is difficult, if not impossible, to model, given there are so many variables that we don't understand. The models used by CO2/AGW fundamentalists did not predict that "warming" would halt for the past near 2 decades, and given that it has halted, can not account for the halt. The newer CFC theory, reportedly, is supported by it's modelling. NASA recently admitted heat was escaping Earth at a greater rate than (CO2/AGW) predicted, and suspect this is because of REAL man made pollution. (WTF?) The AGW scam was fabricated around a supposed "positive feedback" that would be characterised by a temperature in one of the layers of the atmosphere, at about 12 km altitude. This has never, despite the expenditure of M$, been detected. I believe that Venus, and Mars, both lost most of their magnetospheres, due to core cooling. Magnetosphere loss allowed the solar wind to remove most of their atmospheres. Climate changes, always has, always will. CO2 is not the cause. The ice core records show that temperature is the driver of atmospheric CO2 concentration. Again, thanks for your reply.
Geoff Thomas | Wednesday, June 5, 2013, 12:55 PM
Hi Ken, I guess you did not understand as I said that water vapour is NOT a driver, and that it's effect is included in the models, you can disbelieve me, no problem, but you wouldn't want to unless you are a denier and don't want to come to terms with the information. Another thing is that one fact does not disprove another unless the full story is told, for instance there is certainly carbon dioxide being released by rotting vegetation and animal life of all strata, and is taken up by plants when they photosynthesize, however, they can only use so much, at the end of the day, the total amount of carbon dioxide in the atmosphere is increasing all the time, - we recently passed the 400ppm mark, it just increases a tiny bit every day, as does the warming, and now that the human race is taking notice, there are thousands of people all over the world measuring and measuring, satellites all over the sky, rafts submarines etc going deep into the ocean balloons going up very high every day, all over the world. It's called legwork, and humans are quite good at it. Whatever you may have read of temperature 12 ks up, the reality is that the earth down here, and the seas and the ice shields down here, are getting warmer and warmer, - very slowly, but certainly. Whilst Venus has no significant magnetosphere, the Solar wind didn't remove the water and doesn't now remove the carbon dioxide, despite it being the hottest planet in the Solar System. There is a history there and bit by bit we are learning more. Ice cores show that warming in the past preceded carbon dioxide, yes, if the sun puts out more or the earth's orbit changes, which happened in the past, the sea then releases lots of carbon dioxide so amplifying that warming. - Now however, the sun is actually cooling slightly, and no orbital causes happening either but we are digging up billions and billions of tons of carbon, in the coal and oil, and throwing it into the atmosphere faster than the sea can absorb it. So there is no other reason for the warming it is easy to prove that carbon dioxide does create warming and that warming causes more water vapour to be in the air, so amplifying that warming. It is pretty simple science really but there are certain interest groups among the humans who will lose out if less oil and coal etc is mined, and they have a lot of money so can afford to saturate the media with their nonsense. - I don't get the feeling that you Ken are a rich miner, so I hope that you will eventually do more research on global warming and find out the reality, not the propaganda. I wish you well.