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Post by ron on Apr 12, 2009 17:04:09 GMT
Now, if I rolled 20 6-sided dice and got ALL sixes, I'd suspect rigged dice - there's only a 2.7*10^-14% chance of that happening. That's one in 3,656,158,440,062,976. I think. I prefer to imagine it will likely occur in half that many rolls.
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Post by aj1983 on Apr 12, 2009 20:33:51 GMT
Correct me if I'm wrong, but as far as I know the climate models are keeping natural forcings (volcanism, solar activity) as a "constant". This does imply that the "linear" smooth rise as we see in most climate models is of course not accurate. It just shows a trend. Natural variation, which are kept constant (or with solar activity just a variation around an average activity with an average maximum and minimum value) because of their (total) unpredictibility at the moment, will of course lead to variations on top of the trend (simply put because there will be many complicating feedbacks). It's the best that can be done, because astronomers and geophysicists still don't know how to predict them (I don't blame them...) Internal periodic variations (PDO, etc), many of which are also quite hard to predict will have the same effect. I think the reason why some of the climate models have also shown cooling periods is because they treat these internal processes "better" than others. Most of them however believe there is quite a large certainty in the trend. Most/all climate scientists know that there will be variations on the curve the climate models "predict". There is some uncertainty of how much, because especially the solar influence is uncertain because of its link with clouds. None of them (including) me gets upset if the temperature drops a little for a while (it really hasn't done that yet). Most of them however believe that these uncertain natural factors don't have a large influence as long as a dramatic change doesn't happen. By dramatic you could think of a Dalton/Maunder minimum, or a great increase in volcanic activity.
If they happen, it will be a great test of the sensitivity of the climate to those parameters. There will be some of course, because the climate has shown some variability in the past.
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Post by nautonnier on Apr 12, 2009 20:54:51 GMT
Correct me if I'm wrong, but as far as I know the climate models are keeping natural forcings (volcanism, solar activity) as a "constant". This does imply that the "linear" smooth rise as we see in most climate models is of course not accurate. It just shows a trend. Natural variation, which are kept constant (or with solar activity just a variation around an average activity with an average maximum and minimum value) because of their (total) unpredictibility at the moment, will of course lead to variations on top of the trend (simply put because there will be many complicating feedbacks). It's the best that can be done, because astronomers and geophysicists still don't know how to predict them (I don't blame them...) Internal periodic variations (PDO, etc), many of which are also quite hard to predict will have the same effect. I think the reason why some of the climate models have also shown cooling periods is because they treat these internal processes "better" than others. Most of them however believe there is quite a large certainty in the trend. Most/all climate scientists know that there will be variations on the curve the climate models "predict". There is some uncertainty of how much, because especially the solar influence is uncertain because of its link with clouds. None of them (including) me gets upset if the temperature drops a little for a while (it really hasn't done that yet). Most of them however believe that these uncertain natural factors don't have a large influence as long as a dramatic change doesn't happen. By dramatic you could think of a Dalton/Maunder minimum, or a great increase in volcanic activity. If they happen, it will be a great test of the sensitivity of the climate to those parameters. There will be some of course, because the climate has shown some variability in the past. Well we have been assured that the minima did not exist by glc so it would appear that the planet will go on not quite warming and not quite cooling.... it makes one wonder what all the fuss is about.
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Post by glc on Apr 14, 2009 7:32:02 GMT
Well we have been assured that the minima did not exist by glc so it would appear that the planet will go on not quite warming and not quite cooling.... it makes one wonder what all the fuss is about Hold on a minute. Be careful you don't confuse sunspot minima with climate minima. The Dalton Minimum certainly existed in that there was a period (~1790-1820) with low (though perhaps not as low as previously thought) sunspot numbers. I don't accept, though, that the Dalton Minimum was significantly colder than other periods in the 18th and 19th centuries.
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Post by icefisher on Apr 14, 2009 8:20:53 GMT
The Dalton Minimum certainly existed in that there was a period (~1790-1820) with low (though perhaps not as low as previously thought) sunspot numbers. I don't accept, though, that the Dalton Minimum was significantly colder than other periods in the 18th and 19th centuries. Yep, you and Napoleon have something in common. Napoleon was warned by General Rapp that the natives were reporting an unusually severe winter ahead. You see it was fairly common with two Farmers Almanac's gaining popularity in the US but at least Napoleon didn't have the benefit of 200 years of history to potentially relive. Below is the track of the Grand Army complete with strengths and temperatures during the retreat from Moscow. This picture doesn't mess up screen as much. Map uploadable from link at bottom. Map of how to reduce an army of half a million to 10,000 upload.wikimedia.org/wikipedia/commons/2/29/Minard.png
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Post by nautonnier on Apr 14, 2009 11:08:17 GMT
Its no good Icefisher, glc _knows_ that the Dalton* minimum was just normal temperatures no amount of historical evidence will convince him otherwise. Such as the weather during Napoleon's retreat being so cold that the tin buttons on his troops uniforms turned into the white powder allotrope - not particularly useful in freezing temperatures.
* Dalton was a meteorologist and a physicist not an astronomer
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Post by kiwistonewall on Apr 14, 2009 11:21:02 GMT
Australia’s most eminent geologist writes a book: The subject of this column is not small. It is a book entitled Heaven And Earth, which will be published tomorrow. It has been written by one of Australia’s foremost Earth scientists, Professor Ian Plimer. “To reduce modern climate change to one variable, CO2, or a small proportion of one variable - human-induced CO2 - is not science. To try to predict the future based on just one variable (CO2) in extraordinarily complex natural systems is folly. Yet when astronomers have the temerity to show that climate is driven by solar activities rather than CO2 emissions, they are dismissed as dinosaurs undertaking the methods of old-fashioned science.” www.smh.com.au/opinion/beware-the-climate-of-conformity-20090412-a3ya.html?page=-1
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Post by jimg on Apr 14, 2009 19:50:54 GMT
On the other sidw of the Atlantic: Crossing the Delaware
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Post by glc on Apr 15, 2009 10:12:41 GMT
Yep, you and Napoleon have something in common. Napoleon was warned by General Rapp that the natives were reporting an unusually severe winter ahead. You see it was fairly common with two Farmers Almanac's gaining popularity in the US but at least Napoleon didn't have the benefit of 200 years of history to potentially relive. Again you confuse what I'm saying. I didn't say that it wasn't cold - I said it wasn't any colder that other similar periods. Simply trotting out anecdotal evidence from famous historical events means nothing. What about the devastatingly cold Russian winter in which stopped the German offensive in 1941? What about the coldest Jan/Feb in the UK in 1963 when everything was frozen solid for more than 2 months? or 1947? Its no good Icefisher, glc _knows_ that the Dalton* minimum was just normal temperatures no amount of historical evidence will convince him otherwise. Such as the weather during Napoleon's retreat being so cold that the tin buttons on his troops uniforms turned into the white powder allotrope - not particularly useful in freezing temperatures. ...and the Germans in WWII? - which was at the peak of a warming period. In case you're not aware, Russian winters can be pretty brutal. Napoleon and Hitler under-estimated their severity. Icefisher, Nautonnier I get lambasted for using the Scoresby expedition as evidence of "a lack of cooling", but it' ok for you to use a couple of historical anecdotes - one of which suggests Russian winters are cold in winter (amazing!) - and we're supposed to accept them as overwhelming evidence . The Scoresby expedition was, at least, science based. He was charting arctic waters and his findings were partly influential in a statement by the Royal Society in 1817, which reads "It will without doubt have come to your Lordship's knowledge that a considerable change of climate, inexplicable at present to us, must have taken place in the Circumpolar Regions, by which the severity of the cold that has for centuries past enclosed the seas in the high northern latitudes in an impenetrable barrier of ice has been during the last two years, greatly abated.
(This) affords ample proof that new sources of warmth have been opened and give us leave to hope that the Arctic Seas may at this time be more accessible than they have been for centuries past, and that discoveries may now be made in them not only interesting to the advancement of science but also to the future intercourse of mankind and the commerce of distant nations." So in the depths of the Dalton Minimum the RS were considering the possiblity of shipping routes via the Arctic seas. But leaving aside the anecdotal stuff - what about the data? CET, Armagh, Uppsala, De Bilt - none of these long term temperature records indicate anything particularly usual about the Dalton Minimum.
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Post by icefisher on Apr 15, 2009 12:45:14 GMT
But leaving aside the anecdotal stuff - what about the data? CET, Armagh, Uppsala, De Bilt - none of these long term temperature records indicate anything particularly usual about the Dalton Minimum. Well an army of half a million dying from the cold is impressive. Not sure if I have ever heard of any such thing occuring from the heat. Not sure what does impress you or why. In this debate its primarily why people are impressed about the prospects of a warm climate that interests me the most. I would suggest that a lack of impression about history should lead to a good deal of skepticism about new technology that pretends to tell you why it is getting warmer when you know that natural temperature fluctuations are about 16 times greater than we have seen in the last hundred years. Snake oil, witch doctors, and charlatans are every bit as common as percent of the population as they were in 1812 or 6000bc.
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Post by trbixler on Apr 15, 2009 14:24:09 GMT
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Post by steve on Apr 15, 2009 17:17:08 GMT
Steve. When you refer to "4 or 5 out of 20 models show a cooling trend... Do you mean a cooling trend sometime in the future? Or do you mean the current cooling trend? You have quoted me incorrectly, I believe. I said: Basically, if you line up 21st Century observations against the IPCC models, and start off with a zero temperature anomaly in 2000 then 4 or 5 of the 20 models lie below the observations in 2008.
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Post by gettingchilly on Apr 15, 2009 22:45:37 GMT
"Most/all climate scientists know that there will be variations on the curve the climate models "predict". There is some uncertainty of how much, because especially the solar influence is uncertain because of its link with clouds."
Don't think the IPCC have acknowledged that the sun has any effect at all yet. It's just a constant.
"None of them (including) me gets upset if the temperature drops a little for a while (it really hasn't done that yet). "
Now this post 3 years ago would have been true, but after two years of plummeting temperatures and freezing records being broken all over the world would seem to debunk the "hasn't done that yet" claim.
"By dramatic you could think of a Dalton/Maunder minimum, or a great increase in volcanic activity."
Lots of earthquakes happening this year, yes I know, cause/causation etc. but it does seem to be a trend in the making. I would say that yes, we are having a great increase volcanic activity. If I was living in san francisco I might be thinking of moving to the country for a few years.
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Post by nautonnier on Apr 15, 2009 23:57:06 GMT
Steve. When you refer to "4 or 5 out of 20 models show a cooling trend... Do you mean a cooling trend sometime in the future? Or do you mean the current cooling trend? You have quoted me incorrectly, I believe. I said: Basically, if you line up 21st Century observations against the IPCC models, and start off with a zero temperature anomaly in 2000 then 4 or 5 of the 20 models lie below the observations in 2008. Its a pity that the models didn't start from 2000 then - if they had would they still have shown the cooling? As you will agree they didn't from their AR4 start point and start conditions are really important in these models you can't just move a pattern forward and claim that the model would have got it right using different start conditions.
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Post by alex4ever on Apr 16, 2009 5:50:06 GMT
Is it really a fact that seismic activity and volcanic activity increased? Earthquakes occure every day, minor volcanic eruptions are not so uncommon. I know about the volcanoes erupted recently, but its still not a clue that periodicity increased simply because very little time has passed. I woulb be only be pleased if an expert would demonstrate this matter with proof.
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