Separate names with a comma.
Discussion in 'Alpine & Snow' started by Sandy, May 10, 2006.
Discuss the topic.
Daj and/or spice could would either of you like to suggest an area of climate research that we can start focusing on?
Daj - what about the fundermental cause of greenhouse warming. Lets start with the hypothesis that CO2 gases are the major cause of global warming. What is the latest evidence to support this?
Can you either post up links or the text. Some of us dont have regular access to a wide variety of scientific journals.
Then we can restart this for a 4th time.
in response to "Daj - what about the fundermental cause of greenhouse warming. Lets start with the hypothesis that CO2 gases are the major cause of global warming. What is the latest evidence to support this?" we have to distinguish between what are observational facts, what are simple deductions from these facts, and what are more complex extrapolations.
It is an observational fact that global temperatures are warming, that this warming is nearly global (parts of southern greenland and parts of the Antarctic have cooled very slightly over the last 30 years due to polar vortex changes), that this warming increases with height in the tropics. The warming extends through the depth of the upper ocean, and the heat is being transfered from the atmosphere to the ocean.
The last point is critical as is rules out all natural ocean-atmosphere natural variability process that we know of. El Nino warms the atmosphere but it does this by cooling the oceans. You simply can't create heat from nothing.
We know that global climate is always varying, and occasionally quite abruptly, but the natural causes of these variations are readily identifiable in changes to sun spots (solar output ) such as occured during the little ice ages, catastrophic process such as the flooding of the north atlantic which triggered the Youger Dryas cooling 11,000BP, or past warm periods such as the last interglacial which was marginally warmer than the present (due to very high summer time solar radiations levels in the northern hemisphere high latitudes). For the most part the changes are fast, but not nearly as fast as the current 0.2C/decade warming we have seen over the last ~40years.
We have no identifiable cause for the current ~1C warming. We know solar radiation is hardly changed (the changes are to small to cause the warming without an unknown and unmeasured feedback mechanism). The problem with calling on an unknown feedback mechanisms is that it then implies that the earths climate is very sensitivie to small shoves which means that it will respond abruptly to greenhouse gases, and implies that past climate variabitions should have been bigger than they were. We know quite precisely how warm or cool past climate swings were from a range of chemical, glaciological etc evidences (sure these might have uncertainities of a few 0.1 of a degree, but we would need errors 10 or 20 times this size to support a feedback).
It is an observational fact that greenhouse gases are producing an increased downwards flux of energy at the surface. This has been directly measured at the surface, and its amplitude is very close to that predicted by climate models. This observation is supported by satellite observations which show a closing of the greenhouse gas windows which mean these are capturing and returning downwards additional radiative energy which would have otherwise escaped to space.
We know that the earth's surface must find a way to remove this energy. This can be through increased evaporation, increased heat transport, or increased radiation. All of these require a surface warming, the only question is how much.
Of course, the linkage process is much more sophisticated than this using comprehensive models which incorporate all we know about climate processes. These models are extremely complex and based on physics and do an excellent job of modelling the current climate, tracking past climate variations, and in predicting some of the only recently measured phenomena (such as warming of the upper atmosphere, cooling of the stratosphere, entrainment of heat into the deep oceans). Sure, some scientists will say the models can be better, and it would be hard to agree but all the improvements made in the last 30 years made by 10,000s of computer programmers and scientists have changed the headline answer; they have only tinkered at the edges.
I am all for a debate but these issues described above are essentially settled. The debate now is on the feedbacks - for example at what temperature are the tropical forests like the amazon likely to convert to tropical savanna, will methane in perma frost be released, will increases in high cloud increase the warming, will increases in low cloud mitigate some of the warming). None of these debate questions the warming, but there answer will determine whether we have 2 or 5C of warming when we double CO2.
I may become terse in my response to comments such as "you cant predict the weather therefore your models are wrong" as one becomes very tired of dealing with these. They are recycled by key climate sceptics who know that this claim is at best missleading. Weather forecasting has a limited skill range because chaos means that small obsevational errors double about every 36 hours in the forecast. So, for example, if you have a perfect model and measure pressure to withing 0.2hPa, at 36 hours your pressure error will be ~0.4hPa, 72 hours it will be ~0.8hPa, and so on until such time you are just guessing. This error growth does not reflect a problem in your model, and doesn't mean your model has a bad climate. A chaotic system is a system which allows limited prediction of exactly what the weather will be on a day (say july 1), but does not prevent you from know what the average weather will be on that day. In cliamte we do not seek to tell you what the weather will be on a day by day basis, all we try to tell you is what the average weather is for the particular day (or month, or year).
A question to ponder is if this analogy is false, why if the strength of sceptic science is so strong would there be a need to use it?
Ok thanks for that Daj, and thanks for replying. More soon. It is an area where tempers can become strained, so I will try and focus on looking at the facts if others can be a little patient also.
I don't disagree that the earth is warming, however of course we have had stoushes in the past relating to why? I will keep it civil as I want this thread to actually go somewhere.. With regards to your comments above about no identifiable natural causes, I have read some articles that would refute that. One in particular (I.G. Usoskin, S. Solanki, M. Schuessler, K. Mursula, K. Alanko, A millennium scale sunspot number reconstruction: Evidence for an unusually active sun since the 1940's, Phys. Rev. Lett., 91(21), 211101, 2003.) can be found here: http://cc.oulu.fi/~usoskin/personal/Sola2-PRL_published.pdf
There is a great graph in that article showing sunspot numbers (SN) from the last 1150 years. I find it remarkable for a number of reasons but forgive me for pasting the authors comments as I cannot do it justice:
I think this article is a good example that natural forcings may indeed have contributed more largely to the recent warming than some have thought. We often talk about the last 100 years of warming, however many scientists, including those from the IPCC agree that most of the warming in the first 40-50years last century was due to natural forcings. However this study above also demonstrates that the sun may be affecting us far more than many think.
FIG. 2 (color). Time series of the sunspot number as reconstructed from 10Be concentrations in ice cores from Antarctica (red) and Greenland (green). The corresponding profiles are bounded by the actual reconstruction results (upper envelope to shaded areas) and by the reconstructed values corrected at low values of the SN (solid curves) by taking into account the residual level of solar activity in the limit of vanishing SN (see Fig.1). The thick black curve shows the observed group sunspot number since 1610 and the thin blue curve gives the (scaled) 14C concentration in tree rings, corrected for the variation of the geomagnetic field . The horizontal bars with attached arrows indicate the times of great minima and maxima : Dalton minimum (Dm), Maunder minimum (Mm), SpoÂ¨rer minimum (Sm), Wolf minimum (Wm), Oort minimum (Om), and medieval maximum (MM). The temporal lag of 14C with respect to the sunspot number is due to the long attenuation time for 14C .
Spiceman, the IPCC and climate scientists are careful to distinguish between the warming in the first half of last century with what happened in the second. In the first half solar output increased while at the same time greenhouse gas changes were rather small, while in the second half the suns output declined slightly while greenhouse gas concentrations exploded. This is shown very clearly on the data avaliable at the website http://www.brighton73.freeserve.co.uk/gw/solar/solar.htm
The various forcings due to solar, volcanos etc are described in figures in the IPCC figure at http://www.grida.no/climate/ipcc_tar/wg1/fig6-8.htm . Generally speaking a 1W/M^2 in this figure translates into about a 0.7C temperature change.
There is no disagreement that reduced solar output during the Dalton, Maunder, and Sporer periods (with addition of volcanic eruptions) lead to cooler periods, and at the same time the higher levels during the Medieval Warm period lead to slightly warmer conditions. Similarly, there is no disagreement that solar output increased from around 1900 to 1950 and this contributed some if not most of the warming which occured during this 50 years.
The point is that since 1950 (and particularly since 1970) as greenhouse gas concentrations have exploded temperature have started to rise, and rise at a rate which is much faster than that seen previously in any of our records. This rise is attributed to greenhouse gas increases. Natural changes should have cooled things down over the last 50 years.
A couple of cautions on the figure you have linked. It is a wory that the recent data (Green and Black) do not extend back far in time, and similarly that the old data (Red and Blue) don't come up to the present. These are slightly different measures and do not support an interpretation that early 20th century activity was at millenium highs because one is not comparing apples with apples (though this isn't material to what I wrote before). Further, notice how these reconstruction suggest natural forcing alone should have seen the early 20th century temperatures be near or above the temperatures during Medieval warm period, and then of course we have added another 0.6C due to greenhouse gas changes. Further, the curves of solar activity are highly Hockey Stick shaped. This supports the various Hockey Stick Analyses which have been published, with the recent upturn being initially due largely to natural forcings, but the most recent 40 year spike due to the enhanced greenhouse effect.
To clarify what Spicey has said, since maybe he hasn't summarised what it all means.....
Lower sunspot activity corresponds to lower solar output, and consequently, lower temperatures on Earth.
Higher sunspot activity corresponds to higher solar output, and consequently, higher temperatures on Earth.
The Maunder minimum in the late 1600's corresponded to the "Little Ice Age", a period that had significantly reduced temperatures, particularly in Europe.
This is a much better start.
Wild stab in the dark.
Interesting subject, referring sun spots.
As stated, Around the nineteen 40's our sun spot activity increased . Coincidently in May 1945 the first Nuclear Testing commenced at Alamogordo test range New Mexico.
Could expelled Nuclear energy contribute to sun spot activity.
Wouldn't have thought so, as sun spots have a much larger energy release than anything man has developed, their effect on us although measurable is negligent, hence our effect on the sun would be even smaller. Also when those asteroids hit jupiter then they would have triggered something if an atomic weapon on earth can make an impact. Id be more leaning towards our ability to measure the amount of sunspots in a year. What procedures were in pace to watch them b4 1948? was it just independent people making reports, or was there a dedicated society?
Various scientists have been measuring sun-spots using telescopes for centuries. I think there is a bit of uncertainity in the results, but probably not enough to change any conclusions. The results are also broadly colloborated by measures of solar output contained in various radioactive isotopes.
That would be like moving Mt Everest with a Barbie Doll
I wasn't planning to post in here any time yet, but since I seem to have now (courtesy of Sandy), I have to ask - is this really a scientific approach?
So far we have made a good start. Basically we are focussing on the issues of the last 30 years.
Might want to read up on the issues of sunspots if you wish to contribute.
Appreciate your comments daj, I haven't had a great deal of time with work and other stuff keeping me very busy, but if I'm not correct it could be argued even from the graph you posted above and indeed by the study I posted earlier that the only years that have produced an anomoly between man induced or natural forcings could be from the last 26-36 years. I would go so far as to say that considering the temperatures seems to lag the sunspot data by around 10 years that it could be argued that no anthropogenic signal could be found before 1980 with any degree of certainty. However even if we took it from 1970 it still begs the question why the hockey stick is used.
As you know, one of the chief arguments of the IPCC has been that the earth has been warming for the past 100 odd years and that this is unprecedented etc etc. I just find it a little bit convenient considering somewhere between 70-80 years of it really has little if anything to do with anthropogenic causes. I think in the least it has demonstrated that regardless of CO2 emmissions, the temperature would have risen from 1900 to 1980 anyway. I'd like to obviously continue this discussion focusing on the last 36 years as well, but tonight is not the time for me.
>I posted earlier that the only years that have produced an anomoly between man induced or natural forcings could be from the last 26-36 years.
Spiceman it is more like 40 to 50 years, but this doesn't really change the essence of the discussion. Human greenhouse gas forcings only came to dominate natural climate variability after World War 2. This is shown in the IPCC figure at http://www.grida.no/climate/ipcc_tar/wg1/fig6-8.htm . For example, greenhouse gases contributed about 1W/M^2 of forcing from over the 200 years 1750 to 1950, while in the following 50 years they have contributed nearly 2W/M^2. About half of the warming from 1750-1950 was offset by aerosol cooling effects (this could be anywhere between about 20 and 80%). Unfortunately, the aerosol effects are short lived and really once off - the only way for them to continue is through increasing levels of smog which are intolerable to most people. A nasty side effect of their short term effects is that if we were to reduce aerosol concentrations to pre industrial levels (for example by slashing fossil fuel burning) we would trigger a very rapid warming of around 1C with most of this warming occuring in the northern hemisphere.
On the issue of lag, there is no obvious lag of temperatures to sunspots to me. For small radiative forcing changes there should only be a slight lag.
One thing to keep in mind is that the graph above is only really useful for demonstrating the decoupling of temperature variability and solar output over the last 50 years. Increased volcanic activity in the late 20th century largely offset the slightly higher solar output which means that temperatures at 2000 should have been around the level of those at 1900. Instead, they are considerably warmer with the difference almost entirely due to human activities.
The scales used are quite arbitary with the suggestion that all the first half of the centuries warming being due to solar changes is clearly not the case. Human influences are likely to have contributed of order 25% of the intial warming.
Your reference to the Hockey Stick is only partially valid. As I have stated before, the only real thing that a Hockey Stick can tell you is how unusual recent temperature changes are. It cannot distinguish between natural and human induced climate change (though in the absence of natural forcings one can infer that recent unusual warming is probably human induced). The Hockey Stick reconstructions simply tell us that recent temperatures are unusual and that the rate at which they are changing is quite exceptional.
Sorry Sandy, I didn't see your Mk 4 thread when I started it, my bad.
ok, havent been reading or posting in these threads due to threat of being flamed for anything i post. anyways, CO2 yeah, well i would like to know what is the possibility and feasibility of Carbon being 'fixed' by humans? Sandy befor mentioned fullerenes which are C60 structures, and there are C120+ structures around aswell which are essentially 'stores' of carbon. What i wanna know is, can this be done on a large scale process? so much so that it would significantly reduce the amount of Carbon in the spheres significantly? if it can possibly be done on a scale this large, how feasible would it be to do something of this sort? who would do it? and where would the nanotubes be put for storage?
I know it sounds like a crazy idea but it would be a very distinct possibility if it got too out of hand.
On a side note - Aparentely at the current rate of CO2 increasing in atmosphere per year, if/when we get to concentrations of 750ppm in the atmosphere, the Thermohaline circulation would shut down forever, as in it aint coming back, or not at least with the same circulation as it is now. this would have profound effects in the Northern Hemisphere, not so much in the Southern Hemisphere. We're talking 8-9C differences.
Previously posted this before..didn't ever get an answer.
If water vapour is one of the most important greenhouse gases, how will switching from internal combustion cars to hydrogen fuel cell cars (whose output is steam) be any better than having our current cars?
SG1 - Daj said aparentely this wont have any effect because the residence time of WV in the atmosphere is not long enough for it to have an effect.
That's correct - water vapour, at most a few days. CO2 on the other hand, stays in the atmosphere up to 80 years!
Yes correct but water vapour as a green house gas is constantly cycling in and out of being in its gaseous form. While its time in the atmosphere maybe short, it is constant, and variable and yes it is a green house gas, that even the very best models have tremendous difficulties dealing with. (You wont ever hear this. To understand the climate models and how much difficulty they have with water vapour would take a week of discussion alone, and thats discussing the problems!).
Daj from above - it seems that we are really getting down to this last half century and only in this last half century does CO2 increase to a level that affects the climate. Is that correct?
So prior to this last half century and in particular the last 35 years, we have CO2 below a critical factor. Then sometime in the last 35 years we have reached this threshold that suddenly hit the switch that meant that every additional bit of CO2 would directly contribute to green house gas warming. That seems to me the position that your suggesting.
Now Daj, im a sceptic and you know it. You may be proven to be right. If it was clearly right, it would be easy to prove. (I havent read some recent papers released this year, and their rapid inclusion into IPCC 4, without review adds to my concern).
The key point is that we have suddenly hit this delicate trigger switch at around, what 330 ppm, and now we are up around what 350ppm.
Im looking at the science, but lets put that aside for a moment.
To me it seems incredably convenient. In the last 50 years we now have good instruments to determine CO2 levels in the atmosphere. Suddenly mankind through stupidity increases CO2 levels to a point which triggers this switch.
Now this could have happened anytime over the last couple of thousand years, as hunters in Africa burnt lands to flush out game, as humans cleared and burnt the land all through out europe, until less then 5% existed as forest. All round the world mankind has been changing and clearing land for thousands of years.
In clearing that land, they have burnt forests, cleared land, and left vegetation to rot and release CO2.
But no. Its this century, not 1000 years ago, not 300 years ago, now between 1970 - 2006.
But suddenly in the last 35 years we reach this critical point, where natural forcings have become overshadowed by mans use of CO2, which have increased temperatures.
Quick recap for anybody reading this for the first time. Daj, im still having significant trouble getting my head around the temperature over the last century.
If as you say temperature is so sensitive to CO2 increases, then i look at these figures, and dont understand the problem.
From 1918 - 1940 a marked warming, of temperatures similar to recent decades while we had only a 7 ppm increase in CO2. (In other words, relatively small increase in CO2, but dramatic increase in temps.)
1940 - 1970 we had had temperatures dropping and fear of another ice age approaching. During this time CO2 increased by 18 ppm to 326ppm.(Increase in C02 of 6% over previous levels, yet we have a cooling of the planet.)
1970 to present we have seen an increase of 22ppm and we have had an increase in temperatures. (An increase of 7% in CO2 over the previous period and we get the same sort of warming as we did when we had an increase of only 2%.)
From reading your posts i think what your saying is that there is a threshold? Is that correct? At which point the global warming effect kicks in, like a switch being turned on.
Now what is being suggested is that we have turned this switch on on the last 35 years.
Can you see how, this could be construed as being very convenient.
First time ever that we have been in a position to measure and understand that the increase in CO2 once it reaches approx 326 ppm we have induced accelerated global warming.
To me nature is never convenient for mankind.
but, like taipan said, this would have some significant effect if millions of cars started pumping it out every day, all day long would it not?
yes, it's a cumulative effect
Now every volcanic eruption is different, and their effects on the climate are all different. Here is a list of the major eruptions. Does anybody have the details on what positive or negative effects they each had on temperature.
Major volcanic eruptions are as follows.
1902 (3 eruptions) Santa Maria Guatemala, Mount Pelee(Meryinique), Soufriere(Guadeloupe).
1907 Ksudach (Kamchatka)
1912 (Katmai (Alaska)
1928 Paluweh (Indonesia)
1929 Reventador (Ecuador)
1932 Cerro Azul (Argentina)
1942-1947 Hekla (Iceland)
1954 Mount Spurr (Alaska)
1956 Bezymianny (Kamchatka)
1963 Gunung Agung (Indonesia)
1966 Awu (Indonesia)
1971 Hekla (Iceland)
1972 Mt Erubus (Antartica)
1974 Fuego (Guatemala)
1980 Mt St Helens (USA)
1982 El Chichon (Mexico)
1985 Nevado del Ruiz (Columbia)
1991 Pinatubo (Philipines)
1992 Mt Spurr (Alaska USA)
Looking at the period from 1900 - 1940 we have 8 eruptions and an increase in temperatures, and a small increase in CO2 of only 7 ppm.
From 1940 - 1970 we have 9 eruptions (counting heckla as 5 eruptions). We have an increase of 18ppm but a decrease in temperatures.
From 1970 - 1992 we had 8 eruptions of which St Helens and Pinatubo were significant. We had an increase of 22 ppm in CO2 and an increase in temperatures.
By rights we should have had a cooling wouldnt you agree Daj? But in fact we had an increase in temperatures.
No id disagree romfrantic. If we were able to use hydrogen cell cars whose output was steam, we have to consider where did that steam come from. It would have to be extracted from the atmosphere in the first place, converted into steam under pressure, and then expelled.
The water cycle continues.
Fusion vehicles would use a similar principal. However the steam output i dont think would be cumulative. The main thing would be the release of water vapour which has heat energy. While water vapour will move between different forms the heat would need to be absorbed.
This may not be a problem considering the heat of car exhausts.
Water vapour released into the atmosphere, will quickly resume its normal water cycle progression.
No, at the point of combustion the steam is a by product of the chemical process of combining O2 with H in an engine. We'd be adding to the amount of water vapour in solution in the atmosphere. The extra steam would be additional to the water cycle.
Actually conceded. Good point schaden, and apologise romfrantic. It is a conversion of two gases and therefore an increase in the water vapour in the cycle.
It is a valid question - would this be even worse than burning fossil fuels (limited reserves of latter aside). Life spans /cycles of gases need to be considered.
I think that, by and large, relatively small eruptions (less than 30 cubic km ejected) would have short lived effects, and not have much impact on that graph. So in that case, the cooling effect over decades would be swamped by other factors, and would not be very evident.
Im lead to believe that the more erupting volcanos we have on earth the cooler the temps
Yes, that's true, but what I mean is that the 20th century was nothing special so far as eruptions are concerned. i.e. the eruptions are like just about any other "regular" century, neither providing more cooling effect nor less, so the net effect is not significant.
I'm not talking about steam, I'm talking about CO2 having a cumulative effect.
Vemillion your question about fixing CO2 is not "crazy". The most obvious way to do this is through growing trees and either leaving them standing or using them for purposes which keep the Carbon contained for a long period of time. On example is timber building frames etc. Ultimately, these type of options can buy you some "time". The biggest problem with these is that your trading CO2 which is looked up for geological time scales which is looked up for "human" time scales. The other option is geosequestation which will almost certainly play a minor to major role in future strategies to reduce CO2.
>To me it seems incredably convenient. In the last 50 years we now have good instruments to determine CO2 levels in the atmosphere. Suddenly mankind through stupidity increases CO2 levels to a point which triggers this switch.
We have very good measurments of CO2 going back 650,000 years so there is nothing special about the last 50. The fact that CO2 has taken off is simply because fossil fuel use has taken off. The issue is not really that we have switched a trigger, but rather than the earth's climate has slowly transitioned from being dominated by natural processes to being dominated by humans. This transition started around 1700, and was completed by the around 1970.
Appreciate you, spiceman & taipan probably won't be completely swayed, so suggest watching this space. Current estimates are that by 2008 every second year will be on average warmer than the current record holder (1998). Look for lots of records falling in the next few years...
BTW, the IPCC has a very strict well publicised cut-off date for studies to be included in the review process. From memory, the cut-off was "papers had to be published or accepted to be published" by March 2006 for consideration by WG1 and April for WG2.
On the issue of hydrogen fuel, a big problem is leakage. The molecules are so small they leak like crazy and being light that quickly make their way to the upper atmosphere (stratosphere) where they destroy ozone, and also generate water vapour at extremely high atmospheric levels. The associated water vapour is so high it takes a long time to "rain-out" and is a very potent greenhouse gas. I don't think we really know how bigger problem this will/could be.
I know that this is slightly off-topic but with hydrogen powered cars, the problem is that there are no vast untapped sources of hydrogen lying around to be used. The hydrogen has to be produced. One way is electrolyse water by passing an electric current through water which breaks it down into hydrogen and oxygen. On the basis that you don't get "something for nothing" the electrical energy needed for this process is at least equal to or greater than the energy you get back in your hydrogen powered car and in Aust. since most of our electrical energy is produced by burning fossil fuels you are going to produce co2 anyway.
Well, the simple answer is that we can't afford to generate the power that way to produce hydrogen.
Article from yesterday's Sydney Morning Herald here.
id say yes to the last question sandy.
I wonder what you guys will think of this article.
US ads praise carbon dioxide
By Deborah Zabarenko in Washington
May 18, 2006
A LITTLE girl blows away dandelion fluff as an announcer says, "Carbon dioxide: they call it pollution; we call it life", in an advertisement targeting global warming "alarmists", especially Al Gore.
The television ads, screened for the press yesterday and set to air in 14 US cities starting today, are part of a campaign by the conservative Competitive Enterprise Institute to counter a media spotlight on threats posed by worldwide climate change.
The spots are timed to precede next week's theatrical release of An Inconvenient Truth, a documentary film on global warming that features Gore, the former vice president and Democratic presidential candidate.
Against backdrops of a park, a beach and a forest, one celebrates the benefits of greenhouse gas-producing fuels.
"The fuels that produce CO2 (carbon dioxide) have freed us from a world of back-breaking labour, lighting up our lives, allowing us to create and move the things we need, the people we love," the ad runs.
"Now some politicians want to label carbon dioxide a pollutant. Imagine if they succeed â€“ what would our lives be like then?"
The other ad questions media reports of the threat of climate change, especially a Time magazine issue devoted to the topic, and shows film of a glacier melting and then runs in reverse to show the glacier reconstituting itself.
"We had started work on this several months back, but we sort of changed course once the flood of glacier-melting stories began," Sam Kazman, an institute lawyer who worked on the ads, said. "So we did want to get out there before the Al Gore film got into national opening."
Fred Smith, president of the institute, a lobbying group closely allied to the Bush administration, that stresses limited government regulation and a free-market approach to environmental issues, said he had seen the film and found it "very alarmist", although well-produced.
Full article at :
What the?? Are you sure that isn't sourced from The Onion?...
I think the ad is a crock and can't believe people would actualy produce it..... only in the USA.. that's all I can say.