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Post by william on Mar 14, 2010 4:55:01 GMT
I found Lindzen's lecture to be interesting. vmsstreamer1.fnal.gov/VMS_Site_03/Lectures/Colloquium/100210Lindzen/f.htm#It appears the key issue concerning AWG is whether the feedback to increasing CO2 is positive or negative. Lindzen is a senior professor at MIT and has a number of published papers concerning feedbacks. I would be interested in what others think of this lecture.
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Post by glc on Mar 14, 2010 8:51:15 GMT
It appears the key issue concerning AWG is whether the feedback to increasing CO2 is positive or negative.
... or even zero , perhaps. This is exactly the point I have been making on this blog for the past 18 months. All reputable climate scientists (warmers or sceptics) know that if the concentration of CO2 in the atmosphere is doubled then the earth is likely to warm by ~1 deg C. However this figure assumes all other factors, e.g. water vapour, remain the same. If the feedbacks are positive (warmists view) then the warming will be amplified. If the feedbacks are negative (Lindzen's view) then the warming will be reduced.
Current evidence suggests (to me at least) the feedback will not produce catastrophic warming. However natural variability can amplify or dampen any warming trend so it's a bit early to make a definite call. My best guess is a slightly positive feedback.
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Post by poitsplace on Mar 14, 2010 9:31:56 GMT
Yeah, but it wouldn't matter either way because the "apocalyptic" projections by the IPCC are actually within temperature ranges that are harmless.
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Post by william on Mar 14, 2010 10:22:35 GMT
What I do not understand, is why does the IPCC report continue to predict warming for a doubling of CO2 to be 1.5C to 5C which requires positive feedback. If there is zero feedback a doubling of atmospheric CO2 will result in 1.2C of warming. Based on the planet's response to the current CO2 increase, assuming a 100% of the current warming was due to CO2 and ignoring the fact that almost 0.2C of the 20th century warming was due to data manipulation, the feedback response is strongly negative. The consequence of a negative feedback response is that the planet will warm less than 0.75C due to a doubling of CO2 as opposed to 1.5C to 5C. This paper supports Lindzen's paper which shows the planet's to an increase or a decrease in forcing is to resist the change. The planet increase or decrease planetary clouds to stabilization planetary temperature. Lindzen in his lecture discusses the faint sun paradox and its solution which is that planetary cloud cover changes to help stabilize the planet's temperature. ams.allenpress.com/perlserv/?request=get-abstract&doi=10.1175%2F2009JCLI3461.1
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Post by william on Mar 14, 2010 10:49:08 GMT
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Post by jimcripwell on Mar 14, 2010 13:30:45 GMT
glc writes " All reputable climate scientists (warmers or sceptics) know that if the concentration of CO2 in the atmosphere is doubled then the earth is likely to warm by ~1 deg C."
Do you have a reference where someone organized a survey of "All reputable climate scientists", where they all answered that thet know that " if the concentration of CO2 in the atmosphere is doubled then the earth is likely to warm by ~1 deg C."? I suspect not, but if you have such a reference, could you please post it. Or maybe "reputable" means that they agree with this statement.
I suspect a more accurate statement is that there is a hypothesis that " if the concentration of CO2 in the atmosphere is doubled then the earth is likely to warm by ~1 deg C.". However, this hypothesis is based on the output of computer programs. It is impossible to actually measure what would happen in the atmosphere if the amount of CO2 was doubled; and in any event, this change in temperature could not be measured because any feedbacks would obscure the correct value.
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Post by socold on Mar 14, 2010 13:56:10 GMT
What I do not understand, is why does the IPCC report continue to predict warming for a doubling of CO2 to be 1.5C to 5C which requires positive feedback. If there is zero feedback a doubling of atmospheric CO2 will result in 1.2C of warming. Based on the planet's response to the current CO2 increase, assuming a 100% of the current warming was due to CO2 and ignoring the fact that almost 0.2C of the 20th century warming was due to data manipulation, the feedback response is strongly negative. Because the instrumental record is a poor constraint of climate sensitivity, not just because as you mention the entire 20th century temperature record has wider error range in the early part (your assertion that it must be in a certain direction notwithstanding). There is also error range in the forcings (the aerosol forcing is particularly less known). Additionally the oceans present thermal inertia, slowing down any warming - drawing out the time it takes for the planet to get back into energy balance. See the instrumental record based constraints on sensitivity: www.iac.ethz.ch/people/knuttir/papers/knutti08natgeo.pdfThe main problem with this idea of climate "resisting change" makes it quite a challenge to explain changes that we know have happened. For example there was 5C warming from glacial maximum to the current interglacial. If that was despite the climate resisting change, then just how big a change was required! Where could such a large forcing come from? We know the orbital forcing was weak. Ice albedo feedback is not enough to explain the full 5C on top of forcings. It's therefore quite nice explanation to have the climate amplifying the change rather than resisting it. On the otherhand if we assume clouds have a strong negative feedback and overall climate feedback is negative, then we will definitely fall short of explaining 5C warming. And it's not just temperatures lower than today, there is the Eemian interglacial that was warmer than the current one. And for some people there is also a medieval warm period and Holocene optimum "far warmer" than present (grapes growing in siberia..vikings dying of heat exhaustion, etc), how does that tie in with a climate that resists such changes?
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Post by nautonnier on Mar 14, 2010 18:44:34 GMT
What I do not understand, is why does the IPCC report continue to predict warming for a doubling of CO2 to be 1.5C to 5C which requires positive feedback. If there is zero feedback a doubling of atmospheric CO2 will result in 1.2C of warming. Based on the planet's response to the current CO2 increase, assuming a 100% of the current warming was due to CO2 and ignoring the fact that almost 0.2C of the 20th century warming was due to data manipulation, the feedback response is strongly negative. Because the instrumental record is a poor constraint of climate sensitivity, not just because as you mention the entire 20th century temperature record has wider error range in the early part (your assertion that it must be in a certain direction notwithstanding). There is also error range in the forcings (the aerosol forcing is particularly less known). Additionally the oceans present thermal inertia, slowing down any warming - drawing out the time it takes for the planet to get back into energy balance. See the instrumental record based constraints on sensitivity: www.iac.ethz.ch/people/knuttir/papers/knutti08natgeo.pdfThe main problem with this idea of climate "resisting change" makes it quite a challenge to explain changes that we know have happened. For example there was 5C warming from glacial maximum to the current interglacial. If that was despite the climate resisting change, then just how big a change was required! Where could such a large forcing come from? We know the orbital forcing was weak. Ice albedo feedback is not enough to explain the full 5C on top of forcings. It's therefore quite nice explanation to have the climate amplifying the change rather than resisting it. On the otherhand if we assume clouds have a strong negative feedback and overall climate feedback is negative, then we will definitely fall short of explaining 5C warming. And it's not just temperatures lower than today, there is the Eemian interglacial that was warmer than the current one. And for some people there is also a medieval warm period and Holocene optimum "far warmer" than present (grapes growing in siberia..vikings dying of heat exhaustion, etc), how does that tie in with a climate that resists such changes? "For example there was 5C warming from glacial maximum to the current interglacial. If that was despite the climate resisting change, then just how big a change was required!"
You need to understand chaos theory SoCold - it may not require a large change - just a change at the right time at the right place. Like giving the climate an ankle throw.
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Post by william on Mar 14, 2010 19:53:18 GMT
Socold, The paper you quote is a review paper that has no scientific observations (data) or evidence to support the hypothesis that the planet’s response to a change in forcing is positive rather than negative. The paper you quote states the response could be negative or positive. There is no data in that paper. There is in the review paper an appeal that an unstable system is required to explain the glacial/interglacial cycle. (I will address the glacial/interglacial cycle in my next comment.) Lindzen’s and Choi’s satellite data shows the planet’s response is negative. Negative feedback is used in human constructed systems to stabilize the system. A system with negative feedback will resist external forcing changes positive or negative. Did you listen to Lindzen's lecture where he discusses the Faint Sun Paradox? The solar output was roughly 20% to 30% less in the past. Negative feedback helps to explain why the earth's oceans were not frozen when the sun's solar output was less. If the feedback was positive CO2 levels would have need to be 3 times current atmospheric. That is physically not possible. Atmospheric CO2 levels in the past has been high when the planet was cold and low when the planet was warm. That is only possible if the planetary feedback response is strongly negative. (ie. Planetary cloud cover decreases to stop the planet from cooling and increase to stop the planet from warming. Planetary cloud cover regulates planetary temperature which stops the oceans from freezing or the from boiling away. The paleoclimatic data strongly supports negative feedback not positive. As Lindzen and Choi notes in their paper a system with positive feedback if run long enough will continue to increase. The climate during the Holocene is stable. The biosphere expands when the planet is warmer and contracts when it is colder. During the glacial phase a 1/3 of the Amazon rainforest becomes savanna. The planetary precipitation decreases when the planet is colder and increases when the planet is warmer. www.iac.ethz.ch/people/knuttir/papers/knutti08natgeo.pdfSocold's linked paper: www.leif.org/EOS/2009GL039628-pip.pdfLindzen's paper is based on observation and analysis. The planet's response to an increase in forcing is negative. If the planet's response is zero everyone agrees the planet will warm 1.2C. To get the an increase in temperature of 1.5C to 5C the planet's response must be massively positive. There is no scientific data to support massively positive feedback.
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Post by william on Mar 14, 2010 20:13:45 GMT
In reply to Socold's comment: I agree the glacial/interglacial cycle requires an explanation. The glacial/interglacial cycle is caused by a change in the cloud feedback mechanism. Look at how the planetary glacial/interglacial cycle has changed over the last 3 million years. Defer agreeing or disagreeing with the competing mechanisms. There is now detailed precise paleo climatic data that shows evidence of massive abrupt change, not gradual climate change. The abrupt climate change is cyclic. Cyclic abrupt massive climate change requires an explanation. It is caused by an external cyclic forcing event. rsai.geography.ohio-state.edu/courses/G820.01/WI05%20climate%20history/2002PA000791.pdfThe problem in this discussion is we are missing the massive abrupt forcing change that causes the glacial/interglacial cycle and cyclic abrupt climate change. Interglacial periods have all ended abruptly, not gradually. The glacial/interglacial cycle is caused by massive solar coronal mass ejections that force the geomagnetic field. Geomagnetic excursions correlate with the end the last interglacial periods. Past abrupt cooling periods correlate with secular geomagnetic field changes during which time the geomagnetic field tilt abruptly changes. (There have been 10 such archeomagnetic jerks in the last 5000 years.) There are small, medium, larger, and super large cyclic solar coronal mass ejections. When the geomagnetic field is tilted (different angle from the planet's rotation) there is higher GCR at specific regions of the tropics which causes tropical cooling. (Confusing from a paleoclimatic analysis standpoint as there can be both tropical cooling and higher latitude warming. Can you see how the mechanism works?) The CME strike will always eventually be positively or negatively integrate by the liquid core to increase or decrease the intensity of the geomagnetic field depending on which hemisphere the strike occurs. The next strike will occur in the Southern Hemisphere. A Southern Hemisphere strike will decrease the intensity of geomagnetic field. All the data indicates the biosphere expands when it is warmer. The interglacial cycles in the past have lasted on the average 10,000 years. This interglacial cycle is 12,900 years old if it is timed from the massive Younger Dryas cooling period. During the Younger Dryas abrupt cooling period North America cooled 18F in 15 years. New England went from three months of winter to 11 months of winter. The Younger Dryas event is cyclic. There is geomagnetic excursion that correlates with Younger Dryas event. There are burn marks all over the Northern Hemisphere that precisely correlate with the occurrence of the Younger Dryas. The timing of perihelion and the tilt of the planet’s axis determine the how the geomagnetic field intensity is altered and the hemisphere where the strike occurs. The solar super massive CME are cyclic. There resultant depends on orbital parameters as well the position of the continents, whether there are or are not ice sheets on the planet’s surface. (ice is an insulator). The solar magnetic cycle has been currently interrupted. The super massive CME ejections are very, very, large events. Somewhat ironically the AWG crowd by trying to “protect” the biosphere and humans by manipulating the current temperature data, the discussion of published papers, and the media concerning what has happened in the past and what is currently happening.
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Post by william on Mar 14, 2010 20:30:25 GMT
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Post by william on Mar 14, 2010 21:00:29 GMT
Volcanism and millennial climate change The writers of these papers show that abrupt climate change correlates with abrupt increases massive volcanic activity. The massive solar (coronal mass ejections) CME cause the super volcanoes (the occurence of super volcanoes correlates with deep solar minimums.) in addition to abruptly changing the geomagnetic field. (Think of the amount of energy required to change the geomagnetic field. These are very powerful concentrated strikes on the planet's surface.) Volcanic eruptions cool the planet for a few years. The planet was cold after the Younger Dryas event for a over a thousand years. It is the change in the geomagnetic field (tilt and intensity) that causes the long term climatic change that cools or eventually warms the planet. The geomagnetic field intensity is 5 to 6 times greater during the interglacial period. www.pnas.org/content/101/17/6...#otherarticlesadsabs.harvard.edu/abs/2002AGUFMPP61A0298ASimultaneous Volcanic Eruption Paradox
It appears the writers of these papers are only capable of thinking beyond their favorite hypothesis. i.e. They do not read or think outside of their specialization. Perhaps they are incapable of asking questions. How rare are geomagnetic excursions? Doesn't it seem odd that 5 volcanoes from disconnected magma chambers would simultaneously erupt and capature a geomagnetic field excursion? Perhaps the geomagnetic excursion and the simultaneous eruption of five volcanoes with disconnected magma chambers has the same cause. Why is the author of the paper that notes there is correlation of cyclic cooling events with massive volcanic eruptions not capable of connecting the deep solar magnetic cycle minimum which also correlates with the millennium cooling event with the abrupt change in volcanic activity? www.agu.org/pubs/crossref/2006/2006GL027284.shtml
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Post by sigurdur on Mar 14, 2010 21:21:22 GMT
William: Thank you for the great thoughts. I had read a couple of those papers. What all of this shows is how LITTLE we truely do understand climate. For anyone to think that the GCM's have it covered have their heads covered. So much more to learn, and potentially so little time to learn it. Unless......we are lucky and have made a skip.
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Post by socold on Mar 14, 2010 23:12:30 GMT
Socold, The paper you quote is a review paper that has no scientific observations (data) or evidence to support the hypothesis that the planet’s response to a change in forcing is positive rather than negative. It's a review of climate sensitivity estimates, it isn't supposed to contain data. The papers it cites contain the data. Those estimates form the evidence for climate sensitivity and many of those estimates are based on observations (data). Come on! The paper says a lot more than that, it even has a very clear diagram of probability distributions based on the studies reviewed. It doesn't simply say response could be negative or positive, it quite clearly shows that the estimates to date firmly put high climate sensitivity as most likely and low climate sensitivity (let alone net negative feedback) is unlikely. The data is in the studies it references. For example estimates based on the instrumental record use data from the instrumental record. Studies estimating climate sensitivity from the last glacial maximum use data from ice cores. Or perhaps it's the high amount of co2 in atmosphere back then. I do recall an argument complaining that in the distant past co2 was very high but temperature was as today. Well the faint sun would explain that would it not? co2 levels were more than 3 times current levels in the past. Back 500 million years or so co2 levels were a few thousand ppm. I am interested to know what period this was. There was some interesting news recently about snowball earth and the possibility of the planet being largely covered by ice. www.sciencedaily.com/releases/2010/03/100304142228.htmGiven the decrease in absorbed solar radiation if the earth is largely covered in ice, how do you get the earth out of such a locked state if feedbacks are negative? On the contrary - the review paper I posted shows the distribution of paleoclimate data based estimates - they overwhelmingly show positive feedback. See the part "proxy data from millions of years ago" and "last glacial maximum, data" for example. Positive feedback just amplifies any change. It doesn't keep going, it just peaks higher. With higher feedback the glacial/interglacial transition could have been 10C globally rather than about 5C for example. With lower it could have been just 2C. Evidentially there is or all those studies would have managed to rule it out.
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Post by socold on Mar 14, 2010 23:39:02 GMT
You need to understand chaos theory SoCold - it may not require a large change - just a change at the right time at the right place. Like giving the climate an ankle throw. The earth cannot sustain elevated temperatures for thousands of years without it absorbing additional energy. Low climate sensitivity means you need a lot more absorbed energy to raise temperature by 1C than if climate sensitivity was high. For example the glacial - interglacial cycle shows about 5C warming, if climate feedback is negative then you need about 20wm-2 forcing. That's a lot. The co2 increase from glacial to interglacial provides a forcing of about 2.4wm-2. The orbital forcing provides even less. So there is a missing piece of the puzzle of where the bulk of the 20wm-2 forcing comes from if climate sensitivity is negative. On the otherhand if climate sensitivity is positive - about 3C warming per doubling of co2, then co2 alone would provide 40% of the elevated temperature of interglacial periods.
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