Arguments
Recent Comments
Prev 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 Next
Comments 121751 to 121800:
-
Jeff Freymueller at 16:44 PM on 30 March 2010Greenland's ice mass loss has spread to the northwest
Well done again, John. I came across this paper over the weekend and thought of alerting you to it, but got involved in other things. Readers might be interested to know that over the last 3 summers, an extensive GPS network has been established all over Greenland, the new GNET GPS network. Quite a few new sites have been built in Antarctica as well. Over the next few years, the change in ice mass will be weighed very effectively by GPS. -
Tom Dayton at 16:43 PM on 30 March 2010Climategate CRU emails suggest conspiracy
kblood, the raw data were not lost by the organizations that are actually responsible for collecting and keeping them. The U. of East Anglia was only one of many consumers of those data. The data still are available to the U. of East Anglia, and even to, say, you! A big list of links to the data sources has been compiled at RealClimate, for your convenience. -
Jeff Freymueller at 16:30 PM on 30 March 2010Greenland's ice mass loss has spread to the northwest
#5 Arjen, you might want to check out this post at RealClimate by Stefan Rahmstorf, which involves one way to extrapolate accelerating sea level rise. Your idea to extrapolate is interesting, but I agree with John that it is dangerous to extrapolate too far. Nevertheless, here it is, based on Velicogna (2009). After 30 years, the rate of sea level rise would be faster than the present by 5.1 ± 1.5 mm/yr if the present acceleration in mass loss from Greenland and Antarctica continues. If we take the present rate of sea level rise as 3 mm/yr (approx altimetry rate), then after 30 years the total rise would be 16.5 cm instead of 9 cm (linear extrapolation). If you are even more bold and extrapolate out to 100 years, you would get 1.15 meters of sea level rise. Take that with a very large grain of (sea) salt, but that number lies within the range of what Vermeer and Rahmstorf (2009) and others have gotten from fitting an empirical relationship between past temperature and past sea level. Here are the conclusions from Velicogna (2009): "We showed that a detailed analysis of the GRACE time series over the time period 2002–2009 unambiguously reveals an increase in mass loss from both ice sheets. The combined contribution of Greenland and Antarctica to global sea level rise is accelerating at a rate of 56 ± 17 Gt/yr2 during April 2002–February 2009, which corresponds to an equivalent acceleration in sea level rise of 0.17 ± 0.05 mm/yr2 during this time. This large acceleration explains a large share of the different GRACE estimates of ice sheet mass loss published in recent years. It also illustrates that the two ice sheets play an important role in the total contribution to sea level at present, and that contribution is continuously and rapidly growing." -
GFW at 15:56 PM on 30 March 2010The human fingerprint in global warming
@62 johnd. There is ongoing flow in and out of the atmosphere at the same time. Plants take up CO2, animals and decomposition release it. Prior to the industrial revolution you would have found each of the flow pairs air<->sea and air<->plants/animals/ground to be in near perfect balance. In the modern world there's a net flow from burning fossil fuels into the air, and a net flow about half that from the air into the ocean. Therefore you will find a *slight* average gradient with higher concentrations over land and lower concentrations over water. (And of course higher gradients very close to point sources like smokestacks.) Nonetheless, the term "well mixed" is still accurate. On your last point, while it's true that hot air rises and cool air sinks, that applies to gases in bulk, not so much individual molecules. When an IR absorbing molecule absorbs a photon from the ground, it either re-radiates it (randomly in any direction, thus half "down") fairly quickly, or it transfers energy to the other molecules (mostly N2 and O2) around it through thermal motion. So all the air warms up, not just the CO2 ... so the atmosphere remains well mixed, not separating out by molecular type. -
kblood at 15:33 PM on 30 March 2010Climategate CRU emails suggest conspiracy
One thing is how it seems these emails mentions intentions to make graphs fit the claims of Co2 and global warming, another thing is to loose the raw data? Woops, that was unfortunate. Which basically takes just about all the evidence on this website, and invalidates it. Seems it is back to the drawing board. At the moment, too much of the world do not accept the lack of raw data, and the whole thing is being looked looked into. -
johnd at 15:23 PM on 30 March 2010The human fingerprint in global warming
By saying not well mixed I mean that there must be either a constant movement of CO2 towards the surface to replace the CO2 stripped from the atmosphere, or else it tends to congregate closer to the the surface. If CO2 is such an efficient absorber of IR radiation should it not have a tendency to rise away from the surface rather than gravitate towards it. Water vapour only returns to the surface once it has dissipated heat previously absorbed. Does CO2 function differently? -
yocta at 15:19 PM on 30 March 2010The human fingerprint in global warming
RE: johnd #57 Play around with this java animation of particles in two different boxes to see what is meant by gases mixing. At room temperature a single gas molecule undergoes approximately 10 to the power of 10 collisions per second so the diffusion of the gases happens very quickly. Whilst the atmosphere is not a simple box and there are more forces at play this helps us understand what is going on. Definitely watch the other animations on John's page that Tom Dayton linked to. -
Arjen at 15:03 PM on 30 March 2010Greenland's ice mass loss has spread to the northwest
I understand that you are wary of the extrapolation. I am too, that is why I "only" limited it to 30 years, which is stretching it, even in my standards. I will not discredit any paper, simply because I do have not the necessary background to do so in any constructive sense. I do however doubt the overall accuracy of the predicted sea level rise, because in so far I was able to follow it, it has mostly been on the conservative side. Since the current ice loss in in both the Arctic and Antarctic is going faster than almost all of the projections, that would lead to the conclusion that maybe our long term prediction might be off as well. An other factor is, in so far as I have read and am aware of, is that our current understanding of ice sheet dynamics and glacier flows is not that well know as we would like and problematic in some aspects. Coupling that to the astonishing rate that the glaciers are retreating and that some mayor glaciers might not be so protected or constrained as we thought they were, to me gives enough reason to do a re-evaluation of current projections or at least do a major worst case scenario exercise. -
Philippe Chantreau at 14:23 PM on 30 March 2010A peer-reviewed response to McLean's El Nino paper
I missed the previous reference to Lewandowsky, so I did not realize that my previous comment did not introduce anything new, except a link to his piece. It's every bit as worthy of reading as McLean's complaining. Jonicol, you complain, unjustifiably, about people not using their real names, yet don't reveal yours? -
Philippe Chantreau at 14:16 PM on 30 March 2010A peer-reviewed response to McLean's El Nino paper
Nobody disputes that ENSO has a major influence on global temps variations. McLean et al can not use their analysis to even remotely suggest that it can explain any trend since their analysis in essence removes the trend. That's all there is to it. The tiny, sleazy "perhaps" in the conclusion would have been enough to reject the paper. As far as the right to respond, the buck stops when the bulls**t becomes too glaringly obvious. Science journals do not have to endure that kind of nonsense. Here is an Australian's take on this all McLean fiasco: http://www.abc.net.au/unleashed/stories/s2858332.htm He describes the all thing very well. -
Arjen at 14:10 PM on 30 March 2010Greenland's ice mass loss has spread to the northwest
If you extrapolate the current ice loss trends from the Arctic and Antarctic for about 30 years, which are accelerating, what kind of sea level rise would that generate and how would that compare to the current maximum projections for 2040? I have a nagging feeling that they might be above the current maximum predictions that would lead to a 2 meter sea level rise. Other questions, what would constitute a collapse of one of the ice sheets? And do you think there is a failing mechanism for an ice sheet that would lead to collapse? If so, what kind of thing are we looking for. Because of my job in coastal engineering, I'm very interested in sea level rise. Even a one meter rise would lead to a mind boggling amount of problems to current coastal structures. Let alone if we are confronted with a 2 or more meter rise.Response: "If you extrapolate the current ice loss trends from the Arctic and Antarctic for about 30 years, which are accelerating, what kind of sea level rise would that generate and how would that compare to the current maximum projections for 2040?"
I'm wary of statistical extrapolations of the current accelerating trend of ice mass loss. The reason is there are physical constraints on how fast the glaciers can move so one imagines (hopes) eventually the rate of ice mass loss might stabilise. Note - that's the rate of ice mass loss that might level out - I'm not saying mass balance will stabilise. Therefore papers like Pfeffer 2008 are useful in that they look at the physical constraints of Greenland's glaciers, leading to an estimated sea level rise of 1 to 2 metres by 2100. -
Tom Dayton at 14:09 PM on 30 March 2010The human fingerprint in global warming
johnd, in addition to the excellent links yocta gave you, see "CO2 Measurements are Suspect". -
muoncounter at 14:04 PM on 30 March 2010Greenland's ice mass loss has spread to the northwest
Nicely written. Yet another integration of independent data sources pointing to the same thing. GPS, gravity and altimetry would be enough to convince a literate person that the northern hemisphere is in deep trouble -- and that's without using any of the so-called controversial temperature data! (Of course, temperatures also say the same thing). And here's another connection from a recent study of caves in the southwestern US. "Both research teams found that climate in the Southwest oscillated rapidly between wet and dry as the North Atlantic cooled and warmed between 50,000 and 10,000 years ago. Their findings reinforce computer model predictions of similarly abrupt climate change during the coming century, as emissions of greenhouse gases, such as carbon dioxide, heat the atmosphere." -
Philippe Chantreau at 14:04 PM on 30 March 2010Is the science settled?
Shawnet, I'm wondering what your point is too. O large scales, RH tends to remain within certain limits, so, averaged over a global scale, you can not cram more WV in the air than what it will take at a certain temp. Whatever is on top of that will soon rain out. In addition, for your assumption (more water condensing) to materialize, it is necessary for the air to cool below its dew point. Perhaps that will tend to happen as much, or more, or less. Even if it is more watedr condensing than a at lower temps, all it means is a better chance for droplets to become heavy and rain down (less residence time for the clouds to reflect sunlight), and also more latent heat release from condensation. The energy does not go away. That points to possible more frequent heavy precipitation/violent weather but other than that, what? Wild speculation used as a stepping stone to grasp at straws, in order to demonstrate, what exactly? -
Tom Dayton at 14:03 PM on 30 March 2010The human fingerprint in global warming
johnd, the well-mixed state of CO2 is an observed, empirical, fact. Not theory. Not based on "computer models." -
Stuart at 13:59 PM on 30 March 2010The human fingerprint in global warming
@johnd #57: I find it difficult to understand exactly what you're saying here. You say you find it difficult to accept that CO2 is well mixed in the atmosphere, but go on to give a rather convincing argument that it is well mixed in the atmosphere. The very concepts of temperature and pressure in gases are closely tied to their constant motion around the atmosphere. Through this constant motion, if you release a certain volume of gas in an enclosed space, it will quickly diffuse through the whole space and end up well mixed with whatever gas was there to begin with. If you add or subtract CO2 at the earth's surface, it quickly mixes with the entire atmosphere by much the same process. -
johnd at 13:40 PM on 30 March 2010The human fingerprint in global warming
re yocta at 11:33 AM on 30 March, 2010, I find it difficult to accept that CO2 is well mixed in the atmosphere. Given the amount that is sequestered by plants and animals, or absorbed by the oceans, there must be some mechanism that causes CO2 to be driven to the surface where it is stripped from the atmosphere. Given plants are closer to CO2 deprivation rather than being able to access their optimum amount of CO2 they must be stripping CO2 as it becomes available. So is it just air movement that causes it to be replenished, or is there some other force that causes CO2 to naturally gravitate to the surface. Every molecule of carbon locked up as fossil fuels only got there by descending to the surface whatever the reason they were in the atmosphere in the first place. -
Andy Skuce at 13:02 PM on 30 March 2010Greenland's ice mass loss has spread to the northwest
So, it seems the bedrock in coastal Greenland is isostatically rebounding faster than global sea level is rising. Based on recent headlines in the popular misrepresenting climate science, can we expect to see this reported as; "Relative sea level falling at an accelerating rate in Greenland due to climate change"? You read it here first ;) -
michael sweet at 12:51 PM on 30 March 2010Greenland's ice mass loss has spread to the northwest
Good post. It is interesting to see these rapid changes in the ice sheet. What will this look like when it is all linked together in the next IPCC report? Last paragraph typo: pointing painting (delete pointing)Response: "What will this look like when it is all linked together in the next IPCC report?"
We'll have to wait till 2013 to find out.
Thanks for the typo alert. -
GFW at 12:51 PM on 30 March 2010The human fingerprint in global warming
@52 Martin. Well, your English is infinitely superior to my Swedish. I agree with you that we've added carbon to the "fast" reservoirs - the air, the (non-deep) ocean, plants, animals, and the soil. However through agriculture we basically control the latter three, so *almost* all the carbon we've emitted adds to the air and the ocean. (We *could* have stored more in plants if not for rainforest destruction, the pine beetle, etc.) I also agree that we've probably sped up some of the carbon cycle flows. The argument for a constant fraction going into the ocean is like this: If I take a sealed container containing salt water and an oxygen-nitrogen atmosphere, and then I inject x amount of CO2, an equilibrium will be reached with some fraction of the CO2 dissolved in the water and the rest in the air. Holding temperature constant, if I inject another x (for a total of 2x) CO2, the equilibrium will divide the CO2 into the same fractions as before: there will be twice as much in each reservoir. On our planet, there are (at least) two major changes from my little thought-laboratory. Carbon can slowly rain out to the ocean floor in the form of dead organisms, and the temperature is not constant. I would suggest that the rain-out rate is too slow to be apparent on human timescales, and that we haven't *yet* increased the temperature of the ocean enough to significantly decrease the solubility of CO2. Thus, as long as those approximations hold, the "airborne fraction" will remain constant. No, there's no particular reason for the airborne fraction to be close to 50%. It just happens that it is. If we had a dryer planet with smaller oceans, the airborne fraction would be higher (but still constant as long as the above approximations hold). -
yocta at 11:35 AM on 30 March 2010The human fingerprint in global warming
Oops my post is slightly pear shaped. I meant peer reviewed -
yocta at 11:33 AM on 30 March 2010The human fingerprint in global warming
RE# Tarcísio #48 You said:As the CO2 from the combustion, it is logical that he, for his temperature, to go position in the upper layers of the atmosphere. What I think you are referring to is how well mixed the CO2 is in the atmosphere. Alexandre is correct saying that the CO2 is well mixed. I suggest you read John's post here as this discusses further what you are referring to. As an example of pear reviewed research into this areaChahine et al 2008 has a study tracing to trace the sources and sinks of CO2 and if I quote from their conclusion: We have shown that CO2 emissions by surface sources can be observed in the mid-troposphere and how they are transported around the globe. You can also watch a NASA animation here of CO2 concentrations varying on the order of 20ppm in the mid-tropospheric. This visualization shows how it really doesn't matter where the CO2 came from, given enough time. To better quantify the movement of CO2 through these various sinks and sources the Japanese have a satellite called GOBI in orbit right now. -
Alexandre at 10:03 AM on 30 March 2010The human fingerprint in global warming
Tarcísio #48 I am no expert, but the temperature of the CO2 at the moment of its release does not seem relevant to the carbon cycle. The molecules will be mixed up and at the same temp as the surrounding atmosphere within a few minutes. -
Martin Hedberg at 08:25 AM on 30 March 2010The human fingerprint in global warming
@50 GFW. Forgive my English, I am a Swede. I think I didn't express myself clear enough (#49). As the partial pressure of CO2 in the air has increased, so has the diffusion from air to ocean and biosphere. When our emission were smaller, some years ago, so was the partial pressure of CO2 in the atmosphere and hence the diffusion. (However the picture also includes sea-surface temperature, phytoplankton and more). It does not contradict what you call my prediction (However I would rather call it a thought experiment than a prediction). The carbon cycle is defined as flows of carbon, measured in mass (typically Giga tons). As we started to emit carbon, the carbon cycle changed. Not only the reservoars changed, but also the flows. Question: How could there be some law of nature that 50% of our emissions were to be removed from the atmosphere by oceans and biosphere? Put another way: If we doubled our emissions tomorrow, why would the oceans and biosphere increase there removal with the same increment? I still conclude that humanity has managed to keep the emission (by coincidence) about twice as large as the the net extra amount of CO2 being removed by ocean and biosphere. Thus the (about) 50% is not a constant. It can change, either if we change our emissions or if one or more parts of the carbon cycle changes. /Martin -
Doug Bostrom at 08:05 AM on 30 March 2010The human fingerprint in global warming
JohnD, regarding historical cloud data the same folks who recovered beautiful pictures of the Moon from ancient Lunar Orbiter tapes are now doing a repeat performance w/old Nimbus weather satellite data stretching all the way back to the 1960's. They've already turned out some lovely product, some sample shots available here via NSIDC.
-
GFW at 06:25 AM on 30 March 2010The human fingerprint in global warming
@35 Stuart. Thanks! per meg relative to original is likely the correct interpretation. I made two errors that canceled to about a factor of two. @49 Martin. I don't think you're right about that. I believe the short term ocean sink is closer to a simple diffusion equilibrium between the atmosphere and the upper (well mixed layer) of the ocean. That would explain why it's been a roughly constant fraction (even when human emissions were half what they are now, contradicting one of your predictions). Then the remaining fraction has to remain in the air until slower processes remove it (organic "rain" to the bottom of the ocean, geologic burial, etc.) @42 Chris. What I just said to @49 Martin may be a useful way to think about it, but it's a considerable simplification. The IPCC AR4 saysAbout 50% of a CO2 increase will be removed from the atmosphere within 30 years, and a further 30% will be removed within a few centuries. The remaining 20% may stay in the atmosphere for many thousands of years.
which is a more nuanced statement based on a more complete understanding. -
Martin Hedberg at 05:31 AM on 30 March 2010The human fingerprint in global warming
To Chris G #42. I may not be an answer to your question, but worth mentioning: It is no law that it should be about half of our emissions, its more of a coincidence that we have increased the emission to be about twice the amount being absorbed by oceans and biomass. If we reduced our emissions by 50% tomorrow, about the same amount would be absorbed and hence the amount of CO2 in the atmosphere would stay the same. If we doubled our emissions tomorrow, only 25% would be absorbed. Natures capacity to absorb our emissions should rather be measured in tons (mass) than in percentage. Preindustrial carbon-cycle was smaller than the carbon-cycle is today. The absorption in water and biomass has increased as our emission has increased. /Martin -
Alexandre at 05:30 AM on 30 March 2010Was there a Medieval Warm Period?
I´d like to know more about data infilling in this kind of reconstruction. Mann´s paper (at least this one) does not say much about it. Can someone give me some research tip? -
Tarcisio José D at 05:14 AM on 30 March 2010The human fingerprint in global warming
I question the assertion that the relationship c13/c12 may indicate that the increase of CO2 in atmosphere is the result of burning fossil energy. As the CO2 from the combustion, it is logical that he, for his temperature, to go position in the upper layers of the atmosphere. The absorption of CO2 by oceans and plants tend to dominate the CO2 released by decomposition of organic matter (CO2 cold). -
Riccardo at 04:52 AM on 30 March 2010The human fingerprint in global warming
johnd, it's not the (known) effect that matters but its claimed global trend which should drive the frequency. -
johnd at 04:05 AM on 30 March 2010The human fingerprint in global warming
Riccardo at 07:46 AM on 29 March, 2010, as far as I know there is no data regarding cloud cover, and certainly no historical data which is most unfortunate. The relationship of cloud cover and hotter days and warmer nights is as well understood as is the relationship of standing in the rain without an umbrella and getting wet, but whether or not anyone has been able to measure the effects of either and translate that into some objective measurement does not alter the reality of either. -
Steve L at 04:01 AM on 30 March 2010The human fingerprint in global warming
Stuart @35, go to the link I posted @ comment 4. I think you'll find that per meg means change relative to Nitrogen. Ah, now I realize that my link doesn't work (why?), so here I'm going to risk raising our host's ire by posting a url: http://scrippso2.ucsd.edu/how-does-one-relate-ppm-and-meg-units%3F Here is the url I tried to link previously: http://geoweb.princeton.edu/people/bender/lab/research_o2n2.html Sorry John. So, if 4.8 per meg oxygen = 1 ppm, and eyeballing indicates about -200 per meg oxygen (so 42 ppm) and about +25 ppm CO2, it looks like oxygen has dropped quite a bit more than CO2 has increased. As others have indicated, though, we know quite a bit of CO2 has gone into the ocean and soils. If 50% of CO2 or less remains in the atmosphere, then we would expect a decline of at least 50 ppm oxygen. However, because of ocean warming, oxygen is being released to the atmosphere, and therefore we see a decline of only 42 ppm. I hope that's correct. -
Chris G at 03:18 AM on 30 March 2010The human fingerprint in global warming
Thanks Tom, my take-away point from the links is mainly that the sinks that absorb CO2 quickly, in aggregate, also tend to release it quickly, and that the sinks which result in a long period of sequestration are also slower acting on the absorption side. That's pretty much where I was going, but the links helped me get there. Now I'm thinking about ocean cycles and speculating that there may well be 'echos' of CO2 content in the atmosphere as water that went to depth during a period of high atmospheric CO2 content resurfaces. I wonder what that would look like on a graph. -
Tom Dayton at 02:22 AM on 30 March 2010The human fingerprint in global warming
Chris G, there are multiple sinks and sources of CO2, and they operate on different time scales. Click on the links and look at the pages I point to in my comment on another thread. I'm not sure those will answer your question, but if not, say so. -
Chris G at 01:56 AM on 30 March 2010The human fingerprint in global warming
I'm having trouble reconciling a couple of things and I'm hoping someone here can help me with it. The fraction of CO2 that humans emit annually that also stays in the atmosphere is around 40-50%. (Some studies indicate a possible change in the fraction, and some do not, but that is not the point I'm having trouble with.) The CO2 that we put in the atmosphere takes hundreds of years to be absorbed by natural processes. So, my problem is that, if around half of human emissions is absorbed quickly, and that has been the case for most of the time that we've been adding to the CO2 content significantly; why does it take so long to absorb the rest? Is it the case that surface layers on land and sea quickly reach an equilibrium with the atmosphere, but that turning over the land takes, umm, a very long time, and turning over the ocean layers takes hundreds of years? -
mikel01 at 23:33 PM on 29 March 2010Does record snowfall disprove global warming?
Thanks for the response, I went and checked the link to Roy Spencer's blog, I am glad for your ability to put forward the layman's description :). A bunch of questions arise on his content to gain more understanding, but unfortunately not enough time to go and understand this in detail, like most things. Thanks, keep up the good work. -
Arkadiusz Semczyszak at 23:08 PM on 29 March 2010The human fingerprint in global warming
P.S. Thank you John for the Polish version ...Response: Don't thank me, thank Irek Zawadzki who did the translation :-) -
Arkadiusz Semczyszak at 23:07 PM on 29 March 2010The human fingerprint in global warming
This evidence (John C.) is very logical and precise. But not quite. Skeptics still have a lot of work yet. Two examples: ice cores and temperature of the lower stratosphere. 1st Data from ice cores. - even if we reject all 19 charges Jaworowski (http://www.someareboojums.org/blog/?p=7) it will last us - being for decades - "diffusion in firn" - smoothing results from ice cores. - results from the ice core (to 1958) do not have any data to confirm the land. Only data from the cores from the seabed (foraminiferal, Spongia - low resolution in time and are often subjected to high pressure - the slow dissolution of carbonate), confirm the data from the cores. - Data on the land of ancient CO2 concentrations in the atmosphere: delta 13C, ratio of C3/C4 plants, stomata index - they are fundamentally different from data from ice cores. Yes, we can say that these proxies affect temperature, humidity, precipitation. However, - these vectors function; for example, the stomatal index - in a different direction than for the C3/C4 and delta 13C. However, if we compare Graph: "Speleothem evidence for changes in Indian summer monsoon precipitation over the last 2300 years" on those page: http://people.ku.edu/~lgonzlez/ (Kansas University); whit this graph: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC129389/figure/f2/, we see the same pattern of all 3 proxy changes over time. [...] E.g. this paper: "Climate and CO2 modulate the C3-C4 balance and _13C signal in simulated vegetation" Flores et al. 2009, Clim. Past Discuss., 5, 1187–1213; proves that the role of humidity is negligible here, as well as (probably) the temperature. The delta 13C, C3/C4 (density of stomata?) determines only the concentration of CO2. 2nd After each eruption "into the stratosphere," the lower stratospheric temperature increases (http://omsriram.com/GlobalWarming_files/Global19.jpg.). Despite an increase in CO2 concentrations in the atmosphere. Since the explosion of Mount Pinatubo, over 15 years throughout the stratosphere the temperature continues to rise (http://www.acd.ucar.edu/Research/Highlight/strat-cooling.jpg) ... -
Ned at 22:28 PM on 29 March 2010What CO2 level would cause the Greenland ice sheet to collapse?
gallopingcamel writes: You say that NOAA is not throwing away station data. There is a simple way to test this statement. I have emailed the Canada Weather Office to ask them what station data they are currently providing to NOAA, NASA and UEA/CRU. Just out of curiosity, would you mind posting the text of the email you sent? I'm curious about how you worded it. You should be aware that there are actually around 100 stations in Canada north of lat. 60 that have contributed data to GHCN in the past. The problem is that only four of those have been updated with new data since 2008. -
Ned at 22:03 PM on 29 March 2010A peer-reviewed response to McLean's El Nino paper
jonicol, here's a quote from the abstract of McLean et al. 2009: The results showed that SOI accounted for 81% of the variance in tropospheric temperature anomalies in the tropics. Now, is it your understanding from that sentence that McLean et al. showed: (a) SOI explains 81% of the variance in tropospheric temperature anomalies in the tropics full stop, or (b) SOI explains 81% of the residual variance in tropospheric temperature anomalies in the tropics after removing the long-term trend, or (c) something else? It seems to me that McLean have been rather coy about this. It also seems to me that (b) is the correct answer. There is only a single reference to "81%" in the McLean et al. manuscript, in paragraph 19: [19] Using the same technique of derivatives with data exclusions for periods of volcanic activity the line of best fit is dLTT(trop) = -0.0311*dSOI + 0.0252, [Equation 3] where R2 = 0.81. Note that that regression model is based on the derivative data, not the raw data. Given this, what do you think about the following remarks from the Conclusion of McLean et al. 2009? We have shown that the Southern Oscillation is a dominant and consistent influence on mean global temperature. [...] [This] study has shown that natural climate forcing associated with ENSO is a major contributor to variability and perhaps recent trends in global temperature There are two obvious problems here. First, as you yourself emphasized, McLean et al. did not analyze global temperature data, despite the repeated reference to "global" in their conclusions. Second, as shown in Paragraph 19, their calculations were done on a transformed version of the temperature data from which the long-term trend had been removed. Thus, it is not possible to draw any conclusions from their work about whether SOI is a "dominant" influence or whether it is a contributor to "trends in global temperature." A paper demonstrating that SOI has an effect on short-term interannual climate variability would not be very interesting, as everyone already knows that. A paper demonstrating that SOI has an effect on long-term trends in climate would be very interesting, but McLean et al. didn't do that. Finally, jonicol writes: Why do all these criticisms come from un named authors - are people ashamed to show their real name because they have no confidence in what they are saying. The authors of Foster et al. 2010 are all listed at the top of the paper, along with their institutional affiliations. -
Ned at 20:49 PM on 29 March 2010How we know global warming is happening, Part 2
Okay, here are the trends 1979-present for all the data sets: UAH: +0.132 HADCRUT: +0.156 RSS +0.156 NCDC: +0.162 GISS: +0.163 Amusingly, if you round them to two places, all except UAH are 0.16. In any case, there's not exactly a huge gap here. -
jonicol at 20:48 PM on 29 March 2010A peer-reviewed response to McLean's El Nino paper
Albatross You seem unable to understand that the key graph in McLean et al. is Figure 7. This is a plot of the raw data (NOT differentiated data as claimed by Foster et al.) relating SOI, as defined in the paper, against the TROPICAL lower troposphere temperature (LTT)measured from the microwave emissions in the lower troposphere MSU in the band 20 degress North to20 degrees south - not the whole globe. However, since the sun is ocverheasd in the tropics, most of the energy causing higher temperatures on earth are exprienced in the tropics. The point made in McLean's paper is correct and is being totally, perhaps deliberately or if not ignorantly, misinterpreted. The AGU/JGR has broken a long tradition of the right of reply to any criticism of a published topic. This is no surprise in fact since McLean'spaper and the blocking of a reply to any critique by manipulating the editors and reviewers in JGR is openly discussed in the CRU emails recently released. John Nicol. P.S. Why do all these criticisms come from un named authors - are people ashamed to show their real name because they have no confidence in what they are saying. JNResponse: I've reproduced the Mclean Figure 7 graph here:
If you look carefully, you'll find that the top box uses RATPAC weather balloon data while the bottom box uses satellite MSU data. Eg - it's not one continuous datasets but two data sets spliced together. Most importantly, the mean values of RATPAC-A and UAH TLT data during their period of overlap differ by nearly 0.2 K. Splicing them together introduces an artificial 0.2-degree temperature drop at the boundary between the two.
The most curious feature of this graph is that the graph is split into different panels precisely at the splicing boundary. This obscures the difference between the weather balloon dataset and the satellite dataset. It's a misleading way to display a graph and yet is obviously effective in persuading people into thinking that the long term trend in ENSO correlates closely with the long term warming trend.
For the record, I don't hide my name nor does Stephen Lewandowsky. However, the people who really matter are the authors of Foster et al 2010 who are all named. -
Ned at 20:47 PM on 29 March 2010The human fingerprint in global warming
Bob Close writes: Where is the verified experimental or actual measurements to support this strange assumption, or its corollary that ongoing atmospheric increases in CO2 above 400-500ppm will automatically create a tip over effect into runaway spiraling catastrophic warming? "runaway spiraling catastrophic warming" seems a bit over the top, don't you think? Nobody is suggesting "runaway" warming a la Venus. Doubling CO2 will probably lead to around 3C of warming on average. The actual impacts of this will be negative enough, particularly due to amplification of the hydrologic cycle. -
jonicol at 19:54 PM on 29 March 2010A peer-reviewed response to McLean's El Nino paper
John Cook, Stephan Lewandowsky (ABC, Drum Monday, 29 March,2010), Foster et al. and others seem to be unable to read. The findings reported in McLean et al refer to the TROPICAL values of the MSU data, NOT to GLOBAL temperatures. By the Way, John is a very skilled computer scientist who has been working on climate science matters for about four years, in which time he has had the support of internationally renowned climate scientists such as Bill Kinninmonth, one time head of our own, Australia's BOM. John is enrolled as a PhD student and has started out well. It is a measure of the validity of his claims that so many interested persons have sprung out of the woodwork to criticise him and his work, which challenges the “consensus” without ONE single word of science to back up their arguments. Once upon a time, any one worth his scientific salt relished a controversy and welcomed criticism of his/her more than praise, because it made you think! Not any more it seems. Any challenge is seen as a threat to the comfort of conformal thinking – actually conformal unthinking! I have not yet looked up Cook's or Lewandowsky’s crededentials but have glanced through their articles in which they have both demonstrated their obvious inability to refute John McLean's arguments. The paper by Foster et al., which I have studied very closely, does nothing but present a mixture of first/second university theory of the Fourier Transform, including what they thought was a clever simulation – a few random numbers, a linear trend – looks impressive and oh so clever, but all quite well known and absolutely of no consequence here. McLean et al.'s taking of the first derivative ONLY to determine very nicely the seven month time lag shown in Fig 3 is perfectly legitimate and confirms other rougher and less accurate work as is appropriate in a paper of this nature and of this quality. The key graph, is their Figure 7, which Foster et al. have quite mistakenly claimed was detrended. No such thing. It is a plot of ENSO or SOI against the TROPICAL MSU data without any differentials being taken. As tudent in about grade 9 could see that from the caption! It just goes to show that many people who claim to be "scientists" are not only incapable of understanding science but also incapable of reading. As Dean of Science at an Australian University years ago, I used to be particularly interested in students ability in English, as it is a good measure of how well they will perform in science, even the hard sciences such as my own Optical gas spectroscopy and atomic physics and mathematics, geology and chemistry. A careful comparison of the plots in McLean's Figure 7 with other graphs in the paper shows immediately that the FORMER are differentials of the data time series shown in 7. John Nicol PhD (Physics) -
Stuart at 19:47 PM on 29 March 2010The human fingerprint in global warming
Oh, yes... I forgot about the role of burning hydrogen in my quick calculation. For long carbon chains, you get more oxygen going into carbon dioxide than water, so my calculations are in the ball park, but I'd be interested in seeing a slightly more detailed sum. -
thefrogstar at 19:27 PM on 29 March 2010The human fingerprint in global warming
John (or somebody),can you explain a bit more about the units in figure 3, and can we draw any conclusions from the implied stoichiometry ? If I postulate that a lot of carbon has come from methane (oil/gas field "flaring" or release from biogenic stores such as deep-sea clathrates or arctic perma-frost regions), rather than coal, then would or should (or might?) this show up in both ? By which I mean specifically: a) the carbon isotope ratio, and b) the amount of oxygen consumed: that is one atom of carbon will consume one molecule of O2, but one molecule of methane will consume twice as much O2. Does methane in deep-sea clathrates or "permafrost peats" show the same isotope distribution as "fossil-fuels" ? Also, when I look at figure 4, the stand-out effect is the large change in the methane absorption-band. For me, this is consistent with either release from "recent" biogenic stores (permafrost, peat etc) or possibly flaring-off from oil drilling. OK, I don't access to the numbers, but I presume that this issue has been addressed? Figure 1. The up-tick in atmospheric CO2 levels appears to predate the up-tick in CO2 levels attributed to humanity. Why so? I'm intrigued by the addition of data about cement manufacture, something I hadn't thought much about before. I would love to see the estimated numbers on that. -
Stuart at 15:09 PM on 29 March 2010The human fingerprint in global warming
On the other hand, I don't see the need to refer to the oxygen concentration at all. We know how much fossil fuel we're burning, we know how much oxygen it takes to burn it. Is the argument that the oxygen is not being replenished by photosynthesis? I guess I have heard some skeptics make that argument. -
Stuart at 14:55 PM on 29 March 2010The human fingerprint in global warming
GFW (and others who may have a more concrete answer): I'm guessing the value on the right is the fall in O2 concentration relative to the O2 concentration, rather than relative to the full atmosphere. Just eyeballing it, O2 falls by about 200 "per meg" and CO2 rises by about 20 ppm in the same period. Oxygen is about 20% of the atmosphere, so if my interpretation is correct, that's a fall of 40 ppm of the oxygen concentration for a rise of 20 ppm CO2. One oxygen molecule becomes one CO2 molecule during combustion and about half the CO2 ends up in the ocean, not the atmosphere... so the figures are looking remarkably consistent at this point. To anyone familiar with the numbers or papers, is this looking correct? I'm at a loss to explain how people still don't accept that about a third (and rising) of the CO2 in the atmosphere is there because of humans. -
yocta at 13:07 PM on 29 March 2010The human fingerprint in global warming
Interestingly enough Richard Alley by his own admission is not a climatologist but rather an Earth Scientist/Geologist like Bob -
Tom Dayton at 12:07 PM on 29 March 2010The human fingerprint in global warming
Bob Close, you asked how CO2 can be the main driver of global warming, when its direct effect is smaller than the effect of water vapor. Here is the thread where that is explained: Water vapor is the most powerful greenhouse gas. CO2 is the driver of other mechanisms that also increase temperature. Water vapor increase is one of those. Those same positive feedbacks would be driven by an increase in the Sun's radiance, if that were happening now. (But it's not; if anything, radiance has been decreasing since at least the 1970s and maybe as far back as the 1950s.) See climatologist Richard Alley's talk at the 2009 American Geophysical Union conference, "The Biggest Control Knob: Carbon Dioxide in Earth's Climate History."
Prev 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 Next
