Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.

Settings

Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup

Settings

All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Home Arguments Software Resources Comments The Consensus Project Translations About Support

Bluesky Facebook LinkedIn Mastodon MeWe

Twitter YouTube RSS Posts RSS Comments Email Subscribe


Climate's changed before
It's the sun
It's not bad
There is no consensus
It's cooling
Models are unreliable
Temp record is unreliable
Animals and plants can adapt
It hasn't warmed since 1998
Antarctica is gaining ice
View All Arguments...



Username
Password
New? Register here
Forgot your password?

Latest Posts

Archives

Recent Comments

Prev  2568  2569  2570  2571  2572  2573  2574  2575  2576  2577  2578  2579  2580  2581  2582  2583  Next

Comments 128751 to 128800:

  1. How we know global warming is still happening
    WeatherRusty, the duplication of your entries is due to your browser (or the server?) retaining the code for posting your comment, even after the page has reloaded to show your comment. When you reload that page by clicking your browser's reload button, that same code for posting gets sent again. It's happened to me multiple times (sorry, everybody). You might get an alert box after you click the reload button, warning that the browser will "repost" or somesuch phrasing. If you see that, click the Cancel button in that alert box. To avoid all the above, I suggest that after you post, you go to any other page, which will force the posting code to be flushed.
  2. How we know global warming is still happening
    I have no idea why my posts are in duplicate, I hit submit only once. RSVP, "1 degree divided by 300 K = .003333" 288 K is the average surface temperature of Earth and nearly all of that is due to radiation received from the Sun including 33 K amplification due to the greenhouse effect. "0.3% is in the noise, and is due to many factors." The "noise" is not random...it is forced and the job of science is to quantify the forcing. The ~1 K increase is part of a long term trend forced by 1.6W/meter^2 increase in radiative forcing, much of which is being absorbed by the oceans.
  3. How we know global warming is still happening
    RSVP, your water jug analogy is incorrect. The aerosols increasing and decreasing due to a volcano are instead the equivalent of a valve decreasing and increasing the flow of water into the jug. CO2 increasing is like moss growing in the hole at the bottom of the jug, reducing the flow of water out of the jug.
  4. There is no consensus
    Chris, ...RE your post 157 above, ( the Oerlemans paper ), the abstract you posted did not tell me much. So I did some research on the data and as far as I can see, glaciers have been generally melting and receding since about 1850, which is well before massive amounts of man-made CO2 were pumped into the air. Also, the IPCC models only require CO2 input after say 1970. According to the IPCC graphs, before 1970, natural variations can explain most of the temperature increase. Now since 1970, I agree, that glaciers have been generally receding, although in several areas they have actually been advancing. But the important points to note are that : 1) Glaciers started to recede well before 1970 and so the receding of glaciers after 1970 was to be expected simply based on historical ( natural )trends. 2)There has been little or no incresae in the rate of glacial recession since 1970. Thus there is little evidence here for me to conclude that recent man-made CO2 emissions are responsible for glacial retreat. If we look at one hypothetical glacier, is it not true that if precipitation of snow at the higher, source of the glacier decreases then there will be less weight forcing the glacier down the valley. Thus the rate of advance of the glacier can be affected by other factors besides warming.
  5. How we know global warming is still happening
    WeatherRusty said What you view as fanaticism derives from a strong confidence in well established physical principles as they are applied to the issue of climate change. ------------------------------- What I view as fanaticism is OVER confidence in theories that are based on well established principles. 1 degree divided by 300 K = .003333 0.3% is in the noise, and is due to many factors.
  6. How we know global warming is still happening
    Philippe Chantreau at 17:40 PM on 4 October, 2009 RSVP, "a closed system called Earth." Do you really mean that? --------------------------------- The expression is appropriate given that we are considering the Earth as a whole and a discussion that presupposes no changes in solar activity (which of course is not true).
  7. How we know global warming is still happening
    Tom Dayton answers my earlier question, "what brought the temperature back up to "normal" after the Krakatoa eruption." The answer unfortunately is not consistent with the radiation budget of greenhouse models that imply that without a net surplus of radiative energy (as in the case of extra CO2 in the atmosphere) average temperatures should remain at steady state. The model is oversimplied of course, which is the whole point of the question. An analogy may help visualize things. Assume you have a 5 gallon jug vessel containing 3 gallons of water. Water is dripping into the jug from a faucet at the same rate being lost through a hole at the bottom of the vessel, (assume no evaporation). Under these conditions, the level remains at 3 gallons forever, until one day, 1 gallon is removed. All things being equal in terms of flow rates, the level then stays at 2 gallons. There is no reason for the level to return to 3 gallons. At least I have not given one. Likewise, the greenhouse global warming theory assume equilibrium that is disrupted by CO2 levels rising. Without this happening, the Earths average temperatures would remain exactly where they are forever. And applying this same simple incomplete model to the situation after the Earths temperature drops from a volcanic explosion, it should remain low forever as well. You did not explain where the extra energy comes from to get the temperature back to "normal", nor did you explain why it should stop rising when it gets to "normal".
  8. Philippe Chantreau at 17:40 PM on 4 October 2009
    How we know global warming is still happening
    RSVP, "a closed system called Earth." Do you really mean that?
  9. How we know global warming is happening, Part 2
    shawnhet why do you average the heat absorbed by the ocean over the whole earth?
  10. How we know global warming is happening, Part 2
    Thanks for that Chris, I concur that the warming for that period seems to be more like 0.6Wm-2 rather than the 0.82 number mentioned above by John Cook. I just wanted to make sure I was reading it right. Cheers, :)
  11. How we know global warming is happening, Part 2
    BTW..how much of the increase in ocean heat content is due to vulcanism?
  12. How we know global warming is still happening
    RSVP said: "Socrates said, I know I know nothing. (You can even argue about what he really said). My understanding of this statement is that you cant really know anything for sure. I find the spirit of this discussion poisoned by fanaticism, as opposed to skepticism." Science is a logical methodology employed to aid in our understanding of the world. It works rather well, we have learned a great deal of how the world works even if that knowledge is incomplete. We understand quite well the physics as to how material objects are warmed and cool. The Earth is just a body floating in space and warms and cools based on the same physics as any other body. Scientists have much of this figured out. It is not like we know very little, to the contrary what we know is demonstrably the essence of what is responsible for the warming and cooling of Earth. What we don't know very well are some of the details, but the big picture is rather clear. The Earth is warming as a matter of empirical observation and the basic physics as to why that is occurring are well established. This gives us a logic basis for an expectation for a continuation of that warming and an estimation of what that warming will be, allowing for the uncertainty inherent to the less well understood details. What you view as fanaticism derives from a strong confidence in well established physical principles as they are applied to the issue of climate change.
  13. How we know global warming is still happening
    RSVP said: "Socrates said, I know I know nothing. (You can even argue about what he really said). My understanding of this statement is that you cant really know anything for sure. I find the spirit of this discussion poisoned by fanaticism, as opposed to skepticism." Science is a logical methodology employed to aid in our understanding of the world. It works rather well, we have learned a great deal of how the world works even if that knowledge is incomplete. We understand quite well the physics as to how material objects are warmed and cool. The Earth is just a body floating in space and warms and cools based on the same physics as any other body. Scientists have much of this figured out. It is not like we know very little, to the contrary what we know is demonstrably the essence of what is responsible for the warming and cooling of Earth. What we don't know very well are some of the details, but the big picture is rather clear. The Earth is warming as a matter of empirical observation and the basic physics as to why that is occurring are well established. This gives us a logic basis for an expectation for a continuation of that warming and an estimation of what that warming will be, allowing for the uncertainty inherent to the less well understood details. What you view as fanaticism derives from a strong confidence in well established physical principles as they are applied to the issue of climate change.
  14. How we know global warming is happening, Part 2
    We should also bear in mind that each component of the system responds to change differently, according to its' physical characteristics. The oceans represent an enormous buffer as they absorb and emit heat more slowly than the land or atmosphere. It seems to me that we should not expect an immediate correlation between atmospheric cooling and ocean cooling. There will be a time delay. Presently SST data suggests a diminution or even cessation in the warming trend dating from around 2003 which should eventually be reflected in the data for ocean temps. I'm not aware of any direct comparison available for both sets of data...Chris..any suggestions?
  15. How we know global warming is still happening
    RSVP asked what brought the temperature back up to "normal" after the Krakatoa eruption. Answer: The falling out of the atmosphere, of the solar-radiation-reflecting aerosols that the volcano had thrown into the atmosphere. Technically, it's not simply a matter of gravity causing the aerosols to fall out; that is one contributor, but other processes also contribute to the rapid removal of those aerosols. See the page It's volcanoes (or lack thereof) here on the Skeptical Science site for more info. That page contains references to peer-reviewed scientific publications from which you can get all the details you care to see. Or you can go to the US Geological Survey's site, because studying volcanoes is one of their primary jobs. They even have a page titled Volcanoes and Global Cooling. Even more detail is at the USGS page Volcanic Sulfer Aerosols Affect Climate and the Earth's Ozone Layer.
  16. How we know global warming is still happening
    Steve L wrote... "Wind doesn't concentrate heat at ground level thousands of km from global point point sources. Further, it takes more heat to melt ice than to raise air temperature, so for this and other reasons I dispute your assertion that the Arctic and alpine glaciers are the easiest places to detect global warming." It's not about what you can measure, although I can possibly understand the temptation. I was referring to a physics concept not a meteorological concept. The physics concept being that you cant destroy energy and then applying this to a closed system called Earth. The first place you might notice the effects would be in a snow line etc. The method I am using to deduce this possibility is called thinking. Independent thinking as opposed to Googling.
  17. How we know global warming is still happening
    Socrates said, I know I know nothing. (You can even argue about what he really said). My understanding of this statement is that you cant really know anything for sure. I find the spirit of this discussion poisoned by fanaticism, as opposed to skepticism. It is one thing to assert that CO2 has the effect of trapping solar energy, and quite another to conclude that it is the main cause of global warming. Why even bother to continue investigating this subject? Its a done deal. It should be a crime to burn fossil fuels. I suppose that is coming. If not, for sure the price of oil will be going up, and the question of who is thriving on it will be a little more clear. To answer WeatherRusty The major ice ages precede recorded history, but there have been periods of strong cooling in recent times. http://www.drgeorgepc.com/Volcano1883Krakatoa.html Here is an abstact from this article. ---------------------------------------- Upper Atmosphere Effects Ash from the eruptions was propelled to a height of 50 miles (80 kilometers) in the upper atmosphere blocking the sun and plunging the surrounding region into darkness for two and a half days. Climatic Changes It has been estimated that at least 21 cubic Km (appr. 11 cubic mile) was ejected from the eruption of Krakatoa and that at least 1 cubic mile of the finer material was blown to a height of about 17 miles (27 Km). The volcanic dust blown into the upper atmosphere was carried several times around the earth by air currents. This volcanic dust veil not only created the spectacular atmospheric effects described previously but acted also as a solar radiation filter, reducing the amount of sunlight reaching the surface of the earth. In the year following the eruption, global temperatures were lowered by as much as 1.2 degree Centigrade on the average. Weather patterns continued to be chaotic for years and there were major climatological changes which affected the entire globe. Temperatures did not return to normal until five years later, in 1888. ------------------------------------- Whether this was an ice age or not, my question remains. After this cooling, what brought the temperature back to "normal"? This is not directed to anyone in particular, especially readers who only believe a thing is true if it can be answered by a Google search. Preferably a person who can think independently. What brought the temperature back to "normal"?
  18. How we know global warming is still happening
    A real glass greenhouse interior is warmed more by the suppression of convection between the interior and exterior by the glass barrier than by absorption of IR by the glass. The tropopause between the troposphere and stratosphere is a barrier to convection also due to a temperature inversion. Nearly all energy leaving the troposphere and most leaving the glass of a greenhouse is in the form of radiation. This is why the forcing for a doubling of CO2 (3.7W/m^2) is measured from the tropopause I believe. When have volcanic eruptions sent the Earth into Ice Ages?
  19. How we know global warming is still happening
    A real glass greenhouse interior is warmed more by the suppression of convection between the interior and exterior by the glass barrier than by absorption of IR by the glass. The tropopause between the troposphere and stratosphere is a barrier to convection also due to a temperature inversion. Nearly all energy leaving the troposphere and most leaving the glass of a greenhouse is in the form of radiation. This is why the forcing for a doubling of CO2 (3.7W/m^2) is measured from the tropopause I believe. When have volcanic eruptions sent the Earth into Ice Ages?
  20. How we know global warming is still happening
    Well, I guess what's appropriate depends to some degree on what the topic of the post is and whether or not anybody is relying on a particular bit of misinformation (eg from a misnomer) to support an argument. You're not going to get rid of the name -- too much history, etc, and I don't think anybody here gets confused by it (who is thriving upon it?). But, whatever, it was just a PS. Your response regarding your nonsense is also worthy only of a PS. Wind doesn't concentrate heat at ground level thousands of km from global point point sources. Further, it takes more heat to melt ice than to raise air temperature, so for this and other reasons I dispute your assertion that the Arctic and alpine glaciers are the easiest places to detect global warming. Finally, on to your question. Don't worry, this time I didn't get loost. Response 1: That's your question? Then what about all that other stuff about "inhospitable to life". I was going to refer you to PETM. Response 2: What don't you like about any of the internet resources already available that explain the end of ice ages? Check out "ice ages" or "Milankovitch" on Wikipedia. Response 3: Google didn't find much with "delicate sunlight balance theory".
  21. How we know global warming is still happening
    RSVP asked "What caused ice ages to end?" Orbital mechanics (a.k.a. Milankovitch cycles) followed by feedbacks such as greenhouse gases and ice and snow. At the top left of this page, click the link "Climate's Changed Before." Also see the section titled Milankovitch cycles (finally) explained on this page of cce's "The Global Warming Debate" site.
  22. How we know global warming is happening, Part 2
    Shawnhet, I think your analysis applies to an imaginary circumstance where only the oceans absorb heat under the influence of positive radiative imbalance. But additional heat is absorbed by the land, atmosphere, and in melting ice. According to Hansen et al (2005), this amounts to around 0.05 W.m-2 globally averaged. So the globally-averaged heat uptake is of the order of 0.6 W.m-2 during 2003-2008 (according to the analysis of Schuckmann, 2009). If we’re comparing this value with the value estimated by Hansen et al (2005) for example (0.85 W.m-2 in 2003), we should probably consider the fact that the sun was radiating energy at around 1 W.m-2 more (top of solar cycle) than in 2008/9 (smack bottom of solar cycle). If we consider the effect on absorbed solar radiation at the surface, this amounts to a (temporary!) reduction near 0.175 W.m-2 (1 x 0.25 spherical geometry x 0.7 albedo) now, compared to 2003. So we should probably be comparing 0.6 W.m-2 to something quite a bit less than 0.85 W.m-2 (something around 0.75 W.m-2 perhaps). So the heat uptake data determined by Schuckmann 2009 is of a similar order to that determined by Hansen et al 5 years ago. It is somewhat lower than the value determined by Trenberth (2009); however there must be significant uncertainty in these values. The main point is that current data is increasingly at odds with the notion (see blogosphere ad nauseum!) that the oceans are cooling. They’re not. The evidence supports the rather straightforward expectation that a positive radiative imbalance results in absorption of heat and global warming.
  23. How we know global warming is still happening
    To Steve L. For one thing, I dont think it is so inappropriate to point out that the term GREENHOUSE is misnomer. The point here, is that the term was chosen based on a hypothesis, not a theory. If the hypothosis turns out to be in error, keeping the name around only creates more confusion, which apparently is what many people appear to be thiving on. As far my nonsense. I was saying that energy pollution from an automobile for instance is cummulative in a global sense, and if not lost into outer space spreads out wherever the wind takes it. The edges of glaciers and ice caps are the easiest places to observe the effects of global warming. And for the third time my question. The question is simple. What caused ice ages to end? If the Earth maintains a delicate equilibrium as per the CO2 greenhouse model, why in the absense of fossil fuel burning did the temperature of the Earth rise? And why did it stop rising? or did it stop? I hope I did not loose you this time.
  24. How we know global warming is still happening
    Just visiting briefly today -- rsvp, I don't really understand what you're asking. I half gave up on trying to understand you when you replied to my question in 14 with a bunch of nonsense about people carrying the energy all around the world such that the Arctic is the first place we should notice warming. But with the all caps and exclamation marks, it seems very important for you to get an answer to your question. Try laying out your reasoning and asking the question again. PS. I agree with Tom that you should do more reading. Right now you're diluting potentially interesting questions (we'll see) with junk about greenhouses being inadequate analogies for the enhanced greenhouse effect (which is old, well-known, and irrelevant).
  25. How we know global warming is still happening
    ANYONE can say, "hold your question until youve read all that material" to ANY QUESTION. That is a copout! ANSWER THE QUESTION! By the way, in a GREENHOUSE, light is REFLECTED BACK into the chamber. CO2 ABSORBS IR! It CONVECTS energy into the surrounding mass of air around it. Thus the observation that it would saturate. And if it happens to re-radiate, the radiation is isotropic unlike the surface of glass in greenhouse which points the light downward. Now please use the delicate balance theory to explain how the Earth comes out of an Ice Age, without skirting the question::::
  26. How we know global warming is happening, Part 2
    There is a potted history of the(apparent) ocean cooling found in 2007 here: http://earthobservatory.nasa.gov/Features/OceanCooling/ It seems there was bad data from the XBT floats and theArgo floats, one giving consistently high results the other consistently low. Cross checking with ERBES data ( which are not consistent with CERES) and correcting the float data gave a very different picture of ocean heat content. Also there is extensive info on Argo float position and coverage etc plus data at: http://wo.jcommops.org/cgi-bin/WebObjects/Argo.woa/wa/
  27. How we know global warming is still happening
    RSVP: You have not read those sites carefully enough. The experts do agree with each other. And the other issues you just now raised are dealt with in those sites, as well as here on the Skeptical Science site. (Click on "View All Arguments" at the bottom of the thermometer at the top left of this page.) You need to read those sites. All the way through. It won't take long, even if you read thoroughly. Hold your questions until you've read all that material.
  28. How we know global warming is still happening
    Revising wording from above... ...it should be a no brainer to explain how exactly the Earth comes out of an ice age, and what keeps it from warming to a point so hot that it becomes inhospitable to life???? Please use delicate sunlight balance theory.
  29. How we know global warming is still happening
    To Tom Dayton... I have gone to the sites you posted and these bring a lot to the table. Almost too much, in that there is an overriding sense when reading it that even the experts cant agree with each other. For instance, the bit on whether IR absorption saturates, and inacceptance of extensive and laborious computer modeling, etc. At any rate, what I find all this quibbling really points to is that the effect of CO2 on global warming is not violent in the way volcanic eruptions have plunged the Earth into ice ages. In fact, with all the endemic global warming you can imagine from CO2, the effects of a single volcanic eruption could leave us all freezing and starving to death from lack of vegetation within a growing season. Given the theory that average temperatures depend on such a fragile balance of the sunlight's heat, (and with so many experts abounding), it should be a no brainer to explain how exactly the Earth comes out of an ice age without going past a point so hot that it becomes inhospitable to life???? as there seems to be hard feedback mechanisms that take the Earths temperature up from ice ages and hold it steady past this point and others that are ignored when referring to the effects of CO2. Or is CO2 in charge of everything? My last little word would be that it might make some sense that CO2 concentrations as discovered in ice core samples correlate not because CO2 drives temperatures around, but because living organisms that produce CO2 do better when things warm up.
  30. How we know global warming is happening, Part 2
    Is the 0.77Wm-2 supposed to be averaged over the whole surface of the Earth? The graph seems to be referring to oceans on their own. The graph covers 6 years which equals to 6*365.25*24*60*60 seconds = 189345600 seconds(A) Eyeballing the graph it looks as though the six year period has seen an ~1.5*10^8 Jm-2 increase.(B) Dividing B by A gives us ~0.79W-m2(pretty close to the 0.77) storage in the oceans, but the oceans are only ~70% of the Earth's surface. This gives us 0.56Wm-2 averaged over the surface of the Earth. I wonder if we're comparing apples to oranges. Cheers, :)
  31. Some Skeptical Science housekeeping
    Yes, great work John, thank you. A small suggestion. You might watch out for sock puppets if you don't already. I have a gut feeling there may be just one denialist hiding behind several aliases here. But then I have always had a nasty suspicious mind!
  32. How we know global warming is still happening
    "Thinking of it this way also shoots down all the silliness about the 2nd law of thermodynamics that some throw in for more confusion." Absolutely...It is the surface that warms the atmosphere. Earth's average surface temperature at 288K is some 33K degrees warmer than the equilibrium black body temperature of Earth as viewed from space at 255K. The 255K emission is on average given from high in the troposphere (~16,000'), without an atmospheric greenhouse effect the 255K emission would come from the surface. The stronger the greenhouse effect the higher in the troposphere is the 255K emission. The atmosphere does not warm the surface because it is warmer than the surface (it isn't), it does so by inhibiting cooling of the surface. The loss of thermal energy continues outward toward space on average, a cooler atmosphere is not radiatively warming a warmer surface which would violate the Second Law. Sorry if this seems off topic.
  33. Philippe Chantreau at 05:40 AM on 2 October 2009
    How we know global warming is still happening
    Good reminder Weather Rusty. I think the best, shortest, clearest description was given on RC by one of the contributors: the greenhouse effect impairs the cooling of the surface. Increased GH effect means higher equilibrium temperature. It's rather simple. Thinking of it this way also shoots down all the silliness about the 2nd law of thermodynamics that some throw in for more confusion.
  34. There is no consensus
    "So from what you are saying,variations in those natural factors which affect temperature ( sun, El Nino etc )are as likely to affect cyclones, sea-level changes, polar ice-melting etc as man-made CO2 emissions?" That's not really correct. The natural factors generally result in fluctuations around a trend which under normal circumstances is flattish (on the multi-decadal timescale). In a world warming under an enhanced anthropogenic greenhouse forcing, the natural factors result in fluctuations around a rising temperature. It is the rising temperature that causes the sea level rise, ice sheet melting and so on. Of course if an El Nino occurs on a rising temperature trend, this will supplement the warming producing a short pulse of excess heat which temporarily would accelerate warming onsequences like ice sheet melting. A La Nina will provide a slight brake on these warming-induced consequences. However these don't have much long term effect since these are very short lived phenomena. It's really only changes in solar output that potentially have significant long term consequences that could compete with anthropogenic-induced warming, but analysis of long term solar output indicates that solar variations are rather small in their effects on earth surface temperature.
  35. How we know global warming is still happening
    Just for the sake of clarity and proper conception of what is going on when greenhouse gases absorb IR radiation, it must be stated that nothing is trapped as is commonly stated. The radiation absorbed ceases to exist, having been converted to kinetic energy of the molecule. This energy is then emitted again by the molecule as IR radiation or the newly acquired kinetic energy is transfered to adjacent molecules, O2, N2 etc.. The atmosphere is warmed. Adjacent greenhouse gas molecules again absorb the proper resonant radiation countless times and emitted in all directions, some up and some back down. If the atmosphere were transparent to IR it all would escape from the surface to space unimpeded, but due to greenhouse gases the energy is slowed in that escape by countless repeated absorptions and emissions of IR. Nothing is trapped, the flow of outward energy is constant but slowed by countless repeated absorptions and emission.
  36. How we know global warming is still happening
    RSVP, the history of the discovery of CO2's effect answers a couple of the questions you've asked here, and anticipates questions that you'd likely ask next. See Spencer Weart's The Discovery of Global Warming, the section The Carbon Dioxide Greenhouse Effect. I think your time in asking individual questions would be saved by reading some short overviews that answer many of those questions at once and in context. A excellent one is cce's The Global Warming Debate. In that particular site, the section 1. Primer and History covers CO2's absorption of radiation, with links to online versions of the sources of that info; in some cases you'll want to go to the links on those linked sources to see the actual scientists' publications. But I strongly recommend you read the entire site, not just section 1. See also A Saturated Gassy Argument, which is a posting on RealClimate. Another good resource, though not as integrated as cce's site, is RealClimate's Start Here section.
  37. Models are unreliable
    model B is the relevant one Neil. It corresponds most closely to what has happened emissions-wise in the real world. The data in the paper I cited goes up to 2005. That's why I stopped at 2005. Why wait until 2030? The simulations have done a very good job of predicting reality for almost 20 years. So we can say that the real world has "evolved" in a manner that is consistent with our understanding of the greenhouse effect as it stood some 20 years ago. That seems a rather good indication that even 20 years ago we understood the basic elements of the climate system with respect to radiative forcings and heat retention. Obviosuly we know a whole lot more now and we expect our current models to be considerably better (not to mention the vast improvements in computational speed, efficency and data storage and analysis). You need to make up your mind about what you think constitutes a long enough period to assess a computational projection into the future! If you consider we won't "know the "truth" until about 2030", how can you possibly say that "it should be apparent already that to date the real data is diverging from Hansen's more likely scenarios A and B"! Those are trwo mutually exclusive notions. In reality, as i said in my post #118, a projection cannot simulate contingency (giving rise to much of the "noise") in the climate system, and therfore we expect considerable short term divergence of simulated and real word data. That's obvious I would hope! We can see that this is the case by inspecting Hansen's simulated projection (Figure 2 here: http://www.pnas.org/content/103/39/14288.abstract and observe that despite the overall good correspondence between scenario B simulation and real world temperatgure evolution, that there are very large short term deviations (e.g. 1974-1976; 1992-1994; 2008 etc.). We can understand these in hindsight since we kbnow what contingent events (volcanic eruptions; El Nino's etc.) caused them. Since these events result in temporary perturbation of the surface temperature evolution, the temperature response recovers and the long term temperature evolution remains driven by the anthropogenic increase in radiative forcing despite short term fluctuations...
  38. How we know global warming is still happening
    Chris wrote: "I can't think why anyone would attempt to make arguments that are completely opposed to basic physics and empirical and theoretical consideration!" When a train on an east west rail starts or stops, its change in velocity affects the Earth's rotation. That is what the physics says. No one is concerned with this problem because the mass of the train next to the Earth is minute. The argument is quantitative, not qualitative. Aside from my bad joke about cola, I will admit that I expressed my self poorly when I made that reference to a lossy system. (Perhaps if you are non skeptic, it wont matter.) What I was trying to say was that if CO2's job conceptually was to trap the Sun's energy, and any energy that it did not trap was considered a loss, I would agree that the energy trapped would be in direct proportion to the increase in CO2's numeric concentration, no matter how small its concentration was. But, as we know, there are many more factors that cause the Sun's energy to be retained, including the rest of air's chemical components. In fact, when CO2 is produced through combustion, oxygen is removed or displaced in this reaction. What do you think CO2 is warming up anyway? It is passing heat convectively to the nitrogen and oxygen that surround it. I am not denying that CO2 is a contributor to Global Warming, however I would like to see meaningful data before concluding that it is the main culprit to this problem. The kind of testing I described above would be a good starting point.
  39. How we know global warming is still happening
    RSVP re: "..... but doesnt it make you a little suspicious that CO2 levels have been tracked for the last 100 years somewhere on the top of a volcano in Hawaii? Nothing wrong with this in general, but I get the feeling its as if someone out there needs to justify the data taking, and if we were into Global Cooling, someone would be making an argument that the cooling was due to CO2." Knowledge is the scourge of suspicion RSVP, and if one is really interested in atmospheric CO2 measurements one should know that Mauna Loa is only one of a large number of sites for monitoring of atmospheric greenhouse gases. Analysis of atmospheric CO2 data from many different parts of the world gives a very consistent measure of this atmospheric gas: http://gaw.kishou.go.jp/wdcgg/wdcgg.html Additionally, one should know that atmospheric CO2 levels are continuously monitored remotely by satellite, nd these measures are entirely consistent with atmospheric CO2 measured at Mauna Loa and elsewhere: http://photojournal.jpl.nasa.gov/jpegMod/PIA11194_modest.jpg Of course no informed individual "would be making an argument that the cooling was due to CO2", since CO2 is well understood to be a greenhouse gas, the increased concetration of which drives the Earth's surface temperature towards a higher equilibrium value (all else being equal of course). I can't think why anyone would attempt to make arguments that are completely opposed to basic physics and empirical and theoretical consideration!
  40. How we know global warming is still happening
    Tom Dayton wrote: "The amount of trapping is not just theoretical. For more than a hundred years, scientists have been filling tubes with various mixtures of gasses, sending IR radiation through those gas-filled tubes, and measuring how much gets through to the end of the tube." Would you know of a link that points to these results? What I have seen are graphs comparing IR absorption between gases, but I have never seen a graph that shows steady state temperature vs. concentration around the values of CO2 that we are talking about. With a fixed IR source in a controlled environment, I would assume this would be very telling. My expectation is that any measurable increment in temperature will be directly proportional to the incremental percentage of CO2 with respect to the nominal steady state temperature, which of course would always be smaller for higher temperatures. --------------------------------------------- Moving on... Another way to look at the issue of CO2 is to invert the concept of a lossy system. Imagine that the only energy trapped by the Earth was due to CO2. If so, then the doubling of CO2 in the atmosphere regardless of the concentration would most likely double the heat retention. We know however that CO2 is NOT the only thing that holds onto heat. Heat is stored in the oceans, mountains, buildings, and 98% of the gas that you and I breath everyday. I am getting ahead of myself without the data from the test I described above, but doesnt it make you a little suspicious that CO2 levels have been tracked for the last 100 years somewhere on the top of a volcano in Hawaii? Nothing wrong with this in general, but I get the feeling its as if someone out there needs to justify the data taking, and if we were into Global Cooling, someone would be making an argument that the cooling was due to CO2. Here's my real theory... There is a correlation between soda pop drinkers and those that believe in global warming. The extra CO2 is lodging between their brain cells and causing their body temperatures to rise ever so slightly.
  41. Models are unreliable
    Chris, We are talking about basically the same thing in relation to Hansen's scenario C. You are saying that Scenario C is the imaginary situation that greenhouse gas emissions were stopped in 2000. I am saying that it is an imaginary situation in which the CO2 emission's growth was drastically reduced ( as you point out,it represents the case that growth actually stopped ) in 2000. In your comparison above, why did you stop at 2005, when data is available at least up until 2008? As you say, "Of course what happens over very short time periods (a few years) is of little consequence in comparing climate simulations with reality". Therefore to my way of thinking, we will not know the "truth" until about 2030. But it should be apparent already that to date the real data is diverging from Hansen's more likely scenarios A and B.
  42. There is no consensus
    Chris Well thanks at least for confirming some very important points - that there is not a simple relationship between CO2 increase and temperature rise. And that natural forces can affect climate and sometimes, at least, over-ride any perceived temperature increases due to increased CO2. This was one of the areas that I was trying to understand as the IPCC reports and the media frequently talk about recent or possible future catastrophic events such as cyclones which are said to be due to man-made CO2 emissions. So from what you are saying,variations in those natural factors which affect temperature ( sun, El Nino etc )are as likely to affect cyclones, sea-level changes, polar ice-melting etc as man-made CO2 emissions? I can see you are knowledgeable on the subject of global warming. For the record, I do believe in global warming ( that the temperature is presently rising ), but then again the climate never has been and never will be static.
  43. How we know global warming is still happening
    RSVP wrote: The reason I do not believe the greenhouse theory even after attending Al Gores seminar live, is that CO2 comprises such a small fraction of the mass of our atmosphere, something like .04%. I have a very hard time believing that such a small fraction of the total atmospheric mass could possibly contribute to runaway greenhouse warming. Answer Part 1: You shouldn't focus on the fraction of the atmosphere that CO2 comprises, because it is not relevant all by itself. You need to combine that fraction with the number of molecules of all kinds that are in the atmosphere, and with how much volume they fill in between the ground and outer space, to come up with the number of CO2 molecules sitting in front of a long-wave IR photon leaving the ground headed toward outer space. The bottom line is the probability of a long-wave IR photon hitting a CO2 molecule before making it from the ground to outer space. (Okay, it's also important how close to this CO2 molecule, are the other CO2 molecules that could capture the photon emitted by this molecule, but that doesn't change the essence of the answer to your question.) For example, Mars has a much higher fraction of CO2 than Earth does, but the total number of molecules of all kinds in the Martian atmosphere is so much smaller than in the Earth's atmosphere, that far fewer CO2 molecules sit between the Martian ground and outer space, than between Earth's ground and outer space. So the Martian atmosphere traps far less long-wave IR emanating from the ground, than the Earth's atmosphere does. That's one reason Mars is much colder than Earth. So contrary to your intuition, the fraction of the atmosphere that CO2 comprises is in fact sufficient to trap long-wave IR enough to cause significant warming. The amount of trapping is not just theoretical. For more than a hundred years, scientists have been filling tubes with various mixtures of gasses, sending IR radiation through those gas-filled tubes, and measuring how much gets through to the end of the tube. They've also measured IR transmission in the atmosphere at multiple heights. You might wonder that if the fraction by itself is not relevant, why do climatologists talk about CO2's level in the atmosphere in terms of parts per million (PPM)? That's a convenience that suffices because the other factors that I wrote in my first paragraph are, for practical purposes, constant for the Earth. Answer Part 2: With regard to global warming, it's not even the absolute number of CO2 molecules currently present that is important. Rather, the change in number of CO2 molecules is important, because it's the change in the temperature that is the problem. The change in CO2's PPM since the 1800s is huge--an increase of one third! The change in the amount of heat trapped by that extra CO2 is correspondingly large (though not exactly the same amount of change--its more complicated than that). Answer Part 3: The greenhouse warming on Earth is not and will not be "runaway." Probably you were using that term loosely to mean "increasing at an increasing rate." But you shouldn't use that term, because it really means increasing at an increasing rate due to positive feedbacks that feed back at ratios greater than 1. The Earth's CO2-caused greenhouse effect instead always stops feeding back, because the feedbacks (e.g., CO2 causes warming which causes more water vapor which causes more warming which causes more water vapor,...) cause increases smaller than the increases that triggered them. The feedbacks cause the temperature increase from adding a unit of CO2, to be larger than the temperature increase just from the CO2 itself. But that amount of heating due to a unit of increase of CO2 is finite, not infinite. You can think of the feedbacks as a finite amplifier of CO2's heating effect. The reason the temperature keeps increasing year after year is not that the feedbacks run away, but that we keep adding CO2 to the atmosphere year after year.
  44. How we know global warming is still happening
    RSVP: Of course I am not implying that all IR emitted by Earth is absorbed by CO2! It doesn't matter that not all of it is absorbed. What matters is that enough is absorbed to make a difference.
  45. How we know global warming is still happening
    RSVP wrote: "A lot of the incident energy coming from the Sun is also IR. How does this energy make its way down to the Earths surface if it is blocked by CO2 in the upper atmosphere?" Answer: The radiation blocked by CO2 is mostly long-wave IR, not the full spectrum of IR. The radiation coming from the Sun is a lot of wavelengths other than long-wave IR, which make it past the CO2 on the way down. Those other wavelengths of radiation from the Sun are absorbed by the Earth and the energy contained in those wavelengths is re-emitted by the Earth as long-wave IR, which the CO2 blocks (well, absorbs and re-emits, actually).
  46. How we know global warming is still happening
    To Tom Dayton: Are you implying that all IR emitted by Earth heat resonates with IR absorption wavelenghts? I dont think you are, and I have seen the aborption spectrum of IR which is relatively narrow. To Stevel L: I started my entry saying that energy cannot be destroyed. I hold my ground. The atmosphere accumulates energy from all people in all nations carrying it all around the world. The first place you will notice Global Warming is in the Artic and the Alps. That does not mean that it started there. Next time you get to a stoplight, if you turn off your engine, you will help delay Global Warming. About as long as it takes the light to turn green.
  47. Measuring Earth's energy imbalance
    Yep, I'm pretty sure. Why don't you cite a competing estimate (complete with uncertainty) if you think it really challenges the estimates published by the IPCC?
  48. How we know global warming is still happening
    RSVP -- don't you think that if human exothermic activities were responsible, the warming would be greatest near the largest sources of those activities? Instead the Arctic shows the most warming and alpine glaciers are melting. As for something in low concentrations having a large effect, think of DDT, CFCs, ozone, stratospheric sulfur, etc.
  49. Philippe Chantreau at 04:25 AM on 1 October 2009
    How we know global warming is still happening
    RSVP, it does not add up. There is not enough energy emitted by human made exothermic activities to achieve what's been observed. By far.
  50. Models are unreliable
    re #117 Not really Neil. You should really familiarize yourself with the data before attempting to trash it! You can read about the Hansen scenarios and the models here [*](see Figure 2 and accompanying text). Scenario C is the imaginary situation that greenhouse gas emissions were stopped in 2000 Scenario B described as "the most plausible", is a scenario with moderately increasing greenhouse gas concentrations and some volcanic eruptions, much as we've observed in reality. Scenario A is a model used to bracket the high end of likelihood with rapid exponential increase in anthopogenic emissions and no volcanos. If one compares the models with reality based on 2005 data, the results are: predicted temp rise 1998-2005, relative to 1951-198 mean: model A: 0.59 oC model B: 0.33 oC model C: 0.40 oC real world measurement: land suface: 0.36 oC land-ocean surface: 0.32 oC That seems a pretty good prediction (a 17 year projection into the future). The most plausible scenario has been almost smack on. Of course this is a rather lucky observation, since the models cannot predict the noise in the climate system which is rather large especially on the decadal time scale. So one can hardly claim a model hasn't been a rather good predictor of future when it's made a prediction that's very close to real world observations! Of course what happens over very short time periods (a few years) is of little consequence in comparing climate simulations with reality, since as is very obvious, a climate simulation cannot predict as yet contingent events like El Nino's, La Nina's, volcanic eruptions, changes in solar output and so on. So a succesful simulation is expected to produce the broad progression of temperature rise while the fluctuations around the trend is expected to be completely discorrelated with real world observations. [*] http://www.pnas.org/content/103/39/14288.abstract

Prev  2568  2569  2570  2571  2572  2573  2574  2575  2576  2577  2578  2579  2580  2581  2582  2583  Next


The Consensus Project Website

THE ESCALATOR

(free to republish)


© Copyright 2026 John Cook
Home | Translations | About Us | Privacy | Contact Us