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GFW at 19:43 PM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
To follow up on Marcus's answer to HR: in addition to what he said, the solar forcing (slightly lower TSI) during the LIA was also reinforced by higher than average volcanic activity(*). Those two effects were global. It is also suspected, though far from proven, that ocean currents slowed down, strengthening the cooling in Europe and possibly a couple of other regions. So that's how the LIA was cold enough to be a hardship. (*) Volcanoes are a cooling forcing on human timescales because they inject reflective aerosols into the atmosphere. For example Mt. Pinatubo (June 1991): In 1992 and 1993, the average temperature in the Northern Hemisphere was reduced 0.5 to 0.6°C and the entire planet was cooled 0.4 to 0.5°C. The maximum reduction in global temperature occurred in August 1992 with a reduction of 0.73°C. However not much effect remained after 5 years or so. On really long timescales, large scale volcanism can warm the planet with CO2 emissions that outlast the aerosols by orders of magnitude. It is thought that there was a "snowball earth" scenario in the period 650 and 750 million years ago, and that volcanic CO2 was what ended the snowball state. -
jimrhiz at 17:57 PM on 20 February 2010It's cooling
Great site and page thank you! One very small cavil ... "Since 1970, the Earth's heat content has been rising at a rate of 6 x 10^21 Joules per year. In more meaningful terms, the planet has been accumulating energy at a rate of 190,260 GigaWatts. Considering a typical nuclear power plant has an output of 1 GigaWatt, imagine 190,000 nuclear power plants pouring their energy output directly into our oceans." The value 6 x 10^21 Joules per year has one significant digit (similar in accuracy to other figures one the page, like 0.77 ± 0.11). So it gives a misleading idea of accuracy to say "190,260 GigaWatts", with 5 significant digits. It would be better to stick to one significant digit, and conclude: "the planet has been accumulating energy at a rate of about 200,000 GigaWatts" and then also adjust the nuclear power plan count accordingly (bearing mind as well that Barry Brook's comment 5 above challenged the 1GW per plant estimate). -
Marcus at 17:51 PM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
@Ranger. Its called The Carbon Cycle for a reason. All the carbon which goes out is accounted for by Carbon sinks on land & sea (plants, soils, phytoplankton, direct ocean absorption). The only carbon not directly accounted for, IIRC, is from volcanoes & limestone erosion-both of which generate a tiny fraction of the CO2 generated by burning fossil fuels. The reason burning fossil fuels has such a massive impact on atmospheric CO2 levels is because they're fossilized trees which grew in an extremely CO2 rich (3000ppm +) environment several hundred million years ago (the aptly named Carboniferous Era). All plant & animal life alive today has existed in the "carbon constrained" environment of the Quaternary period, where CO2 levels have never exceeded 290ppm (they are now close to 400ppm). Hope that makes sense. -
Marcus at 17:46 PM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
Humanity Rules. What you need to remember is that this modeling covers only 100 years. The Little Ice Age occurred over a multi-century time period (over 300 years IIRC). That's a long time for the negative energy imbalance to build up and cause *significant* cooling. That cooling event was offset by the return to "normal" TSI over the 250 year period up to 1950 (which gave a warming trend of around +0.06 degrees per decade). Since 1950, the sun has either been stable, or in a mild decline, yet warming trends are even *faster* than the previous 250 years. -
Tom Dayton at 16:44 PM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
Ranger, fossil fuels are highly concentrated forms of plant material. You'd have to burn a huge amount of grass, wood, or any other plant material, to get the same energy as a tiny amount of fossil fuel. That's a major reason we use fossil fuel. Think of fossil fuel as distilled plants. That distillation concentrates not just the energy from the plants, but also the carbon. In fact, the concentrated carbon is that concentrated energy, in the form of the chemical bonds that the carbon is involved in. So when a small amount of fossil fuel is burned, it releases both the huge amount of energy of the huge amount of plants, and as an inevitable result the correspondingly huge amount of carbon. -
GFW at 16:21 PM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
Ranger, think of it this way. Plants grow. They can be burnt, be eaten, or fall down and rot. All of those result in the carbon returning to the atmosphere ... to feed more plants. Before significant human intervention, the total amount of carbon in plants would remain roughly the same (different areas burn, suffer locust plagues, or whatever each year) on average over years. Thus the total amount of carbon in the air was also roughly the same over years. Even significant human agriculture and other land use changes have only had a relatively small effect on the total amount of carbon in plants at any given moment, although we may be cycling it in and out of plants faster. The thing that's causing the major change in atmospheric carbon dioxide is that we are taking carbon that was locked away for tens of millions of years as fossil fuels and burning those. The following article gives a good overview of the carbon cycle and particularly how much carbon is where (in plants, in the soil, in the air, in the ocean, etc.) That's table 1. http://www.eoearth.org/article/Carbon_cycle One part of the article is missing an important point though. The part that talks about "missing carbon" is wrong so far as I can tell, because there is no mention of ocean acidification. Currently, when humans add carbon to the biosphere by burning fossil fuels, it gets divided roughly in half - one half for the air, and one half for the oceans. Unfortunately this has the effect of reducing the pH of the oceans. This has now been measured as an average drop from ph 8.2 to 8.1. That may not seem like much, but if we keep going, it could cause mass extinctions. -
pmheideman at 15:51 PM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
"So seems to me that historic fires produced as much co2 back then as burning fossil fuels do today. " Seems to you based on what, your guestimation? In fact, we know how much CO2 was in the atmosphere hundreds of years ago, and it was quite a bit less than there was today (see graph here http://www.skepticalscience.com/The-Dunning-Kruger-effect-and-the-climate-debate.html). If your theory that anthropogenic emissions were merely replacing those of wildfires, we wouldn't see the massive spike that we do. Beyond your folksy wisdom, there is no evidence to support the scenario you construct. -
Ranger at 14:42 PM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
Ned , yes that is my question, but I still don't get it. I guess one could do the research to find out how much land burned every decade, say hundreds of years ago versus the tiny tiny fraction of land that burns today. So seems to me that historic fires produced as much co2 back then as burning fossil fuels do today. Plus if you consider that tonage wise, more cultivated crops produce much more plant matter than short grass praires would have. These crops like corn, milo, soybeans, Sudan Haygrazer.... would recycle much more carbon that grass does, plus the uncultivated land is still covered with plant life. I have spent more time outdoors horseback than most people have spent in their beds. I realize that since the the late 1980's the climate has got warmer. But I also see that in the last few years I have been colder. I also like to read, mostly History. History is full of antedotes down thru the centuries of the earth's tempature being hotter then colder. Thanks Albany, Texas -
Ned at 14:14 PM on 20 February 2010Visual depictions of CO2 levels and CO2 emissions
RSVP writes: When I made that remark #18, I was attempting to let Alexandre consider what he told theendisfar, taking his remark it to its logical conclusion, and so point out an untruth. Not trying to be rude or anything, but Alexandre has a much better understanding of this than you do. Thus, your tone here smacks a bit of the whole D-K effect. -
Doug Bostrom at 14:10 PM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
Not to be the slightest bit pejorative, but Ranger has brought the brushfire matter up several times of late here, on several threads, and he has always received the same basic response without apparently acknowledging these answers. Ranger, would you mind responding to Ned's answer, just so we know you're reading the answers you're eliciting? -
Ned at 14:06 PM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
Ranger writes: Why did'nt all that co2 belched into the atmosphere in past history cause global warming? As I understand it, you're pointing out that in the days before fire suppression (and still occasionally today) there were big wildfires in many places. Presumably those put a lot of CO2 into the atmosphere, right? So why didn't that cause global warming? If you think about it, you can't keep having fires unless stuff grows back between the fires to create the fuel load for ... more fires. In other words, in a pre-fossil-fuel time, the carbon added to the atmosphere by fires was then removed from the atmosphere by the regrowth of plants. What's different today is that instead of just cycling the same carbon through the system over and over again, we're injecting into the atmosphere a heck of a lot of fossil carbon that was laid down over a period of tens of millions of years. -
Ned at 13:54 PM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
HumanityRules writes: I also have another question. The implication in the articlet is that the LIA was a regional phenomenon. As far as I'm aware the sun shines down on the whole of the planet. How can it's effect be regional? And if there is a regional explanation how can any other forcing dodge this regionalism? Actually, due to the nature of feedbacks and the transfers of energy within the climate system, even a uniform global forcing won't produce uniform regional impacts. Thus, for example, anthropogenic CO2 becomes well-mixed in the atmosphere within a few years but the warming that results from it is very unevenly distributed (e.g., more warming in the arctic, and in the N hemisphere, and over land, etc.) Right? -
Ranger at 13:51 PM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
Ok, I just a West Texas cowpuncher and have not had my question answered by you scientific guys. My question is at the end. For thousands of years wildfires burned up ba-zillions of acers grassland, forrest and brush annually. Where I live in West Texas we had a little grass fire one April day2006, that burned over a million acres and killed 12 people and thousands of beef cattle, some horses and untold wildlife. That was with scores of City Fire Depts, Rural Fire Depts, US Forrest Service, Ranch firefighting rigs, Interstate Highways, State Highways, County Roads, large parcles of cultivated land; all trying to frustrae and stop this fire. Before White European Settlement, fires like this kept our part of the world praires. Brush, TREES, Prickly Pear now cover the land. Once home to the Antelope and Buffalo now prime Whitetail Deer Habitat. Why did'nt all that co2 belched into the atmosphere in past history cause global warming? -
Ned at 13:40 PM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
oracle2world writes: "What would happen if the sun fell to Maunder Minimum levels?" It would get cold. Any questions? You didn't actually read the post, did you? The whole point of this thread is that it probably wouldn't get particularly cold. As John said (in a turn of phrase that I find amusing) "the effect of a Maunder Minimum on global temperature is minimal". -
HumanityRules at 13:08 PM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
Tony Noerpel #19 Surely the physics are the same in 1700's and 2100's. If a grand minimum produces a 0.09-0.3oC drop in 2100 then it does the same in 1700 no matter what the base position you are starting at. Given that, my question is, can the 1700's be recognised as a cold period of history with that level of change? If not then we have to get rid of the LIA from history. This just appears a circular argument. Having assumed in the model that solar has a negligible effect the scientist asks the question what is the effect of a Grand Minimum. No surprise when the answer comes back negligible. I also have another question. The implication in the articlet is that the LIA was a regional phenomenon. As far as I'm aware the sun shines down on the whole of the planet. How can it's effect be regional? And if there is a regional explanation how can any other forcing dodge this regionalism? -
oracle2world at 12:46 PM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
"What would happen if the sun fell to Maunder Minimum levels?" It would get cold. Any questions? -
Gaia_Dee at 11:28 AM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
The oceans are huge heat reserves, aren't they? It is ocean currents, more than the air, that affects whole seasons of weather for any part of the world. Currents keep Europe warmer than it should be for it's latitude. The El Nino phenomenon is what has determined the cold weather this winter. All of the above are considered "weather" which is not the same as "climate". It is probably better that we not even use the word "climate", but to refer to, instead, the mean temperature of the earth's ocean's rising and the increasing reflectivity of the atmosphere. I think using the word "climate" has a weather connotation to the common ear. The danger we are facing is our increasing the heat energy we are storing inside our atmosphere and ocean. The more energy that is added, like to any closed system, the more changeable the currents and air streams are; the more ice melts and sea levels rise, the more turmoil and swell differences in the oceans, and the more variety in storm characteristics. All of these mean changes in where the rain falls, flooding some, making others into deserts, turning rainforests into savannas, changing what we can grow where, et cetera, et cetera. Here we will have multiple climate changes all over. If we look at the planet as a big system that is keeping more heat than it is giving up, then one can better imagine, based on high school level experiments in thermodynamics, what this phenomenon means for humanity. The "icing" on this terrible cake is the ocean becoming more acidic, which is certain to cause extinctions of vulnerable species (like our food fish). All this because a few "deniers" say that the laws of physics don't apply to the earth? that we "can't change" from coal and oil to nuclear, wind, geothermal, and solar? Considering that, if Edison had his way, we would have been all driving electric cars already. If Three Mile Island hadn't scared people away from nuclear, just think of where we would be in addressing this issue. If Carter had gotten his gas tax applied as the prices for gas were dropping, our cars would not be the monsters they are today. -
Philippe Chantreau at 10:38 AM on 20 February 2010Is CO2 a pollutant?
The diagram makes sense, you don't understand it. Net outgoing IR is 390-324= 66. Thermals and evaporation 78+24=102 Total net outflow from surface: 102+66=168. Now can you clarify what you were trying to say with your double sided solar panel idea? -
Is CO2 a pollutant?
On the CO2 absorption/insulation: More scatter events in the atmosphere due to higher CO2 concentrations, in addition to back-reflection to the ground, also increase atmospheric path length. This increases chances of IR absorption by other gases -> heating, as well as CO2 energy increase due to non-radiative heating of the CO2, which I believe (I work with fluorescent dye systems) occurs as a low probability event on IR absorption. -
carrot eater at 09:54 AM on 20 February 2010Is CO2 a pollutant?
You guys have more patience than I do. suibhne "Even on one side it does not add up 342 solar from Sun On Earth surface 168 solar + 324 back radiation" What does this even mean? On the diagram, I can count three places to draw an envelope for checking the First Law. One is the earth's surface, and it checks. Second is the atmosphere, and it checks. Last is the top of the atmosphere, and it checks. Nowhere is there net heat transfer from a colder to a warmer body. Nowhere. And 'heat' is perfectly acceptable for referring to transfers of thermal energy, by either radiation, convection or conduction. Everything checks out thermodynamically, suibhne. Perhaps you should invest in a radiometer. One that covers longwave IR, mind. -
Is CO2 a pollutant?
suibhne: The Kiehl-Trenberth graphic is an excellent summary of a balanced energy system. Using their numbers for illustration, the input energy from the sun (342-107, or 235 watt/m^2) is balanced by the output (165+30+40 = 235 watt/m^2). Without atmosphere, the surface would directly radiate 235 w/m2 in balance, but the atmosphere insulates by radiating energy (324) back to the surface, allowing a considerably higher surface temperature that radiates ~390 plus thermals + evaporation heat. Increasing back reflection (above 324) with higher CO2 levels decreases the energy emitted to space - energy accumulates (heating the surface and atmosphere) until radiated energy increases from 390/surface and 165/atmospheric to some higher level that pushes a total of 235 out past the insulation, and the system reaches balance again. Note that this does not include potential positive/negative feedback mechanisms - those are outside the current discussion. As to the back-reflection and what I understand of the GT arguments: More CO2 means more scattering and absorption/reemission events from CO2/IR interactions, more IR diverted from direct surface emission to off angles, which means more heads back to earth (total scatter angle -> down). This is a mass effect; single photon tracing CAN be used to show the same thing IF you sum up the probabilities of CO2 interception and radiation scattering angles - choosing a single case where a photon escapes doesn't say anything about mass effects. -
Chris G at 09:14 AM on 20 February 2010Visual depictions of CO2 levels and CO2 emissions
@ RSVP at 06:27 AM on 20 February, 2010 I understood that you were referring to the interaction between theendisfar and Alexandre. You were setting up a straw man that was a) beyond any reasonable inference from what Alexandre said, and b) pretending that the people who study the atmosphere and climate are unaware that there is such a thing as convection. I used the term "rattle around" because there are two models for EM radiation, as waves and as particles, I was thinking in terms of individual quanta, and I decided that it the context of a blog, I was not subject to the same precision of language requirements as would be required in a journal article, as long as the meaning was clear. -
Squidley at 09:07 AM on 20 February 2010Skeptical Science now an iPhone app
Android! Oh, please, oh, please, oh, please! -
johnd at 09:07 AM on 20 February 2010Is CO2 a pollutant?
When it is claimed that the increased CO2 has upset the balance, what exactly is the critical balance between CO2 and water vapour, because that is the balance that is most relevant if CO2 is a forcing agent. The graph shows how the CO2 has increased over the last 10,000 years, but given the planet has warmed over that period, the amount of water vapour would have increased faster than the CO2 has thereby gradually decreasing the amount of CO2 per unit of water vapour for much of that time span. -
Doug Bostrom at 07:37 AM on 20 February 2010Is CO2 a pollutant?
Suibhne, I suspected it was a mistake to extend my model by including lightbulb dwellers. Just to be sure you understand the model, would the lightbulb be warmer if it was concentric to the reflective sphere? If you think not, how would that be so? -
suibhne at 07:29 AM on 20 February 2010Is CO2 a pollutant?
doug_bostrom ........... if you were a strange being living on the surface of the lightbulb...... Which surface,inner or outer? Philippe Chantreau .... the way you interpret Trenberth diagram does not seem to make any sense at all. Even on one side it does not add up 342 solar from Sun On Earth surface 168 solar + 324 back radiation Your right it does not make any sense at all. -
Alexandre at 07:29 AM on 20 February 2010Visual depictions of CO2 levels and CO2 emissions
RVSP, Please correct: closer to the *former* (not the latter) And also: The saturation argument and the "atmosphere has so little CO2 that it doesn't have any effect" argument are pretty much mutually exclusive. -
Alexandre at 07:26 AM on 20 February 2010Visual depictions of CO2 levels and CO2 emissions
RSVP, I assume you're using the saturation argument. Following the question you stated: does it simply raise the radiative source or does the energy hover somewhere forever? Well, if we had to pick one, the answer would be closer to the latter. The correction I'd point is not that it "simply" raises the source. This has consequences. You must keep in mind that it's not exactly "absorption", but attenuation by scattering. So the energy caught by CO2 at some point of the atmosphere is reemited to random directions, including upwards. The upper layers get somewhat less energy than the lower ones, and so the warming goes on even if these lower layers are already at their saturation. This webpage does a nice illustrative mathematical model of this. There's also the RealClimate post on this. -
Philippe Chantreau at 06:53 AM on 20 February 2010Is CO2 a pollutant?
Suibhne, the way you interpret Trenberth diagram does not seem to make any sense at all. The energy leaving the surface as IR radiation is the same energy that was previously received as mostly SW radiation (sunlight). The surface "converts" the SW energy into IR. The surface is not an energy source, neither is the atmosphere. If you are attentive to laws of thermodynamics, the energy coming from the Sun has to go somewhere, less the surface increase indefinitely in temperature until it reaches equilibrium with the Sun itself. Why are you shocked to see energy leaving the system? Where do you think it should be going? Thye panel example is inappropriate since these are average, global flows but let's look at it anyway. If you interpose a solar panel between the down going radiation and the surface, the diagram will obviously be radically altered. Your panel will get only 198 watts from above and, after a relatively short time for the surface to reach equilibrium, nothing from the bottom. The energy that was heating the surface is now received by the panel, the surface is not going to radiate IR as it was. If you think it could be otherwise, explain how. As for G&T, it is all about semantics indeed. Understood in the frame of thermodynamics, there is no heat transfer between the atmosphere and the surface, insofar as this would refer to a net heat transfer. G&T base the confusion on equating the simplification "the atmosphere makes the surface warmer" with "there is heat transfer between the atmosphere and the surface", implying it is a neat heat transfer. That's not what happens at all. The atmosphere just makes the equilibrium temperature of the surface higher than it would otherwise be without it. A radiant barrier makes the inside of a spacecraft warmer but there is no net heat transfer between the barrier and the craft. G&T is nothing but a multi page erudite obfuscation. -
RSVP at 06:27 AM on 20 February 2010Visual depictions of CO2 levels and CO2 emissions
Chris G "Near the surface, the GHGs may be relatively opaque and energy would rattle around for some time before gradually making progress outward; " When I made that remark #18, I was attempting to let Alexandre consider what he told theendisfar, taking his remark it to its logical conclusion, and so point out an untruth. In doing so, you use the term "rattle around". Why not diffuse or disperse? -
Chris G at 06:20 AM on 20 February 2010Visual depictions of CO2 levels and CO2 emissions
...but that doesn't mean that evaporation+convection somehow anticipate a change in energy flux and prevent it from having an effect. Otherwise, there would not be the wide range of climate conditions seen in the geologic record. Those same changes in climate that are often cited as evidence that humans are not altering the climate now somewhat preclude the idea that convection has a strong buffering effect. -
Tony Noerpel at 06:02 AM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
Hello HumanityRules Given the information provided by Jesus Rosino, we see that the solar forcing during the little ice age was between .14 and .23 W/m2. maybe that sounds small but that is over every single square meter of the Earth surface. So if we multiply by 4 X pi X (6371000) X (6371000) we get total power in joules/second. then by multiplying by 60 X 60 X 24 X 365 we can compute how many joules in each year of the MM that there was an energy imbalance. we get 3 X 10^21 joules each year. So that would explain the cold weather. but the interesting thing is that the energy imbalance today is about 1.8 W/m2 or about 6 times more intense. And that would be the problem. If I've made a math mistake, my appologies in advance. Tony -
Chris G at 05:53 AM on 20 February 2010Visual depictions of CO2 levels and CO2 emissions
theendisfar at 01:38 AM on 19 February, 2010 RSVP, "The GHE is a misnomer and has been grossly overestimated as to its ability to 'trap' heat, especially when taking into account the massive cooling effects of Convection and Evaporation. " Not sure what you mean by the cooling effect of evaporation. The gas media becomes a little warmer and the liquid media becomes a little cooler. Conservation of energy dictates that the net effect is zero. Of course, if the gas media becomes warmer, then convection becomes stronger, but that doesn't mean that evaporation+convection somehow anticipate a change in energy flux and prevent it from having an effect. As far as the size of the effect goes, the best estimates so far of a doubling of CO2 concentration are a base effect of, in round numbers, 1 K, and a fast-feedback of around 3 K. That's roughly a change of 0.5% and 1% in temperature, respectively. Granted, that's not much of a change on an absolute, physics scale, but it's quite a change within the band of what we think of as a temperate climate. -
Chris G at 05:24 AM on 20 February 2010Visual depictions of CO2 levels and CO2 emissions
@ RSVP at 03:45 AM on 20 February, 2010 Not 100% sure if you are making this mistake, but be sure you are not thinking of the atmosphere as being of a uniform density. It gets less dense with altitude quickly. Near the surface, the GHGs may be relatively opaque and energy would rattle around for some time before gradually making progress outward; as energy moves outward, the lower density of the GHGs makes it more likely for it to travel a further distance before being captured by a GHG molecule. At higher altitudes, any bits emitted outward are more likely to continue outward. Increasing CO2 concentration effectively raises the altitude at which it becomes more likely for the energy to escape than not. That aside, convection plays a large role in the process of transporting energy up from the surface as well; so, no matter how thick the atmosphere is with GHGs, the energy will not 'just stay there'. -
Doug Bostrom at 05:01 AM on 20 February 2010Is CO2 a pollutant?
suibhne at 04:19 AM on 20 February, 2010 Imagine a lightbulb illuminated in an evacuated void, radiating. Now wish a silvered sphere into being, with the lightbulb concentric to the sphere. What happens to the temperature of the lightbulb? Is the sphere heating the lightbulb? Perhaps more to the ultimate point of the discussion here, would it matter to you whether the sphere was heating the lightbulb, if you were a strange being living on the surface of the lightbulb and you liked the temperature the way it was without the sphere? -
johnd at 04:43 AM on 20 February 2010Visual depictions of CO2 levels and CO2 emissions
I would be interested in an animation of how CO2 moves to the surface in order to exchange with the vegetation and waters as this is where the greatest interaction occurs and ultimately all CO2 will be cycled through there, at least statistically. -
Riccardo at 04:29 AM on 20 February 2010It's the sun
Cliff Oates, indeed no one ignores it and we are grateful to the sun for pulling us out of the LIA. And we are also grateful for not increasing activity from the '50s at least up to now, it could have been worse. -
suibhne at 04:19 AM on 20 February 2010Is CO2 a pollutant?
CBDunkerson Some of the back radiation from the Earth must reach the SUN eventually. Would it make any sense at all to say the Earth heats the Sun? -
Cliff Oates at 04:11 AM on 20 February 2010It's the sun
Sunspot numbers averaged 45.8 from 1749 to 1920. they averaged 72.7 from 1920 to October 2009. This is an increase of 59 percent. If the Maunder Minimum from 1640 to 1710 was somewhat responsible for the Little Ice Age, this increase cannot be ignored. -
RSVP at 03:45 AM on 20 February 2010Visual depictions of CO2 levels and CO2 emissions
Theendisfar, "I suggest you research and calculate how much our "very transparent to IR" atmosphere can attenuate an IR beam in just a few meters - particularly at the 15um range." Let's suppose (in the worst case) every ounce of IR energy were absorbed within a few meters. This would simply raise the radiative heat source a few meters off the ground... or is the energy just going to stay there forever hovering over the ground? -
Dikran Marsupial at 03:37 AM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
HumanityRules @ 15 IIRC (it is always possible I don't ;o), the models tell you of the effects of an increase in radiative forcing, whether the increase in radiative forcing is due to changes in solar activity or due to a rise in atmospheric CO2 concentrations doesn't make any difference. The change in radiative forcing due to increasing carbon and solar activity are relatively well understood, it is how the climate responds to the change in forcing that is uncertain. In other words the models don't assume a weak effect from solar radiative forcing, it is weak because the solar forcing is weak. However, I am no climate modeler, just MHO, ask an expert like Gavin Schmidt @ RealClimate -
Alexandre at 03:37 AM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
Thanks Tony and Jesús. One of my mistakes was to neglect the cicles - hence my 2 W/m2 amplitude. -
SNRatio at 03:01 AM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
@15, HumanityRules It is not about having "developed theories" here. It's about looking at the actual data. And the _very_ interesting thing is that the temperature variations in the not so distant past to a large degree seem to come from such _relatively small_ fluctuations in solar irradiation. The models do _not_ assume a very weak effect from solar changes, but they try to take all forcings into account, adequately quantified. And even if you can't simply equate solar and GHG forcings, their effects seem to be comparable. -
HumanityRules at 02:55 AM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
The question I have is that if a grand minimum has an affect of between 0.09-0.3oC how was it possible to recognise the previous MM cold period. Would these be sufficient for people to recognise 1700 as a particularly cold period in history. Would this be sufficient to see the Thames freeze up and the other effects seen through Europe? As well as throwing away any significant cooling effect in the 21st C you also have to throw away the cooling effect around the MM. -
HumanityRules at 02:39 AM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
What's the point of this? If you have models that assume a very weak effect from changes in solar radiative forcing then you are going to get a result that suggests a MM will have a minor effect on the temp over the next century. Having developed theories that have minimised the LIA and MWP whats the point of doing this experiment? -
Riccardo at 02:35 AM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
Spencer Weart, it's always invaluable to have it put in the correct perspective. Thank you a lot. -
ProfMandia at 02:20 AM on 20 February 2010What would happen if the sun fell to Maunder Minimum levels?
John, Thanks for this gem. I will adding it to my site today. -
ProfMandia at 02:00 AM on 20 February 2010The Dunning-Kruger effect and the climate debate
How timely! I just linked to this thread because it does a great job (as usual) of illustrating the point I am making in my latest blog post titled: A Conversation at a Poker Game -
CBDunkerson at 01:52 AM on 20 February 2010Is CO2 a pollutant?
Suibhne, so... what? The entire G&T argument is some kind of semantic game? 'Greenhouse gas absorption and re-emission doesn't transfer HEAT to the surface of the Earth... just energy... which generates heat.' -
suibhne at 01:37 AM on 20 February 2010Is CO2 a pollutant?
carrot eater Philippe Chantreau If we space two lamps one irradiating from the top(492w) and one from the bottom (390w)of a double sided solar device then this light energy can be utilised in some way. Now instead of lamps look at your diagram to see the absurd situation. The energy all must ultimately come from the Sun which is only supplying 342w/m2 CBDunkerson The atmosphere does not transfer heat to the surface of the Earth. Look up the definition of heat in a thermodynamics book. Heat is sometimes mixed up with energy when people talk loosely and for a lot of situations the confusion wont matter much. A bit like some people use interchangeably the mass and weight of an object. However there are situations where such woolly thinking will lead you astray.
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