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scaddenp at 14:19 PM on 28 June 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
Just one other note - a global average temperature isnt really that complex a thing. For any planet rotating fast enough to equilibrate temperatures, then surface temp is function of incoming solar radiation, planetary albedo, geothermal heatflux (insignificant on earth) and atmospheric composition (GHG). eg a calculator or here for some of the equations. The tricky bit is predicting how atmosphere composition and albedo will change if alter something. -
scaddenp at 13:52 PM on 28 June 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
curiousd - my understanding of the calculated temperature in Fig 3, is that depends on only 3 inputs - CH4, CO2 and sealevel. However, they are are not directly "fitted" to a curve. N2O is also important but not preserved, but because it strongly correlated with CO2 and CH4, its contribution is added in as a 1.12 multiplier on the forcing strength of CO2 + CH4. This no. being consistent with radiative codes. Albedo is sum of a great many changes - ice shelves, ice sheets, changing land/ocean ratios, changing vegetation, but the earlier work (2007 from CLIMAP 1981) showed that it could estimated by sealevel alone as a "good enough" approximation. Clouds are problematic but clouds have both positive and negative effects and net forcing for current time is thought to be close to zero. There is no proxy for clouds but this data is at least consistent with assumption that net contribution has been very small compared to GHG and albedo. Note the cause of the ice-age cycle is solar variation but solar forcing isnt included. The global solar forcing is very small but the regional distribution means that it is expressed an albedo forcing. Note also, that the climate sensitivity that produces the good fit is dependent on 4.5C temp difference between LGM and Holocene. Use a different temp diff and you get a different sensitivity as discussed in detail in the paper. -
Pierre-Normand at 12:37 PM on 28 June 2012Mercury rising: Greater L.A. to heat up an average 4 to 5 degrees by mid-century
Michael, I only pointed out that your reference 'denies that...' in the sense of 'affirming the falsity of...' in its conclusion. That was an innocent use of the word "denies". The paper concludes that the UHI doesn't introduces significant bias in temperatures reconstructions. But that conclusion doesn't speak at all to Daisym's question. Daisym only seemed to be inquiring if the UHI effect (that your reference acknowledges to be real and significant albeit not a source of measurement bias) is accounted for in the models predictions. This is a good question, it seems to me, since the models are so finely gridded so as to geographically discriminate some industrial from residential or rural areas. -
curiousd at 11:20 AM on 28 June 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
To someone who needs to explain/impress both smart but non technical students, and to physics phds who are nearly ignorant of climate change, that figure 3 above could be a "game changer". The agreement between experiment and theory is rather like one sees in many areas of condensed matter physics. For instance it is like one obtains in fitting extended x-ray fine structure (EXAFS)data to a structural model. But one needs to know the number of adjustable parameters. When I first read the article, I thought that since they were able to figure out the albedos, CO2 concentrations, and temperatures that that figure represents only one adjustable parameter, the short term (transient) CO2 climate sensitivity. Now I am not so sure because of the mention of the N2O and CH4. In EXAFS theory a big deal is made about the number of independent data points and the number of adjustable parameters. If it is only one (or two ) (or three) parameters that are being fitted here the result is spectacular. (Nobel Prize Hanson?) Any help on what you think the number of adjustable parameters is? BTW...he gets rid of the "clouds" uncertainty by this empiricle method, right? Another "Lindzen ism" dealt with? -
Chemware at 10:32 AM on 28 June 2012North Carolina Lawmakers Turning a Blind Eye to Sea Level Reality?
@ newcrusader To quote Bohr's retort to Einstein ... Stop telling God what to do. -
Chris G at 08:47 AM on 28 June 2012North Carolina Lawmakers Turning a Blind Eye to Sea Level Reality?
John (#3), It would be nice if they read it and acknowledged the reality of what scientific studies indicate, but it is not as though there were not plenty of other evidence that they have chosen to pretend doesn't exist. I don't think a little more would make any difference to them. -
newcrusader at 08:21 AM on 28 June 2012North Carolina Lawmakers Turning a Blind Eye to Sea Level Reality?
The legislature in NC denies global warming because God will not permit it. -
John Hartz at 05:53 AM on 28 June 2012North Carolina Lawmakers Turning a Blind Eye to Sea Level Reality?
Every member of the North Carolina State Legislature should be required to read: Hot spot of accelerated sea-level rise on the Atlantic coast of North America This peer-reviewed paper by Asbury H. Sallenger Jr, Kara S. Doran & Peter A. Howd published online June 24 by the journal Nature Climate Change. -
shoyemore at 04:09 AM on 28 June 2012North Carolina Lawmakers Turning a Blind Eye to Sea Level Reality?
The legislators of North Carolina should remember that the original King Canute (or Knut) lived during the Medieval Warm Period, no doubt enjoying wine from the many English vineyards which flourished back then. But even he had to show humility in the face of sea level rise, which respects neither King nor commoner. -
vrooomie at 02:32 AM on 28 June 2012North Carolina Lawmakers Turning a Blind Eye to Sea Level Reality?
I remember thinking, while first reading about this mind-numbingly stupid story, that I thought (imputation of dishonesty snipped) I take some solace in that, eventually, the sheer stupidity of this will become apparent to all but the dimmest of lights, and that science, once again, shall become valued and heeded. That they NC lege "torpedoed" the amendment may be a sign of rational thought triumping over those who would deny science, at any and all costs. With the help of all here, and all who endeavor to hold out against the forces of dark, and by"common' scientists like me speaking to those we can, we might just win the day. *Maybe*. "No matter how cynical you get, it's impossible to keep up." -Lily Tomlin, "The Search for Signs Of Intelligent Life In The Universe."Moderator Response: TC: Please refrain from suggestions of dishonesty and all caps, both of which violate the comments policy. -
shoyemore at 02:18 AM on 28 June 2012Adding wind power saves CO2
Paul D :)) -
dana1981 at 01:59 AM on 28 June 2012Simply Wrong: Jan-Erik Solheim on Hansen 1988
angusmac @66:Dana, you seem to be focused on "Hansen would have been right"
No, you're still not understanding. It's not about whether or not Hansen was right (no model is ever "right"), it's about what we can learn from comparing his projections to real world observations.Your 2.7°C sensitivity Scenario D is running ≈ 12% above LOTI (1984-2012), which has a sensitivity ≈ 2.4°C.
LOTI is the land-ocean temperature index (observational data, not a model) so I have no idea where you get this 2.4°C sensitivity figure from.Furthermore, Hansen's temperature projections were used by policy makers
What does that even mean? First of all, the USA has not implemented any climate policy. Second, if they had implemented policy, it would not be dependent on the precise sensitivity of Hansen's 1988 model.Additionally, the errors in Hansen's scenarios are higher than the 40% stated by you.
First we're not talking about errors, we're talking about the amount by which the model sensitivity was too high. And my figure is correct. You're probably using the wrong baseline in addition to not accounting for the Scenario B forcing being 16% too high. -
dana1981 at 01:51 AM on 28 June 2012Gleckler et al Confirm the Human Fingerprint in Global Ocean Warming
Thanks Albatross. I think this is a very useful paper in responding to the misconception of a large model-data OHC discrepancy that we've previously discussed. As the authors note, most other studies have only used one or two models, whereas their study uses several from the CMIP3 ensemble for a much more thorough survey. The difference between the models incorporating volcanic effects and those excluding them is also very interesting and useful to know. And Domingues' feedback was very helpful. There's another post in the pipeline for which I got feedback from Trenberth and Dessler. It's nice that these prominent climate scientists are willing to take the time to help us make sure we get the science right in our blog posts. -
Albatross at 01:12 AM on 28 June 2012Gleckler et al Confirm the Human Fingerprint in Global Ocean Warming
Excellent summary Dana. It was very kind of Dr. Domingues to provide SkS with valuable feedback, especially given how busy scientists are preparing papers for the deadline for the fifth IPCC assessment report. This is a devastating paper for the fake skeptics and those who deny the theory of AGW. [So expect push back and obfuscation from the usual suspects] For example, "Gleckler et al. on the other hand examine several different CMIP3 models, and do not identify a notable model-data discrepancy" So much for the much touted claim on blogs by fake skeptics that the models grossly overestimate the warming in the climate system Also, Domingues et al. show that "...when we continue to consider longer and longer trends, the human-induced signal becomes more and more evident (stronger relative to the noise)." This is of course the very reason why fake skeptics and those who enable advocates of delaying taking meaningful action to reduce GHG emissions (e.g., Dr. Pielke Snr.) insist on focussing on unrealistically short periods when examining the climate system, even when strongly advised to the contrary. The paper also indicates why the same fake skeptics can continually cherry-pick their start and end points to try and disappear the warming and accumulation of heat in the climate system. All this compelling evidence right before people's eyes, yet some continue to deny the reality and deny the science at everyone's peril. -
angusmac at 00:13 AM on 28 June 2012Simply Wrong: Jan-Erik Solheim on Hansen 1988
Dana@53, I read all of your post, including the final section, and I comment as follows. "What this tells us is that real-world climate sensitivity is right around 3°C." Dana, you seem to be focused on "Hansen would have been right" - if only he had used 3°C. Nevertheless, this sensitivity value appears to be a little high. Your 2.7°C sensitivity Scenario D is running ≈ 12% above LOTI (1984-2012), which has a sensitivity ≈ 2.4°C. Furthermore, Hansen's temperature projections were used by policy makers. He gave them temperature estimates that were significantly too high. Consequently, he was wrong. Additionally, the errors in Hansen's scenarios are higher than the 40% stated by you. When compared with LOTI (0.52°C in May 2012), the errors are as follows: Scenario A 1.18°C (126%) Scenario B 1.07°C (105%) Scenario D 0.67°C (28%) -
michael sweet at 22:57 PM on 27 June 2012Mercury rising: Greater L.A. to heat up an average 4 to 5 degrees by mid-century
Pierre: It appears to me that Daisym is challenging the OP, claiming that UHI has not been properly taken into effect. Perhaps I am incorrect, Daisym could tell me if that is the case. The link I provided was the first of many that show UHI has a small effect on these types of measurement. My reference "denies" nothing. They provide data that show the UHI effect is small. I could have cited Watts paper where they show "improperly" located weather stations have no effect on temperature trends. In general, UHI is a non effect that deniers cite to confuse people. AGW fake skeptics often raise tone questions of this type to suggest data issues that do not exist. What is your point? -
Paul D at 21:05 PM on 27 June 2012Adding wind power saves CO2
Cheers Shoyemore nice gentle ski slope there! -
Dikran Marsupial at 20:26 PM on 27 June 2012Simply Wrong: Jan-Erik Solheim on Hansen 1988
angusmac on what basis would you arrive at plus minus 20% or 30% range? Is this subjective, or is there a scientific methodology that you have used to arive at these figures? -
Pierre-Normand at 19:48 PM on 27 June 2012Mercury rising: Greater L.A. to heat up an average 4 to 5 degrees by mid-century
Michael, you seem to have misread both Daisym's comment and your own reference. Daisym didn't suggest that the UHI has the effect to bias temperature anomaly reconstructions. And your reference only denies that the UHI causes any significant such bias. That's in part because "urban meteorological observations are more likely to be made within park cool islands than industrial regions" -
angusmac at 19:26 PM on 27 June 2012Simply Wrong: Jan-Erik Solheim on Hansen 1988
Dikran Marsupial@49 When modelling semi-random systems, I would expect results in the ± 20% range to be good. However, for results that were significantly larger than the ± 30% range, I would suspect that there was something wrong with my physics. -
Fred Staples at 18:38 PM on 27 June 2012Simply Wrong: Jan-Erik Solheim on Hansen 1988
(-SNIP-)Moderator Response:[DB] Long, specious "What if...?" strawman rhetorical argument snipped.
You have been counseled against this line of posting, which constitutes sloganeering, previously. Continuance in this line of comment construction will necessitate a revocation of posting privileges. You will receive no further warnings in this matter.
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shoyemore at 17:31 PM on 27 June 2012Adding wind power saves CO2
You can get real time wind power data and CO2 emissions (calculated by a formula) from the Eirgrid website. Anyone who is in the business of refuting Udo & Co may find it useful. Eirgrid data The following shows CO2 emissions on the y-axis, and fraction of demand taken up by wind generation on the x-axis.
I had to split the data because Excel gets huffy with more than 32,000 data points.
Further calculations showed ~0.45tCO2/MWh, which I think is in line with industry expectations.
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scaddenp at 14:05 PM on 27 June 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
By the way, the albedo estimates and modelling used go back to Hansen et al 2007, which for input relies heavily on the accumulated data from multiple sources in CLIMAP 1981. -
scaddenp at 13:46 PM on 27 June 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
Past sealevel is important for determine land/sea boundaries in albedo estimates. In a glacial period, the ice-sheets on Eurasia and North America are major contributors to albedo. Antarctica and Greenland were frozen then as now so dont contribute much to change in albedo. Ice extent is from geomorphology etc. Sea ice extent is inferred from plankton in sediment core. Some species only occur in open water, others under ice. This leads to chemical biomarkers too. I dont have the papers but putting "sea ice biomarker" into scholar.google.com will give quite a few papers. There are a number of techniques used to infer paleo sealevel. Try here for coral reef work. Have you had a look at Chpter 6 of the AR4 IPCC? This links to many papers on this topic. -
curiousd at 13:17 PM on 27 June 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
Questions on great Hanson and Sato paper: 1. They estimate Albedo from sea level since the sea level is determined by the major ice sheets. Clever!! Sea level is unaffected by floating ice packs, of course, such as ice now floating in the Arctic (but not for long, unfortunately). So does this mean that the contribution of the Arctic sea ice pack to the albedo is negligible compared to Greenland and Antarctica? 2. How does one determine sea levels going back 800,000 years? -
scaddenp at 10:18 AM on 27 June 2012Glimmer of hope? A conservative tackles climate change.
Patrick, I believe what is meant by revenue neutral is that tax is collected on carbon emission and all of it distribute back on per capita basis. That way is it is not adding to government or redistributing wealth to the unworthy - concerns for the right wing. -
Patrick 027 at 09:37 AM on 27 June 2012Glimmer of hope? A conservative tackles climate change.
'inequities' probably a better word choice for last word of 2nd-to-last paragraph of my first of 2 prior comments; sorry for being nit-picky. -
Patrick 027 at 09:35 AM on 27 June 2012Glimmer of hope? A conservative tackles climate change.
... on national boundaries - the tax itself could come along with some tariff (somehow proportional to emissions (if all countries did this, then I think it would only be the emissions only in what was done to a product/service in the last country, not the entire upstream chain)/export subsidy (not proportional to emissions on a per product/service basis - why reward our own polluters just because another country would?) proportional to the tax and to differences among national policies. -
Patrick 027 at 09:29 AM on 27 June 2012Glimmer of hope? A conservative tackles climate change.
I'm curious about the logic of 'revenue neutral' here. Setting aside general justifications for government R&D for new technology, and some other things, following the concepts of an efficient market and externalities, the tax rate is justified by the public cost, so it would make sense to spend the revenue on those costs. Of course, the way in which the costs are realized is somewhat up to us even given a particular forcing scenario - relocation verses adapation in place, paying for injuries as the happen verses proactive actions. We could concievably spend the money now on adaptive water supply infrastructure - or those bits which we can design now given our climate knowledge (some additions might concievably have to wait until we know more details about where and when the rains will go, etc.). There could also be agricultural R&D. And some costs will be incurred by the government itself, of course. One caveat is that you would generally want to avoid spending money to subsidize innefficient adaptation means. One might want to pay compensation once for a reduction in property value suffered or for upgrades (but maybe only up to a point, since people (setting aside more caveats) already have had opportunity to retreat from coasts and drying and heating-up regions, for example), but wouldn't want to mask the price signals when insurance costs rise at some location, as that may encourage people to relocate to a less risky place. Maybe some mix between tax and dividend (equal per capita) and tax and cut other taxes could be seen as an economic investment, so that there will be more wealth in the future that can be taxed when public spending on the costs of climate change will be necessary, and also as a general compensation to people now for what they or their heirs may deal with later or for there proactive measures taken now, but there will be inequalities. And compensation, in some form, will eventually have to cross national boundaries... -
Tom Smerling at 23:51 PM on 26 June 2012Glimmer of hope? A conservative tackles climate change.
More conservative advocates of a revenue-neutral carbon tax: A short list of quotes from other conservative supporters of a revenue-neutral carbon tax can be found at CarbonTax.org. The Frum Forum hosts a Kenneth Silber post titled, "How the GOP Should Explain Climate Change," with a sample speech for a Republican candidate that includes a ringing call for a carbon tax: "My plan is straightforward and honest. We will raise taxes on carbon emissions across the board, while cutting taxes on payrolls and incomes. That means more money in people’s pockets, and more incentives for industry to develop cleaner and safer energy supplies." [links to the above can be found at the bottom of the original post at ClimateBites.) -
Cornelius Breadbasket at 23:38 PM on 26 June 2012Review of new iBook: Going to Extremes
99p here in the UK. And it is a brilliant piece of work and extremely good value! It is, however, rather depressing, particularly in the light of the failure of Rio. -
michael sweet at 22:52 PM on 26 June 2012Mercury rising: Greater L.A. to heat up an average 4 to 5 degrees by mid-century
Daisym This peer reviewed paper shows little effect from UHI on urban temperatures in the USA. Fake skeptics claim UHI causes everything. Can you provide a peer reviewed study that suggests UHI affects the result of the opening post or are you just hand waving? Hand waving arguments can be dismissed with a hand wave. In any case, UHI changes are well known to have little effect on decade level temperature changes. -
sol6966 at 22:49 PM on 26 June 20122012 SkS Weekly Digest #25
"Should SkS increase its coverage of the science of renewable energy?" In keeping with this site's MO, Sks could focus on Myths about mitigation options. For example, Renewable Energy, Energy Efficiency, CCS, Nuclear Energy. All these options have their Boosters and Detractors, as a result there are many Myths. I see Sks' roll in Debunking Myths about climate science as being very helpful in informing rational debate about climate change. I believe Sks could be just as helpful in informing rational debate about mitigation options. -
Jen at 19:46 PM on 26 June 20122012 SkS Weekly Digest #25
"Should SkS increase its coverage of the science of renewable energy?" I don't think so - better to concentrate on climate change itself, rather than the various mitigation policies. -
macoles at 18:41 PM on 26 June 2012An exponential increase in CO2 will result in a linear increase in temperature
Turns out GISS gave the highest warming acceleration. Here are my results for all the datasets using the same range and method as before: GISS 0.0579C per decade per decade, or +0.01C per decade every 21 months. UAH 0.0531C per decade per decade, or +0.01C per decade every 23 months. CRU 0.0301C per decade per decade, or +0.01C per decade every 40 months. NCDC 0.0273C per decade per decade, or +0.01C per decade every 44 months. RSS 0.0062C per decade per decade, or +0.01C per decade every 194 months. So while acceleration is apparent, it does look like there is not enough datapoints yet to get a value that all the datasets can agree on. -
Tom Curtis at 13:21 PM on 26 June 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
curiousd @27, if you want a record of the changes in forcings from different GHG over the last three decades, go here. You will see that CH4 and NO2 forcing rose consistently through to about 1998, after which CH4 forcing leveled of while NO2 continued to rise. In contrast, CO2 forcing rose slowly during the 1990s, but sharply after 2000. Consequently, and contrary to expectations, CO2 was less important as a contributor to warming in the 1990s than it was in preceding decades, and in the 2000s. That in no way challenges Hansen 81. Climate scientists do not, by virtue of their expertise, claim any greater ability to predict things like the collapse of the Soviet Union (the cause of reduced CO2 emissions in the 1990s) or global financial crises. That is why they make projections conditional on certain plausible scenarios of growth in forcings rather than predictions. Of course, fake "skeptics" insist, implicitly, that AGW is falsified because Hansen did not predict that when Reagan said, "Tear down this wall", Gorbachov did so; or that the early 2000's would be dominated by El Ninos while the last few years have been dominated by La Ninas. Real skeptics are more sensible than that.
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curiousd at 12:30 PM on 26 June 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
Input wanted on Hansen's year 2000 article in Proc.Nat. Acad. Sci 97, pp. 9874 - 9880. Please!! Here he says "..rapid warming in recent decades has been driven mainly by non-CO2 greenhouse gases (GHGs), such as chlorofluorocarbons, CH4, and N2O, not by the products of fossil fuel burning, CO2 and aerosols."" Wow folks, doesn't this contradict the seminal 1981 paper? What happened here????? -
Tom Curtis at 09:08 AM on 26 June 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
curiousd @23, relative humidity tends to be greater over ocean than over land, so increasing the surface area of the Earth's Oceans would indeed increase the relative strength of the Water Vapour feedback. It would also increase the strength of the negative feedback from the Lapse Rate feedback, which is the reduction of the Lapse Rate with increased humidity. The two effects do not cancel out, so that if the Earth was a 100% water world it would be warmer, all else being equal. However, it would not be sufficiently warm to initiate a runaway-greenhouse effect. The reasons why are discussed by Chris Colose here. The essence of the argument is that positive feedbacks reduce the outgoing radiation for a given surface temperature. If, but only if, the positive feedback reduces the OLR such that arbitrarily large increases of surface temperature are required to match the incoming solar radiation will you get a runaway feedback. For the Earth, with the water vapour/lapse rate feedback, effective insolation (insolation*(1-albedo) would need to be just over 320 W/m^2 rather than the current 240 W/m^2. The effective insolation needed to reach runaway greenhouse is called the Kombayashi-Ingersoll limit. Put another way, the Earth will only achieve a runaway greenhouse effect with current insolation if its albedo is reduced to 0.05 (give or take a bit for uncertainties). -
Bob Loblaw at 08:56 AM on 26 June 2012Mercury rising: Greater L.A. to heat up an average 4 to 5 degrees by mid-century
daisym: Well, UHI is usually a function of the logarithm of population (Oke, 1967), so the effect tapers off as growth continues, and it's usually caused by changing land use (pavement replacing natural surfaces, heat retention in artificial structures, etc.). How much more growth can the LA basin handle, and how much of it is still left in a natural state, to pave over? -
Eric (skeptic) at 07:50 AM on 26 June 2012Mercury rising: Greater L.A. to heat up an average 4 to 5 degrees by mid-century
The heat around the LA area depends almost entirely on offshore versus onshore winds. The global model cannot predict that pattern so they used downscaling. Reading through the study here http://c-change.la/pdf/LARC-web.pdf I see in the appendix that the offshore vs onshore parameters (alpha and beta) are determined from a minimizing the error between the global and regional models. Thus, alpha and beta are a function of three parameters from the global model (lapse rate, along with warming and ocean to desert contrast). The most obvious flaw is that the onshore vs offshore regime will depend on the larger climate pattern. For example the past winter's La Nina created more offshore winds. It does not appear that there is any connection from such climate regimes in the global model to the local model as they state in the paper the connections are mostly through temperature, contrast and lapse rate. Here's an alternative scenario: [LINK]Moderator Response: [RH] Shortened link that was breaking page formatting. -
daisym at 06:46 AM on 26 June 2012Mercury rising: Greater L.A. to heat up an average 4 to 5 degrees by mid-century
Los Angeles is one of the largest urban heat islands in the U.S. Is Alex Hall's predicted temperature increase for the L.A. region NET of UHI temp increases arising from projected population growth? What did Hall use as the projected L.A. temperature increase due to population growth through mid-century? -
cynicus at 06:37 AM on 26 June 2012Adding wind power saves CO2
Fyi, Fred Udo is great friends with De Groot and Le Pair, so don't be surprised when his 'science' appears as cherry-picked and deeply flawed like the others. He also trots out the false 'OCGT stations balance wind so CO2 savings are nil' argument. -
funglestrumpet at 06:23 AM on 26 June 2012Mercury rising: Greater L.A. to heat up an average 4 to 5 degrees by mid-century
They are lucky, The U.S.A. being one of the places in the world that will be least affected by climate change. Some poor sods stand little or no chance of adapting to it other than by burying their dead, of course. It would be nice if, when planning their adaptation strategies, these American experts could offer advice to their less fortunate fellow humans who live in parts of the world that will be most affected by it. Especially seeing as these people often have neither the expertise nor the time, what with subsistence farming to cope with, and Aids and water shortages and and and. -
miffedmax at 06:14 AM on 26 June 2012Response to Vahrenholt and Luning
One can only hope there is a special place in academic hell for those who repeatedly cherrypick the work of others to cite conclusions that are the exact opposite of what the original researchers conclude. -
Jim Powell at 03:04 AM on 26 June 2012Review of new iBook: Going to Extremes
It should show up in the Dutch store soon and the price should be $0.99U.S. or the equivalent in each currency. It will only work on an iPad, not in Linux. -
Bob Lacatena at 02:21 AM on 26 June 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
Here's the image from that link, changed to also include the atmosphere rolled into a ball alongside the oceans. Note that all of the biomatter on earth is an almost invisible spec, the size of one pixel, in this image:
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Bob Lacatena at 02:14 AM on 26 June 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
curiousd, No. It's really, really hard to get to a runaway. It has nothing to do with the surface of the earth, or how much water. Surface area means nothing, (everything is in units per square meter, it doesn't matter how many square meters in total). There's more than enough water on earth, too, the problem isn't that the system runs out of water. But there are negative feedbacks in place as well, the largest of which is the Planck effect... the hotter it gets, the more it radiates (power of 4), so it gets harder and harder to push that envelope. The "doubling" rule of CO2 applies to water vapor as well. Then there's the lapse rate feedback... as the earth warms, the lapse rate changes, and it becomes easier to radiate energy to space (i.e. more of the temperature change is higher up, where it can escape more easily to space). In the end, achieving a runaway is really, really hard. On how much water there is on earth... enough, but just for fun look at this. -
curiousd at 00:48 AM on 26 June 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
O.K. think I kind of dig it, esp thanks scaddenp who points out about the time step in the computer models respond to each temperature so the kind of effect I am talking about is IMPLICITLY calculated. One follow up question...I get the feeling from the old 1981 Hansen paper that his water vapor feedback on the CO2 initial temperature increase is positive but less than unity which is a really good thing!! The temp of the earth if no greenhouse gases would be given by (S is solar constant) S/4 = emissivity x stef boltz const x T^4, so the surface area of the earth cancels out. But if the surface area of the earth were larger, and it contained proportionally more water, then once the greenhouse effect were taken into account I suspect you could get closer to a runaway condition, even if distance from sun is same as in real case. Yes? No? (Here I am trying to see the kinds of things that go into the modeling....probably one of them is how much water there is on earth?) -
Bob Lacatena at 00:04 AM on 26 June 2012Response to Vahrenholt and Luning
renewable guy, Until the link is properly fixed in the post, you can find this excellent talk by the American geologist Richard Alley here.Moderator Response: [DB] All links fixed. -
Bob Lacatena at 23:40 PM on 25 June 2012Hansen and Sato Estimate Climate Sensitivity from Earth's History
19, curiousd, The short answer to your question is "yes." The long answer is that climate sensitivity (in addition to Tristan's distinction between transient, fast feedback and Earth System) is a lot of different things, because it doesn't really exist as some fixed universal constant. As explained previously, every system configuration will respond differently. In casual conversation and for simple box models we use a single scalar to represent sensitivity relative to a doubling of CO2. But in a physics based climate model, for instance, you don't tell it the sensitivity, you tell it how atmospheric water vapor responds to a change in temperature, and how temperature responds to a change in water vapor... and a hundred other things. Then the model plays out and tells you what the climate sensitivity is in that scenario, as a (grossly oversimplified) scalar value. So to answer your question more directly, if you are talking about a climate model, the non-runaway-vapor-thing is included as a matter of physics, and if you're talking about a simple scalar value from paleoclimate or other observational study, the non-runaway-vapor-thing is included because you're looking at the "end result difference," and if it's a value computed in some other way it includes the non-=runaway-vapor-thing unless the person who put the number together was stupid.
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