NEW 4/10/09: There is an update to this post, see below the “read the rest of this entry” – Anthony
Guest Post by Richard Lindzen, PhD.
Alfred P. Sloan Professor of Meteorology, Department of Earth, Atmospheric and Planetary Science, MIT
This essay is from an email list that I subscribe to. Dr. Lindzen has sent this along as an addendum to his address made at ICCC 2009 in New York City. I present it here for consideration. – Anthony
Simplified Greenhouse Theory
The wavelength of visible light corresponds to the temperature of the sun’s surface (ca 6000oK). The wavelength of the heat radiation corresponds to the temperature of the earth’s atmosphere at the level from which the radiation is emitted (ca 255oK). When the earth is in equilibrium with the sun, the absorbed visible light is balanced by the emitted heat radiation.
The basic idea is that the atmosphere is roughly transparent to visible light, but, due to the presence of greenhouse substances like water vapor, clouds, and (to a much lesser extent) CO2 (which all absorb heat radiation, and hence inhibit the cooling emission), the earth is warmer than it would be in the absence of such gases.
The Perturbed Greenhouse
If one adds greenhouse gases to the atmosphere, one is adding to the ‘blanket’ that is inhibiting the emission of heat radiation (also commonly referred to as infrared radiation or long wave radiation). This causes the temperature of the earth to increase until equilibrium with the sun is reestablished.
For example, if one simply doubles the amount of CO2 in the atmosphere, the temperature increase is about 1°C.
If, however, water vapor and clouds respond to the increase in temperature in such a manner as to further enhance the ‘blanketing,’ then we have what is called a positive feedback, and the temperature needed to reestablish equilibrium will be increased. In the climate GCMs (General Circulation Models) referred to by the IPCC (the UN’s Intergovernmental Panel on Climate Change), this new temperature ranges from roughly 1.5°C to 5°C.
The equilibrium response to a doubling of CO2 (including the effects of feedbacks) is commonly referred to as the climate sensitivity.
Two Important Points
1. Equilibration takes time.
2. The feedbacks are responses to temperature – not to CO2 increases per se.
The time it takes depends primarily on the climate sensitivity, and the rapidity with which heat is transported down into the ocean. Both higher sensitivity and more rapid mixing lead to longer times. For the models referred to by the IPCC, this time is on the order of decades.
This all leads to a crucial observational test of feedbacks!
The Test: Preliminaries
Note that, in addition to any long term trends that may be present, temperature fluctuates on shorter time scales ranging from years to decades.
Such fluctuations are associated with the internal dynamics of the ocean- atmosphere system. Examples include the El Nino – Southern Oscillation, the Pacific Decadal Oscillation, etc.
These fluctuations must excite the feedback mechanisms that we have just described.
The Test
1. Run the models with the observed sea surface temperatures as boundary conditions.
2. Use the models to calculate the heat radiation emitted to space.
3. Use satellites to measure the heat radiation actually emitted by the earth.
When temperature fluctuations lead to warmer temperatures, emitted heat radiation should increase, but positive feedbacks should inhibit these emissions by virtue of the enhanced ‘blanketing.’ Given the model climate sensitivities, this ‘blanketing’ should typically reduce the emissions by a factor of about 2 or 3 from what one would see in the absence of feedbacks. If the satellite data confirms the calculated emissions, then this would constitute solid evidence that the model feedbacks are correct.
The Results of an Inadvertent Test
Above graph:
Comparison of the observed broadband LW and SW flux anomalies for the tropics with climate model simulations using observed SST records. The models are not given volcanic aerosols, so the should not expected to show the Mt. Pinatubo eruption effects in mid-1991 through mid-1993. The dashed line shows the mean of all five models, and the gray band shows the total rnage of model anomalies (maximum to minimum).
It is the topmost panel for long wave (LW) emission that we want.
Let us examine the top figure a bit more closely.
From 1985 until 1989 the models and observations are more or less the same – they have, in fact, been tuned to be so. However, with the warming after 1989, the observations characteristically exceed 7 times the model values. Recall that if the observations were only 2-3 times what the models produce, it would correspond to no feedback. What we see is much more than this – implying strong negative feedback. Note that the ups and downs of both the observations and the model (forced by observed sea surface temperature) follow the ups and downs of temperature (not shown).
Note that these results were sufficiently surprising that they were confirmed by at least 4 other groups:
Chen, J., B.E. Carlson, and A.D. Del Genio, 2002: Evidence for strengthening of the tropical general circulation in the 1990s. Science, 295, 838-841.
Cess, R.D. and P.M. Udelhofen, 2003: Climate change during 1985–1999: Cloud interactions determined from satellite measurements. Geophys. Res. Ltrs., 30, No. 1, 1019, doi:10.1029/2002GL016128.
Hatzidimitriou, D., I. Vardavas, K. G. Pavlakis, N. Hatzianastassiou, C. Matsoukas, and E. Drakakis (2004) On the decadal increase in the tropical mean outgoing longwave radiation for the period 1984–2000. Atmos. Chem. Phys., 4, 1419–1425.
Clement, A.C. and B. Soden (2005) The sensitivity of the tropical-mean radiation budget. J. Clim., 18, 3189-3203.
The preceding authors did not dwell on the profound implications of these results – they had not intended a test of model feedbacks! Rather, they mostly emphasized that the differences had to arise from cloud behavior (a well acknowledged weakness of current models). However, as noted by Chou and Lindzen (2005, Comments on “Examination of the Decadal Tropical Mean ERBS Nonscanner Radiation Data for the Iris Hypothesis”, J. Climate, 18, 2123-2127), the results imply a strong negative feedback regardless of what one attributes this to.
The Bottom Line
The earth’s climate (in contrast to the climate in current climate GCMs) is dominated by a strong net negative feedback. Climate sensitivity is on the order of 0.3°C, and such warming as may arise from increasing greenhouse gases will be indistinguishable from the fluctuations in climate that occur naturally from processes internal to the climate system itself.
An aside on Feedbacks
Here is an easily appreciated example of positive and negative feedback. In your car, the gas and brake pedals act as negative feedbacks to reduce speed when you are going too fast and increase it when you are going too slow. If someone were to reverse the position of the pedals without informing you, then they would act as positive feedbacks: increasing your speed when you are going too fast, and slowing you down when you are going too slow.
Alarming climate predictions depend critically on the fact that models have large positive feedbacks. The crucial question is whether nature actually behaves this way? The answer, as we have just seen, is unambiguously no.
UPDATE: There are some suggestions (in comments) that the graph has issues of orbital decay affecting the nonscanner instrument’s field of view. I’ve sent a request off to Dr. Lindzen for clarification. – Anthony
UPDATE2: While I have not yet heard from Dr. Lindzen (it has only been 3 hours as of this writing) commenter “wmanny” found this below, apparently written by Lindzen to address the issue:
“Recently, Wong et al (Wong, Wielicki et al, 2006, Reexamination of the Observed Decadal Variability of the Earth Radiation Budget Using Altitude-Corrected ERBE/ERBS Nonscanner WFOV Data, J. Clim., 19, 4028-4040) have reassessed their data to reduce the magnitude of the anomaly, but the remaining anomaly still represents a substantial negative feedback, and there is reason to question the new adjustments.”
I found the text above to match “wmanny’s” comment in a presentation given by Lindzen to Colgate University on 7/11/2008 which you can see here as a PDF:
http://portaldata.colgate.edu/imagegallerywww/3503/ImageGallery/LindzenLectureBeyondModels.pdf
– Anthony
UPDATE3: I received this email today (4/10) from Dr. Lindzen. My sincere thanks for his response.
Dear Anthony,
The paper was sent out for comments, and the comments (even those from “realclimate”) are appreciated. In fact, the reduction of the difference in OLR between the 80’s and 90’s due to orbital decay seems to me to be largely correct. However, the reduction in Wong, Wielicki et al (2006) of the difference in the spikes of OLR between observations and models cannot be attributed to orbital decay, and seem to me to be questionable. Nevertheless, the differences that remain still imply negative feedbacks. We are proceeding to redo the analysis of satellite data in order to better understand what went into these analyses. The matter of net differences between the 80’s and 90’s is an interesting question. Given enough time, the radiative balance is reestablished and the anomalies can be wiped out. The time it takes for this to happen depends on climate sensitivity with adjustments occurring more rapidly when sensitivity is less. However, for the spikes, the time scales are short enough to preclude adjustment except for very low sensitivity.
That said, it has become standard in climate science that data in contradiction to alarmism is inevitably ‘corrected’ to bring it closer to alarming models. None of us would argue that this data is perfect, and the corrections are often plausible. What is implausible is that the ‘corrections’ should always bring the data closer to models.
Best wishes,
Dick
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PeteB (02:20:37) :
Just out of curiosity let me ask you a couple questions:
1.) Do you think adjusting past temperatures downward is valid? I haven’t bookmarked one, but many people have done blink comparators that show how the hot 30s were reduced .. making a wavy graph look more like a straight line.
2.) Do you have a counter-example of corrections going the other direction? It seems every time there is a correction recent temperature are moved up, past temperature are moved down. Does this seem reasonable to you?
1) OK – from the IPCC Assessment Reports – I apologise this is big picture – but I’m interested in if this had made a significant difference
1st Assessment Report (1990) – Our judgement is that: global mean surface air temperature has increased by 0.3 to 0.6 oC over the last 100 years…;
2nd Assesment Report (1995) –
Global mean surface air temperature has increased by between about 0.3 and 0.6°C since the late 19th century; the additional data available since 1990 and the reanalyses since then have not significantly changed this range of estimated increase.
3rd Assement Report 2001 – The global average surface temperature has increased over the 20th century by about 0.6°C;
4th Assesment Report (2007) The 100-year linear trend
(1906-2005) of 0.74 [0.56 to 0.92]°C1 is larger than the corresponding
trend of 0.6 [0.4 to 0.8]°C (1901-2000)
Those all seem pretty consistent to me given the temperature has risen 1988- 2005 (the cutoffs for AR1 to AR4) by a fraction under 0.4 deg C (from the woods for trees plot)
PeteB (04:05:06) :
I think you misunderstood my question #1. I mean the temperature measurements of the 30-40s, which were hotter then today, have been adjusted downward. This makes all the difference between having a trend and no trend …
I found a link to a blink comparator to show what i mean — http://zapruder.nl/images/uploads/screenhunter3qk7.gif
And I assume you were not able to find a counter-example (where adjustments went against the trend). When we are dealing with a signal buried in noise and all adjustments go one-way, well .. that seems unlikely, to put it mildly 🙂 .
I think we are at an impasse. I respect your position; its logically and you have done your research and I concede might be correct, however I remain skeptical. There is a LOT of room for skepticism as the above graph shows just one piece of. If there was a strong and obvious ‘unadjusted’ signal … there would be no argument … but we to have succumbed to arguing over noise.
Cheers to you and thank you for your respectful and intelligent debate.
Cheers Ian, thank you
(to be honest I didn’t look for a counter example)
Apart from the predictable direction of every correction made to data in disagreement with alarmist models, I do not understand the changes in orbit depicted in Wong paper (http://asd-www.larc.nasa.gov/~tak/wong/f20.pdf figure 1). How can a satellite orbit decay be stepwise? It should be gradual, with almost constant slope until final re-entrance.
any explanation to that?
Dear Prof. Lindzen, Thank you for your clear and concise thoughts on this matter. So few published articles employ scientific fact and hard data to make their point, thank you. If people only knew that these proposed “solutions” to a non-existent problem will so deadly to the poorest and most vulnerable amongst us, they would call these snake-oil salesmen on their lies. But as always, hindsight will be 20-20 for most. Please keep up the good work.
Steven M.
Lexington MA
I like this quote from Lindzen:
“That said, it has become standard in climate science that data in contradiction to alarmism is inevitably ‘corrected’ to bring it closer to alarming models.”
It sort of reminds me of how computer simulations were run regarding ice melting on Mars and they concluded “that the planet’s albedo-induced warming may be responsible for as much as 60 percent of that loss.”
“May be” and “as much as 60%” is an awful lot of wiggle room.
bill (17:33:17) : A real world example in UK (from the docment I referenced above
The hot summer of 1995
I find this amusing. A tale of woe and disaster from the runaway heat wave in the UK causing drastic failure that can not be mitigated… sheep dropping like flies from the heat… Why amusing?
Because I grew up in farm country in one of the most productive places on the planet, regularly attending the county fair in August to tour the animal barns (including cattle, sheep, pigs, etc.) When it was regularly 110 F in the shade (and there aint no shade…)
Now if you hit over about 105 F for long times it’s a good idea to swap over to heat tolerant breeds like the brahman breeds, but my Dad ran a standard brown / white beef breed with no ‘issues’ and the hotter it got the more the pasture and grains grew. Oh, it it’s a good idea to shear the sheep at the start of summer. (You know, last time I looked they grew a lot of sheep in Australia out in the way hot… I remember driving past a lot of them on a very hot day)
Cereal yields and quality were good. The protein content of grain rose, which was good for bread-making wheat but not for malting barley. The harvest was large and early, allowing farmers to make a cost saving with fewer working days and less grain drying,…
Yup. More food more easily. Oh, and it’s OK to malt high protein barley, but if it really bothers you, just constrain the nitrogen fertilizer a little.
Cattle enterprises suffered because of a shortage of grass and forage, although upland forage for beef was less restricted. Many areas could only take one silage cut, and grass production in the driest areas dropped by 20-30%. Maize yields were down by 30%, and other feeds such as potatoes were in short supply. All this resulted in food supply problems over the winter, with farmers buying in feed or selling off animals.
Sounds more like a drought / planning problem than a heat problem. Plant more dry tolerant varieties and move on. As a one time fluke, you got caught unprepared; longer term this is very manageable. (I remember my Mom saying that she was going to visit home in England during July in the hope of finding the sunny day that year 😉 She got rained on the whole time… An English drought is when the frogs don’t drown… BTW, burmuda grass is highly productive in heat and we always had clover / vetch growing like crazy in the summer. At most you need to slightly change what you plant to take advantage of increased heat, if you get any.
One beneficial effect of the summer was that, although hay and forage prices were high, cereals had produced a lot of good quality straw, which some farmers used to supplement rations.
OK, maybe it’s a language issue, but where I grew up it was “straw” when it was loose and it was “hay” when it was bailed, but more specifically straw was the stem of a grass. So I’m having trouble with the idea that hay was having problems but straw wasn’t… Maybe you had a particular kind of hay in mind, like Alfalfa, that doesn’t have a straw since it’s not a grass?
Pigs and poultry both responded to the heat by reducing feed intake. This resulted in lower slaughter weights for pigs and reduced egglaying, low broiler growth rates and increased mortality in poultry.
Unless you have the wimpiest pigs and sheep on the planet, this is just silly. I’ve slopped pigs on a friends pig farm in Illinois one summer and Dad raised them on the farm in Iowa as a kid. Summer in either one is not exactly cool. Again, unless you were over 100F every single day for 30+ days with many days in the 110 F range, you are not talking heat… Iowa is rather well know for producing a lot of pork products… I can’t imagine England ever coming close to an Iowa summer. But for real heat, let’s talk Texas. There is a wonderful part of Texas called “The Hill Country”. About 5 years ago I drove across it in July. Darned Hot. 100 something and not much cooler at night (unlike California). Stopped a couple of times to admire the goat herds and once or twice to look at some fine cattle.
Based on your description of Dire Straights all of the American Heartland, our most productive farming on the planet, is on the verge of sterility and animals are prostrate and wasting away…
Now go to equatorial countries where agriculture is already heat stressed what will happen there?
You mean places like Brazil, the rising star of global agriculture with record yields of sugar cane and a growing force in the global soybean industry?(since they have enough heat to really crank out the production!) I expect them to record continuing record production of sugar, beans, grains, cattle, etc. They have some fine cattle and great beef steak (for darned cheap prices!) Though they did have snow in southern Brazil this last year, a bit of a surprise…
Some places will be better off others will go under leading to forced migration polewards. Politics will not allow this.
Pardon me, but your silliness is showing… There is a large and persistent migration happening, but it’s from North to South. Loads of folks have turned Phoenix into a major metropolitan region. BTW, Phoenix is an example of where heat does limit production. During the peak of summer when it hits 120+ there are some crops you can’t grow. So you end up with only a 9 month growing season for some crops. I’ll let that soak in a minute.
OK, so that’s your limit case. If you presently don’t have a 9 month growing season due to cold winters, you gradually move through ever longer growing seasons until you reach the 12 months of California. Then, and only then as you reach 120 degrees F, you will compress your growing season back to 9 months for cool season crops. But in exchange for this you get to have all the citrus, strawberries, sweet corn, soybeans, nopalitos (nopales – cactus pads, it’s a TexMex CaliMex, Mexican thing…) tepary beans, black eyed peas, collards, etc you could ever want. Oh, and sugar cane if you have the water. The Phoenix area production in it’s two major growing seasons exceeds that of most areas in their seasons.
Heat grows more food, not less. It moves when you grow them. Period.
It lets you choose to grow cold season crops in the winter (like kale, cabbage, peas, etc.) and heat tolerant in the summer for year round production. You just can’t do that under 4 feet of snow or at minus C or F in winter.
So until the entire planet is as hot as the center of one of the hottest deserts in North America, we get more production not less.
If you would like to test this for yourself, get a “planting calendar” for Fairbanks Alaska ( peak temp 60F to 70F some years for a couple of months maybe) and for Phoenix. Then plan you garden, orchard, and pasturing. Figure out the degree-day needs of each species and variety you will grow. Then show your work.
You will find that in Alaska, it’s a race to get 60 day crops to mature (though the 24 hour sun helps) and things like 120 day corn (maize) are just not possible. For Phoenix it’s ‘anything goes’ but you may need to limit your cold season crops to around December and not plant some things in June July August (time for the hot plants instead: Tomato, Peppers, tepary beans, letting early season beans and corn dry for dry grains, canning nopales, harvesting citrus etc.)
Which is easier to live with? 60 days of maybe growing a few varieties of fast foods or year round production with a bit of care to avoid peas and kale in summer? Now you know why folks move to Phoenix from Boise…
BTW, TWC is reporting Colorado getting “pounded with this one” at Vale with new snow and a late skii season… I’m looking forward to an early skii resort report from New Zealand too…
George E. Smith (APR 03, 13:08:06) to Mike M ((APR 03, 08:44:52) :
“Mike I would say that is a fair statement; except that most of the radiation that comes from the sun would not be in the IR.”
Well I certainly wasn’t insinuating that it was.
What I believe it overlooked by modelers is that UV that is not reflected by concrete makes the concrete hotter and re-emit IR but much of the UV that is not reflected by plant leaves is converted into chemical energy – NOT re-emitted as IR. (Thus a partial explanation of the “UHI effect”.) So… doesn’t it stand to ponder that because more CO2 causes most plants to convert UV energy into chemical energy at a higher rate, that more CO2 it also therefore a negative feedback to temperature especially in the tropics in addition to convection per Dr. Lindzen?
It has to be true. Though I do not have a clue how much, it ain’t in any climate model I’ve ever heard of.
Off topic a litte but…. E.M.Smith (21:42:29) – Adding insult to injury, even IF warming was as pronounced as claimed and we ended up getting much more expanded agricultural capacity as you rightly point out – it still will not be enough to feed all the IC machines in rich countries like ours and in Europe exclusively with “bio-fuels’ thus starving the third world where some families cannot afford to feed their families right now at the current prices. So mandating bio-fuel while trying to stop global warming at the same time is shear insanity.