Guest commentary by David Karoly, Professor of Meteorology at the University of Melbourne in Australia
On Saturday 7 February 2009, Australia experienced its worst natural disaster in more than 100 years, when catastrophic bushfires killed more than 200 people and destroyed more than 1800 homes in Victoria, Australia. These fires occurred on a day of unprecedented high temperatures in south-east Australia, part of a heat wave that started 10 days earlier, and a record dry spell.
This has been written from Melbourne, Australia, exactly one week after the fires, just enough time to pause and reflect on this tragedy and the extraordinary weather that led to it. First, I want to express my sincere sympathy to all who have lost family members or friends and all who have suffered through this disaster.
There has been very high global media coverage of this natural disaster and, of course, speculation on the possible role of climate change in these fires. So, did climate change cause these fires? The simple answer is “No!” Climate change did not start the fires. Unfortunately, it appears that one or more of the fires may have been lit by arsonists, others may have started by accident and some may have been started by fallen power lines, lightning or other natural causes.
Maybe there is a different way to phrase that question: In what way, if any, is climate change likely to have affected these bush fires?
To answer that question, we need to look at the history of fires and fire weather over the last hundred years or so. Bushfires are a regular occurrence in south-east Australia, with previous disastrous fires on Ash Wednesday, 16 February 1983, and Black Friday, 13 January 1939, both of which led to significant loss of life and property. Fortunately, a recent report “Bushfire Weather in Southeast Australia: Recent Trends and Projected Climate Change Impacts”(ref. 1) in 2007 provides a comprehensive assessment on this topic. In addition, a Special Climate Statement(ref 2) from the Australian Bureau of Meteorology describes the extraordinary heat wave and drought conditions at the time of the fires.
Following the Black Friday fires, the MacArthur Forest Fire Danger Index (FFDI) was developed in the 1960s as an empirical indicator of weather conditions associated with high and extreme fire danger and the difficulty of fire suppression. The FFDI is the product of terms related to exponentials of maximum temperature, relative humidity, wind speed, and dryness of fuel (measured using a drought factor). Each of these terms is related to environmental factors affecting the severity of bushfire conditions. The formula for FFDI is given in the report on Bushfire Weather in Southeast Australia. The FFDI scale is used for the rating of fire danger and the declaration of total fire ban days in Victoria.
Fire Danger Rating FFDI range High 12 to 25 Very High 25 to 50 Extreme >50
The FFDI scale was developed so that the disastrous Black Friday fires in 1939 had an FFDI of 100.
To understand the environmental conditions associated with the catastrophic bushfires on 7 February 2009, we need to consider each of the factors and the possible role of climate change in them.
Maximum temperature: This is the easiest factor to consider. Melbourne and much of Victoria had record high maximum temperatures on 7 February (2). Melbourne set a new record maximum of 46.4°C, 0.8°C hotter than the previous all-time record on Black Friday 1939 and 3°C higher than the previous February record set on 8 February 1983 (the day of a dramatic dust storm in Melbourne), based on more than 100 years of observations. But maybe the urban heat island in Melbourne has influenced these new records. That may be true for Melbourne, but many other stations in Victoria set new all-time record maximum temperatures on 7 February, including the high-quality rural site of Laverton, near Melbourne, with a new record maximum temperature of 47.5°C, 2.5°C higher than its previous record in 1983. The extreme heat wave on 7 February came after another record-setting heat wave 10 days earlier, with Melbourne experiencing three days in a row with maximum temperatures higher than 43°C during 28-30 January, unprecedented in 154 years of Melbourne observations. A remarkable image of the surface temperature anomalies associated with this heat wave is available from the NASA Earth Observatory.
Increases of mean temperature and mean maximum temperature in Australia have been attributed to anthropogenic climate change, as reported in the IPCC Fourth Assessment, with a best estimate of the anthropogenic contribution to mean maximum temperature increases of about 0.6°C from 1950 to 1999 (Karoly and Braganza, 2005). A recent analysis of observed and modelled extremes in Australia finds a trend to warming of temperature extremes and a significant increase in the duration of heat waves from 1957 to 1999 (Alexander and Arblaster, 2009). Hence, anthropogenic climate change is likely an important contributing factor in the unprecedented maximum temperatures on 7 February 2009.
Relative humidity: Record low values of relative humidity were set in Melbourne and other sites in Victoria on 7 February, with values as low as 5% in the late afternoon. While very long-term high quality records of humidity are not available for Australia, the very low humidity is likely associated with the unprecedented low rainfall since the start of the year in Melbourne and the protracted heat wave. No specific studies have attributed reduced relative humidity in Australia to anthropogenic climate change, but it is consistent with increased temperatures and reduced rainfall, expected due to climate change in southern Australia.
Wind speed: Extreme fire danger events in south-east Australia are associated with very strong northerly winds bringing hot dry air from central Australia. The weather pattern and northerly winds on 7 February were similar to those on Ash Wednesday and Black Friday, and the very high winds do not appear to be exceptional nor related to climate change.
Drought factor: As mentioned above, Melbourne and much of Victoria had received record low rainfall for the start of the year. Melbourne had 35 days with no measurable rain up to 7 February, the second longest period ever with no rain, and the period up to 8 February, with a total of only 2.2 mm was the driest start to the year for Melbourne in more than 150 years (2). This was preceded by 12 years of very much below average rainfall over much of south-east Australia, with record low 12-year rainfall over southern Victoria (2). This contributed to extremely low fuel moisture (3-5%) on 7 February 2009. While south-east Australia is expected to have reduced rainfall and more droughts due to anthropogenic climate change, it is difficult to quantify the relative contributions of natural variability and climate change to the low rainfall at the start of 2009.
Although formal attribution studies quantifying the influence of climate change on the increased likelihood of extreme fire danger in south-east Australia have not yet been undertaken, it is very likely that there has been such an influence. Long-term increases in maximum temperature have been attributed to anthropogenic climate change. In addition, reduced rainfall and low relative humidity are expected in
southern Australia due to anthropogenic climate change. The FFDI for a number of sites in Victoria on 7 February reached unprecedented levels, ranging from 120 to 190, much higher than the fire weather conditions on Black Friday or Ash Wednesday, and well above the “catastrophic” fire danger rating (1).
Of course, the impacts of anthropogenic climate change on bushfires in southeast Australia or elsewhere in the world are not new or unexpected. In 2007, the IPCC Fourth Assessment Report WGII chapter “Australia and New Zealand” concluded
An increase in fire danger in Australia is likely to be associated with a reduced interval between fires, increased fire intensity, a decrease in fire extinguishments and faster fire spread. In south-east Australia, the frequency of very high and extreme fire danger days is likely to rise 4-25% by 2020 and 15-70% by 2050.
Similarly, observed and expected increases in forest fire activity have been linked to climate change in the western US, in Canada and in Spain (Westerling et al, 2006; Gillett et al, 2004; Pausas, 2004). While it is difficult to separate the influences of climate variability, climate change, and changes in fire management strategies on the observed increases in fire activity, it is clear that climate change is increasing the likelihood of environmental conditions associated with extreme fire danger in south-east Australia and a number of other parts of the world.
References and further reading:
(1) Bushfire Weather in Southeast Australia: Recent Trends and Projected Climate Change Impacts, C. Lucas et al, Consultancy Report prepared for the Climate Institute of Australia by the Bushfire CRC and CSIRO, 2007.
(2) Special Climate Statement from the Australian Bureau of Meteorology “The exceptional January-February 2009 heatwave in south-eastern Australia”
Karoly, D. J., and K. Braganza, 2005: Attribution of recent temperature changes in the Australian region. J. Climate, 18, 457-464.
Alexander, L.V., and J. M. Arblaster, 2009: Assessing trends in observed and modelled climate extremes over Australia in relation to future projections. Int. J Climatol., available online.
Hennessy, K., et al., 2007: Australia and New Zealand. Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, M.L. Parry, et al., Eds., Cambridge University Press, Cambridge, UK, 507-540.
Westerling, A. L., et al., 2006: Warming and Earlier Spring Increase Western U.S. Forest Wildfire Activity. Science, 313, 940.
Gillett, N. P., et al., 2004: Detecting the effect of climate change on Canadian forest fires. Geophys. Res. Lett., 31, L18211, doi:10.1029/2004GL020876.
Pausas, J. G., 2004: Changes In Fire And Climate In The Eastern Iberian Peninsula (Mediterranean Basin). Climatic Change, 63, 337–350.
OffTopic, cause there are no open threads with an appropriately related subject:
Collected a whole bunch of temp info from different collators, by land, sea, nh / sh, global, month and putting in the parms for January+Crutem3v and February+Crutem3v, it struck me that for the winter months, the variability of mean temperatures was much greater from 1850 through 1930-1940, after which the temps for the winter months moved in a much narrower band, with upward trend. The chart I made putting an annual line curve over a 3 month mean line over a month of year, makes that abundantly visible. So the question is: “Is there a recognized and understood reason why that is for land, 29% of the global surface!”
Mario, you’re telling us your opinions at length and saying that you don’t have sources for them.
And you say that your beliefs should be used in carbon accounting. Would you like to believe some numbers as well as general handwaving?
There is ample work done on carbon accounting already. You wish to change it simply by proclaiming you believe something different.
You can start by going to a library. Tell the librarian you know what you believe, and you would like help finding citations to support what you believe.
Let us know how it works out.
Mario, you’re telling us your opinions at length and saying that you don’t have sources for them.
Yes Hankio, forums are also places for opinions and should be places where prevailing thought can be challenged. My opinions are not lead by the opinions of scientists, but they are not inconsistent with the very wide range of scientific studies out there.
I don’t need an individual scientific study to tell me that a piece of wooden furniture (or newspaper) buried in a landfill is going to lock the carbon up more than woodchip (or newspaper) used as mulch on my garden.
I don’t like using forums to link to the matching opinions of others, I like them to be sources of new, considered thought.
Dhogaza (294), I never claimed the estimates are too high; I never claimed the learned estimates are wrong; I have never refuted evolution. But, zero for three ain’t real bad!
Your rants might sound more credible if you removed your head from your butt, first.
Mark, a molecule absorbibg a discrete photon into its vibration energy has virtually no connection with Planck’s blackbody radiation or the S-B constant. By happenstance the photon originated from blackbody radiation, but the molecule has no knowledge nor care about that. The emission of a photon from the vibration energy likewise is not blackbody type, has no connection with S-B constant, and has no dependence on T^4. That blackbody radiation is used to analyze the global atmospheric effect of radiation absorption and energy transfer is strictly a convenient construct with nothing to do with the actual physics of this specific type of absorption.
Mario (I made a typo earlier, not meant to offend) — I’m sure you’re wrong about forests versus wood products, comparing carbon storage in a forest versus carbon storage by logging and building with the wood.
You’re ‘moving the goalpost’ by comparing a wood chip in a landfill versus one on the ground, but still telling us what you want to believe. And this really has been studied seriously, you can find it.
From a landfill we get mostly methane. From aerobic dead wood we get mostly consumption of the wood by fungi and insects. That’s what makes soil.
http://scholar.google.com/scholar?q=old+forest+logging+carbon+storage
Now if you want to argue in favor of sustainable certified forestry and careful building of furniture and buildings that people will want to keep for centuries — we’re in agreement.
And being careful about using wood only where it’s really needed, too:
http://www.nrdc.org/land/forests/gtissue.asp
Damn this overeager spellchecker, that’s _Marco_ not Mario.
Dictionary inspected, eviscerated, and defenestrated.
I hate software.
If I didn’t need it to use hardware, I’d never touch the stuff.
Mark wrote in 298:
I only “repeated” myself when you seemed unable to make a distinction. But I think a large part of that had to do with your getting defensive, feeling as if your intelligence were under attack. Unfortunately, when someone gets defensive they tend to make mistakes that they normally wouldn’t make.
In any case, personally I think your intelligence is an asset. Defensiveness? Not so much. But we learn. And there may also have been points at which I simply honestly misunderstood you. If so, I apologize. Clearly there was some form of complementary schismogenesis going on, something that I would normally back away from. But I wanted to be understood — and was hoping that the discussion could become less hostile — particularly since we both seem to be on the same side.
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Mark wrote in 298:
How do you get from a dimensionality of L to a dimensionality of LT-1? And even assuming you do… Well, we will get to that in a moment.
Mark wrote in 298:
You are speaking of deriving formula of earlier theories as approximations of later theories. Not dimensionful constants, that is constants that are measured along a given dimension, which are contrasted against dimensionless constants. (I have been making the distinction between fundamental constants with dimensionality — or dimensionful constants — vs. pure numbers — or dimensionless constants — as far back as 244 and 254.)
So let’s talk about correspondence principles. They require that the predictions of a more advanced theory coincide with the predictions of a less advanced theory over domains for which the less advanced theory is known to hold.
Thus for example Schwartzchild was able to derive the simplest of solutions to Einstein’s field equations within Einstein’s gravitational theory — for an uncharged point mass without angular momentum — everything except for one constant. G — Newton’s gravitational constant, which he was able to solve for only by recourse to Newton’s gravitational theory. (Bergmann, Peter Gabriel, Introduction to the Theory of Relativity, Chapter 13: Rigorous Solutions, Pg.202. PB) The constant was known independently of Einstein’s gravitational theory, and its status as a fundamental constant was preserved. Insofar as General Relativity referred to Newton’s gravitational constant, it referred to it as a fundamental constant from which its own results would be derived.
What this would roughly correspond to in your hypothetical example of somehow deriving the speed of light from the scale of a microscopic dimension would be the derivation of the scale as something unknown from the speed of light as something which is already known.
Mark wrote in 298:
If you are speaking of a dimensionless constant, which clearly you are in this case as it is the exponent in the inverse square law, then you are dealing with the problem that I suggested — of attempting to explain a dimensionful constant, that is a constant which requires one or more units of measurement with which to establish its value. Changing fundamental constants results in an observationally different universe only in the case of dimensionless fundamental constants, e.g., the fine structure constant.
If the hypothetical change in fundamental constants occurs only in dimensionful fundamental constants (e.g., doubling the speed of light), then by changing one or more units of measurement (e.g., halving the unit of time, e.g., the second) one is able to establish a correspondence to a universe in which no such change took place. This is what renders a change in the scale of dimensionful fundamental constants meaningless — the observational indistinguishability of the universe before and after such a change.
Mark wrote in 298:
“Could be”? Irrelevant to our discussion since you are dealing with a dimensionless constant. But I wouldn’t wish to confuse people — MOND isn’t so sophisticated that it posits hidden dimensions. However, I realize that you were simply expressing that as something which hypothetically could be the case.
Take care.
Rod, again, your views on radiative physics are ill founded. You haven’t bothered to learn the subject. No one molecule’s emissions or absorptions can be considered blackbody, but in the aggregate when the matter and energy field come into equilibrium, both the emission and absorption approximate blackbody radiation. The treatment in Landau and Lifshitz is very clear. I STRONGLY recommend it. I have not found other treatments quite as clear (e.g. Pathria, Reif).
The basic argument goes that photons do not interact with photons, so the only way a photon gas can come to equilibrium is via interactions with the surrounding matter. All the emissions and absorptions must be between available energy states (e.g. quantum processes). However, in the aggregate, when both the photons and the matter are in equilibrium, the result will be blackbody emission and absorption.
Quick correction to 308 — the following sentence should contain the bolded word “not”:
Yes, tim, 310, if I were speaking of a dimensionless constant which I was IN ONE EXAMPLE bot NOT all of it, then I am not dealing with the problem you suggested.
However, in the cases (note plural) were I AM talking about constants with a dimensional element, I AM dealing with the problem you suggested.
Ray, 309, a key element should be mentioned for people who think RodB is on to something: in thermalisation of radiation (and hence a body being a black body) is the extreme number of collisions, absorbtions and reemissions. In the classic case of the radiating cavity, you have a large black pot with a small hole at one end and a spike on the opposite side to stop direct reflection straight out of the pot and out of the hole.
Why?
Because you need many, many collisions before thermalisation of energy is practically guaranteed.
In astrophysics, this is formed by considering “optical depth”. The
temperature (and hence also the brightness) of the sun’s photosphere depends on the temperature of the gas in the sun’s atmosphere where optical depth is 1. And, where there is enhanced absorbtion of the photon at a particular energy, this optical depth is higher up the sun’s atmosphere, where it is cooler and therefore the brightness of radiation at this level is lower.
Astronomers call this “absorbtion spectra”.
And it is an identical process to what happens on the earth with it’s atmosphere that is optically thick in the IR range.
So if CO2 isn’t a greenhouse gas and CO2 cannot cause warming because of kirchoff’s law, please tell the astronomers looking at the stars that they are looking at something that doesn’t exist.
Rod is kidding on he doesn’t know so he can keep saying “you got it wrong” because if he did know, he would be unable to say that since he could prove it right himself.
RodB, yes it does.
Another similar photon could hit, it could collide inelastically with another element losing or gaining energy. The photon preferentially absorbed can change because of red or blue shift of the photon in the molecule’s frame of reference because it is moving with relation to the original photon emitter, making the absorbtion a spread band rather than a discrete line.
These are all stochastic processes and if they occur frequently enough, then the spread will become wider and eventually form into the black body radiation.
How else would the classical black body pot work? Or did you skip class that day?
Tim #308 you only repeated me too. And many others repeated me. I said they are fundamental constants and cannot be derived from logic only measured under our understanding of the universe. You then repeated that they were fundamental constants and cannot be derived from logic, only measured.
And said “Mark, you’re wrong” yet when they then stated what should, gramatically speaking, be the counter (and hence the truth from your POV and why you said I was wrong), you said what I said.
So if from your POV what I said was true, why did you say I lied?
So stop talking about how these fundamental constants can be derived. You can’t. It isn’t possible.
RodB 304. You have NEVER said that there could be an underestimation of GW under the IPCC papers. You never said that warming per doubling of CO2 could be more than 5C. You ONLY ever said it could be lower than 2C.
You ONLY take uncertainty to mean that AGW is LESS of a problem. NEVER more.
OK, so you never said “the uncertainties must make it less of a problem” but then when you say “It could be less than 2” and NEVER say “It could be more than 5” then you ARE saying that the undertainties must make it less of a problem.
From a landfill we get mostly methane. From aerobic dead wood we get mostly consumption of the wood by fungi and insects. That’s what makes soil.
Most studies that I could find on methane and landfills don’t detail the individual sources within the landfill – just that landfill is a very significant source of methane. There was another scientific article which did study the use of wood and paper and how to best to ensure the sequestration of it. I got the impression that the burial of wood/paper was, in principle, a good way to ensure long term sequestration. From a reasonable look at how our local landfill works, almost all the rotting matter was neither paper nor wood but rotting food and various other organic matter eg nappies etc. Termites wouldn’t get a look-in because of the depth and pattern of grading of the site. Other bacterial processes are another story – http://www.cbmjournal.com/content/3/1/1. “Carbon sequestration via wood burial” article indicates this is very slow. Quote:Other studies have shown that organic matter, especially wood, in landfills decomposes extremely slowly
However, just next door to the landfill is a green-waste recycling operation. My feeling is that no matter how high or deep the pile of wood is, very little methane gets generated there (There is a fire risk from all that fuel however)
Maybe, Hank, with your more extensive Google knowledge, you have found long term studies showing that the wood/paper, no matter how deep in the typical landfill, cannot be considered sequestered.
The scientific study featured on Landline http://www.abc.net.au/landline/content/2008/s2490568.htm was what made me realise that as much as we know about the carbon cycle, there’s an awful lot we don’t know.
I think there is enough citations to counter your assertion that (at least) wooden furniture in landfills gets converted to methane. Paper might be a little different, but I would be surprised if that turned out to be the case.
I think there is also a reasonable case to bury greenwaste rather than recycling it.
> you only repeated me … and others repeated me …
Mark, it’s not all about you.
We’re all trying to describe the natural world.
In particular, the natural world of bushfires-and-climate, here.
We’re not trying to rewrite _you_.
You’re magnificent.
You _know_ that.
You work with _Astrophysics_.
But you’re often wordy, self-absorbed, and are not writing at a level readers who will inherit this world.
Think of the children.
Think of the topic.
Bless your heart.
Mark’s entire post in 311 consists of:
Are you expecting me to look for signs of life in a parrot that you claim is merely pining for the fjords?
Time for us to move on, I believe.
Marco, I can chase the goalposts but it won’t help. You stated a broad general belief about the forests vs. furniture as carbon sequestration.
I pointed out that there is a lot of study done worth reading.
Weigh the forest, not just the trees. Consider how carbon turns over in forests — much moves through consumption by other living organisms. (There is more life in a fallen tree than a ‘live’ standing tree, as most of the wood inside a ‘live’ tree is dead.) Weigh the sawdust and waste as well as finished furniture. Count the energy consumed. Weigh the length of time the wood stays wood.
You can make an argument for your general point of view: you look at the work being done — it’s a major area both in biology and in economics and carbon accounting is being studied in detail.
http://www.fpl.fs.fed.us/documnts/pdf2000/skog00b.pdf
http://www.cbmjournal.com/
This is yet another area where there is a huge amount of money at risk and a huge impetus for industry to skew the science to claim funds or claim tax credits. It’s going to take serious nitpicking attention to what gets published — ask who funded the research, who funds the publication; check the cites.
Remember how industry works. Gotta watch closely:
http://scholar.google.com/scholar?q=%22sound+science%22
In response to Rod, Mark states in 315:
Actually Rod’s main argument is that the issues surrounding anthropogenic global warming are debatable — because after all we clearly willing to debate them with him. However, I must admit that this is rather implicit.
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Captcha Fortune Cookie:
Federal ALLIES
Tim 320, but he NEVER argues that IPCC has underestimated the problem. Only overestimated.
HAnk, I’m not magnificent. But I never said that these things were not fundamental constants yet lots of people decided they needed to tell me that.
Whoo for reading!
OFF TOPIC…
There is a little piece I wrote a while back dealing with a conspiracy of silence that at least some creationists believe exists regarding evidence against evolution. I think it might be of value for us since we sometimes encounter the same sort of thing with those who are “skeptical” of climatology. However, it also deals with issues of being able to find value in what is said by others even in the face of disagreement, the differences between debate, discussion and dialogue — and the power of dialogue.
So for anyone who might be interested:
A conspiracy of silence
By Timothy Chase
http://www.bcseweb.org.uk/index.php/Main/AConspiracyOfSilence
Mark wrote in 322:
I am not disagreeing with you. Just bringing to the table one of my own insights — for whatever it is worth.
Timothy Chase said: “Actually Rod’s main argument is that the issues surrounding anthropogenic global warming are debatable — because after all we clearly willing to debate them with him. However, I must admit that this is rather implicit.”
This misiterpretation only arises when you misconstrue the purpose of this site being debate rather than education. There are plenty of people here who have looked into the science deeply and are willing to help educate those who want to learn. In so doing, some of us may also learn things ourselves. However, to contend that there is any serious debate about the consensus theory of Earth’s climate and therefore the inescapable conclusion that we are the cause of the current warming epoch is naive to the point of risible.
Ray Ladbury wrote in 325:
Funny — I made a similar point in comment 244 of Linking the climate-ecology attribution chain before reading yours:
You were first… and more succinct, though.
Marco, I can chase the goalposts but it won’t help. You stated a broad general belief about the forests vs. furniture as carbon sequestration.
I pointed out that there is a lot of study done worth reading.
I am honestly not trying to move the goalposts. I am trying to make clear my nuance in thought – That the studies that show that there is net absorption of carbon from forest(excluding rainforest) and the planting of trees in general, cannot take into account that the place that the carbon is being stored is a place (active layer of soil upwards) where readily or accidentally (through ever-increasing fuel) and the movement of the carbon from flora to fauna back to CO2 etc. should not be considered sequestered until it safely tucked underground as coal (etc.) again.
I am not trying to give credence to various claims being bandied about, but the more carbon a non-rain forest absorbs, the harder it is to keep it permanently locked where it is.
Marco Parigi (327) — Your last sentence does not agree with various abstracts of papers about, for instance, PNW forests.
Marco, the place to watch on this is when you find that argument being used by timber companies as an argument for liquidating old growth timber. That’s the least susceptible to fire and the best for longterm carbon sequestration, and it costs nothing to leave it alone (to the extent we manage to avoid changing the climate around it, of course).
Seriously, if you look any of this up using Google Scholar,
http://scholar.google.com/scholar?q=“old+growth”+carbon+sequestration
noting year of publication and checking “cited by” articles, you’ll find some of your opinions are supportable by the published science, to some extent.
look within that at the recent work in major journals that’s cited approvingly by science sources.
Then — compare a Google search instead of Scholar. Look at the opinion sources and see if you detect any spin going on.
Seriously, being aware of the published work will help you if you think the science is worthwhile.
Example:
http://www.nature.com/nature/journal/v455/n7210/abs/nature07276.html
Some PR work by the timber lobby is, I think inevitable.
“… in forests between 15 and 800 years of age, net ecosystem productivity (the net carbon balance of the forest including soils) is usually positive. Our results demonstrate that old-growth forests can continue to accumulate carbon, contrary to the long-standing view …. Old-growth forests accumulate carbon for centuries and contain large quantities of it. We expect, however, that much of this carbon, even soil carbon/9, will move back to the atmosphere if these forests are disturbed….”
Cited by four:
http://www.nature.com/cited/cited.html?doi=10.1038/nature07276
For those interested in the bushfire/AGW debate I’ve just had a short article accepted to the front page of slashdot. It includes this little tidbit from the DSE’s 2008 annual report;
‘[The DSE] achieved a planned burning program of more than 156,000 hectares, the best result for more than a decade. The planned burning of forest undergrowth is by far the most powerful management tool available…’
Marco, the place to watch on this is when you find that argument being used by timber companies as an argument for liquidating old growth timber.
I realise this, and perhaps I wasn’t quite making myself clear about which “forests” I’m talking about. I’m talking about forests of which the current fire situation in Victoria would threaten. I used the general term “rainforest” as those old growth forests which are a low fire risk which I am not talking about. I know of their ability to squirrel away carbon without any particular human management. The fire-prone forests are a different story altogether. Intense human management across the whole spectrum of the fire-prone areas will give much better results, and, in my opinion we need not prevent productive commercial use of the wood whether it is for furniture, building or paper, as long as soil carbon, replanting and fuel management is given very high priority.
Thank you for your persistent, thoughtful shuffling through sites also. You seem to be almost omnipresent at Realclimate over the years…
Alan I think the quote should have read –
“The planned burning of forest undergrowth is” … by far the most damaging process to forest ecosystems, and of little benefit in fire prevention.
Re #323
I was attempting to point out that “bushfire expert” David Packham was peddling misinformation in the BBC article linked to in my slashdot article.
He was quoted by the BBC as saying: “The mismanagement of the south-eastern forests of Australia over the last 30 or 40 years by excluding prescribed burning and fuel management has led to the highest fuel concentrations we have ever had in human occupation”
I’m a computer expert not a bushfire expert but as with most complex issues I don’t think the picture is as black and white as you paint it.
Mark (315), I said to dhogaza that I never claimed the estimates are too high nor claimed the learned estimates are wrong. Why are you taking me to task for not saying or saying other stuff I didn’t say??
Tinothy, thanks, but to clarify a wee bit, I have skepticism and doubts with some parts of the AGW thinking, not the entire theory of global warming.
Mark, Ray: As I said in 305 while the physics of blackbody radiation and of GHG absorption of infrared radiation (at discrete frequencies) is different, the climatologists have found it much more convenient, with little loss of accuracy, to analyze emission, absorption and re-emission in successive arbitrary layers of a planar global atmosphere by using blackbody radiation estimates — with S-B constants, T^4 and all that jazz. That’s a construct — and a decidedly helpful construct — but not a description of the physics. Blackbody radiation has a virtually different source: the acceleration of charge (dipoles, ions, electrons, e.g.) form the physical movement of the real particles. The acceleration stems predominately from collisions (but not absorption, etc. — though there is some aspect of that with quantized electronic energy states) as Mark says. Blackbody radiation, resulting mainly from something akin to translation energy, does not occur, for all practical purposes, between quantum energy states ala rotation and vibration. That’s where the continuous spectrum, a base characteristic of blackbody/Planck radiation, comes from.
Ray says, “…in the aggregate … both the emission and absorption approximate blackbody radiation.” That’s absolutely true, which is why they generate the analytical construct; the numbers are presumed (appropriately) to come out about the same. But, for the umpteenth time, the physics is not the same.
Frankly I am totally astounded and perplexed over your stated disagreement with this, given your illustrious education and study in this very field. I can only guess that you might be reading far more into what I say than I actually do. But that is just a wild guess — I don’t really have a clue.
The same can be said for Ray’s denial of Algebra-II. I will no longer say to you that X[ln(N)] = ln(NX) — it seems to upset you greatly, but it sure is befuddling!
Rod B., OK, I’m all ears. ‘Splain to me how you get emission and absorption/emission by matter at frequencies other than those corresponding to quantized energy states. And if you are willing to stipulate that such absorption is not possible, then how do you get a blackbody spectrum. Enough with the refusal to learn the physics. Work it out for yourself or go back and learn it from a text book.
Ray, you tell me: how DO you get, physically, continuous blackbody emission from those quantized energy states?
335. It’s first year degree level physics.
Lots of collisions.
Lots of random spreading on each collision.
And your majot problem is that this:
“the acceleration of charge (dipoles, ions, electrons, e.g.) form the physical movement of the real particles. ”
Is not why you get black body radiation and not why you get line absorption. depending on what you mean, they ALL are governed by this. The line spectrum absorption is caused by resonance with the incoming radiation and, like a string at the right frequency, picks up the energy and begins to vibrate itself. Which is what happens with thermalised radiation: the electrons in the body absorb and emit by the electrons being shaken and releasing a photon because of the movement.
Try this one, Rod.
http://www.chemie.unibas.ch/~tulej/Spectroscopy_related_aspects/Lecture7_Spec_Rel_Asp.pdf
And then ask “why doesn’t this apply to an optically thick medium?”
RodB #334. You never said they were anything other than an overestimate.
Like the house of commons, where you cannot call someone a liar, MPs use “The right honourable gentlemen is incorrect” or “is misrepresenting the facts”. They MEAN “he’s lying”.
Same deal here.
Mark (340), My assertion was that the estimate is based on loose physics. I never said the estimate was too high, too low, or even incorrect. Quit looking under rocks. You clearly can find stuff I did say that you can fuss about; no need to make up things that you wished or thought I said.
RodB, 341, but you never mention error except to say it could be lower.
Selection bias is indicative of a bias.
Mark (338, 339), I’ll respond to your assertion in 338 with a quote taken from your reference in 339: “Electrons and ions of matter were treated as a simple harmonic oscillators (springs) subject to the driving force of applied E-M fields; matter becomes polarized by induction of electric dipoles [sic].”
While there is emission and absorption with changes in intramolecular electronic energy levels, the overwhelming generation of blackbody type radiation is intermolecular (interparticle) collision of charges of one sort or another. The former has a role but it is insignificant for basic blackbody radiation. (Though it is significant for other things like line spectral analysis as you say.) As you also say, collisions are also responsible, in great part, for the line broadening in the emission/absorption of quantized vibration and rotation energy levels — in addition to their responsibility for the different (ala its physical source) blackbody radiation.
Ray, a PS to my #337. We might be having a semantics problem, in that blackbody radiation is not really continuous in a pure sense: it is quantized but with the granularity like the energy of a pendulum or a baseball is quantized — teeny tiny quantum step levels, so much so you never see (nor could you ever) them in any of those ubiquitous blackbody graphs. This is an entirely different quantization from the vibration and rotation energies. Strictly speaking they are both quantized — but no where near the same physical thing.
“While there is emission and absorption with changes in intramolecular electronic energy levels, the overwhelming generation of blackbody type radiation is intermolecular (interparticle) collision of charges of one sort or another.”
Which is one reason why the optical thickness of a gaseous or even aqueous medium is much, MUCH less for a given physical depth through the medium.
However, in both a gaseous and aqueous medium, the electron receiver is free to (and indeed MUST) move in response to the interception of a photon. This movement removes some of the energy from the photon and transfers it into a essentially random motion that may change its emission with respect to a set inertial frame (say, for example, the radiation source).
Such repartitioning of energy if it occurs often enough causes the energy to be repartitioned until it appears as effectively a black body radiator.
This DEMANDS enough collisions to happen.
At optical wavelengths, the atmosphere is optically thin and so most of the incoming radiation doesn’t thermalise with the atmosphere. Radiation reflected rather than absorbed from the earth likewise doesn’t interact enough with the atmosphere to thermalise and so you see a “blue planet”. However, for the photons that ARE absorbed by the earth/sea/etc, the re-release is in the IR range, where the photon will encounter many, many absorbtion/reemission scenarios, each scenario repartitioning the energy such that the laws of energy flow, statistical resampling and so on mean the atmosphere is a black body.
Re to your PS, nope, the quantisation doesn’t exist except on the planck scale, since the velocity of each emitter is distributed as per Boltzman equation and the uncertainty principle likewise causing a spread in the frequency of any “discrete” photon emission to ensure that energy is spread throughout the spectrum.
Such a spreading of the spectrum is why a meta-stable transition of Caesium is used to determine the frequency that defines the second. Such a metastable state has less uncertainty in its emission since the time to emit is longer and so the determination of the frequency (the number of peaks divided by the time taken to emit all the energy) is more accurate *even from the POV of the quantum emitter*.
This was all done in my first year at university. It was a long time ago (90’s) but they shouldn’t have cut THAT much out of the curriculum…
RodB, could you do two things for me:
1) Go to your nearest University Stellar Physics department and tell them they have got it completely wrong, ‘cos line absorption doesn’t do it that way. Bring ear defenders, because the laughter may be deafening. Bring a book, pen and calculator in case they ask you what the temperature profile and constituents of the solar photosphere are in “what really happens” physics.
2) Explain how, despite dry food being surprisingly transparent to microwave radiation, a microwave still manages to cook your food (water has a line absorption at 2.4GHz).
The third thing I’d like you to do probably won’t get past the sensors.
Rod B. Horse Puckey! First, there are no true blackbodies–no perfect absorber/emitters. All real matter absorbs and emits with a spectrum. The closest you get is looking at a light emitted from a small cavity–that is because such an arrangement allows plenty of absorptions/emissions so that the light and matter come to equilibrium.
Rod, this is fundamental. Physicists have understood this since the turn of the last century. Go learn it. I’ve already given you the proper references. If you don’t understand blackbody radiation, the concept of emissivity and other basic ideas, you will never understand the physics of how greenhouse gasses work. The things you have to understand are:
1)The density of states for a photon gas.
2)Photons are non-interacting.
3)Absorption/emission of a photon by a material is quantized.
4)The approach to equilibrium by a photon gas in the presence of matter.
Do not embarrass yourself any more before you learn this. Blackbody radiation is not a special type of radiation that is not subject to quantization. It is quantized, but the lines are somewhat broadened by doppler shifting etc. to look more continuous. There are no true blackbodies.
Mark (344), I might not have absorbed every detail of this post, but I agree with it, and find it pretty much in line with what I have been maintaining. To clarify one point my “teeny tiny” quantization specifically did mean Planck quantization.
Then your 345 befuddled me. Tell them they have WHAT wrong? Or did I misread what you were trying to say in 344? Line absorption comes from the different bound electron energy levels for, predominately, the visual spectrum; and from the different vibration and rotation intramolecular energy levels for, predominately, infrared and microwave. None of that is blackbody radiation per se, even though the absorbed radiation may have originated as blackbody ala the emission from the surface of the Earth.
The Sun’s blackbody radiation predominately comes from the collision/acceleration of free electrons and ions, of which it has a Wholelotta
Just for the drill: dry food still has jillions of water molecules which absorb microwave radiation into their rotation energy levels which then transfers into translation energy via collision which then makes the substance hot.
Ray (346) I’ll see your Horse Puckey and raise two BS’s. Your statement “…there are no true blackbodies…” is a red herring non sequitur that has no bearing on my contentions. When I refer to “blackbody” feel free to put in any emissivity you want. There is some detail missing, but none-the-less I agree with your four points, as stated. However you will probably never give up the ghost of, for example, believing that infrared absorption or emission in CO2 at 15um to or from a quantized vibration energy level is the same physical process that emits or absorbs Planck-type (quantized — but differently — as I said) blackbody radiation [from a body with an emissivity of ____ (fill in the blank)]. But it is not.
RodB, how does H2O absorbtion of the 2.4GHz radiation heat your food (and therefore make it radiate like a black body in the ~80C range)?
I mean, that would be taking a line spectra and making it a continuous one. And something that you ***KNOW*** cannot happen!
So how can microwaves work?
Must be a conspiracy from electronics manufacturers and waveguide makers to sell microwave ovens…
“To clarify one point my “teeny tiny” quantization specifically did mean Planck quantization.”
But that isn’t quantisation, Rod. It’s an inherent uncertainty that is a boundary of knowledge in this universe.
That isn’t quantisation.
And when your CO2 absorbs 15um radiation, it is most likely to collide with something else. A collision that is very likely to be inelastic, since there is extra energy that DOESN’T BELONG THERE. And unless this other object is likely to have more or equal energy, the release of this energy means that this excited object can no longer emit 15um radiation. Maybe it will have only enough excited energy to release 30um radiation. Maybe it will change it for a different state and some extra motion (random motion being what we call “temperature” when it appears in a constituent of an ideal gas).
This faster moving object may hit another object and pass on some of that kinetic energy to another object either as kinetic energy or as a nono-kinetic component such as a vibrational state (think “Boing!!!!”).
This excited vibrational state may relax either through transference to other vibrational modes, releasing the energy change between these states as maybe microwave emissions (which may be absorbed by H2O) and the cascade through these vibrational states can make one 15um photon end up as 100 150um far IR photons.
These photons may be absorbed and the combined energy may then result in an emission of instead of 15um radiation, 13.5um radiation.
Millions of such interactions will cause the photons to partition themselves as per Boltzman distribution. Turn the number of photons into energy totals and you get, what? The Planck Black Body Radiation Curve.
But that’s unpossible!!!!
Well, I guess you won’t give up your delusion come hell or high water, will you. The explanation I’ve given has not been for you, it’s been for anyone else reading this and wondering “well, how *does* it happen”. You won’t change, but I can make sure the meme you want to spread dies.