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.
Hank Roberts wrote in 195:
In principle however this is reducible to quantum statistical mechanics, and certainly to varying degrees of approximation physicists can explain the experimental values — just as quantum statistical mechanics has been used to explain the properties of water — when given a sufficiently powerful supercomputer.
*
Rod B. wrote in 192:
You might want to check out some of the earlier posts at this point.
For example:
At low pressures absorption is taking place at the peak of the absorption band. This is where you get your forcing as a linear function of concentration. At moderate pressures the absorption takes place primarily along the slope between the peak and the and the wings. This is where forcing is proportional to the square root of the concentration. At higher pressures additional absorption takes place principally in the wings — and this is where forcing is roughly proportional to the logarithm of the concentration.
If this really does interest you, you might want to check out:
Sunday, July 08, 2007
High Pressure Limit. . . .
http://rabett.blogspot.com/2007/07/high-pressure-limit.html
*
Rod B. wrote in 192:
… I believe that is the radiative forcing which is a function of the concentration — and it is derivable from line-by-line calculations over the atmospheric column. It is when you get to climate sensitivity (with feedbacks as well as forcings) that things get more complicated and scientists have to lean more heavily upon empirical results — such as what they get from extensive paleoclimatological studies — that taken together strongly suggest climate sensitivity is approximately 3 C per doubling of CO2.
In any case, I think what Ray wrote in 180:
… stands. You and I don’t understand this anywhere near as much as the people who do it for a living. But it is pretty clear to me that when they claim that they are confident regarding their calculations involving radiative forcing and a little less confident when it comes to feedback, they are probably right. So perhaps we can set this aside for the time being (perhaps placing spontaneously decaying states of molecular excitation right next to leaping tree frogs) and focus on the factors affecting bushfires — which may be a little easier for us to understand — at least without any advanced physics degrees.
It seems that by the time we have proof of climate change and its effects, that most people will accept, it will be far too late to do anything about. Personally it appears obvious that even with drastic immediate action by the global community, there will still be extreme effects of climate change. If the Australian and other governments approach this issue with their current lack of balls then we are all totally screwed. Action unlike that ever seen, putting aside big business and their greedy short term dollar hungry focus, is absolutely required if there is any hope!!!
From:http://www.climateinstitute.org.au/images/stories/bushfire/fullreport.pdf
Bushfires are an inevitable occurrence in Australia. With more than 800 endemic species, Australian vegetation is dominated by fire-adapted eucalypts. Fire is most common over the tropical savannas of the north, where some parts of the land burn on an annual basis. However, the southeast, where the majority of the population resides, is susceptible to large wildfires that threaten life and property.
The “natural” order of yearly, risk-reducing bushfires is still in place in northern savannah zones partly due to the influence of aboriginal traditions, which dictate that fires need to be started purposefully and regularly to retain the sustainable “Australian-ness” of the countryside.
Most fire experts agree that yearly burns in Victoria (Large-scale Land clearing of fire-breaks are a smokeless alternative) as they had occurred for tens of thousands of years before white man arrived would mean risk of loss of buildings and innocent humans to reduced to a negligible figure.
So to put into perspective the related climate induced risk since 1788 –
Risk increase allocation due to white man’s changes in land use in affected areas 99%
Risk increase allocation due to Anthropogenic Global Warming 1%
[edit] This article is written by one man and covers a range of extremely complex topics. It is a largely naive simplistic view. There is enough rubbsih published on “climate change” and I would ask that people who wish to write on this topic please make sure you know what you are talking about. You ask the question, “did climate change cause these fires” and answer “no” to a different question “did climate change start these fires”. To either of these questions the answer is wrong. I have discussed this article and issue with many collegues and will give a brief list of areas that are extremely obvious to anyone with common sence.
1)Climate change affects the… climate, therefore climate factors that started the fire, like lightning may have occured as a result of climate change. Obviously lightning occurs without climate change but the lightning that occured on that day to cause those fires may not have occured if it wasn’t for climate change and its affects on that days weather. This is the case for all climate related causes of the fires.
2)Climate change may have caused the heat spells or just increased their severity and length, therefore causing the fire fuel to be more volatile. If it was not for this volatile fuel the fires may not have started. For example lightning striking on damp or wet fuel may not have resulted in a fire.
3)Arsonists have different reasons for lighting fires. Without the extreme temperatures and dry fuel it is possible that an arsonist would be less compelled to light a fire as the results would be insufficient. Without climate change and the resulting extreme fire danger the arsonists may not have been compelled sufficiently to light the fires and therefore climate change may have even had an indirect cause of fires in this area.
The points above are mearly brief areas where the above author clearly does not understand. Although the points are not by any means conclusive, they defenitely leave open the possability that climate change did cause atleast some of the bushfires. [edit – be polite]
The article is very good, but will fall on deaf ears. Those who deny climate change do so not because they don’t believe in it, but they ‘don’t want to believe’ in it.
In other words, no amount of science or evidence will change their minds.
Those who put forward ‘hoax’ theories do so because they are willing to do or say anything before they will admit that they were wrong.
There has even been a theory put forward by the “Catch the fie ministries” that the bush fires are an act of revenge by God, to punish Australians for allowing abortion.
Softly, softly, catch a monkey.
http://www.bom.gov.au/bmrc/wefor/projects/fire_wx_workshop_jun_05/08gould.pdf
When you compare what Karoly has to say, with this document prepared by Dr Gould of the Bush Fire CRC and presented at a conference with the BOM and the CSIRO.
For instance Karoly doesn’t say that the Fire Indices do not include the very important variables of:
1. Fuel Load
2. Risk of ignition
3. Fire controllability- based upon the historical performance of a well equipped brigade.
4. Value of the assets at risk
But the rating assessment is defined as an expert assessment of the difficulty of suppression of a fire burning under the rated conditions of Low, Medium, High, Very High and Extreme.
One would have to say that if this is the case, then the rating assessment is not very useful at all, other than as a general warning to the public at large.
But it would be even worse if one added to the list the multiplying parameters of terrain, and the possibility of lightning strikes in the area, and their likely impact under the conditions being assessed.
It seems to me that rather the bothering trying to skirt around whether or not AGW is to blame, a bit more thought and homework is required into the basic management regimes involved in bush fire prediction and control, absent the role of arson of course.
MacArthur’s FFDI is based on a fuel loading of 12 tonnes /hectare. MacArthur goes on to say that for every doubling of fuel load the fire INTENSITY increases 4 fold. Some fuel loadings in the fire area were higher than 50 tonnes per hectare. this means that the fire INTENSITY was MORE than 16 times HIGHER than that which MacArthur used in his FFDI. I suggest we really need to understand more about fuel loading together and in combination with FFDI to realistically issue bushfire warnings in the future.
I suggest that this research is far more important than trying to link the fires to global warming.
Marco Parigi in 203 referred to the natural order of fire being the indigenous burning that is practiced in the northern savannahs of Australia, suggesting that were we to burn frequently in this way 99% of fires would be prevented. I feel it necessary to point out here that the Arnhem land people are only a small part of the 700 Aboriginal nations in Australia, and that the Victorian fires were not burning in tropical savannah.
Aboriginal people were/are not unintelligent as our Australian fire myth implies. Management for Savannah is very different than management for Spinnifex, Mulga, Stringybark, tall Ash or sub-Alpine country. In mountain forests for instance, Indigenous burning was focused on small discrete stands close to camping/hunting areas or travel routes. Broadscale fire as we practice it today was unheard of and invoked serious penalties as the fire was outside of the control of practitioners.
It was a brave move to try and put a statistic to the relative influences of climate change and fuel management, but unfortunately it has been shown conclusively that as the FFDI increases, the role of fuel in the equation becomes very minimal. As I have described earlier at 179, the particular role of climate change here was even more pronounced. Sorry, but this is definitely a climatic matter!
In GCM radiative models, constructs such as the idea that a doubling of CO2 produces a forcing = ln (2^5.35) are not actually used. High clouds are not given specific instructions to warm, low clouds to cool, or for methane to produce a “larger forcing” per incremental change in absorber concentration. Rather, it is necessary to model radiative transfer explicitly and with the spectral resolution to account for band overlaps between clouds and various greenhouse gases. Also, it is necessary to determine the individual component contributions of individual greenhouse gases to the total 33 K greenhouse effect– reported for instance in Kiehl and Trenberth 1997. Line-by-line radiative transfer work is necessary because of the number of absoprtion lines and corresponding broadening which precludes simple formulas and hand-done analysis (the broadening of absorption lines is very important since one needs to consider a finite interval of wavelength; there would be no effect on radiative transfer if there were nothing but indiviudal lines of zero width scattered throughout the spectrum).
The absorption of outgoing longwave radiation for CO2 and water vapor follow in a logarithmic function, and thus it is the fractional changes in concentration (not the absolute changes) which matter for climate change. The physics behind this effect has to do with band saturation as others have correctly stated. For CO2 the absorption coefficient in the principal band decays exponentially from the center.
This is the reason why methane is often stated to have “20-30 times the potency of CO2,” a statement which has more to do with its current atmsopheric concentrations than some natural property of the gas itself. An apples-to-apples comparison would show that CO2 is actually a much more effective greenhouse gas at Earth-like concentrations. In fact, if methane were measured at 380 ppmv and CO2 at 2 ppmv, the same statement would be said about CO2 being much more powerful than methane.
This forcing relation documented in Myhre et al 1998 applies specifically to current Earth-like conditions and would not be applicable to other planetary situations, where forcing would be different. The log relation goes away at very high concentrations as well, possibly at concentrations which allegedly accumulated at the end-snowball.
Rod writes, for the Nth time, where N increases without bound:
The 5.35 is a proportionality constant, Rod, not an exponent. The equation is
RF = 5.35 ln (CO2 / CO2o)
It’s true that this is mathematically equivalent to
exp(RF) = (CO2 / CO2o) ** 5.35
but what the heck quantity is exp(RF)???
The mere fact that you can rearrange an equation so that a coefficient becomes an exponent doesn’t make that rearrangement reasonable in physical terms.
Rod B:
Why don’t you take your own advice and carefully read what I wrote (#184) so that you don’t get confused between the two points. First point:
Second point:
The point about much being unknown was in the first point. The point about alarmism was in the second point. You have confused the two points. The change in meaning was made by your own confusion. Go back and read it again and ask specific questions if you want to.
Malcolm Hill:
I wouldn’t expect weather dependent fire indices to depend on highly localized variables. Karoly’s reference 1 does point out how the fuel load required for an ‘uncontrollable’ fire (3,500 kW/m) varies with FDDI. Those forests at Kinglake were nice and wet and growing rapidly right through until the end of December so the only way an uncontrollable fire could have been prevented in the weather of the 7th of February was by having a burn-off after the growing season immediately before the height of summer (early January). It is just not practical to burn the entire forest area of Victoria every year so it is not practical to prevent the risk of uncontrollable fire in weather conditions such as those of the 7th of February. The risk of uncontrollable fire can be practically reduced for less severe weather conditions however.
As far as global warming goes, the fact remains that the FDDI increases by 3.4% or thereabouts for every 1 degree C of temperature increase (Karoly’s reference 1). You might say that 3.4%/deg C is not much but it’s not nothing either. The unavoidable fact is that warming increases fire danger, unless you can show that warming necessarily reduces one of the other factors.
RodB, I was pointing out what I perceive as contradictory in “truth’s” post: an over-emphasis on the unknown in the climate science relevant to GHGs, and complete certainty as to the terrible economic effects of any mitigation effort. (The latter completely unsupported within the post, BTW.) I went back and read it again after reading your post, and I have to say, it still looked the same to me.
I don’t think that this “asymmetry of skepticism” is accidental–there appears to be an all-too-familiar agenda at work. Deny, obfuscate, and above all, delay.
I reiterate my emotional reaction: frustration. The time for effective mitigation is wasting.
Malcom,” this is, after all a site about climate change; is it so strange that the post deals with the portion of the issue relevant to climate change?
Fire brigade competency is certainly important, but not what (I dare say) most of us come here to read about.
Oops, sorry for the busted HTML in 207. Note to self: *always* preview.
Firstly, my thanks to all those at RealClimate.org for not getting paid whilst trying to bring some semblance of reality to an often confused debate. And my thanks to all those who have posted the wide variety of related info.
I am not a climate scientist so am unable to add much to it all. However, as a student of soil and botany for almost 6 decades I would like to clear up a few misconceptions concerning these related areas.
The increase in eucalypt forest cover IS anthropogenic (Aboriginals are no less human than white men), the dominant species until about 50-40,000 yrs was the casuarina (not well fire adapted), the arrival and spread of humans needing food changed all that. Unfortunately, fire, whilst useful, is a crude tool, in the wrong place at the wrong time, leads to soil erosion, depleted soils allow the proliferation of other species -including many eucalypts, not only fire tolerant but poor soil tolerant as well -it’s not just down to fire tolerance/adaptation. Another point to note is that not all eucalypts are fire adapted, some species when left to their own devices, actually create rain forests, whilst I can’t point to neat scientific graphs produced from high tech satelites, I have seen large numbers of photographs and read the journals of settlers and know that much of southern Victoria had thousands of square kilometres of temperate rainforest, largely eucalypt (you only get a 100 mtr high canopy when you have adequate rainfall to support it, euc. regnans appropriately named). Also, if any of you wanted to don a decent pair of boots and go for a walk, dig a few holes, you would discover that southern Victoria did not have annual burns, in fact if my hole digging is anything to go by it was a rare occurrence. And if the eroded embankment 300mtrs from this computer is anything to go by, there were NO bushfires here EVER (my bit of Gippsland) until about 80 yrs ago; I can smell the ‘Prom’ burning as i write. So the following quote is not accurate
“Most fire experts agree that yearly burns in Victoria (Large-scale Land clearing of fire-breaks are a smokeless alternative) as they had occurred for tens of thousands of years before white man arrived”
I would also like to mention that large scale land clearing was government edict for 150 yrs and a large part of the reason we have the problems today, whilst it may be a smokeless alternative, it leads to massive soil erosion, allowing the introduction of many pest species and fire tolerant eucs whilst speeding the drying of the micro climate. Also, another problem with controlled burns are the windows of opportunity for this are often quite short and at short notice -and cost cash wary govmnts Money which they have to spend in areas where there are very few votes.
One of the problems with many introduced species, e.g. exotic grasses (read northern hemisphere, also govmnt edict) is that once dry (and these species are not drought tolerant, thereby drying faster) they burn far better than native grasses, accelerating fire spread -native grasses are not good for beef or sheep and make a damnably poor bowling green. However we are now at a point where annual burns are neccesity, as recommended by a recent govmnt panel, and then completely ignored by the govmnt that set it up !!! No, I dont want to get political but generally humans only produce intoxicated clowns for leaders (Intoxicated ? well read SciAm on that one).
I could go on for ages yet, human stewardship of most of the planet has been a total cock-up, but as for AGW ? it started with the first sizzling steak and has only got progressively worse (do the math its easy). Ya want proof ? dont look at the clouds, go dig a hole, after all, the answer lies in the soil.
Good to see that a number of posters here haven’t bought the “prescribed burning stops bushfires and it’s ok because Aborigines did it” forester ideology (see http://www.blognow.com.au/mrpickwick/128862/The_worst_of_times.html). A throwaway comment on one (just one) news bulletin a few days ago noted that the massive and unstoppable Wilson’s Prom fire is burning through an area that also suffered a massive bushfire (not “prescribed burn”) just three years ago. This kind of information is rarely made available. To repeat what I said at #38 above – there is no evidence that Aborigines used fire to modify the forest, and they certainly did nothing like prescribed burning. If they had done there would have been massive extinctions of plants and small animals over the last 50,000 years, plants and animals that are still there. Two extended discussions are found here http://www.blognow.com.au/mrpickwick/Fire/ and http://www.blognow.com.au/mrpickwick/History_Conquerors/ .
Hank (196), my assertion stems directly from Ray’s clear implication that “we” know all there is to know of the science, then chided me for presumably just not listening as it was explained. My assertion is that “we” do not know the complete science (the part in my example) as you also implied in your post 195. Fishing for goats and red herrings have no connection what-so-ever.
FurryCatHerder (198), I meant all of the science is not solid. Some, maybe even most, as you point out, is very solid.
Ray (199), you say “…5.35 is a coefficient determined by a fit.” I said, “…is numerical controlled lab observations…” Same thing. There is no fundemental theory of physics where you can derive the 5.35. You can only get it with model or lab experiments and trying to make it fit your observations, as you said.
The other is an inane argument. I’ll briefly throw out some sophomore algebra: (N)log(X) = log(XN). But if you want to use only the former and ignore the latter, I don’t suppose it makes any difference — O.K. with me.
> clear implication
In other words, it’s not there but you see it anyhow.
This is the problem I’m trying to point out. It sets people off.
You know it does. It distracts from the topic and gets people to retype stuff they’ve typed in reply to you over and over. Why?
Rod, The logarithmic dependence does in fact come from the theory. Only the coefficient is determined. If this bothers you, then I’m afraid you’d have a bone to pick with about 95% of physics. Most of the time all the physics gives you is the form of the equation, and you have to get the proportionality constant from data.
Examples:
Relativity tells you the speed of light is a constant. However, you have to measure it to determine it’s value.
Theory tells you that radiant energy scales as the 4th power of the temperature, but you have to measure the Stefan-Boltzmann constant.
Lev Landau was the master at coming up with dependencies based on dimensional analysis and basic physics–but you always had to determine the proportionality constant.
My point is that there’s nothing at all unusual here–it’s standard procedure in physics, and if you have a problem with it, it is because you don’t understand how physics works. I’ll give you a hint: it ain’t geometry, where you come up with proofs based on a few axioms. Measurement and fitting data are a part of the game.
Just had a quick chance to re-read the names of these postings and would like to point out that we have a Monty Python problem arising. My post #216 is from a completely different Bruce to post #33. (sorry about that)
Nathan (#172): Hot rock geothermal is a hot (sorry) prospect in Queensland. Geodynamics has a project in the state at Cooper Basin, which has the potential to generate 10GW, over 74% of Queensland’s projected power demand by 2015/16. I guess this is why the Qld government is spending hundreds of millions of dollars on “clean coal” and billions on coal infrastructure, while leaving Geodynamics to find their money from private sources.
They have two big start-up costs: raising the capital for building the plant itself, and the cost of long-haul power lines (the are on the border with South Australia, which means, for those who don’t know the country, we are dealing with distances in the order of 1,000km).
Why you would neglect to put government money into the one project that could solve the base load problem for clean energy I do not know.
I’ll have to ask that question a few times now the election’s been officially called (for 21 March; for the non-Australians: we don’t have fixed terms, and the state premiers and federal prime minister have the prerogative to call early elections).
#216 However we are now at a point where annual burns are neccesity, as recommended by a recent govmnt panel, and then completely ignored by the govmnt that set it up
#217 Wilson’s Prom fire is burning through an area that also suffered a massive bushfire (not “prescribed burn”) just three years ago
It is fairly clear that fuel load is cumulative, year by year, and that enough fuel can grow in a year to dangerous (but not catastrophic) levels. Yearly burns would still have some risks of property loss each time, and very unpopular smoke issues. The clearing of land around ones own home have saved some houses where the rest in the street were completely wiped out. These people broke the law and paid hefty fines at the time. I re-iterate that it is the Anthropogenic poor land use management that has increased the risk to life and property the most, and Anthropogenic Global Warming is a convenient whipping boy so that we can spread the blame to everyone else on Earth.
Timothy Chase (201), you actually concurred with my assertion rather than refuted it. I inferred from your post that your were justifying the use of the mathematical constructs. I said and agree with that. The scientists have looked at this diligently and have come up with the best numerical answer so far possible; and, I agree, they have to run with that until some improvements or tweaks come along. All perfectly reasonable from a scientific viewpoint. But it is not “solid physics” ala a = F/m.
You’re correct: I do not fully understand this aspect of the science, but this is a non sequitur. I can understand the folks that have worked with it alot maybe believing in its unassailable robustness; but that doesn’t mean per se that that belief is correct.
Rod,
It’s the science that is rock solid which says that rising CO2 levels is a bad idea. The science that is kind of mushy at the moment mostly deals with what the climate will be like, not that the climate will be different and more energetic. Whether or not the different, more energetic climate is a good idea is a value judgment and likely depends on where one lives …
Now, does the mushy science make a difference? I dunno, and given what I believe about other areas of life, my thoughts are that reducing fossil fuel consumption is a very important objective at this point in human existence. I can imagine there are parts of the planet that would benefit from whatever climate changes are in the pipeline. But I can also imagine that no one is going to benefit if we don’t shift from the dwindling supply of fossil fuels to something with a longer lifetime, so I don’t concern myself with the issue — I just tell people to conserve energy, switch to renewables, and get away from anything involving dinosaurs or prehistoric swamps.
PS: Timothy Chase, you are right that this has grown too big for this threads britches, and probably won’t get resolved anyway.
Following a fire, you get brush growing up. It grows up particularly in the shade of the surviving trees where there’s some protection from sun and some extra moisture, both brought up by the deep roots of the surviving tree and from some condensation around it, some dew collected that drips around it and so on. The _next_ fire is the one that runs through at ground level until it reaches the brush grown up around those trees and climbs the “fire ladder” into the treetop while heating it to death around the base with radiant heat. It’s the _second_ fire that’s often the more thoroughly destructive one.
The effort involved _after_ a fire includes controlling regrowth, removing fire ladder brush and dead and fallen wood, and otherwise making sure the _next_ fire will burn through gently at ground level between the trees, and without heating up the living treetrunks and bushes enough to kill them off.
On my own hobby restoration site our second fire, started by lightning, worked out pretty well on the areas we’d prepared for it; surrounding areas left to recover naturally from the earlier fire were toast because of brusha nd fire ladders. On mys ite, any place that a dead trunk had been left within a foot or so of a live tree, the live tree got heat damage. A dead trunk more than a foot away would burn out without badly hurting a living tree next to it.
A dry tree on the ground, remember, is not a _point_ source, it’s a _linear_ source, so the heat radiation from it doesn’t fall off as the inverse square of the distance.
That’s the same reason a typical long freight train can be heard for such a long time coming and going, even from a long way away — again it’s a linear source (of sound) rather than a point source.
Basically saying — one fire isn’t enough. You need a fire regime, a fire pattern, a fire plan. It _will_ burn again. Prepare it.
Shorter Rob:
I don’t understand the science, but I’m sure they’re wrong.
Common denialist ploy, be it climate science denialism, or evolutionary biology denialism.
It’s always the same …
Ray,
actually the S-B constant is derivable. It’s actually a bunch of constants (speed of light, planck’s constant, pi, and a bunch of other terms which I don’t have memorized) which is all conveniently grouped together into “sigma.” They emerge from spectrally integrating Planck’s law.
Your overall point is valid and I don’t know what Rod is arguing exactly. The behavior of radiation absorption as a function of concentration is well understood and is rooted in both theory and experiment; it’s not going away anytime soon, sorry.
Rod B wrote in 226:
Would this be similar to the “clear implication” which Hank analyzes in 221 with,
Rod, when I respond to someone, I try as a matter of habit to quote what they said that I am responding to and hyperlinking to their comment so that people can read the whole enchilada if they want to. This way people can see for themselves whether I am misreading what was said and check to see just how much of the comment I actually responded to. You on the otherhand are engaging in a fair amount of interpretation — and people are having problems with how you have interpretted what they said. I do as well.
*
When you state in 226:
… this makes no sense to me if you are speaking of the radiation transfer theory since the quantum mechanics which forms the foundation for our understanding of radiation transfer theory is the most exacting and solid physics available to humanity. This makes very little sense if you are speaking of line-by-line calculations over the atmospheric column since, once one has analyzed the atmospheric constituents in that column, their distribution, temperature and pressure, this simply reduces to a physics problem to be solved with well-established physics. And this makes only some sense if you are speaking of feedbacks which I mentioned as requiring appeal to paleoclimatology — since you hadn’t gotten as far as feedbacks but were trying to claim that our understanding of greenhouse gas forcings is niether strong nor robust.
*
Rod B wrote in 226:
No, in a cartesian sense according to cartesian standards, their belief isn’t “necessarily” correct. But fortunately the scientific method left Descartes’ “Six Meditations” behind centuries ago.
Rod, physicists are always putting error bars and ranges of uncertainty on their statements, whether they are speaking about physical constants, complex sets of calculations which require the use of supercomputers or what have you. As such we know that many and perhaps nearly all statements are ultimately approximations. However, saying that they are approximations doesn’t make them any less strong or robust. When you give your example of a solid statement with a = F/m, I presume you are recalling that principle of Newtonian mechanics. Well, if so, that is an approximation — which breaks down as one approaches the speed of light, the quantum scale, or strong gravitational fields. But it is certainly more than sufficient to guide us under a very wide set of circumstances.
*
In any case, I notice that Hank’s question of “Why?” in 221 still lacks a response.
*
Captcha Fortune Cookie:
Special waving
Re. Marco Parigi in 225. The published literature shows that mature Alpine Ash accumulates 6 t/Ha in the first year after fire. I don’t have the figures for Mountain Ash but these larger trees accumulate litter even faster. If we apply the McArthur model (which gave us the FFDIs)to the Marysville/Kingslake area, factor in the FFDI of approximately 150 and an average slope of about 20 degrees, 1 year’s fuel accumulation gives us 60 metre flames and a rate of spread of 4.5 km/h. I’d still call that catastrophic, and possibly even more so if everyone living in the area believed the line that because it had all burnt last year they didn’t need to worry.
Tom Griffith’s definitive work on Mountain Ash “Forests of Ash” summarises at one point: “The magnificent Mountain Ash forests that exist today are also products of history with a distinctive ecology, and they resist some of the generalisations about rainforests on the one hand, and dry forests on the other. They have little resistance to fire. Their regeneration is precarious. They were not burnt lightly and regularly by Aborigines. Holocaust fires are endemic. Vast areas of Mountain Ash were cleared by settlers, and other areas were denuded by repeated fire.”
Less than 2 centuries ago, European settlers encountered what may have been the tallest forests on earth. We’ve destroyed most of them by either cutting them down or burning them too often. The science you’re quoting says that even annual burning wouldn’t have prevented what happened, but you’re suggesting that we consider it. More frequent burning wouldn’t fix the fire problem, it would destroy the last of the Mountain Ash, and you suggest that this is better land management. Why don’t we just not build houses where we know they’re going to burn down?
Rod B., The logarithmic dependence of CO2 forcing is exactly analogous to F=ma–the theory tells you acceleration should be proportional to net applied force, but you still have to measure the proportionality constant, that is, the mass. You seem to be suspicious of anything that isn’t linear.
Do you at least appreciate the irony in you saying that you don’t understand the physics, but that you think it is incorrect. OK, what is the alternative to logarithmic dependence? And what is the alternative to determing proportionality constants empirically. Isn’t science about theoretically guided empiricism? How is this different?
This question is for Ray Pierrehumbert:
Does the Southern hemisphere not currently receive significantly more solar radiation than the Northern hemisphere?
The Earth’s orbit is eccentric, and its tilt causes a multi-decadal oscillation in the balance of energy between hemispheres — that’s not in question.
But where are we in this cycle right now? Does the SH currently receive direct sunlight at perihelion or aphelion, or somewhere in between?
Which phenomenon dominates the amount of solar energy reaching Earth: proximity to the Sun, or orbital angular velocity?
Do climate models include this rather important parameter, which directly impacts the total amount of solar insolation at any given date, at any given point on Earth?
John Olson,
Yes, Earth is closer to the Sun during the Southern Summer/Northern Winter. This effect is included in the models. However it is not a huge effect.
re: John Olson #235.
Does the difference in solar radiation explain the difference?
Orbital mechanics already answer the rest of your questions and they ARE included. Why do you think they would be left out? Because this would then prove AGW wrong? Well if that were the truth, don’t you think some of the scientists who don’t believe in AGW would have pointed it out now?
Would you consider that if the opponents of an idea haven’t thought of such a thing that maybe that thing doesn’t exist? And so the change in insolation IS included in models?
Just possibly??
Marco, nobody is trying to downplay the other factors that may be important in fire control. But this is a climate blog, so you should logically expect that we will talk about climate. (What else might we talk about–frogs? ;-) )
And there is good reason to think that AGW is part of the picture in this tragic story, including peer-reviewed studies from around the world studying just that link. (See here, here and here.)
Chris, #231. However, how is Plank’s constant arrived at? And the speed of light, etc.
It’s sophistry to make it an issue, since only one (pi) of the constants are theoretically derived under current knowledge of physics.
Mark, Ray had written in 222:
We know however that:
… so when Chris Colose writes in 231:
… he is correct.
Moreover, he does not seem to think it is that great an issue since he states in 231:
… so he is in no way engaged in the sort of sophistry that you accuse him of. But he is making the point that our understanding of black body radiation is well-grounded in quantum theory — which would seem relevant to the discussion with Rob.
However, when you state that only one of the constants from which the Stephan-Boltzmann constant is derived is itself derivable (namely, pi), I myself am not exactly sure what to make of this. What units should Newton’s gravitational constant be derivable in terms of? And what of Planck’s constant? The speed of light? Are we speaking in terms of the English system, the Metric system, etc.. These systems of measurement are at least in part accidents of human history. Why should the numerical values of the universal constants be derivable in terms of accidents of human history?
A universal measurement system may however set the gravitational constant, speed of light and Planck’s constant all equal to 1. And in that case you are speaking of natural units — Planck-Wheeler units of…
length = 1.6163×10−35 m
http://en.wikipedia.org/wiki/Planck_length
time = 5.39124(27) x 10-44 s
http://en.wikipedia.org/wiki/Planck_time
mass = 2.17645(16) × 10-8 kg
http://en.wikipedia.org/wiki/Planck_mass
Marco Parigi:
Karoly’s reference 1 specifies an “uncontrollable” fire as generating 3,500 kW/m and it has a graph (Figure 1) showing the amount of fuel loading required for an uncontrollable fire at differing Forest Fire Danger Indices. At an FDDI of 100, only 5 t/ha or 0.5 kg/sqm of fuel load is needed for an uncontrollable fire. Documents such as this one suggest that other forest types easily produce more than 0.5 kg/sqm of fuel load in one year so preventing uncontrollable fires in FDDIs of 100 or more (such as occurred on the 7th of February) would require burn-offs every year.
Most of the houses saved were saved by good house design alongside firefighting.
Houses need to be able to be defendable regardless of the factors causing bushfires. Nevertheless, I’d guess that uncontrollable bushfires will always be undesirable for one reason or another. It’s just a simple fact that increased temperature increases the risk of uncontrollable fire. Anything else is a strawman.
Tim, 240, but you have to make those length determinations et al by measuring. Unlike pi, you can’t find a reason for the plank length/time/mass to be those reasons. They are apparently arbitrary and we have no theory as to WHY the planck length is that length. Or planck time of that duration. Just that they are.
So Simon saying “ah, but we just get those numbers from other constants” isn’t really saying anything that is different in phenomena from what Ray said.
One University Lab work was to use a photometer and a diffraction grid to determine what value Stephan’s constant was.
Measuring the value of Planck’s constant was I think outside the ability of an undergrad course in physics.
Fascinating debate. Most of the science is way over my head, but hey! When Australia is abandoned sometime round 2050 (or maybe sooner) because it will no longer be habitable – much like the Empty Quarter in Saudi today – climate deniers will still be arguing about the interpretation of the scientific data. It won’t make any difference on the ground, though.
Mark wrote in 242:
They aren’t arbitrary. Planck-Wheeler units are natural units. And as far as I can see, it isn’t meaningful to ask why the Planck length is the length that it is. If you understand how it is defined (i.e., in terms of a black hole where the mass is equivilent to the energy the magnitude of which is equal to the minumum uncertainty in energy for a duration equal to the time that it takes for light in a vacuum to travel a distance equal to the radius of the black hole), then that is all that is required to understand what it is.
But to understand it as it stands in relation to a human (and largely arbitrary) system of measurement will of course require more. Yes, one has then to perform physical measurements. It is afterall a physical constant, one that has a dimensionality (i.e., length), unlike the affine constant, and it is not at all comparable to those mathematical constants which we may call “pure numbers.” Numbers like e (the base of the natural logarithm, which may be defined by means of an infinite sum or infinite product), pi (the circumference of a circle divided by the diameter — which may also be defined in terms of an infinite sum), or phi (the ratio of the golden mean — one half of the sum of one and the square root of five).
Mark wrote in 242:
I thought we were speaking of what was said by Chris Colose.
And actually it is saying something different — insofar as it reduces the number of free parameters which are required to describe the laws of physics which govern our world. Furthermore (as I pointed out previously in 240) it suggests that our understanding of black body radiation is largely something which may be derived in terms of quantum mechanics — and it is in fact derivable from the quantum statistical mechanics — as the union of quantum mechanics and thermodynamics. Ray said that it was measurable. Chris said that it is measurable but also derivable — meaning that you can derive it from other physical constants — and implying a deeper theoretical unity between the study of black body radiation and quantum statistical mechanics.
Marco #225
Whilst I consider that bush fire prevention/mitigation is wandering a bit from the original thread, it goes beyond recent Victorian problems (e.g. Spain, Italy, Greece, California, Brazil et al). Housing design, construction and maintenance were proven to be the main problems in property loss after examination of the ’83 bush fires. A properly designed, built and maintained timber structure is more fireproof than a poorly built brick/stone equivalent. Do the soffit boards fit properly ? What sort of glazing ? On raised buildings, are the stumped areas properly sheilded ? Does the shape of the structure funnell the prevailing winds to vent a stray ember ? As a bush fire will increase wind strength locally, I bet no one bothered to fit structural wind extras (legally only required within 30kms of Bass Strait) onto their homes as regulations dont require it in most of the bush fire areas. Also good odds that most of the places that went up were built pre ’98 and had cheap/poor glazing structure and design.
You can clear all shrubbery for 100 mtrs from the structure and if you havent cleaned your gutters the place will still go up like a torch.
As to the smoke problems from controlled burns, not nice I agree, however it is a tiny fraction of the social and fiscal cost of fire/weed control.
As to fining offenders, most of coastal Vic. has regs against taking out trees, but a chainsaw at 5 a.m. will increase the property value 20 G’s by 7 a.m. and the fine might come to 5 G’s -if you get caught, the neighbours will hear/see nothing, the resulting erosion wont be noticed for a decade -and then the whole community will pay to fix the problem; what’s known as a nice little earner.
Also botanical knowledge is sadly lacking amongst most of the population and that includes a number of the farming community; not far from here I can take you to paddocks where the farmer has cultivated wind breaks with shrubbery that is considered a noxious weed by the Ag board, is fire prone and near state forest !
Thanks to #241 for reference, went bush walking amongst the sequoia there as a lad, will be a good read, however nth Calif has different rainfall patterns and has somewhat diff attitude to timber theft, the only place where I’ve seen forest rangers with flak jackets and automatics !
As for ACC/AGW, when you think of all the zillions of little things that humans thoughtlessly do every day that detrimentally affect the planet, bad bush fires are just the beginning. This whole climate thing is a bit more complex and corrupt than most people (including me) realise.
There are two things that are infinite, the universe and human stupidity, and I’m not sure about the universe (thank you Albert).
My apologies to all those that want to keep this strictly on climate.
These might have been previously unrecorded extreme fire danger days, but the main reason for the severity and death toll of these (and other fires) should be searched for elsewhere: no fire without fuel. This link will point you in the right direction:
http://fhsarchives.wordpress.com/2009/02/10/historian-stephen-j-pyne-on-the-australian-fires/
Under similar, or worst fire weather (the ciclone Alby event), Western Australia has avoided these tragedies thanks to an active fire management policy.
“Do climate models include this rather important parameter, which directly impacts the total amount of solar insolation at any given date, at any given point on Earth?” – John Olson
John, do you realise quite how insulting this question is? Do you really think climate modellers are a bunch of complete ignoramuses? That even if they were, none of the solar physicists they talk to would have pointed out this elementary fact? Why don’t you stop wasting everyone’s time?
Tim 244. OK, so why is the Planck length that exact length. What way could that value be ascertained that the planck length is that length. Pi can be calculated from geometry. What leads you to the actual value of the planck length. The thing that, if you had small enough fingers you could say “it’s [this] big”?
I would be very welcome to hear from you what calculation will give you the length of the planck length in this universe.
So would the Nobel Prize team for Science.
You still have to measure something rather than derive the value (like you can with Pi) from principles.
Mark, Planck units emerge from the values of certain fundamental constants–e.g. h, c, G, etc. They turn out to be natural scales on which to discuss some physical phenomena–especially the Planck length and time. See
http://en.wikipedia.org/wiki/Planck_units
My bad on the S-B constant–which started this descent into off-topicness.
Yes, Ray. and h, c G are all measured. They don’t fall out of “the way things MUST be”.
I’ve not said that using the plank length is not a natural unit to use. Never had and have no pigging clue where everyone keeps yibbering on about how they are natural units to use.
All I’m saying is that they have to be measured and are at the moment of current understanding, not “the way things MUST be” but merely “the way things are”. Pi, in a euclidian geometrical formulation MUST be the value it is.
h? Well, it could be something else. Not much different else we would have noticed something or not even had anything stable.
Same with c. Just a number that is what the speed of light in a vacuum actually is.
And on “these are natural units”, please. Do you measure your height in planck lengths? Your time to travel to work in planck times? The amount of garlic put in your meal in planck masses? The speed of your motorcar in units of c? No? Then they aren’t natural units. They are CONVENIENT units for certain problems.
And they must be measured.
That h turns out to be what it is, or G is the value it is may turn out naturally from something in the standard model or the energy of the Higgs boson. But at the moment, there’s nothing that we can do to find these figures than measure something that relates to it and calculate.
And, please, stop telling me they are natural units. Convenient units and this is the VERY FIRST TIME I’ve said anything about that expression. Leave it.