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536 AD and all that

Filed under: — gavin @ 2 March 2008 - (Deutsch) (Español)

“during this year a most dread portent took place. For the sun gave forth its light without brightness… and it seemed exceedingly like the sun in eclipse, for the beams it shed were not clear.”

This quote from Procopius of Caesarea is matched by other sources from around the world pointing to something – often described as a ‘dry fog’ – and accompanied by a cold summer, crop failures and a host of other problems. There’s been a TV special, books and much newsprint speculating on its cause – volcanoes, comets and other catastrophes have been suggested. But this week there comes a new paper in GRL (Larsen et al, 2008) which may provide a definitive answer….

It’s long been known that tree-rings (such as the one pictured from Arizona) often show an extremely small growth ring for AD 536 (you can count back from the marked AD 550 ring). In fact, if you look at the mean anomaly in a whole range of tree ring constructions, this event stands out along with 1601 and 1815 (known volcanic events) as being exceptional over the last 2000 years.

Average of the high-frequency components of 7 northern European tree ring reconstructions from Larsen et al, 2008. The filtering ensures that uncertainties in long term trends (which are not important in this context) don’t confuse the issue.

These data match the written sources quite well. However, tying it to a cause has always been plagued with problems of chronology. An initial attempt to tie this event to a volcanic pulse in the Dye3 ice core in Greenland foundered when the chronology was revised to put it 20 years earlier. However, there has recently been a concerted effort to place all the Greenland ice cores on a common timescale based on annual layer counts (Vintner et al, 2006). Because all the cores are being counted together, ambiguities in one can be corrected by reference to the others. Once the dates have been better established, the sulphate records (which generally show the impact of volcanic aerosols) can be examined to see if they line up. And low and behold, they do:

The second peak in the picture is dated at 534 AD which is close enough to 536 AD given the one or two year uncertainty in counting. Note that the 534 AD peak is actually smaller than the one a few years earlier. In assessing the importance of an eruption though, it isn’t enough to have just a peak in Greenland. That could simply signify an eruption that was close by. Instead, people look for a matching peak in Antarctica. This signifies that the eruption was likely tropical and the aerosols were carried into both hemispheres by the stratospheric circulation. Here is where previous attempts often faltered. The dating of ice cores in Antarctica is less exact than in Greenland because the accumulation is slower (it doesn’t snow as much). However, the relatively new Dronning Maud Land (DML) core has comparable resolution to the Greenland ones, and this one does have a clear sulphate peak at about 542 +/- 17 years. That is good enough to be a match to the 536 AD peak in Greenland. The correction you’d need to make to align them exactly would also fix some other apparent offsets for smaller events in the subsequent 100 years.

So it probably was a volcano, somewhere in the tropics, and it was likely the size of Tambora in 1815. There has been some speculation that it was an earlier eruption of Krakatoa (which went off again in 1883), but that is uncertain, as are the numerous consequences such as the fall of the Rome or the rise of Islam which have been attributed to this event. While not exploring that too deeply, this quote from Michael the Syrian indicates dramatically the potential for climate events like this one to really spoil your day:

“The sun was dark and its darkness lasted for eighteen months; each day it shone for about four hours; and still this light was only a feeble shadow … the fruits did not ripen and the wine tasted like sour grapes.”


160 Responses to “536 AD and all that”

  1. 101
    Bruce Tabor says:

    Re. 93 Lynn Vincentnathan, 65-70 metres

    The most rapid known rise in sea level occurred at the end of the last ice age during the so-called Meltwater Pulse 1A. I’ve seen various estimates, but a typical one is a 25 metre rise in 500 years or 5 metres per century, 0.5 metres per decade.
    http://en.wikipedia.org/wiki/Image:Post-Glacial_Sea_Level.png

    The actual forcing that triggered this was small compared to current climate forcings – initially only about 0.25 W/m^2 – we currently have 0.75 +/- 0.25 W/m^2 and rising. Somehow this initial trigger led to the build up of GHG’s and albedo changes (and more forcing) that resulted in this rapid rise in sea level. I don’t know exacly how soon after the trigger it occurred, I suspect it’s unknown.

    You could theoretically calculate a maximum rate based on climate forcings and some albedo feedbacks, and an assumption of how much of the forcing went into melting ice. Let’s assume 100% of the forcing went into melting ice.

    Lets say 1 W/m^2 forcing – thats 5*10^14 W over the globe.
    The latent heat of melting for water is 334J/g or 3.34*10^17 Joules/km^3 water equivalent – i.e. water volume once melted.
    Over the whole globe over a year, 1 W/m^2 corresponds to:
    1W/m^2*(500*10^6km^2)*(1*10^6m^2/km^2)*(3600sec/hr)*(24/day)*(365day/yr)=1.58*10^22Joules

    Dividing these two results gives:
    1.58*10^22Joules/3.34*10^17 Joules/km^3=47,000km^3 melted water per year.
    This is distributed over 350 million km^2 of ocean
    47,000km^3/350 million km^2=0.13*10^-3km/yr=0.13 metres per year.
    (For comparison each of Greenland and West Antarctica is estimated to be losing about 150 km^3 per year, for a combined sea level rise of a little under 1mm per year.)

    So if all that 1 W/m^2 forcing went into ice melting it could raise sea level by 1.3 metres per decade or 13 m/100yrs. This is unlikely in itself as a good proportion of heat must go into warming the ocean, although this may stop if large amounts of ice spread through the oceans as ice sheets break up – creating an efficient way to transfer heat from ocean to ice, which incidentally is half of the key to the whole process – the other half being albedo changes on the ice itself (eg. meltwater ponds, soot), which transfer heat straight to the ice.

    If you wanted to speed things up for fictional purposes you could double the forcing due to albedo changes, eg loss of the polar sea ice, formation of large meltwater lakes on ice. You could then add release of CO2 and methane from permafrost. In addition, in some areas, especially West Antarctica, the ice won’t need to melt – it will just flow off the surface it rests on once enough lubrication and buoyancy is present – this could happen in a decade or less (5 metre rise). Almost as rapid collapse is possible in Greenland – 7 metre rise. The stable ice sheet is East Antarctica – equivalent to about a 55-58 metre rise.

    In short, I’ve no idea of the maximum possible rate. I could believe extreme conditions could do it within a century, but a number of worst-case positive feedbacks would have to be present.

    What do others think?

  2. 102

    J. Hansford writes:

    [[So… Ten years now, there has been no warming trend.]]

    Not true. Look again:

    http://members.aol.com/bpl1960/Ball.html

    [[ Despite the Hypothosis that Increasing CO2 drives warming… Now we have a cooling…. No mechanisms explained… Nor for the 40’s until 70’s cooling period either…]]

    Industrial aerosols.

    [[We also just happen to have the lowest activity of sunspots…
    Sunspot activity makes a better fit than does Athropogenic CO2.
    ]]

    No, it doesn’t, actually. There’s a fairly good relation between solar activity and temperature up to about 1940, but sunlight has been essentially flat since 1950, so it can’t explain the present sharp upturn in global warming.

  3. 103
    Les Porter says:

    Well, scientists are often myopic too. Really. Some latch onto something they are certain is rock solid and then tectonics or KT gets reasoned and evidence observed, and the raft floats around and the sky occasionally falls, and catastrophic terminations and punctuations rule.

    Gavin, and Ray Pierre know clearly and well enough that there is an effort to fund and seriously study the “Sulfate Aerosol Shield,” and more and more people are starting to realize this workable scheme will be supported by Big Carbon Inc., with lots of money, since it would “allow” much more CO2 to be pumped and dumped in the Commons of our Air, as Ray noted, in Science article quote. NCAR has done recent work. As well as a solid body of “modeling.”

    http://sciencenow.sciencemag.org/cgi/content/full/2008/222/1

    The “quote” probably Ray to Eli Kintisch in a phone interview. . .

    http://www.agu.org/pubs/crossref/2008/2007GL032179.shtml
    The Work.

    Paul Crutzen is Author #2, above paper.

    You can do this in your head.

    Viz.

    Pulverize to 1 micron thickness a cubic meter of sulfur. That single pulverized cubic meter of sulfur will cover a million square meters of stratosphere surface and it would take ~555 billion cubic meters to make a 1 micron thick sulfur shield over the entire earth. If a pre-pulverized cubic meter of sulfur weighs a ton (density ~1) then 1.5 GtS, could make an aerosol shield 3 microns thick, and cool the planet enough to counteract some of the global warming for a while. That would get you lots of Big C Inc. funding.

    Ray points out that once started there is a global stability issue, and a maintenance issue that lasts a long time. I do NOT like the shield idea, without a simultaneous mechanism to suck 10 to 25% of the atmosphere into a device to remove and sequester the CO2. Nature can’t do this or we would not have AGW.

    Lag Time

    The “lag” time for 385-390 ppm CO2 thermal equilibrium with its 25 F temp rise is 143 years (according to Carl Johnson, who computes the length of time it takes to use air to heat a column of rock 3000 feet deep, to the temperature 83F) Carl’s wrong “of course” (but where?) and the rise is only . . .?

    http://mb-soft.com/public3/global.html

    (This is the website that needs holes punched in it, legitimate holes with straight-forward physics. )

    This line of analysis, leading to some real disturbing conclusions, is part of why James Hansen is hawking 350 ppmv. (I favor 300 ppmv)

    No Matter. The rate at which the new equilibrium is approached, and its value, can be argued (The rate.) But the final temperature is an issue to all of life on earth. Hmmm, “issue” is understatement.

    Poke some honest reasonable holes in Carl’s approach. Please. (Ignore his 1353, Solar constant from way B.C. I thought the ocean could moderate, but water vapor only may not be enough. Aerosol shield any one?)

    I don’t know if the image here will make it into the comments section, but here is an illustration of a global “sulfate aerosol shield” that reflects 70% of incident solar irradiance, and keeps the temp down to about 900 F. uniformly. Of course, there is some CO2 that keeps the temperature that high.

    The 536 AD event is relevant, especially WRT the agricultural output. Too cold or too hot? The deniers need rope for support. The real point is this: The system is critically balanced. WE humans have screwed that up. We have the rope, not the will. Sea change coming. Billions die. Species time could be over. But doesn’t have to be.

  4. 104
    Bruce Tabor says:

    Re. 93 Lynn Vincentnathan,
    Further to my earlier comments. Prehistorically, sea level rise at the end of glacial periods was rapid, in contrast to the slow build up of ice sheets over tens of thousands of years. Current GCMs almost certainly do not capture the break-up of ice sheets accurately. It has become obvious that ice sheet collapse is a rapid, nonlinear and “wet” process. Rapid breakdown in the past coincided with Heinrich Events, where armadas of glaciers broke off from ice sheet glaciers:
    http://en.wikipedia.org/wiki/Heinrich_event
    Some process or processes had to destabilise these ice sheets before this happened and we are beginning to see some sign of this in the Greenland and West Antarctic ice sheets (GIS and WAIS). Once breakup of an ice sheet proceeds far enough it generates its own positive feedbacks and is virtually unstoppable.

    To understand the mechanisms of ice sheet collapse it is worth looking at some of Jim Hansen’s publications:
    http://pubs.giss.nasa.gov/authors/jhansen.html
    Some are quite technical, but others are more readable:
    Hansen, J., 2007: Climate catastrophe. New Scientist, 195, no. 2614 (July 28), 30-34.
    http://pubs.giss.nasa.gov/docs/2007/2007_Hansen_2.pdf

    Hansen, J.E., 2005: A slippery slope: How much global warming constitutes “dangerous anthropogenic interference”? An editorial essay. Climatic Change, 68, 269-279
    http://pubs.giss.nasa.gov/docs/2005/2005_Hansen.pdf

    This one is a bit more technical, but it looks at the mechanisms underlying previous rapid sea level rises and specifically, how “paleoclimate evidence [shows] how sensitive climate and sea level are to even weak climate forcings”:
    Hansen, J., Mki. Sato, P. Kharecha, G. Russell, D.W. Lea, and M. Siddall, 2007: Climate change and trace gases. Phil. Trans. Royal. Soc. A, 365, 1925-1954, doi:10.1098/rsta.2007.2052.
    http://pubs.giss.nasa.gov/docs/2007/2007_Hansen_etal_2.pdf

    Another good Hansen source are his mailing list posts and presentations – see:
    http://www.columbia.edu/~jeh1/

  5. 105
    henry says:

    Again with the “multiple” theory:

    The following link is to a map showing just the islands of Indonesia, with over 60 eruptions since 1900.

    http://vulcan.wr.usgs.gov/Volcanoes/Indonesia/Maps/map_indonesia_volcanoes.html

    I can imagine this area was pretty active then, and that’s why I’m asking about smaller eruptions in same area, over short periods of time…

  6. 106
    mg says:

    98. Engulfment of critical nodes (power stations, refineries, industrial plant, etc) at current coastline in global supply chains with BAU-induced SLR of about 5 metres by 2100 would substantially terminate the global economy by mid-century. Thus, mitigation and BAU scenarios could both lead to large-scale anthropogenic emissions reduction, aleit for very different reasons. In effect, BAU could collapse anthropogenic streams within about 4-5 decades, depending on ice sheet dynamics. Triggered emission flows (under both BAU and potentially subcritical mitigation pathways) unlocked from natural storage would still be present. Urgent throttle back to 300-350 ppm CO2 would seem sensible.

  7. 107
    SqueakyRat says:

    Global food supplies are already at a historically low ebb. A rerun of 536 AD would probably result in major famine world-wide.

  8. 108
    Hank Roberts says:

    Les, I just glanced over that website you point to, and I’m no expert, but when I see “A very highly respected expert in this field has said…” with no footnote, then an argument against what he says somebody said, I think, he needs to cite his sources.

    The claims I can check — like that nobody’s noticed the thermal mass of the Earth — can be checked and disproved, thus:
    http://www.google.com/search?q=climate+borehole+temperature

    And he writes this: “Using Stefan-Boltzmann backwards, we can easily calculate that … even if the carbon dioxide concentration would only get up to double today’s (around 770 ppm) the average temperature of the surface of the Earth would necessarily become around 45 degrees F hotter than today …”

    That makes me think
    – hmmm, he should be using metric units, and
    – hmmm, he should wonder why he’s an outlier.

  9. 109
    David B. Benson says:

    Bruce Tabor, in comment #101, said What do others think?

    I’ve been a long time amateur student of the so-called ice ages. I suspect the sea stand maximum rise rates for, say Meltwater Pulse 1A, are under-represented in the paleo-records. Extreme pulses (of anything) tend to be smeared in the geological formations, so appearing to take longer and thus have a lower maximum.

    While I don’t know the extent to which this occured for the sea stand rise from LGM to now, it seems resaonable, at least for a future fiction story, to suppose a doubling to say, one meter per decade averaged over several decades, with a peak year rise of again one meter.

  10. 110
    Nigel Williams says:

    Thanks folks – that’s great info re ice melt etc.

    Regarding the ‘wish-list’ of 350 to 300ppm – its not going to be done BY us is it; its going to be done TO us.

    I do not see any sequestration process on the books that will be able to be actively and deliberately implemented across all emission sources that will have any material effect on emission rates. Particularly with the ongoing rate of coal fired power station builds. A similar CO2 extraction system will have to then pull CO2 back from about 400ppm (we’re at what – 384 and rising fast now?) and how many tonnes is that?

    From http://en.wikipedia.org/wiki/Carbon_dioxide_in_the_Earth%27s_atmosphere – the atmosphere weighs about 5.1 x 10^15 tonnes – say about 5,000 Gigatonnes (Gt). Of that the 384ppm of CO2 is just about 2 Gt (ignoring molecular weights etc – for the purists!). Overall we release 27 Gt CO2 into the air each year from human activities and natural sources release about eight times that amount. Fortunately natural sinks absorb most of this, leaving us with the balance in the air to live with.

    This sort of mass-flux of CO2 (say 240Gt per year plus or minus) impresses me with how incredibly fine the difference between increasing or decreasing CO2 levels is. It seems the entire atmosphere contains only about 1% of our annual human emissions of CO2 – the remainder is pulled out by sinks such as plants, dissolution in the oceans and rock formation. And from this it looks like only a tiny change in the absorption or production rate (say +/- 1%) is needed to lead to a massive swing in CO2 content. I assume that the absorption systems are to a degree responsive to changing CO2 levels which flattens the impact of changes – but never the less (if my sums are right) the extreme sensitivity is apparent.

    We recall that recent research has shown the biosphere is not absorbing as much as it did in the past – which is exacerbating the rate of rise. Yet at the same time does this show how a practical reduction in emissions could see the existing natural sinks start to pull levels down at a useful rate? Or am I missing something?

  11. 111
    David B. Benson says:

    Nigel Williams (110) — You are missing the on-going ocean acidification. The consequences of that are, IMHO, likely to be much worse than sea stand rise, etc.

    The only solution is to permanently sequester all the excess carbon added to the active carbon cycle, mostly by burning fossil fuels. Others have estimated that this is about 500 GtC, with about 8.5 GtC aded yearly just now.

    Big job, but not insuperable nor damagingly expensive to the world economy.

  12. 112
    Hank Roberts says:

    > 2 Gt (ignoring molecular weights ….)

    No. No, no, no, no.

    Call Avogadro and ask. I’m sure you have his number.

  13. 113
    Nigel Williams says:

    Opps! My previous post should read “”…about 10% of annual human emissions or 1% of total global emissions of CO2..”. Thanks. N

  14. 114
    Nathan Brain says:

    Nuclear power plants can generate thousands of tons of radioactive waste a year (3,000 tons in 1976, 13,000 tons in 1983). It would be very expensive if not impossible to fly the space shuttle out so often to dispose of this waste. And space shuttles are not fail safe. Uranium has a radioactive half-life of 80,000 years. Where can all this accumulating waste be stored and then guarded (uranium makes a handy weapon of mass destruction) if Lovelock’s proposals were adopted? The health of uranium miners will be threatened as will anyone living near the mines. It takes just one particle entering one cell to cause cancer or genetic mutation. It’s impossible to build a nuclear power plant that does not constantly leak small amounts of radiation into the surroundings. And the Chernobyl explosion released a thousand times more radioactive materials.

  15. 115
    Nigel Williams says:

    Thanks Hank – good to know you’re there!

    Without fretting the detail my point is that the flux of CO2 in and out of the atmosphere is a significant portion of the total mass of the atmosphere – in this case its about 240Gt of 5,100Gt or about 5%.

    CO2 is a fraction of a percent of the atmosphere’s mass, so the persistence of anything like a steady-state CO2 balance is more of a miracle than a certainty. (Thats if my maths is right this time!)

    Anything – either way- that unbalances that can (I suggest) lead to a rather major swing in the CO2 left in the air which in turn will line up all the usual suspects in the case of our untimely (but sadly apt) demise.

  16. 116
    Steve Bloom says:

    Re deglacial sea level rise, we have to be careful to look at conditions that were about similar to the present (i.e. starting with a similar amount of ice that is then subjected to added warming). Looking at what happened during the big melt 12ky ago is thus not useful, but the tail end of the last deglaciation (the Eemian) is more useful since it involved a bit more melting than we have seen so far.

    The recent paper on this subject is here and a perhaps more useful interview with the lead author here (noting that someone linked the abstract above). The upshot is that all else being equal (to the Eemian) we’re looking at 1.5 to 2.5 meters/century (the latter being the worst case).

    All else may not be equal though, since the late Eemian melt was driven by increased high-latitude insolation due orbital changes rather than GHGs and since we could apply more forcing.

  17. 117
    Alex says:

    Theres a new solar variability article out in physics today: Scafetta & West. I’d be really interested to hear what you think.

  18. 118

    Re #110:

    The only solution is to permanently sequester all the excess carbon added to the active carbon cycle, mostly by burning fossil fuels. Others have estimated that this is about 500 GtC, with about 8.5 GtC aded yearly just now.

    Nah, better solution — immediately ban discarding (landfill) or recycling anything that contains carbon. Start refining the carbon out of everything we dispose of — the tons and tons of trash and refuse every year — and sequester THAT. Let the sun do the job of converting CO2 to something we can more readily get carbon from.

  19. 119

    Re #106:

    98. Engulfment of critical nodes (power stations, refineries, industrial plant, etc) at current coastline in global supply chains with BAU-induced SLR of about 5 metres by 2100 would substantially terminate the global economy by mid-century.

    This and most other Doomsday scenarios assume people are utterly and completely stupid and keep rebuilding the breaking down infrastructure where the water level is determined by the position of the moon relative to the local zenith or nadir …

    A lot of that infrastructure isn’t going to be around in 92 years, and a lot of that infrastructure was BUILT in the last 92 years. Let’s try to remember what things were like 92 years ago. Don’t much recall nuclear power plants being built in 1916, and the number of massive oil refineries and megavolt transmission lines in 1916 compared to today were nil.

    But all this ignores the fact that sooner or later, we’re going to have to face the Next Big Natural Disaster, because they aren’t going to stop happening just because we want them to.

  20. 120
    GlenFergus says:

    #94 Thanks Chris, very well put. Only one gripe. “Solar energy will not sustain the current world population at the level required by our industrialized societies.” Why not? One Chinese manufacturer is already talking seriously of $2/peak watt photovoltaics. Halve that, and you’d have the cheapest source of peak electricity, bar none. $1000/installed MW. Not coal. Not nuclear. Maybe large hydro on an excellent site. Gas currently goes close, but you have to buy the damn fuel.

    And even if the solar efficiency is only 10%, the total collector area required is tiny, probably less than the existing global roof area(?). As Hansen says, we’ll burn all the oil and gas anyway. It’s coal-fired electrictity that’s the swing emitter. The task is to find a serious alternative.

  21. 121
    Lawrence Coleman says:

    Could any of you answer this question… 3 mil years ago the earth’s temp was 5C hotter than it is today and that caused a sea level rise of more than 80ft or 25m….why then do scientists say that greenland and antartica if they were to completely melt would only constitute a moderate 7m rise a piece for a tot. of 15m..where’s the other 10m coming from? However they did not have 7bil little CO2 producing factories running around the planet 3mil years ago + livestock. They aslo did not have the wanton deforestation going on as we do now..and I bet the ocean’s acidity wasn’t conspiring to kill of CO2 absorbing/O2 producing plankton either. In those days we had plenty of negative feedback mechanisms in place..nowadays these essential feedback mechanisms have failed or are failing by anthropogenic means..giving rise to +ve amplifying more and more +ve everywhere you care to look..and a vicious and deadly cycle has begun in earnest with NO escape route. Still back to the original question where does te additional 10m come from?

  22. 122
    Harold Pierce Jr says:

    RE: #102

    What cooling from about 1950 to 1975? Print the typical plot of global mean temperature and then get your French curve(s). If you ignore the mysterious “temperature bump” centered on 1940, and few other minor bumps, you will find that there was a very slight rise in temperature until 1975. If you also ignore the “bump” and the “dip” around 1900-10, you can get a really nice curve that from 1880 declines slowly and smoothly to 1915, then rises slowly to 1930 at which point the curve starts the very slow rise until to 1975, where curve rises up quite quickly and linearly to the end of the graph at 2005.

    Anybody got an explanation for this bump? The winters in Europe from 1941 thru 1944 were some of the coldest on record IIRC. Lastly, were there any large volcanic eruption around 1910 the would have cause the temp dip?

  23. 123
    Les Porter says:

    #108, Hank Roberts.

    Hank. 1st of all — Thanks!

    I used borehole values trying to correlate his 143-year lag-time to other earlier climate events, but find them smeared a wee bit too much to refute or change his values as smoothed. The correlation is weak since the values are small. Clearly, of course, the borehole information depicts the current characterization of global warming, and does so globally. (I really did dig into the borehole stuff, and can’t refute Carl with that.)

    I re-worked the entire set of values Carl espouses, and I used extant values as proxy data for temperature characterizations.

    I used Sachmann, Boothroyd and Kraemer values for solar fusion over the last 4.567 billion years, trying to see “when” the 1353 value actually existed from an energy production standpoint — and decided that the 1353 to 1367 doesn’t matter for the approximation, and it would be nice to actually understand sunspots and solar variability, (or get big carbon to get an anti-sunspot law through our congress, with fines.)

    Despite his use of engineering “units” (which leads to our logical thought-bottleneck by his not converting the units into metric) — the comparison of the 188 ppmv ice-age value to the 288 ppmv interglacial value and the correspondent temperature rise (Heck, call it the combination of H2O and CO2, and CH4 as the ‘natural’ GHG’s) and a linear expression is not all that much of a “stretch.”

    Meaning, the only possible invalidation of that linear comparison of ice-age proxy temperatures must come from the fact that the orbital changes that end the cold times rely on H2O(vapor) for a major part of the temperature rise — not simply the additional CO2 from the ocean and the thawed biomass decaying from what was ice-age grip.

    —– With a 10% solar flux increase (~1.1 billion years A.D.) our oceans begin to migrate in large quantities into the air. If we some how increase with CO2 blanketing, the surface wattage, I’m not sure haw we can stop the buildup of a runaway greenhouse. But — this is new ground. Even though 1300 ppmv to 2300 ppmv CO2 is implied in the 80 to 100 Mya period (Karen Bice, et. al.) remember the “hot tub ocean” — the solar constant was possibly in the 1270 – -1300 W/meter squared range. —

    Using the simplistic approach Carl uses is not an outlier. But it is repugnant! Bugs the heck out of me. And Hank, what can you suggest (forget boreholes) that can refute the proposition?

    To make a nice little world everyone can “believe-in” really requires this approach be fully, and doubly (by a second line of data) refuted.

    The highly respected fellow he mentions is James Hansen. And lots of people are afraid Hansen is right. 350 ppmv. The aerosol shield? As raypierre points out, a shield means a species commitment. You can’t just to it for a few years. I say on top of the shield we must commit to generation-long removal of the CO2, and its interment.

    Thanks so very much. It is a real challenging road we leave the future next 5 generations — with species self-termination a real possibility — and in so short a time!

    If you don’t do a solid refutation, hmmm, this is going to bother you, hmmm? (Smile)

  24. 124
    Wim Benthem says:

    You misplaced 3 zero’s. 5.1 x 10^15 tonnes about 5 million gigatonnes.

  25. 125
    S2 says:

    - the atmosphere weighs about 5.1 x 10^15 tonnes – say about 5,000 Gigatonnes (Gt).

    Try 5,000,000 Gt. 1Gt = 10^9t, not 10^12.

  26. 126
    Lawrence Coleman says:

    re: 118 FCH…nice idea, there is a way to utilise the carbon in plastics and rubber products ie: old tyres and mix that with iron ore to supplement the carbon content of the ore. Works quite well! The process of refinement however also produces one hell of a lot of CO2 and other greenhouse gasses..unless the iron refinary is directly over an area where geo-sequestration is possible.

  27. 127
    Lawrence Coleman says:

    re:114 Lovelock did mention the wide spread use of nuclear power was the ‘best of the other evils’. However, wide spread nuclear use should have been adopted at least 20 years ago, we have left it a little late at this stage we are at. It would have been a good interim source of power while ‘cleaner’ ways were being developed 20 years ago. Even we were to suddenly embrace the virtues of nuclear tomorrow it would still take 10-15 to get enough plants up and running to make any significant impact on north american let alone global energy efficiency. I still believe it is possible to increase the energy efficiency of photo-voltaics to above 20% and mass production wil keep the cost low. One example..on a street corner with say-4 houses, if one house agrees to cover their entire roof with solar panels, that house could supply the other 3 with power and they would get paid by the occupants of the 3 houses for monthly power consumed. Solar is so very versatile and with the cost falling buy the day, it should be the preferered energy source.

  28. 128
    Lawrence Brown says:

    Re:#123 on the subject of an aerosol shield,in addition to a long term commitment problem,I don’t believe we know enough about the complex interactions between all the systems involved to experiment this way. What will be the effects on agriculture and on marine biota,for example, of a screened out Sun? We might do more harm than good or as they say ‘the cure could be worse than the disease’.

    The objejctive should be to mitigate the anthropogenic effects of climate change,not possibly add to them. This can best be done by radically reducing the human component of GHGs.A good example is the wedge approach proposed by Pacala and Socolow of Princeton University.
    http://www.princeton.edu/~cmi/resources/stabwedge.htm

  29. 129
    Hank Roberts says:

    Lawrence — rate of change, and rate of change of rate of change.
    We’re putting CO2 into the atmosphere very fast.

    Natural geological and biological processes change — slowly! — but rapid changes cause extreme outcomes.

    We’re provoking one now. Ward’s argument, from the geological record, is that this has happened before, at times CO2 increased a hundredth as fast as we’re increasing it now.

    See Ward’s book; audio interview here.
    http://www.astrobio.net/podcast/TysonFreeFM971.mp3

  30. 130
    Hank Roberts says:

    Les — see all the work done on climate sensitivity. The guy with the Physicist page has a number so extreme that it doesn’t match anything from the geological record, and he’s getting it by logic.

    If his number were right, the past geological record would be wrong.
    I don’t believe the strata are unreliable to that extent. Yes, we’re changing the world far faster than any past event short of an asteroid impact or “Deccan Trap” basalt flow. But that’s not what he’s talking about.

    The “Physicist” illustrates the old way of doing science, reasoning what the world must be like from a few basic truths. It’s the “founder” approach — this is why people try to find “founders” for evolution and climate science, because logical pyramids often become logical houses of cards built on a foundation that can be shaken.

    http://web.sbu.edu/history/tschaeper/Hist101/101wwwfbacon.html

    Our brains didn’t change 200 years ago. Somehow, though, people began to think beyond founders and logic to empirical science.

    Look at the geological record, read at the current estimates from the IPCC, read
    http://www.realclimate.org/index.php/archives/2007/10/the-certainty-of-uncertainty/

  31. 131
    David B. Benson says:

    Lawrence Coleman (121) said why then do scientists say that greenland and antartica if they were to completely melt would only constitute a moderate 7m rise a piece for a tot. of 15m..where’s the other 10m coming from?

    They don’t. Greenland completely melting, about 7 m sea stand rise; West Antarctic Ice Sheet completely melting, again about the same. East Antarctic Ice Sheet is assumed not to melt.

  32. 132
    mg says:

    121 see http://pubs.usgs.gov/fs/fs2-00/ for a breakdown of the constituent elements of an 80 metre sea level rise

  33. 133
    Nigel Williams says:

    Thanks! My passion and maths dont mix well eh! From wiki total mass of atmosphere 5.1361×10^18 kg = 5.1e15 tonnes = 5.1 Petatonnes = (as you correctly say) 5,000,000 Gigatonnes. That drops the percentages in my CO2 calcs by 1e-3, BUT it retains the relationship between the annual flux of CO2 of 240Gt and the content of CO2 in the atmosphere of about 2Gt and that’s my point.

    So the ins and outs are (I think!) 100x the residual we breath, and so marginal changes in either the emitter or the sink could have drastic effects on the CO2 content. It appears that the amount of CO2 in the atmosphere is about the equivalent of around 3 days total (all sources) emissions and about a month’s worth of anthropogenic emissions.

    At present we are pushing in the wrong directions with both ends of the deal – we are trashing the sinks by destroying forests and other natural sinks, while we are continuing to increase emissions by burning oil at peak production rates and steadily increasing coal burning as we open a new coal powered generation plant every two days. It would not be hard to see a situation where over a relatively short period (months) atmospheric CO2 could double! The impact of that forcing would be impressive to say the least!

    Is this sensitivity real – if not what is it that’s acting as the buffer here?

  34. 134
    Les Porter says:

    RE: # 130,#123,#108,#103

    Thanks Hank.

    You took a look. You missed.

    There is “no comparable geological period” to refer to. None. Ever, and the reason? The reason is this is new ground. The sun’s irradiance, the solar constant, has never been here before, except during the era of solar fusion ignition. CO2 has been up and down. But the sun brightens inexorably, steadily, and where we are now on its projected main sequence burn is about halfway to red giant. The solar constant has not been as high as it is now, for 4.567 billion years. When the sun ignited, for a brief time it 17 times its current luminosity. Then within 50 million years it settled down and burned at about 70% of what it is now. It has been a nice linear burn from 70% to 100%. But never has the solar constant been as it is now.

    There are no comparable geological times past.

    Use some simple numbers to show the error of Carl’s ways.

    Thanks! You may have what I assume is the last word. If you comeback with something in the numbers and easy, hey!

  35. 135
    Steve Bloom says:

    Re #117: The Scafetta & West Physics Today article (pdf here) is just a review of their prior work. Why it got published is a mystery to me, although perhaps PT was making a point when they categorized it under “opinion” (see table of contents here). Giving them plenty of rope?

    One can but stand back and admire this paragraph:

    “Thus, the Sun’s influence on Earth’s temperature is subtle because it is not just an energy transport process but also an information transfer. According to linear response theory in statistical physics, a network S responds to a perturbation P by means of a linear transfer equation, whose kernel, the response function, is determined by the fluctuation–dissipation theorem given that the perturbation is sufficiently weak. When S and P are non-Poisson renewal processes, the response of S is maximal when the complexity of the two networks, as measured by the inverse power-law indices, is matched. For the Sun–Earth one-way linking, S is the Earth and P is the Sun. The complexity-matching effect in the Sun–Earth network is evident in the equality of the inverse power-law indices.”

    Chasing solar butterflies?

  36. 136
    Les Porter says:

    b>Comparable geological period?

    There is “no comparable geological period” to refer to. None. Ever, and the reason? The reason is this is new ground. The sun’s irradiance, the solar constant, has never been here before. CO2 has been up and down. But the sun brightens inexorably, steadily, and where we are now on its projected main sequence burn is about halfway to red giant. Although ignition and settling on the main sequence appears to fit best with 70% of present value, Sachmann and Bothroyd tried to fit a slightly different model to something that would give you a young wet Mars. (I never accepted that model, but it gives you a shot at a wet Mars.)

    I have a good understanding of the IPCC stuff.

    I enjoy the links, they are illustrative of your approach, and mine.

    I’ve used a few of the NCAR models, read all the IPCC stuff, especially their extremely accurate characterizations and estimates relating to the vanishing polar sea ice. The preferred IPCC models are off one standard deviation, 1 sigma.

    I addressed Carl’s hypothesis directly to him — he thinks I have attacked him, so I am not on a good footing with him. But have not completed my complete reanalysis of what he has done. So I could refute it.

    Thanks Hank. Just do the numbers. Or do some numbers, using his approach and refuting the whole idea.

    Use his numbers or your numbers to show he is wrong; point out precisely where his numbers are wrong and by how much. (I have used your arguments already.)

    Granted. He is pretty irritating in his manor and means of pronouncement. He has some practical works if you explore the rest of his postings, and he has made some money on wood stoves, I guess several million, he has an interesting abode, he is greener than most. But I ask you to attack the preposterous conclusion with numbers and extant empirical, observational data, and there is nothing wrong with working Stefan Boltzman backwards, that is how we first determined the energy output of the sun, blackbody thermodynamics, absolute zero, things like that.

    Try to do some numbers. I can cite a thousand places and papers, and none of them refute either his approach or conclusion. As I said, the most likely contributor to the Temperature at 188 and the warming Temperature at 288 is a larger quantity of H2O vapor aloft at the ice-age terminations.

    That H2O really helps with the warming — so I am suggesting that adding nearly 1/4 more CO2 to the 288, or when the CO2 rises from 188 to 288 then 388 the temperature change is not linear. (yes, I know we are right at 385 now, and we passed the 350 in 1989)

    When do you reach equilibrium? How do you plainly and easily compute it? That is, how long does it take to reach equilibrium with 385 -390? That is what (my supercilious friend) Carl is getting at. How soon do we cook, and how well-done do we get.

  37. 137
    Ellis says:

    Thank you Gavin for your response to 80. It provided an impetus to research further the idea of an energy imbalance. Before I get to that, just one question about your response. Was the 255k you quote as the mean emitting temperature based on an equation derived from the fact that outgoing emission has to equal incoming absorption? The reason for the this question is pretty obvious, as you, yourself point out, with others, the earth is in an energy imbalance. Specifically, how does that imbalance effect the equation
    πr²(1-a)So=4πr²σTe. Secondly, or more importantly, if the earth is emmitting less energy than what is absorbed, due to the ocean, would that not imply that the atmosphere is cooling. I mean think about it, if energy is going into the ocean than it would not be available to the atmosphere. Of course, I realize that science has a history of proving the most counter-intuitive theories as plausible, and in no way doubt the veracity of Hansen et al 1(2005), but still, when the same person tells me that

    However, the cool Pacific Ocean only enhances the planetary energy
    imbalance [Hansen et al., 1997, 1999] which tends to increase surface temperature.

    and then states,

    Confirmation of
    the planetary energy imbalance can be obtained
    by measuring the heat content of the
    ocean, which must be the principal reservoir
    for excess energy (3, 15). Levitus et al. (15)
    compiled ocean temperature data that yielded
    increased ocean heat content of about 10 W
    year/m2, averaged over the Earth’s surface,
    during 1955 to 1998 [1 W year/m2 over the
    full Earth È 1.61  1022 J;

    I belive you can understand why I am confused. As I said, from an intuitive perspective, the ocean cooling i.e. shedding energy, would imply to me an atmospheric warming, whereas an ocean warming would mean less available energy for the atmosphere, and thus atmospheric cooling. Fortunately, I accept that you know more about this paradox than I, and can only hope your response will not include the heads I win, tails you lose argument found in the published papers.

  38. 138

    Re #133 Nigel Williams:

    Thanks! My passion and maths dont mix well eh! From wiki total mass of atmosphere 5.1361×10^18 kg = 5.1e15 tonnes = 5.1 Petatonnes = (as you correctly say) 5,000,000 Gigatonnes. That drops the percentages in my CO2 calcs by 1e-3, BUT it retains the relationship between the annual flux of CO2 of 240Gt and the content of CO2 in the atmosphere of about 2Gt and that’s my point.

    Oops indeed. The content of CO2 in the atmosphere is also 1000x larger, 2000 Gt (or 3000 Gt with correct molecular mass), so… the annual flux is only 8% of this. It takes ten years for full recycling.

    Often you see the argument that these natural fluxes are so much bigger tham our industrial output of CO2, that the latter can be ignored by comparison. The misconception is due to missing that the biological carbon cycle preserves carbon: what is taken out by plants is put back, precisely, by digestion, decay etc. sooner or later. Atmospheric (+oceanic) CO2 can only change if some non-biological process either adds or removes carbon from the cycle.

    Only three mechanisms come to mind:
    1) volcanism and rock weathering + carbonate deposition — small capacity, long term (tens of thousands of years)
    2) deposition of fossil fuels — slow.
    3) release of fossil fuel carbon — very fast. This overwhelms the first two.

    You can think of the metaphor of a company with a large turnover, but a small but constant loss year-over-year. It will go bankrupt.

  39. 139

    re: 118 FCH…nice idea, there is a way to utilise the carbon in plastics and rubber products ie: old tyres and mix that with iron ore to supplement the carbon content of the ore. Works quite well! The process of refinement however also produces one hell of a lot of CO2 and other greenhouse gasses..unless the iron refinary is directly over an area where geo-sequestration is possible.

    I’m talking about refining things that contain carbon into a more pure form of carbon, not using carbon for stuff. That’s a fairly simple process involving heat and not so much air. That giant ball of fire in the sky provides plenty of heat. Just take the leftover charcoal and bury it in the ground, instead of pumping massive amounts of CO2 into the ground for generations to come to have to deal with.

  40. 140
    David B. Benson says:

    Les Porter (136) — The natural climate system takes thousands of years to reach a quasi-equilibrium.

    FurryCatHeader (139) — Either biochar or biocoal, about which more can be found at

    http://biopact.com/

    will certainly be sequestered for thousands to millions of years. However, preliminary studies indicate the same is true for various forms of sequestering liquid CO2.

  41. 141
    Nigel Williams says:

    Whew! Thanks Martin 138 for getting us the right numbers. Thats helped my understanding of the mechanisms I was fretting about a lot. 8% in and out a year in total and so I guess its about 1% per year that’s anthropogenic.

    Gives us an idea of how much difference say a 10% reduction in our emissions would make to the overall flux. Not much in time. Interesting.

  42. 142
    Meltwater says:

    in #101 Bruce Tabor said:

    The most rapid known rise in sea level occurred at the end of the last ice age during the so-called Meltwater Pulse 1A. I’ve seen various estimates, but a typical one is a 25 metre rise in 500 years or 5 metres per century, 0.5 metres per decade…. The actual forcing that triggered this was small compared to current climate forcings – initially only about 0.25 W/m^2 – we currently have 0.75 +/- 0.25 W/m^2 and rising. Somehow this initial trigger led to the build up of GHG’s and albedo changes (and more forcing) that resulted in this rapid rise in sea level. I don’t know exacly how soon after the trigger it occurred, I suspect it’s unknown.

    Current climate forcing is indeed more extreme, but Meltwater Pulse 1A (thanks for the link, Bruce) occurred as an ice age was ending, when there was greater extent and quantity of ice and snow vulnerable to rapid melting and other destabilization. I consider it likely, therefore, that the melt which human unburied carbon emissions are provoking will not be as fast for as long as Meltwater Pulse 1A probably was. Which may have been down to half as fast and up to twice as long as the estimate you cite, within the uncertainties, IIRC.

    in #116 Steve Bloom put it like this:

    … look at conditions that were about similar to the present (i.e. starting with a similar amount of ice that is then subjected to added warming). Looking at what happened during the big melt 12ky ago is thus not useful, but the tail end of the last deglaciation (the Eemian) is more useful…. The recent paper on this subject is here and a perhaps more useful interview with the lead author here (noting that someone linked the abstract above).

    That was I, Steve. Thanks for the URLs. My own link to the article from when I first read it was no longer working, and I had never seen the Scitizen interview with Rohling before. I’ve cited both now in my blog entry.

    The upshot is that all else being equal (to the Eemian) we’re looking at 1.5 to 2.5 meters/century (the latter being the worst case).

    If I may quibble I think the .5 in both numbers is a .6 in the original. In any event sea rise at that rate would be disastrous even though it would not match Meltwater Pulse 1A.

    All else may not be equal though, since the late Eemian melt was driven by increased high-latitude insolation due orbital changes rather than GHGs and since we could apply more forcing.

    Aye, there’s the rub.

  43. 143
    dick roman says:

    Could someone separate out the different topics in this stream of responses? Each could be a separate discussion. thanks

  44. 144
    David B. Benson says:

    Related to the speculation of what would happen when another 536 CE type event occurs, here is some commentary regarding the current world food shortage:

    http://www.iht.com/articles/2008/03/09/business/crop.php

  45. 145

    Re #141 Nigel Williams:

    Thanks Martin 138 for getting us the right numbers. Thats helped my understanding of the mechanisms I was fretting about a lot. 8% in and out a year in total and so I guess its about 1% per year that’s anthropogenic.

    Gives us an idea of how much difference say a 10% reduction in our emissions would make to the overall flux. Not much in time.

    But, read also what I wrote about the carbon cycle balance. The 8% is indeed in and out, the 1% is in, but not out. It’s “profit” (or from the human viewpoint, loss), not turnover. The 10% of 1% reduction appears on the bottom line, never mind the turnover.

  46. 146
    LesPorter says:

    # 140
    referring to my #136 but apparently not doing the background reading. . . RE: # 130,#123,#108,#103
    David Benson??? (Tongue in cheek! Thanks. Are you kidding?)

    What is really obvious is that “this” is not a “natural climate situation” that will take thousands of years to gradually arrive at and reach equilibrium.

    It may be hard to think in punctuated terms. Like the period at the end of a sentence. The gradual acceptance of tectonics and the gradual recent grasp of the KT impactor are two different ideas.

    Tectonics is long and continual and gradual, but we in the community accepted it once we saw the mechanisms. (Sea floor spreading, magnetic pole reversals in the tracks, mapping the continental shelves, identifying the exact same rock groups in Africa and South America.) Tectonics is almost as geologically gradual as erosion.

    Differentiation in the mantle must still be the mechanism carrying the rafts of light rock around on the surface. . .?

    Uniformitarianism is still a nice way to look at tectonics, but there is some understanding the earth is old enough for 30,000 foot tall mountains of granite to have had time to be scraped or weathered to dust.(sedimentary rock) The Canadian shield was unlikely ever that tall and it is good to see some of the old (crust) still around.

    The AD 536 sulfate cooling did affect Ag around the world. It was a punctuation kind of event. The KT impact was definitely a punctuation event, and life really went a different direction at the end of that sentence.

    If we are unable to prevent the serious consequences of the massive amounts of CO2 we have floated into the Commons, this period of human presence in the geologic record will look like a period at the end of a sentence? Or a layer like the KT boundary layer?

    How long do YOU think it will take for the Atmosphere and the Land beneath it to reach equilibrium? Carl suggests 143 years for 390 ppmv, IPCC and some NASA models suggest as long as 500 years. I think more than 143 years, but not as much as 500 years as per the performance of the Arctic Sea Ice.

    But the question really is: How long would it take nature to remove what we have added, or can it do so by itself? Were we gone tomorrow, all of us in a flash, would life accomplish the adaptations needed to survive what we have done — if the temps reach 12C to 15C (22F to 27F) above our current average. Could life adapt in time? Some could walk north or south and high.

    But would the plants of the tropics survive 150 to 160 F or more, so things that eat the things that eat plants that we and other things eat could survive. Plants run slowly. We would lose many. And if we lose too many we die.

    If the time to reach “quasi-equilibrium” is 143 years or 500 years — does that enhance the running speed of plants?

    I think we are looking at more than a million years to begin to recover life aplanet without us, or without our help. If we are the best-brightest life form on earth and can survive, I think we can’t do BAU.

    Thanks for your comment — and realize, neither you nor I are likely to live to experience what is coming.

  47. 147
    David B. Benson says:

    LesPorter (146) — Not only do I read all the comments on every thread, I actually read some of the climatological literature. One paper, of several, which treats the current pulse of global warming (so-called greenhouse) gases being added by human activites is the Archer/Ganopolski 2005 paper. I’ve posted about it before, but in any case it is easily obtainable from David Archer’s publications web page.

    Another is a recent paper (possibly still a preprint) by Hansen et al. demonstrating effects continuing for over 1500 years.

  48. 148
    Les Porter says:

    #147,

    David, thanks

    Just pop out those web locations and I’ll read what is available with out elsevier and ingenta or such.

    If Jim did the work with NASA connections support, etc., it should surely be available soon. If he did it at home, I used to do that too.

    In leiu of that — when and if most of the land plants are gone with a temperature higher than they can adapt to, how long does it take to return to lower than 350 ppmv?

    I again need to clarify. Without reduction down to Jim Hansen’s 350 ppm — what will the temperature be in 1500 years? If a sufficient quantity of plants still exist in a warmer ocean, but few plants are able to reclaim the land, how long does it take to cool the planet so that some kinds of lush plants can gobble CO2 from land?

    My concern is what happens if we do loose control and we may have passed that point — so that the equilibrium is 20 to 30 F higher — and stays that way?

    I’d be interested in reading those papers. You cite no locations, but I’ll see if I can find them anyway, yes, starting with Dave Archer’s page.

    Thanks again.

    Thanks.

  49. 149
    Hank Roberts says:

    Les, good clues to how long it takes in a Science paper a while back, I mentioned it in an earlier thread here and elsewhere.
    http://www.realclimate.org/index.php/archives/2006/02/james-lovelocks-gloomy-vision/#comment-8709
    and on how the PETM started
    http://environment.newscientist.com/article/dn11726-did-the-north-atlantics-birth-warm-the-world.html

  50. 150
    David B. Benson says:

    Les Porter (148) — Google search is your friend. For example “David Archer Chicago” gets you there. Probably also works for “James Hansen NASA”, but here is the link which contains .pdf files of interesting papers:

    http://www.columbia.edu/%7Ejeh1/

    Also, here is a summary & commentary on a recent paper in Geophysical Research Letters which you will find of interest:

    http://scitizen.com/screens/blogPage/viewBlog/sw_viewBlog.php?idTheme=13&idContribution=1495


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