Guest commentary by Barry R. Bickmore, Brigham Young University
If you look around the websites dedicated to debunking mainstream climate science, it is very common to find Lord Christopher Monckton, 3rd Viscount of Brenchley, cited profusely. Indeed, he has twice testified about climate change before committees of the U.S. Congress, even though he has no formal scientific training. But if he has no training, why has he become so influential among climate change contrarians? After examining a number of his claims, I have concluded that he is influential because he delivers “silver bullets,” i.e., clear, concise, and persuasive arguments. The trouble is his compelling arguments are often constructed using fabricated facts. In other words, he makes it up. (Click here to see a number of examples by John Abraham, here for a few by myself, and here for some by Tim Lambert).
Here I’m going to examine some graphs that Lord Monckton commonly uses to show that the IPCC has incorrectly predicted the recent evolution of global atmospheric CO2 concentration and mean temperature. A number of scientists have already pointed out that Monckton’s plots of “IPCC predictions” don’t correspond to anything the IPCC ever predicted. For example, see comments by Gavin Schmidt (Monckton’s response here,) John Nielsen-Gammon (Monckton’s response here,) and Lucia Liljegren. Monckton is still happily updating and using the same graphs of fabricated data, so why am I bothering to re-open the case?
My aim is to more thoroughly examine how Lord Monckton came up with the data on his graphs, compare it to what the IPCC actually has said, and show exactly where he went wrong, leaving no excuse for anyone to take him seriously about this issue.
Atmospheric CO2 Concentration
By now, everyone who pays any attention knows that CO2 is an important greenhouse gas, and that the recent increase in global average temperature is thought to have been largely due to humans pumping massive amounts of greenhouse gases (especially CO2) into the atmosphere. The IPCC projects future changes in temperature, etc., based on projections of human greenhouse gas emissions. But what if those projections of greenhouse gas emissions are wildly overstated? Lord Monckton often uses graphs like those in Figs. 1 and 2 to illustrate his claim that “Carbon dioxide is accumulating in the air at less than half the rate the UN had imagined.”
Figure 1. Graph of mean atmospheric CO2 concentrations contrasted with Monckton’s version of the IPCC’s “predicted” values over the period from 2000-2100. He wrongly identifies the concentrations as “anomalies.” Taken from the Feb. 2009 edition of Lord Monckton’s “Monthly CO2 Report.”
Figure 2. Graph of mean atmospheric CO2 concentrations contrasted with Monckton’s version of the IPCC’s “predicted” values over the period from Jan. 2000 through Jan. 2009. Taken from the Feb. 2009 edition of Lord Monckton’s “Monthly CO2 Report.”
It should be noted that Lord Monckton faithfully reproduces the global mean sea surface CO2 concentration taken from NOAA, and the light blue trend line he draws through the data appears to be legitimate. Unfortunately, nearly everything else about the graphs is nonsense. Consider the following points that detail the various fantasies Monckton has incorporated into these two graphics.
Fantasy #1.
Lord Monckton claims the light blue areas on his graphs (Figs. 1 and 2) represent the IPCC’s predictions of atmospheric CO2 concentrations.
Reality #1.
The IPCC doesn’t make predictions of future atmospheric CO2 concentrations. And even if we ferret out what Lord Monckton actually means by this claim, he still plotted the data incorrectly.
The IPCC doesn’t really make predictions of how atmospheric CO2 will evolve over time. Rather, the IPCC has produced various “emissions scenarios” that represent estimates of how greenhouse gas emissions might evolve if humans follow various paths of economic development and population growth. The IPCC’s report on emissions scenarios states, “Scenarios are images of the future, or alternative futures. They are neither predictions nor forecasts. Rather, each scenario is one alternative image of how the future might unfold.” Lord Monckton explained via e-mail that he based the IPCC prediction curves “on the IPCC’s A2 scenario,which comes closest to actual global CO2 emissions at present” (2). In his “Monthly CO2 Report” he added, “The IPCC’s estimates of growth in atmospheric CO2 concentration are excessive. They assume CO2 concentration will rise exponentially from today’s 385 parts per million to reach 730 to 1020 ppm, central estimate 836 ppm, by 2100,” which is consistent with the A2 scenario. In other words, Monckton has picked one of several scenarios used by the IPCC and misrepresented it as a prediction. This is patently dishonest.
Monckton’s misrepresentation of the IPCC doesn’t end here, however, because he has also botched the details of the A2 scenario. The IPCC emissions scenarios are run through models of the Carbon Cycle to estimate how much of the emitted CO2 might end up in the atmosphere. A representative (i.e., “middle-of-the-road”) atmospheric CO2 concentration curve is then extracted from the Carbon Cycle model output, and fed into the climate models (AOGCMs) the IPCC uses to project possible future climate states. Figure 3 is a graph from the most recent IPCC report that shows the Carbon Cycle model output for the A2 emissions scenario. The red lines are the output from the model runs, and the black line is the “representative” CO2 concentration curve used as input to the climate models. I digitized this graph, as well, and found that the year 2100 values were the same as those cited by Monckton. (Monckton calls the model input the “central estimate.” )
Figure 3. Plot of atmospheric CO2 concentrations projected from 2000-2100 for the A2 emissions scenario, after the emissions were run through an ensemble of Carbon Cycle models. The red lines indicate model output, whereas the black line represents the “representative” response that the IPCC used as input into its ensemble of climate models (AOGCMs). Taken from Fig. 10.20a of IPCC AR4 WG1.
Now consider Figure 4, where I have plotted the A2 model input (black line in Fig. 3), along with the outer bounds of the projected atmospheric CO2 concentrations (outer red lines in Fig. 3). However, I have also plotted Monckton’s Fantasy IPCC predictions in the figure. The first thing to notice here is how badly Monckton’s central tendency fits the actual A2 model input everywhere in between the endpoints. Monckton’s central tendency ALWAYS overestimates the model input except at the endpoints. Furthermore, the lower bound of Monckton’s Fantasy Projections also overestimates the A2 model input before about the year 2030. What appears to have happened is that Lord Monckton chose the correct endpoints at 2100, picked a single endpoint around the year 2000-2002, and then made up some random exponential equations to connect the dots with NO REGARD for whether his lines had anything to do with what the IPCC actually had anywhere between.
Figure 4. Here the black lines represent the actual A2 input to the IPCC climate models (solid) and the upper and lower bounds of the projected CO2 concentrations obtained by running the A2 emissions scenario through an ensemble of Carbon Cycle models. This data was digitized from the graph in Fig. 3, but a table of model input concentrations of CO2 resulting from the different emissions scenarios can be found here. The red lines represent Monckton’s version of the IPCC’s “predicted” CO2 concentrations. The solid red line is his “central tendency”, while the dotted lines are his upper and lower bounds. Monckton’s data was digitized from the graph in Fig. 1.
John Nielsen-Gammon also pointed some of this out, but Lord Monckton responded:,
[Nielsen-Gammon] says my bounds for the 21st-century evolution of CO2 concentration are not aligned with those of the UN. Except for a very small discrepancy between my curves and two outliers among the models used by the UN, my bounds encompass the output of the UN’s models respectably, as the blogger’s own overlay diagram illustrates. Furthermore, allowing for aspect-ratio adjustment, my graph of the UN’s projections is identical to a second graph produced by the UN itself for scenario A2 that also appears to exclude the two outliers.
It is fair enough to point out that Fig. 10.26 in IPCC AR4 WG1 has a plot of the projected A2 CO2 concentrations that seems to leave out the outliers. However, Monckton’s rendition is still not an honest representation of anything the IPCC ever published. I can prove this by blowing up the 2000-2010 portion of the graph in Fig. 4. I have done this in Fig. 5, where I have also plotted the actual mean annual global CO2 concentrations for that period. The clear implication of this graph is that even if the A2 scenario did predict atmospheric CO2 evolution (and it doesn’t,) it would actually be a good prediction, so far. In Figures 1 and 2, Lord has simply fabricated data to make it seem like the A2 scenario is wrong.
Figure 5. This is a blow-up of the graph in Fig. 4 for the years 2000-2010. I have also added the annual global mean atmospheric CO2 concentrations (blue line), obtained from NOAA.
Fantasy #2.
Monckton claims that “for seven years, CO2 concentration has been rising in a straight line towards just 575 ppmv by 2100. This alone halves the IPCC’s temperature projections. Since 1980 temperature has risen at only 2.5 °F (1.5 °C) per century." In other words, he fit a straight line to the 2002-2009 data and extrapolated to the year 2100, at which time the trend predicts a CO2 concentration of 575 ppm. (See the light blue line in Fig. 1.)
Reality #2.
It is impossible to distinguish a linear trend from an exponential trend like the one used for the A2 model input over such a short time period.
I pointed out to Lord Monckton that it’s often very hard to tell an exponential from a linear trend over a short time period, e.g., the 7-year period shown in Fig. 2. He replied,
I am, of course, familiar with the fact that, over a sufficiently short period (such as a decade of monthly records), a curve that is exponential (such as the IPCC predicts the CO2 concentration curve to be) may appear linear. However, there are numerous standard statistical tests that can be applied to monotonic or near-monotonic datasets, such as the CO2 concentration dataset, to establish whether exponentiality is being maintained in reality. The simplest and most direct of these is the one that I applied to the data before daring to draw the conclusion that CO2 concentration change over the past decade has degenerated towards mere linearity. One merely calculates the least-squares linear-regression trend over successively longer periods to see whether the slope of the trend progressively increases (as it must if the curve is genuinely exponential) or whether, instead, it progressively declines towards linearity (as it actually does). One can also calculate the trends over successive periods of, say, ten years, with start-points separated by one year. On both these tests, the CO2 concentration change has been flattening out appreciably. Nor can this decay from exponentiality towards linearity be attributed solely to the recent worldwide recession: for it had become evident long before the recession began.
In other words, the slope keeps getting larger in an exponential trend, but stays the same in a linear trend. Monckton is right that you can do that sort of statistical test, but Tamino actually applied Monckton’s test to the Mauna Loa observatory CO2 data since about 1968 and found that the 10-year slope in the data has been pretty continuously rising, including over the last several years. Furthermore, look at the graph in Fig. 5, and note that the solid black line representing the A2 climate model input looks quite linear over that time period, but looks exponential over the longer timeframe in Fig. 4. I went to the trouble of fitting a linear trend line to the A2 model input line from 2002-2009 and obtained a correlation coefficient (R2) of 0.99967. Since a perfectly linear trend would have R2 = 1, I suggest that it would be impossible to distinguish a linear from an exponential trend like that followed by the A2 scenario in real, “noisy” data over such a short time period.
Temperature Projections
Atmospheric CO2 concentration wouldn’t be treated as such a big deal if it didn’t affect temperature; so of course Lord Monckton has tried to show that the Fantasy IPCC “predictions” of CO2 concentration he made up translate into overly high temperature predictions. This is what he has done in the graph shown in Fig. 6.
Figure 6. Lord Monckton’s plot of global temperature anomalies over the period January 2002 to January 2009. The red line is a linear trend line Monckton fit to the data, and the pink/white field represents his Fantasy IPCC temperature predictions. I have no idea what his base period is. Taken from the Feb. 2009 edition of Lord Monckton’s “Monthly CO2 Report.”.
FANTASY #3. Lord Monckton uses graphs like that in Fig. 6 to support his claim that the climate models (AOGCMs) the IPCC uses to project future temperatures are wildly inaccurate.
REALITY #3.
Monckton didn’t actually get his Fantasy IPCC predictions of temperature evolution from AOGCM runs. Instead, he inappropriately fed his Fantasy IPCC predictions of CO2 concentration into equations meant to describe the EQUILIBRIUM model response to different CO2 concentrations.
Monckton indicated to me (5) that he obtained his graph of IPCC temperature predictions by running his Fantasy CO2 predictions (loosely based on the A2 emissions scenario) through the IPCC’s standard equation for converting CO2 concentration to temperature change, which can be found here.
The problem is that the equation mentioned is meant to describe equilibrium model response, rather than the transient response over time. In other words, they take the standard AOGCMs, input a certain stabilized CO2 concentration, and run the models until the climate output stabilizes around some new equilibrium. But it takes some time for the model systems to reach the new equilibrium state, because some of the feedbacks in the system (e.g., heat absorption as the ocean circulates) operate on fairly long timescales. Therefore, it is absolutely inappropriate to use the IPCC’s equation to describe anything to do with time evolution of the climate system. When I brought this up to Lord Monckton, he replied that he knows the difference between equilibrium and transient states, but he figures the equilibrium calculation comes close enough. But since the IPCC HAS published time-series (rather than just equilibrium) model output for the A2 scenario (see Fig. 7,) why wouldn’t he just use that?
Figure 7. Ensemble AOGCM output for the A2 emissions scenario, taken from Fig. 10.5 of IPCC AR4 WG1.
The answer is that if Lord Monckton had used the time-series model output, he would have had to admit that the IPCC temperature projections are still right in the ballpark. In Fig. 8, I have digitized the outer bounds of the model runs in Fig. 7, and also plotted the HadCRUT3 global annual mean temperature anomaly over the same period. The bottom line is that Monckton has put the wrong data into the wrong equation, and (surprise!) he got the wrong answer.
Figure 8. The blue and green lines represent the upper and lower bounds of the global average temperature anomaly from AOGCM output for the A2 emissions scenario during the 2002-2010 period. The black line represents the HadCRUT3 global temperature anomalies for that timeframe, normalized to the same base period.
Summary
I have shown here that in order to discredit the IPCC, Lord Monckton produced his graphs of atmospheric CO2 concentration and global mean temperature anomaly in the following manner:
- He confused a hypothetical scenario with a prediction.
- He falsely reported the data from the hypothetical scenario he was confusing with a prediction.
- He plugged his false data into the wrong equation to obtain false predictions of time-series temperature evolution.
- He messed up the statistical analyses of the real data.
These errors compound into a rather stunning display of complete incompetence. But since all, or at least nearly all, of this has been pointed out to Monckton in the past, there’s just no scientifically valid excuse for this. He’s just making it up.
Total ice pertains to latent heat uptake by melting
Land ice pertains to sea level rise (but ice shelves affect glacial flow) (even if the ice is grounded below sea level, so long as some of it’s weight is supported by the crust, loss of that portion of the mass will contribute to sea level rise)
Areal coverage and location and quality of snow/ice pertains to albedo (feedback) – the sea ice might be more important there, especially in the short term, particularly in terms of mass (of course, sea ice can lose mass without a corresponding loss of area, although thinner ice may reflect less solar radiation and also conduct more heat, keeping the surface warmer than otherwise if it is below freezing; snow cover on the ice would affect these things; however, there is only so much mass of ice that can be lost before there is no sea ice area, and it is much less mass than would generally have to be lost from a unit area of ice sheet to accomplish the same (and if grounded above sea level, the surface albedo after ice-removal will tend to be higher; of course, if there are more clouds over the ocean, then the relative importance of surface albedo is reduced there); of course, an ice sheet could lose mass even if some portions increase in thickness, which would bring about thinning at the edges sooner for the same mass loss (pattern associated with more rapid flow and greater snowfall in the interior)).
Kevin McKinney @450 — You might care to read about the fall of the Akkadian Empire, the world’s first.
446, Silk: What happens in Antarctica, except where it impacts on the above, is not of as much interest to the majority of humans.
I can’t disagree with that. I did mean a more narrowly focused question about Antarctic Ice: for the minority of humans whose interest in Antarctic Ice relates to how ice changes relate to AGW, is there a single most important quantity? I take it that the consensus is no: Warmer Earth can produce: more snowfall, more underwater melting, and shifting of ice mass large distances.
“Areal coverage and location and quality of snow/ice pertains to albedo”. Seasonality also plays an important role – the albedo of winter ice formed around Antarctica when insolation is low or nonexistent plays a small role in planetary cooling, whereas the open water that replaces it in the summer will absorb a lot of solar radiation.
The denialist “fair and balanced” comparison of the increase in winter ice in the Antarctic to the loss of perennial ice is an “error”. In order to accurately balance these disparate quantities, scaling factors need to be applied. The area, thickness, and age are all climatologically important; I will argue that the Antarctic increase in winter sea ice (1 year, 2 meters thick, ~ 1e6 km2), and the loss of the Larsen B ice shelf (~12000 years old, 220 meters thick, 3.2e3 km2) when properly scaled(age*area*thickness) show a net loss climatologically.
Antarctic sea ice: 1.0 year * 2.0m * 1.00e12m2 = 2e12 y-m3
Larsen B: 1.2e4y * 2.2e2m * 3.25e9m2 = 8.58e+15 y-m3
Arctic sea ice: 1.0e2y * 3.0 m * 4.00e12m2 = 1.20e+15 y-m3 (assuming perennial ice has only been around 100 years, which is confirmed by exploration – Arctic sediment cores indicate that perennial ice has been a feature for much longer than that – and assuming a thickness of 3 meters.)
One can see that the highly touted increase in Antarctic sea ice is mathematically insignificant.
Brian Dodge (#454)
The reason why lots of skeptics are talking alot about extent in antarctica is because it was made into a big story in 2007. For instance see,
http://www.cbc.ca/canada/north/story/2007/09/21/science-arctic-ice.html
I can find many more, but I think that illustrates the type of reporting on the subject right after the 2007 summer minimum. Now, everyone is being much more nuanced talking about volume (which I will agree with). I don’t think your comparison makes much sense however, although I would agree that the age is important. I would say it’s more important in how it changes the physical properties (such as density) and using it as a parameter in this sort of comparison isn’t all that helpful. By adding an age factor (totally artificial) you’re changing a positive number in the antarctic to a negative number which seems more like changing the data to suit your argument. Considering the latest reasearch seems to suggest that this increase is consistent with GW than I would say it’s needless in any case.
http://wattsupwiththat.com/2010/08/16/georgia-tech-on-resolving-the-paradox-of-the-antarctic-sea-ice/
That’s the only link describing the paper I found and Watts has a follow up post (an opinion piece that I don’t think most here would want to read) that links directly to the paper for those interested.
sambo @ 455: You say “The reason why lots of skeptics are talking alot about extent in antarctica is because it was made into a big story in 2007.” And then provide a link to a CBC article about artic sea ice that doesn’t even include the word “antarctic.”
Maybe you should try again.
sambo, in your comment currently numbered 455 you seem to have the Arctic confused with the Antarctic.
For example you begin by saying “extent in antarctica … was made into a big story in 2007″ and then you give a link to a 2007 CBC article about the melting of Arctic sea ice.
What’s up with that?
453 Septic Matthew says,
Look the most important thing to measure in Antarctica is the Land Ice status because it dictates Antarctica’s sea level contributions. Antarctica has very little multi-year SEA ICE therefore there are big differences between there and the Arctic which makes it a bit less important in the Antarctic. (When multi-year ice melts in the arctic, it results in more sunlight reaching the ocean during the summer, Antarctica generally loses most of its sea ice each summer anyways). Regardless, Antarctic LAND ICE is losing mass extensively and will continue to do so into the future because of widespread outlet glacier accelerations on the West Coast and in small parts of the Eastern Basins.
Another thing,
if you’re really interested in understanding these topics look at 3 posts I put together on the topic:
http://www.skepticalscience.com/Part-One-Why-do-glaciers-lose-ice.html
http://www.skepticalscience.com/Part-2-How-do-we-measure-Antarctic-ice-changes.html
http://www.skepticalscience.com/Part-Three-Response-to-Goddard.html
Note: these posts were originally caused by a dispute with steven goddard at WUWT. When the errors with his posts were pointed out to Goddard and he replied they were ad hominem and never answered them.
“I don’t think your comparison makes much sense however,”
Me either &;>); I forgot the smiley emoticon to indicate that I was parodying the deceptive quantitative numerology of Monckton, in my second paragraph.
The collapse of Larsen B taught science a lot about ice shelf dynamics, and how they constrain the flow of glacial ice off Antarctica, and was a stark reminder of how uncertainty and inaccuracy in the known science may underestimate AGW consequences. Quantitatively, the number of joules reflected by its 3e3km2 of perennial ice is insignificant, ~3 orders of magnitude less than the decline in perennial Arctic summer sea ice http://www.woodfortrees.org/plot/nsidc-seaice-s/from:1990.07/mean:3/every:12/plot/nsidc-seaice-n/from:1988.5/mean:3/every:12. The accumulated energy difference over 10 k years has had some effect on the climate – the joules reflected didn’t melt ice, or increase evaporation and rainfall in the Sahel, or trigger cyclones, or warm SST and increase phytoplankton productivity – but sorting out how the accumulated energy difference was partitioned is lost in the “butterfly effect”.
Larsen B’s age is qualitatively important as a refutation of skeptical claims about the 400 year Medieval Warm Period being as warm or warmer than today; Larsen B slept, along with Oetzi the Iceman in the Italian Alps, through that period, indicating that the MWP wasn’t as warm or as widespread as some would wish you to believe.
The volume of ice that disappeared when Larsen B collapsed was ~715 km3. Greenland is quietly losing about 300km3 every year, and this number is increasing, and of greater consequence long term. Glacial surges are known, but poorly understood, and occasionally make the news http://www.nasa.gov/topics/earth/features/jakobshavn2010.html http://www.udel.edu/udaily/2011/aug/greenland080610.html. Science doesn’t know of mechanisms that would caused abrupt collapse of the Greenland Ice sheet, but until Larsen B collapsed, it’s mechanisms weren’t known either. Using Rignot’s numbers from http://news.nationalgeographic.com/news/2006/02/0216_060216_warming_2.html, and projecting linearly to 2100, ice loss then will be ~1650 km3 per year, and the cumulative total will be 90900 km3. Using Zwally’s estimate of 0 loss in ’96 results in a cumulative loss of 136350 km3 by 2100. Does the spread in these values, and your confidence that the losses will remain linear inspire you to invest in seashore property?
458, Robert.
thank you.
Rick Brown (#356) & SecularAnimist (#357)
I realize what I posted, but I didn’t think I had to spell out what was meant, since I assumed everyone was familiar with the data. My point was that skeptics started tracking and reporting sea ice extent because of the big story in 2007 about the arctic ice extent (cbc story). Since they’ve been following the extent more closely, they’ve seen the arctic extent recover slightly from the low anomoly in 2007 and the antarctic has seen an increase in extent. While I agree that ice mass is the important factor in this case, the optics of when the emphasis was made on ice mass only (seemed) to occur when the data was showing recovery in the ice extent. BTW, you don’t have to point out that I should be looking at the long term trend in any case, I’m only trying to explain why this argument is being made. At the same time, I would say the headlines shouldn’t have been so dramatic in 2007.
Brian Dodge (#459)
I guess I didn’t understand the sarcasm in the comment (#454). Just curious, do we know how the Larsen B ice shelf evolved from the MWP to when it collapsed? If it grew significantly (became more unstable) then it would’t matter if it was warmer at the time, it still wouldn’t have collapsed.
#461–
“At the same time, I would say the headlines shouldn’t have been so dramatic in 2007.”
I don’t agree. It was an incredibly dramatic event, and was appropriately reflected in the headlines.
“The optics” may be as described, but claims of Arctic sea ice recovery are disingenuous at best, IMO.
Kevin (#462)
I agree (re: recovery) which is why I also think it was disengenious to claim the 2007 event as important and then change story when it didn’t suit anymore. To be fair, I think much of this had to do with media hype before AR4 and Al Gore’s movie/book.
“. . . to claim the 2007 event as important and then change story when it didn’t suit anymore. . .”
Who’s saying it wasn’t important?
Some may, with the benefit of hindsight, decided it wasn’t so much “the beginning of the end” as “the end of the beginning.” But that’s about the greatest change I’ve noticed, and I don’t think that you can fault anyone for reinterpreting in the light of further developments. To do otherwise is–shall we say, “beyond stubborn?”
sambo — 20 August 2010 @ 12:27 PM “do we know how the Larsen B ice shelf evolved from the MWP to when it collapsed? ”
earthobservatory.nasa.gov/IOTD/view.php?id=2288 “Larsen B shelf was about 220 meters thick…”
gef.nerc.ac.uk/documents/publications/824.pdf shows accumulation of about 118m/100years on the Antarctic Peninsula, accelerating over the last 100 years. This would mean that it would take about 200 years for the Ice to accumulate to the thickness of Larsen B. Theses measurements aren’t in the accumulation area for Larsen B, but 400km south; http://www.antarctica.ac.uk/met/momu/International_Antarctic_Weather_Forecasting_Handbook/update%20chnages%20in%20Antarctic%20snowfall.php, figure 1, shows higher rates of snowfall on the spine of the Peninsula north of the sample site and west of the Larsen shelf, so it may have taken less time for the ice to accululate.
http://www.glaciologia.cl/textos/RignotetalGRLPeninsulaAccel.pdf in2000, shows that seaward motion of the Larsen B ice shelf was ~ 500 meters per year, and the width is about 60km, so the calving ice at the seaward edge is(oops, was) about 120 years older than the ice at the landward margin.
The Larsen B ice shelf is a feature, like the Mississippi River. The ice in the shelf is like the water in the river, changing much faster than the feature.
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch4s4-6-2-2.html “Thinning of about 1 m yr–1 (Shepherd et al., 2003; Zwally et al., 2006) preceded the fragmentation of almost all (3,300 km2) of the Larsen B Ice Shelf along the Antarctic Peninsula in fewer than five weeks in early 2002 (Scambos et al., 2003).”
“Deformation rates depend on the gravitational stress (which increases with ice thickness and with the slope of the upper surface), temperature, impurities,…”
“An ice shelf moves forward, spreading and thinning under its own weight, and fed by snowfall on its surface and ice input from the ice sheet.”
The presence of seawater beneath the shelf (by definition) constrains the temperature to be between -2.5 and 0 degrees, between the freezing point of sea water and the melting point of the ice shelf. Regardless of the temperature of the glacier feeding the shelf , the seawater will add heat, raising the temperature toward the melting point, softening the ice and increasing the thinning due to gravitational forces from its own mass. The balance between seawater on the bottom, and colder average temperatures at the surface in the coldest parts of the Ross Ice Shelf, plus the effects of landward and upstream (into the feeding glaciers) dynamics support a thickness of roughly 750 meters. As it flows seaward, it thins from gravitational spreading and melt[1], reaching a thickness of ~240 meters at the calving front.[2] It appears to me that once an ice shelf thins to ~200-250 meters, it breaks up by calving. If the average surface temperature is significantly cooler than freezing, the shelf will be mechanically stable to annual warming and occasional meltwater ponds. The thickness will be determined by the rate of ice coming from feeder glaciers and snowfall; the bottom will be warmer, heat will flow up through the thickness, and as long as the ice input equals or exceeds bottom melting the shelf will be stable. Higher input flows will result in greater thickness, and mass balance will be maintained by outflow to the calving front. As the average temperature at the surface approaches the freezing point, the average temperature of the shelf will warm, and the ice will mechanically weaken. It will thin from faster gravitational spreading, bottom melting, and top melting seasonally. When the volume of water in seasonal ponds has a larger heat content than can be removed by the heat capacity of colder ice surrounding cracks, the hydrodynamic cracking extends through the entire thickness of the ice shelf and it collapses. Larger melt ponds and a warmer shelf through its thickness, driven by global warming, both contribute.
Significant growth would require average surface temperatures cold enough so that snow could accumulate, and/or more input from glacial flow from higher colder altitudes. The asymmetry between snow accumulation dynamics and melt water runoff dynamics pushes the average temperature transition between accumulation and loss below zero. With surface ice temperature and air boundary layer at zero, the lapse rate in the troposphere means that the air temperature falls below zero, and no energy is available for melting from conduction and convection, but downwelling IR radiation from CO2 in the troposphere will provide energy for melting. Because most meltwater will run off (there is a downhill gradient towards the calving edge and the ice shelf surface is relatively flat) the wet surface will stay near zero degrees, with variations of energy input causing more or less melting but not temperature change. For snow to fall and accumulate, the surface temperature must be near zero, and the snow will start at altitudes where the lapse rate insures temperature well below zero. As it falls, and if it accumulates, it will cool the lower layers and boundary layer. This limit on temperature increase by melting as energy flows in, but no limit on fall as snow accumulates, plus the adiabatic lapse rate “pumps” the average temperature where accumulation occurs below zero. Accumulation and growth of the ice sheet requires energy dynamics that limit heat input from the bottom, and have a colder surface, with heat flow from the bottom – a situation that makes the ice shelf stable.
[1]quakeinfo.ucsd.edu/~helen/GL11409W01.pdf
“A significant fraction of the ice flowing from the interior of the Antarctic ice sheet is lost by melting under the deeper parts of ice shelves [Jacobs et al., 1992]. This melt cools and freshens seawater circulating in the sub-ice-shelf cavity, and can lead to accretion of \marine” ice elsewhere under the shelf [Jenkins and Doake, 1991].”
[2]http://www.igsoc.org/journal/32/112/igs_journal_vol32_issue112_pg464-474.pdf
“We have therefore used the simpler Figure 7a grid and contours to obtain a mean thickness of 240 m for the 20 km band nearest the ice front. That is slightly more than half the average Ross Ice Shelf thickness of 427 m…”
Finally –
http://www.asoc.org/Portals/0/pdfs/Domack-Larsen-Nature080405.pdf
“All the evidence indicates that LIS-B has been a stable component of the northwestern Weddell Sea since the Late Pleistocene to Holocene transition, 11.5 kyr BP. In contrast, the northernmost portions of a much larger Larsen ice shelf system and small ice shelves on the western side of the Antarctic Peninsula experienced periods of decay and open marine conditions during the Holocene[mangled footnotes]. Our observation, that the modern collapse of the LIS-B is a unique event within the Holocene, supports the hypothesis that the current warming trend in the northwestern Weddell Sea has exceeded past warm episodes in both its magnitude and duration.”
Is there any way to use html tags to put parody/sarcasm/jokes/intentional malapropisms (e.g.”ad hominid”)into a different font – say Chancery?
Might as well have a go if for nothing but entertainment value, as this thread has devolved into a discussion of antarctic ice. Sort of interesting, but far from it’s original intent. The HTML code you would use looks like this:
<font style=”font-family:Comic Sans MS”>text in different font</font>
But certain blogs, and perhaps this is one of them, will only allow a subset of HTML to be used in reader comments, so the only way I can test is by actually posting since there is no preview option:
Here is some text in default style, and we briefly switch to Comic Sans MS and then back again.
Nope, didn’t work :-\ The tags were stripped out.
Sambo, the 2007 collapse of Arctic sea ice was significant in precisely the same way a record temperature year is significant: It gives us a peek at the extremes of the distribution AND it gives us information about the overall distribution. Beyond that, it´s weather watching.
The 2007 collapse could not have happened in a healthy Arctic. Ice has been thinning and retreating for nearly 40 years. Collapse happens in thin degraded ice.
Just a general thought. So far rebutting Monckton, Lomborg, and others, is sort of like playing whack-a-mole with zombies that just want to eat more brains. Return of the living dead aside, I thought some might enjoy a fun little diddy I grew up with that my dad used to play on the old Victrola . . .
I just found it on youtube: The Zombie Jamboree
http://www.youtube.com/watch?v=p4k5XftdTMs
—
Fee & Dividend: Our best chance – Learn the Issue – Sign the Petition
A Climate Minute: The Natural Cycle – The Greenhouse Effect – History of Climate Science – Arctic Ice Melt
Brian Dodge (#465)
Thanks for the info. It took me a while but I was able to read through most of it, and I did find it interesting.
Ray Ladbury (#469)
The satellite record only goes back to 1979, and while you’re probably right that the 2007 event probably couldn’t have been as extreme without recent warming, we don’t know how it compares to (for instance) Arctic extent during the 30’s or even during the “MWP”. What’s more, Watts et al. love to showcase news stories they can find from all over the place that show in X year there was no ice in such and such location. They then compare it to today and either (lo and behold) there’s ice OR they pull up the latest story claiming that no ice in this location is a clear sign of climate change.
If you want exhibit A, see
http://wattsupwiththat.com/2010/08/21/worlds-worst-heatwave-the-marble-bar-heatwave-1923-24/
Using 2007 to “peek at the extremes of the distribution” AND give “information about the overall distribution”. I’m all for that. Using the weather watching to write “scare” stories. It’s only giving ammunition to Watts et al.
BTW, regarding the sarcasm. I think it’s part of the medium that snark like that may not be understood as meant, especially by someone like me who is relatively new to the blog. While I’ve been lurking for some time, I may not know everyone’s snark signature yet ;).
“Snark signature”–subject to internal variability, I’m afraid.
You might try a span with the appropriate font style. Something like [span style=”font-family:comic-sans;”]text you want to be ironic[/style]. Replace with square brackets, of course.
469, Ray Ladbury: Sambo, the 2007 collapse of Arctic sea ice was significant in precisely the same way a record temperature year is significant: It gives us a peek at the extremes of the distribution AND it gives us information about the overall distribution. Beyond that, it´s weather watching.
The 2007 collapse could not have happened in a healthy Arctic.
That’s well said. The Joint Statistical Meetings recently held in Vancouver had sessions on modeling extremes, one of them specifically devoted to modeling changes in the distribution of extreme values related to AGW.
As noted by Sambo, we can not always be sure that recently identified “local extremes” are “global extremes” (local and global with respect to time), or even the “most extreme of the last 1,000 years.” For example, what if any was the most extreme Arctic Ice melt during the era of grape growing in Vinland, and was it evidence for a global warming or merely a local warming? (there I mean local and global in geographic extent.) Even the 3 decades long overall melting of Arctic ice is not known to be unprecedented.
Exactly when was this precedent set?
dhogaza: Septic Matthew is playing that silly old “you can’t prove it isn’t” game.
Take CO2. We know that CO2 is higher than any time in the last 50 years from direct measurements. Ice core measurements show that it is very likely to be higher than any time in the last 400 thousand years. And proxy estimates show that it is probable that current levels are higher than any time in the last 20 million years.
Can we “prove” this? No, but that’s not the point.
Oh, it’s not like I’m expecting a verifiable answer …
SM, proof isn’t available in science.
Correlation is, and the paleo folks are very aware this is needed.
See for example:
https://www.realclimate.org/index.php/archives/2007/09/perspectives-from-china/
where Gavin, back from a meeting, remarks on their awareness of
“… the overwhelming focus on downcore records (the patterns of change at a single point through time) and the relative lack of integrated products that either show spatial patterns of change at a single time, or that try to extract common elements from multiple events in the past. There are of course numerous exceptions ….”
Hank Roberts wrote: “… proof isn’t available in science.”
With all due respect that is one of the WORST things that people say when arguing for the scientific reality of AGW.
Of course proof is available in science.
I suspect that when you say that, you mean that axiomatic “proofs” like those found in mathematics are not available in science.
But that is only one sense of the word “proof”.
As it happens I have sat in a jury in a criminal trial, and have been instructed in detail and at length by the presiding judge as to the various standards of “proof” that prosecutors must meet in order for the jury to return a guilty verdict — which in that particular trial could send the accused to prison for decades.
In a civil case the standard of legal proof might be “the preponderance of the evidence”.
In a criminal case, as most people who have ever watched TV know, the standard is “beyond a reasonable doubt”.
The scientific reality of anthropogenic global warming — and many of the specific components of our understanding of that reality — have indeed been proved beyond a reasonable doubt.
Keep in mind, that in some states of the USA, that standard is sufficient to sentence an accused person to death.
I understand that many scientists are probably bigger fans of mathematics than they are of law, and they are enamored of the elegance and abstract truth of pure mathematical “proofs” in which premises and logic lead inexorably and irrefutably to a conclusion; and they perhaps tend to disdain the inherently subjective legal standard of “proved beyond a reasonable doubt”.
But it is really the legal standards of “proof” that are relevant here — relevant to the central, crucial question of “what should we do about AGW?”
And every time some scientist says “there are no proofs in science”, what the general listener hears is not the careful distinction between a mathematical, axiomatic “proof” and an empirical-evidence-based “proof” which it so pleases scientists to draw.
What the general listener hears is “climate science cannot prove beyond a reasonable doubt — and perhaps not even by the preponderance of the evidence — that AGW is either real or dangerous”, and the listener therefore finds the accused (fossil fuels) not guilty.
BBC 2 Newsnight on the disastrous floods.
[The Montford thread appears to be closed for comments so this appears to be the best alternative place for it]
I cannot comment reliably on Susan Watts report, because I missed the beginning.
But then we had a climatologist together with Andrew Montford being interviewed by Kirsty Walk. Every time Montford spoke he was acompanied by a subtitle describing him as the author of the book “…”. This must have been very pleasing to him and to Nigel Lawson.I do not remember John Haughton’s book being given such free advertising.
Then Kirsty Walk repeated the usual BBC question i.e. whether the climatologists statement about the floods had been affected by Emailgate. The climatologist appeared to agree with her. Isn’t it about time that the BBC finds some new questions? and shouldn’t climatologists prepare a more robust answer? Did he know anything about Montford or his book?
Bob Ward has a comment here:
http://www.bbc.co.uk/blogs/profile.shtml?userid=13870806
which I think is slightly understated.
479 SecularAnimist – valuable points, to which I add:
Consider the level of confidence required to print something in a (quality) college-level textbook or (reputable) encyclopedia…
Consider how many people get into their cars and drive somewhere without having any philosphical or mathematical proof that they will come back alive and intact.
… funny aside on reputable encyclopedias – I used to have a World Book encyclopedia (printed before I was born), which stated that the goose is one of the proudest birds of the animal kingdom, or something to that extent. I wonder which psychological studies they based that on… OT but funny! Not to cut down my last comment too much. I’ve looked at more recent World Book encyclopedias and don’t recall anything like that; and of course, there’s Britannica and McGraw-Hill.
Sambo and SM,
I would say that it is very unlikely that melting in the 30s and 40s reached the extremes of 2007 or even this year. The reason is because we did not have the same sort of long-term melting trend going on. It is the long-term trend that is important. Of course when you have a long-term trend that renders the distribution nonstationary, you are going to get more “extremes”. The 100-year event of today is the 1000 year event of 1780.
It is utterly pointless to argue with microWatts and his denizens. As Mark Twain said, “Never teach a pig to sing. It doesn’t work and it annoys the pig.” The only purpose I’ve ever been able to find for folks with such amazing ability to deny reality is ridicule.
483, Ladbury: I would say that it is very unlikely that melting in the 30s and 40s reached the extremes of 2007 or even this year. The reason is because we did not have the same sort of long-term melting trend going on.
I don’t know whether you are wrong or right. We never before had a long term melting trend, or long-term stationarity, documented.
Re 484 Septic Matthew
It might not demonstrate that the sea ice has never had a summer/fall minimum as deep as 2007 in the last ~ 80,000 or ?0,000 years, but I think it says something that we have such a thing as polar bears. Takes at least some time to evolve. Perhaps there is a history of polar bear population written in the sediments on the shores of Canada and Alaska that might be used to infer some greater information. Perhaps there is sediment on the Arctic sea floor that could tell us something.
Ray Ladbury (#483)
I was able to find the following paper on historical arctic ice extent. It cites Kinnard et al. (2008) in support of an ice extent graph reconstructed from proxies since 1870 (at least what I understood was proxies). In this paper I couldn’t see what the uncertainties were, although I didn’t have access to Kinnard et al. I think the missing part of the equation is what the probabilities are associated with these extreme events. Is 2007 a once in 30 year event? or is more like once in 100? What about back in 1870, will it occur more frequently during 2010 – 2020? It seems likely that the probabilities are decreasing, however we don’t seem to know what those probabilities are doing relative to past climate (general trend is decreasing but how much and how fast). My guess is the uncertainties in the proxy reconstruction would likely temper any firm conclusions that we can make. Does anyone have access to Kinnard et al in order to enlighten me?
History of sea ice in the Arctic
by Polyak et al (2009)
There has been recent papers on using seaice biomarkers to estimate historical extents. Eg here and here.
I think it is still early days for this method but I would love to data for when was the last time that the pole was ice-free in summer.
SecularAnimist, I think your comment #479 puts it all in pretty good perspective. Just don’t forget that many an innocent person has been found by judge or jury guilty beyond a reasonable doubt.
Patrick 027, true, people get into their cars and drive somewhere without having any philosphical or mathematical proof that they will come back alive and intact. And some don’t!
SM:
Ahhh … so you DID beat your wife some years ago.
Now I understand what proof means to you …
485 Patrick says, “It might not demonstrate that the sea ice has never had a summer/fall minimum as deep as 2007 in the last ~ 80,000 or ?0,000 years, but I think it says something that we have such a thing as polar bears. ”
Bears are very adaptable and the arctic was quite warm 8,000 years ago. I wonder if the Holocene climate optimum produced hybrid bears like we’re seeing now.
Re 489 Rod B – yes, the weakness of using that analogy, but… Do you think it is in the best interest of the world for everyone to refuse to ever drive again? Now imagine if there were an almost 100 % change of coming back alive and intact, but there was a risk of getting stuck in an epic traffic jam along the way?
Re 488 Rod B – there is an intense personal cost attached to being found guilty of a crime, or even being found responsible in a civil case, which is not generally found in general policies that address some type of widespread externality.
When people make decisions they have to make decisions based on expectations, including a reasonable margin of error.
Suppose a new species of large powerful animal with large teeth were found, and someone is planning to keep one as a pet, unfenced, near a school. Should the school not petition for some action preventing the keeping of this pet at least until more information is found/provided (even if this species has no known record of causing harm)? And if the species were not new, but say, a lion… and maybe we don’t know something, maybe it has a mutation, maybe it’s been trained really really really really well (but even then…)…
And note that with a C-tax, it isn’t an all-or-nothing deal. We can always adjust the tax rate as new information becomes available. If something goes wrong, it’s probably going to be more like getting stuck in traffic (try a different route the next day), rather than getting into a serious accident.
“The scientific reality of anthropogenic global warming — and many of the specific components of our understanding of that reality — have indeed been proved beyond a reasonable doubt.”
What do you mean by “scientific reality of AGW” : the fact that the man have contributed to warm the climate ? the fact that GHG have warmed the climate ? or something stronger about the exact amount of this warming ? or even stronger about the influence of this warming on the human societies ? what is “proved beyond any reasonable doubt” in your mind ? (of course proving each further step requires stronger and stronger evidence)
“Vinland” probably means “pasture land”, not “land of vines”, and there is no evidence grapes grew north of where they do today, in New Brunswick (which was probably included in the area referred to as Vinland).
There’s the Chapman and Walsh dataset covering Arctic sea ice from 1880 to 1998. The seasonal and annual plots of that dataset are in a number of publications and web pages: e.g. the TAR WG1 report and in Johannessen in Atm Ocean Sci Lett 1 (2008) 51.
And Stroeve et al. plot September sea ice extent in Geophys Res Lett 34 (2007) L09501 (see p. 2) using various obs and models.
Proof beyond reasonable doubt
The legal useage is too weak. You always have some remaining doubts in science, because the observations might be revised as well as the theory. But huge and basic revisions are rare and unlikely in a mature science.
The difference between consensus climate science and the contrarian version, is that the former may perhaps turn out to be partly wrong, the latter, has in most cases, been found to be wrong already
If you want to approach certainty then consider the disproof of Gerlach and Treuschner at both theoretical and observational levels. That example should not be considered in the light of , the often misunderstood asymmetry principle of Popper, but by considering the
actual case e.g. at Ely Rabett’s site.
For other examples just read the lead articles here.
As for a good approximate proof, consider the one of the greenhouse effect i.e. by pointing an infra-red spectrometer upwards and observing the carbon dioxide emission/absorption lines in the downward flux.
You don’t have to stick to observations. If you add energy to a system it warms, thats an example of a good theoretical principle which can be part of an approximate proof.
Gilles@493,
I imagine SecularAnimist means what he says, which is quite clear.
490, dhogaza: Ahhh … so you DID beat your wife some years ago.
An assertion for which there is no evidence. Perfect.
494, Nick Gotts: “Vinland” probably means “pasture land”, not “land of vines”, and there is no evidence grapes grew north of where they do today, in New Brunswick (which was probably included in the area referred to as Vinland).
OK. It would still be nice to have actual evidence of previous extremes of Arctic summer ice melt.
#498 Matthew, Phil Scadden posted some links at #487.
Hank Roberts also had a couple of nice references somewhere else – can you repost those, Hank?
Or, Matthew, you could look for this stuff yourself…
> sea ice biomarkers
Guessing you may recall one of these:
http://www.google.com/search?q=site%3Arealclimate.org+sea+ice+biomarkers
(I’ve forgotten how to limit searches to a particular person’s posts)