RealClimate logo


Filed under: — gavin @ 24 December 2011

Two slightly off-center topics that Realclimate has covered in the past have recently come up again. The first is an analysis of Freakonomics by statisticians Andrew Gelman and Kaiser Fung in American Scientist, while the second is a recent reimagining of Washington crossing the Delaware.

The Gelman and Fung piece goes through a number of the errors found in the Freakonomics ouevre (from Steves Levitt and Dubner), and specifically references Ray Pierrehumbert’s critique of the climate change chapter in SuperFreakonomics (also discussed here). The whole piece is worth reading for how trust in their networks might be undermining Levitt and Dubner’s ability to critically view the ‘contrary’ positions they highlight.

“Washington crossing the Delaware” in 1776 was featured on RealClimate in a piece on ‘Art and Climate‘ back in 2006. We had noted that the icebergs seen in the classic scene (painted in 1851) did not resemble anything that you would likely see on the Delaware:

Well it seems that the re-commission of this scene was driven by the need to fix a number of historical inaccuracies in the classic Emanuel Leutze painting, not least the use of an anachronous flag, a row-boat instead of a ferry etc. but, in addition, the nature of the river ice!

The ferry cuts through thick layers of ice, which Mr. Künstler says corresponds with the photographs he obtained of the actual way the Delaware freezes.

People will clearly differ on the artistic merits of the resulting picture:

but the improvement in climatological veracity is to be praised. Maybe Levitt and Dubner will take note.

Happy Holidays.

44 Responses to “Recycling”

  1. 1
    Edward Greisch says:

    Who has the history of the ice on the Delaware river?

  2. 2
  3. 3
    John Pollack says:

    For a good account of the weather at the crossing (but not much about river ice) see pp. 98-99 of Early American Winters 1604-1820 by David Ludlum, pub. American Meteorological Society (1966).

  4. 4
    BobN says:

    Living just a few miles downstream of Washington Crossing, NJ and having observed the ice floes in the river over the course of many winters, I agree, that in all likelihood, the ice floes depicted Leutze painting were probably not realistic. Ice floes on the Delaware are typically fairly flat, with no more than a few inches above the water (unless they get tilted by current or collision with other ice slabs), and can be from a few feet to about 10 yards across. Also, many times, particularly early in a freeze-up, the ice will resemble a chunky Slurrpy. So, in this regard, the newer painting in likely more accurate.T

    The only time I have seen something kind of akin to the high, chunky ice floes depicted in the Leutze painting was when a there was the break-up of a large ice dam much father north along the Delaware (in 1996, I think). However, if I recall from some reading, there had been a bit of a warm spell just prior to the nor’easter that hit on Dec. 24, 1776, so it is possible that an ice dam may have broken upstream, but overall, as to the depiction of ice, the newer painting is more accurate.

    However, as to the use of a ferry instead of rowboats, unless all of the historical research and re-enactments are entirely inaccurate, Washington did use, among any other reavailable craft, several very large rowboats, which were known as Durham boats (see ). The river at Washington’s Crossing is nearly 300 yards wide. Further, at the time of the crossing, the flows were reportedly very high. Given that, I am not sure it would have even have been physically possible to use a rope guided ferry and a very low profile raft without the current causing either the raft to flip or the rope to break. So, in that regard, Leutze painting is defintely more accurate.

  5. 5
    dhogaza says:

    Who has the history of the ice on the Delaware river?

    Don’t know that, but rivers tend to freeze flat, as does the sea (i.e. the arctic ocean).

    Icebergs are caused by calving of glaciers …

    Different process, why would one expect the Deleware to, that year, show “mounds” of ice, when freezing of rivers at that time (and now( show a flat freezing?

  6. 6
    Eli Rabett says:

    Althugh it was an excellent article (there is another winner in that issue), as Eli pointed out, Gelman and Fung miss the Churnalism driver. Leveraging their initial best-seller, the Steves created a franchise, and like Mickey D’s, franchises require tons of raw meat, though quality is not necessary Any cow to be slaughtered is welcome and they have to grind up a lot of it. Careful testing and research are optional in churnalism.

  7. 7
    Mark A. York says:

    I just finished dealing with many of these Revolutionary paintings so I can identify with the accuracy of the paintings, many of which were created long after the fact. My book Patriot on the Kennebec: Major Reuben Colburn, Benedict Arnold and the March to Quebec 1775 comes out in the spring. This disastrous attempt to attack Quebec City was hampered by freezing cold in October and to top it off a hurricane that hit them full force in the wilds of Maine. Overnight water rose 8 feet on the Dead River and then froze over. Previously the woods were dry and deer remained scarce. They ate two dogs and boiled candles and leather shot pouches. The Continental army was screwed in a myriad of ways by weather.

  8. 8
    Susan Anderson says:

    Perhaps this belongs in the open thread, but there is a tenuous connection to ice here. The leadership commentary identifies good stuff necessary and in many cases already being shown by many of my favorite climate science warriors:

    “credible commitment to a larger purpose and flexible, imaginative methods to achieve a goal — is increasingly important in our tumultuous times.”

  9. 9
    Andy Revkin says:

    I have to say that I’ve seen many cold years on the Hudson River near West Point and Peekskill with lumpy, crushed floes similar to those in the original painting – and I can’t imagine that the Delaware is much different. Here’s video showing what conditions were like in January 2010 (and the ice can be far lumpier than this even out far from shore):

  10. 10
    BobN says:

    Andy – what your video showed was somewhat akin to what I was trying to describe in my post above, where flat sheets of ice are pushed up onto each other and have a chunky look, but are not sitting quited as high out of the water as shown in the Leutze painting. Thinking about it further having paddled my kayak between some of the ice floes on the Delaware, I think that probably both paintings show a bit more ice than was likely present. Remember that only about 10% of the ice is above water, so if you have a couple of inches above the surface, you might have 15 or more inches below the surface. Moving any type of boat through a fast flowing current with even widely dispersed slabs of ice 8 or more inches thick would be quite problematice. Trying to cross the Delaware with the amount of ice shown in either painting would be nearly impossible. Regardless of historical accuracy, I like both paintings.

  11. 11
    Russell says:

    There was no ice in view when I was dragooned into the crossing’s annual reenactment in 1959.

    To be sure, the Delaware freezes from the Water Gap to Trenton often enough in mid to late January, but a hard freeze in December may be pushing the statistical envelope.

  12. 12
    Radge Havers says:

    Ah, artists.

    Season change, picturing the winter:

    ” Without further ado, here are some of the images that some of today’s finest illustrators think of when they think of winter.”
    –Irene Gallo
    A Solstice Celebration

    via lines and colors

    A very diverse selection.

    Also see:
    Dutch Winters at Schiphol
    at lines and colors

    Artists don’t always get the science, but they do some pretty cool stuff nonetheless (also cold stuff).

  13. 13
    climatehawk1 says:

    Flyspecking: correct spelling is “oeuvre.”

  14. 14
    Edward Greisch says:

    4 BobN and the quote Hank Roberts leads us to makes me wonder whether they walked across a river frozen solidly enough to support wagons, horses and cannons. Otherwise, I don’t see how they could have mustered enough horsepower to cross a flooded river in 65 foot long 8 foot wide rowboats with a 3 inch draft. Nor do I see how wooden boats could have withstood impacts with the ice. Nor could men with poles necessarily have prevented impacts between ice and boat.

    If the Delaware is an estuary at Washington’s Crossing, perhaps the flow was zero at the moment of crossing, and the boats were on top of the ice. That makes more sense. Flat bottomed boats would spread the load on ice that was not quite thick enough.

    75 years [1851-1776] is plenty of time to get the details lost. To report accurately in 1851 a person would have to be at least 90 years old. There weren’t many people that old in 1851, much less with accurate memories. We would have to have something written in 1776 by somebody who was there at the crossing to get the details right, preferably several such documents.

    Washington crossed the Delaware. How we don’t know. Ice is devilishly difficult to deal with unless you have a lot of experience with it. Ice on rivers causes a lot of drownings.

  15. 15

    Thin fresh or sea ice sheets can get smashed together during a thaw and refreeze, thaw and refreeze several other times forming irregular ice pans as the painting suggests, there are such things as river ice dams which would create similar ice. If the Washington painting is accurate it means the Delaware weather was really between very cold and warmer winter atmospheres. It depends of the weather records.

  16. 16
    Hank Roberts says:

    > makes me wonder whether they walked across a river … I don’t
    > see how they could have mustered enough horsepower …

    C’mon, you can look this stuff up, but you have to think about the answers you find — don’t take an example someone like me gives as the full answer. You’ve taken a huge leap without understanding how it works. Try here:

  17. 17
    Russell says:

    Since the original version of Leutze’s meisterstuck was painted in his Dusseldorf studio in 1848 (it perished in 1942, when an air raid destroyed the Museum in Bremen), the painting may be less at an idealized Delaware Valley landscape than an imaginary sketch of Washington Crossing The Rhine.

    The river froze often and hard enough in the 4th and 5th centuries to famously support mass crossings into Gaul by the Teutonic confederation, and the Alamanni, Burgundians and Sueves, hence all those Franks in France.

    Had the Hessians in Trenton known of the irony to come, it could but have ruined their Christmas further.

  18. 18
    Utahn says:

    Sounds like they still don’t get it over there, apparently Dubner still thinks the many valid criticisms were “slime jobs.”

    And looking at what they’re posting about they apparently still enjoy playing the contrarian to our religion…

  19. 19
    Russell says:


    What religion is traduced by your second link’s conclusion :

    “: the more you know, the more you know that what you know is true — even when it’s not.”

  20. 20
    John Pollack says:

    I’m with Russell @11 – there was probably little ice at the time of the crossing. It was a nasty nor’easter they crossed in, and it would have probably put that torch out. I’ll quote from David Ludlum’s Early American Winters Vol. 1, pp 98-99.

    “The early part of the winter continued mild up until December 20th.” Not much time for a freeze-up.

    “Close to the important military action, we have a full meteorological report at Philadelphia where Phineas Pemberton, a member of the American Philosophical Society, kept a watch on the weather. On Christmas morning the area was enjoying pleasant anticyclonic conditions with the barometer at the high level of 30.50″, the wind light out of the north. The sky, though decked with some clouds, had a bright sun shining. The mercury stood at 32.” (Temperatures in Fahrenheit)

    “During the day a falling barometer and shift of wind into the northeast heralded a coming storm. By evening snow and ‘hail’ (more properly sleet) set in as the southern disturbance spread its precipitation canopy northward. The Philadelphia and Trenton areas remained on the northern edge of the heavy precipitation sector of the storm and did not receive the deep snowfall which covered North Carolina and Virginia. Pemberton described the 26th, as a ‘very stormy day with much rain & hail & snow at times. Cleared about 5 PM.’ At mid-afternoon his barometer had dropped to 29.53″, probably close to the low point as the wind had already shifted into the northwest. His thermometer stood at 33.”

    Ludlum also noted that Thomas Jefferson reported 24 inches of snow from this storm at Monticello VA, where the precipitation was all snow.

  21. 21
    Susan Anderson says:

    Ice and time:

    I remember old-timers at Martha’s Vineyard saying the bay used to freeze over for long periods on a regular basis, while now it hardly freezes at all. Narrative evidence like this is available everywhere, absent a few cantankerous contrarians who would assert the reverse no matter what.

    I’ve spent time at both the Delaware where Washington crossed and the Hudson, and the climates are quite different. The Hudson is significantly colder and the surroundings steeper and wilder, while that part of New Jersey is more like Delaware. The rivers are not comparable, though this is a guess I think the Delaware is shallower as well.

    Though I believe Russell has the facts rights about studio paintings and the Rhine, it is not unlikely that New Jersey was much colder then than it is now – in fact it is a lot warmer now than it was 50 years ago when I was a young teenager.

    As for the freakonomics franchise, it is more about popularity than useful information, as noted above. Sadly, it’s about important information and provides yet more hot air for the phony skeptics.

  22. 22
    Edward Greisch says:

    20 John Pollack: That explains it. The amount of ice on the real river was zero or close to zero and very thin. Their lamps had to be under a roof to prevent glass breakage.

  23. 23
    Utahn says:


    “What religion is traduced by your second link’s conclusion :

    ‘: the more you know, the more you know that what you know is true — even when it’s not.'”

    I think I may be stumped by your question, but I’m guessing Zen Buddhism? It kind of looks like a lame attempt at a Koan… If not that, Patmichaelsism?

    Or (as I suspect) did I not understand your question correctly?

  24. 24
    Russell says:

    Until someone identifies General Washington’s weather intelligencer, I suggest we defer to the contemporary observations of the philosophical gentlemen of Philadelphia, and the College of New Jersey, rumored by that date to have installed one of the ingenious Herr Fahrenheit’s thermoscopes in Nassau Hall.

    As to the past , it may be more present than Susan assumes.

    Though I have skated on Vineyard waters salt enough to house oysters and seen the Atlantic end of Nantucket solidly icebound, yet I have run into ocean sunfish and seriously lost tropical wrasse in the same waters in summer, and swum ( briefly ) in them in November, for there is no telling when or where the Gulf stream will enliven matters by shedding an eddy or two .

  25. 25
    Dave Person says:

    Perhaps one of the best histories of the crossing is David Hackett Fischer’s “Washington’s Crossing”. He includes daily temperature data and weather observations for the months of December and January 1776-77. Phineas Pemberton of the American Philosophical Society, who recorded the data at 8:00 AM and 3:00 Pm every day at a location 2 miles west of Philadelphia. I suspect temperatures near Trenton were a little colder than Pemberton recorded. During December 1776, the daily high temperature recorded at 3:00PM was below freezing on only 6 days, 2 of which were Dec 24 and 25. The daily lows recorded at 8:00AM were below freezing during 10 days, with 3 consecutive freezes occurring on Dec 23,24, and 25. During the month, lows ranged from 19-52 degrees F. I doubt there was very thick ice on the river. With respect to Kunstler’s painting, the troops used both ferries (for the artillery and horses) and Durham boats for the men. These boats were 40-60 feet in length, double ended and flat bottomed. They could plow through several inches of ice easily. According with tradition, Washington crossed in a Durham boat commanded by John Glover’s sailors from Marblehead, MA.


  26. 26
    Jim Eager says:

    Re Andy Revkin @9: “I have to say that I’ve seen many cold years on the Hudson River near West Point and Peekskill with lumpy, crushed floes similar to those in the original painting”

    As have I, but the Hudson remains tidal that far up, which means the ice is pushed to and fro twice daily, even as new ice continues to be carried down stream, which helps explains its jumbled condition.

    I don’t know if the Delaware is tidal at Trenton, but I’ve seen jumbled ice piled high on the decidedly non-tidal Walkill at New Paltz, NY as a result of ice damming.

  27. 27
    Hank Roberts says:

    A brief quote from the first-linked piece:

    “… The strongest parts of the original Freakonomics book revolved around Levitt’s own peer-reviewed research. In contrast, the Freakonomics blog features the work of Levitt’s friends, and SuperFreakonomics relies heavily on anecdotes, gee-whiz technology reporting and work by Levitt’s friends and colleagues. Just like good science, good writing takes time ….”

  28. 28
    John McCormick says:

    Thanks for the link to the Freakonomics analysis. Its references included a link to Dr. Pierrehumbert’s open letter to Levitt on RealClimate @ That RC post will be a good read this afternoon.

  29. 29

    I’ve got a new, shorter, simpler, hopefully better summary of the main argument.

  30. 30

    #29–Very crisply written, Barton. I like it.

    Of course, your conclusion will provoke comment (and perhaps some ire)–but that may not be a bad thing.

  31. 31
    John McCormick says:

    Barton, here is a pdf of:

    On the Temperatures of the Terrestrial Sphere
    and Interplanetary Space

    Jean-Baptiste Joseph Fourier


    provided by R. T. Pierrehumbert 1 September, 2004
    Chicago, IL,USA

    for your reading enjoyment.

  32. 32
    Dave says:

    The Delaware is definitely affected by tides at Trenton, although not really estuarial (fresh, not brackish, maybe 30 miles above the salt line?) – it’s technically above the fall line as well, and not navigable above Bordentown (a couple of miles south), but daily flow rates are very much affected by the tides. (I work in Trenton, and often cross the river bridges on foot at lunch time.) Washington Crossing is about six miles farther upstream, so I’m not certain how much the flow rates would fluctuate with the tides – but at Trenton, you see virtually slack water for a few hours, followed by similar periods of rapid current.

    If the historical weather reports are to be believed (daily highs at or above freezing, some overnight lows below freezing), my experience says there wouldn’t have been much ice on the river. The Delaware only freezes when we get truly cold snaps – when the daily highs stay below freezing, and for more than a couple of days.

    As for high water from the reported nor’easter, it would depend on how much it rained, where, and when. The Delaware comes up after heavy rains, but typically not really quickly. The highest water/fastest currents would typically occur after the storm, not during it. We’ve seen flood crests a full day or two after serious storms (Irene, Lee, Floyd, etc.).

  33. 33
    Louise Doughty says:

    BPL @ 29
    Nice clear summary. I wondered about the use of degrees K though. These days I struggle to remember what 0C is in Kelvin and most Americans seem to use F anyway, so perhaps for them it would help if you put the farenheit temps in brackets?

  34. 34
    Russell says:

    Over at The Spectator, James Delingpole is seeking moolah on behalf of systems administrator and WUWT censor Roger “Tallbloke” Tatterstall, lately interviewed by the Norfolk constabulary regarding a certain theft of e-mails :

    Any funds not eventually used for necessary legal expenses will be donated to a selection of climate sceptic organisations. Accounting procedures will be put in place in compliance with the requirements of the UK regulatory system governing the proper use of Client monies held by UK solicitors.
    Stephen P R Wilde. LLB (Hons.), Solicitor.
    Wilde & Co. Cheshire England
    This blog urges all readers to think of the Spirit of Christmas and give generously.
    Here are just some of things your money might buy:
    50p buys a week’s supply of maggoty gruel to serve to the Lead Authors of the IPCC’s assessment reports, if and when they are eventually tried and imprisoned for crimes against science, economics and Western Civilisation.
    £20 buys a set of handcuffs for one member of the Hockey Team
    £25 buys the extra special set with spikes laced with marmite
    £500 buys a course in Excel basics for Professor Phil Jones
    £1000 buys a large island in Greece on which to imprison the Climategate 2500
    £2000 buys… Fill in as appropriate. I’ve got to go off on a Christmas walk with my brother.

    Fancy that

  35. 35
    Edward Greisch says:

    BPL: Thank you. I am directing people to your web site.

  36. 36

    Thanks, guys.


    Scientists use K because you can only do useful temperature math with an “absolute” scale. For what it’s worth, Earth’s radiative equilibrium temperature, Te = 254 K, is -19 C, water’s freezing point of 273 K is 0 C, and Earth’s mean global annual surface temperature of Ts = 288 K is 15 C (some studies say the actual figure is closer to 14 C). In Fahrenheit those figures would be -2.2, 32, and 59 F (or 57.2 F). Some equations:

    Tc = Tk – 273 = (5/9) (F – 32)
    Tf = 1.8 Tc + 32
    Tk = Tc + 273 = (5/9)F + 256

  37. 37

    Nice one. Is the suggestion that the original painting has more artistic merit than something realistic an analogy with Freakonomics? The American Scientist article is well worth a read, for anyone taken with the rogue scientist meme.

  38. 38
    Louise Doughty says:

    Hi Barton
    Thanks for your reply. I wasn’t sure who the page was aimed at. I was thinking along the lines that I obtained a degree in Physics (BSc) in the late 60’s but, by now, couldn’t remember exactly what 0C in Kelvin, and that the average lay person may not even have heard of degrees Kelvin. If the page is intended for practicing scientists that’s fine.

  39. 39

    A bit OT but the South Pole had a new record maximum on 25 December 2011. worth noting for trivia collectors.

    [Response: Glad to hear it, as I may be working there in a few years, and I don’t like the cold. But… don’t you know any and all temperature changes at South Pole are just made up, to try to get the gummint to institute a carbon tax..? ;) –eric]

  40. 40
    S. Molnar says:

    Eric, the record temperature at the South Pole is real, but it’s due to the urban heat island effect – too many scientists in Antarctica these days.

  41. 41
    Andy says:

    I think the original painting may well be an accurate depiction. I’ve seen this before. It’s a heavy accumulation of wet snow sitting on top of the ice.

  42. 42
    timg56 says:

    RE: #39

    Dr. Steig, I tried getting selected for Operation Deep Freeze while in the Navy, unfortunately they didn’t have too many positions for torpedomen. Ended up in submarines. I do have a good friend who spent some time there and I’m still envious. If you want someone to shlep your bags and equipment, let me know.

  43. 43
    Gbolu says:

    Apparently, cover everything at once leads to frustration and without becoming obsessed with something, we cannot solve or progress on an issue

  44. 44
    Hank Roberts says:

    > didn’t have too many positions for torpedomen

    In an alternate world line, they did: