Exploring abrupt climate change induced by comets and asteroids during human history

Teaching the Younger Dryas Impact

The Tusk has characteristically hit a summer communication drought. But that doesn’t mean we can’t toss up a YouTube here and there from the coast. It’s welcome to see college courses fully integrating the Younger Dryas Impact into their thinking about the Younger Dryas and climate change. Here’s a great effort from Middlebury College.

Gotta love this guy’s building enthusiasm at 4:29. And 45,000 views!

10 Responses

  1. They mentioned the fullerenes with He inside, but they never tried to debunk or dismiss that. So, there was an impact.

    They tried at the end to dismiss the Hiawatha crater as too small to be from a 4 km comet, as if the fact that it is ana impact crater can be dismissed by that one not being a crater from an arbirtrarily conjured size of a 4 km. Even more, they did not took into account that this is a crater below ~2 km of ice, so it had to be considerably smaller because of that. Considering further the wide range of densities of comets, from 0.4 – 1.0 g/cm³, the object which impacted might have even been a 5+ km in diameter comet.

    They are fully correct about this being a highly improbable event to happen (again). Yet, the probability of all past events is always 100%. Events are only improbable before they happen, not after.

  2. The main impactor struck Saginaw Bay as demonstrated amply by Antonio Zamora’s excellent work on the formation of the Carolina Bays and Nebraska ‘rain water basins’ as secondary impacts caused by ice shrapnel which can be traced back using ballistic trajectories to Saginaw Bay. Greenland (+ others) may have therefore been part of a fragmented impact coincident in time with the main impact, increasing the size and range of the YDB debris field globally.

  3. Zamora is indeed correct about the Carolina Bays being the secondary impact craters. Yet, Davias is wrong about the Saginaw Bay being the main impact site. For one thing, size matters. The Saginaw Bay is 300 km from edge to edge. Chicxulub of the dinosaurs is only 180 km.

  4. Both the gamma radiation and the water outflows are the only firm data we have, as we are dealing with two separate impacts on an ice sheet. The LLodminster Uplift is generaly ignored, as people are not used to dealing with impacts on ice sheets.

  5. And now for the latest from NASA via SWRI:


    Factually, it is comets that cause Extinction Level Impact Events, and they come every 26 million years or so with a stochastic periodicity. We’ve known this since Clube and Napier The SWRI numbers are off by a factor of 10.

    Aside from that, the smaller object impact hazard is also minimized.

    The important part of all of this is the promotion of the South West Research Institute, while the NEOcam fro JPL languishes.

    73P is fragmenting in the inner solar system.

  6. Casual Visitor – A point of clarification:

    You said, “The Saginaw Bay is 300 km from edge to edge.” Actually Saginaw Bay averages about THIRTY kms across – varying from about 20 kms to about 40 kms. Would you like a mulligan on that statement? 150 km radius is most of the way across the Lower Peninsula. Or about to the far shore of the lower part of Lake Huron.

    You must be basing that 300 kms on something, but it is not obvious. “The Saginaw Bay” is pretty explicit, and the bay sure isn’t anything near that wide “from edge to edge”.

  7. A general note on the presentations in the video:

    It seems clear that this was some sort of group assignment at Middlebury. Young voices. They all seemed to take the original papers’ assertions at face value. They don’t seem to have read the rebuttals and the rebuttals to the rebuttals in the same journals.

    Doing this from memory from a decade or so ago:
    Survell’s sampling was taken to task for how he didn’t know his a__ from a hole in the ground about taking field samples, and Pinter got stuck with Surovell’s sloppy work to work with and make himself look bad. I.e., Surovell took far too wide (vertically) of samples, causing the spike layer to be blended in with non-spike soils. That was really a rookie mistake. That and several other assertions by the anti- side have long ago been refuted, and the students did not seem to be aware of the errors that Pinter et al. had made and had been refuted.

  8. The idea of the Mackensie River outflow was presented with little understanding of the history that includes Wally Broecker’s St. Lawrence surge out of Lake Agassiz. The Mackensie is a latter day Plan B. The Mackensie dumps into the Beaufort Sea only about 275 kms from Alaska. So, the bit about the Beaufort Sea saline levels is basically nonsense. Even if it is fresher as it flows out of the river, by the time it gets over to and around Greenland, it has nothing to limit its mixing with more salty water. From the Beaufort Sea is around 5,800 kms to where it meets the Gulf Stream (if they meet south of Iceland) – and 9400 kms (if the waters follow the Labrador Current after rounding Greenland).

    I maintained back when they first proposed that that the Mackensie was a ridiculous route. I have no reason now to change that thinking. I stand by it. They are just trying SO hard to get Lake Agassiz water into the thermohaline circulation, they will try anything. It is nonsense – but they’ve got no other fresh water source, so they have to force it. “Crowbar it,” as I used to say here.

    Googling current speeds —
    -Arctic Ocean: “The surface currents (speed: 0.1 to 0.5 metres per second) are caused by the action of the wind. The deep currents, which are much slower. . .” This converts to 0.36 kph to 1.8 kph. An average of 1.08 kph.

    -Gulf Stream: “The average speed of the Gulf Stream. . . is. . . 6.4 kilometers per hour.” This is 5.9 times as fast as the Arctic Ocean current average of 1.08 kph. That is a massive difference. And the Gulf Stream heads straight for the area east of Iceland. Unless it has been amended since my days in school, this current is driven by the Coriolis effect, and is not mainly driven by winds, but by the rotation of the Earth. It appears that they call it the “oceanic gyre” now. Same thing.

    A 1.08 kph current over near Alaska would only take 8700 hours. 362 days. One year, essentially.

    I don’t buy it.

  9. The students bringing up that insulting fungal thing really griped my arse. But it also was clear that they took Surovell’s nonsense at face value – and didn’t read the rebuttals.

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