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On Mowing a Virginia Lawn … And Contemplating a Greenland Iceberg

Posted on 6 September 2011 by Bud Ward

A guest post by Bud Ward reposted from The Yale Forum on Climate Change & The Media.

What if my “discovery” of a long horizontal blue streak the length of a huge iceberg’s tunnel were the veritable missing link in the climate science puzzle. Alas. It  wasn’t to be, but the random thought made the lawn mowing all the more enjoyable.

I get some of my best ideas atop my lawnmower tractor. And, admittedly, also some of my real clunkers.

This time was perhaps no different, save for the extraordinarily beautiful mid-70s cloudless, sunny, and breezy day so unusual in summer in this tidewater section of Virginia. There’s something about just being as one atop the brute power of that 22.5-horsepower Craftsman.

It’s a lawn I’ve mowed many times, mind you, certainly hundreds. This time, my mind turned to a photo I had taken earlier this summer in Greenland. A photo of a large iceberg, and through its full length a large tunnel. So large, in fact, that we thought about running our eight-passenger “Arctic Cirkel” outboard through it (we passed on that idea).

But what most occurred to me while mowing was that distinctive horizontal blue streak running the length of the tunnel. It shows up pretty clearly in this photo:

So, while mindlessly mowing, I got to thinking: What if that blue streak is important? What if it’s, like, the missing piece that helps some climate scientist or geologist support or challenge a particular hypothesis? If only …. and so forth, my thoughts flowed.

Probably not. But. What if?

Most likely, I anticipated, it’s nothing at all. Nothing unusual or the least bit meaningful in any scientific way.

But, I couldn’t escape wondering: What if …?

It was then that the most interesting aspect of my mowing-induced wonderment sunk in. It occurred to me, sitting there, that I hadn’t cared a twit whether my opportunistic “finding” of the blue streak might benefit one side or the other of the climate controversy: Be it of help to the majority of scientists fretting about their evidence, or to the few, but highly vocal, roundly rejecting that same evidence — it didn’t matter to me in the least.

My daydream had been that the streak would be important, worthwhile, valuable even in the pursuit of climate science understanding. Not, assuming it might have any intrinsic value in the first place, that it might help or hinder this or that side of the political debate.

I don’t think I actually needed that re-affirmation of my own pursuit of and commitment to evidence-based “truth.” I hadn’t doubted my creds on that point.

But, all the same, there it was, right in front of me, smacking me like a 2-by-4 as my mighty steed — or, rather, Craftsman — inched forward.

If only that photo of the streak could be useful in some way, I daydreamed. Kind of makes me glad we’re still in grass-growing season. Can’t wait until next time I get to mount that mighty Craftsman and see what ideas emerge.

ADDENDUM: Alas … From Richard B. Alley … The Truth Doesn’t Hurt

So. Shortly after debarking from my trusty mower, reality set in with this note from Penn State glaciologist Richard B. Alley, who kindly replied to my e-mail seeking his guidance:

The blue streaks are almost always refrozen meltwater that penetrated a crevasse. This is seen very commonly. In the most extreme cases, there is almost as much refrozen meltwater as snow; in other cases, just a single blue slab (seen as a line where it cuts the surface).

As to the details of why blue, I believe it is mostly linked to seeing into the berg. Ice is blue in the same way as water — a little bit looks clear, but a long view shows the blue color, which arises because the water molecules interact with red a little more than blue, so red is absorbed and so lost along a very long path through water or ice. In most snow, the reflections are so strong that you don’t see far in. If you take a deep, clean snowdrift, poke a pole in and then remove the pole to leave a long, thin hole, then look into that hole (blocking the sun with your hands), you’ll see the beautiful blue of ice, with the light reaching your eyes having passed through the snow (taking a long path with multiple reflections) and then up the hole. The blue band of nearly clear ice with few or no bubbles that formed from refrozen meltwater, cutting through the snow or bubbly firn and ice, serves the purpose of the hole in the snowdrift, letting light reach your eyes after having passed through a lot of ice.

So now back to reality. And to weeding.

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Comments

Comments 1 to 5:

  1. I can't help but wonder how efficient that lawn mower is. I am hazy on the reasons, but two stroke engines are less efficient. One presumes a riding mower would be 4 stroke, but it isn't clear.

    I think, too, the above comment shines a light on the fundamental difference between science oriented and denial oriented minds. The science oriented questions everything. I admit the first thing I thought of was the climate impact of the mower - not in a gotcha, but just where my mind goes. Everything is on the table, and grey exists.

    I think for many "skeptics", the same observation would be in gotcha mode, as in "why should we listen to you - you use a polluting, gas powered device to mow your lawn" - as is endlessly done to Al Gore and Dr. Mann, Dr. Jones, etc.

    Kind of hashing my point here - it seems to me that there is a fundamental difference between skepticism (question everything, by nature) and the blind ideologue approach I see in US politics (on the right in particular (indeed it has become a distinguishing feature between the left and the right) that questions anything that doesn't support the current talking points, but gives the rest of reality a pass.
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  2. My first up close experience with bergs brought a similar mystery. A berg with beautiful grooves in it. Almost like they were made with a giant rake with a thousand teeth. The local iceberg expert explained it to me at the time but darn if I have not forgotten the exact reasons. Something to do with currents.
    Here it is: http://mactardis.com/photos/main.php?g2_itemId=18708



    I may not know exactly the cause of this but my first thought is not to chalk it up to magic or a higher power but to ask how it happens. We live in a country where far too many find it much more comforting to invoke the magic.
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    Response:

    [DB] Embedded picture.  You can even see the seabirds flying in the foreground.

  3. An interesting little article. Illustrative of the scientific mindset, too!

    The first question that popped into my mind, though, was this:
    What caused that tunnel through the iceberg?

    I'm guessing one of two things - a vertical meltwater channel (is 'moulin' the right word?), or something carved by wind & wave action since the berg calved from the glacier.
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  4. People on this site should also read this article
    Gobsmacking Greenland Glacier Loss

    Alarming, genuinely, not simply "alarmist". :(
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  5. Posted on behalf of Penn State Professor Richard Alley (in rsponse to question posed by Bern, #3) at his request while his e-mail access is limited:


    The tunnel in the iceberg is beautiful! To be honest, I don’t know why they form, although someone may. But, I have seen a lot of them. A few thoughts:

    In glaciers from regions with abundant surface melt, there are lots of healed crevasses and moulins (meltwater channels), sometimes including meltwater channels that melted their way down into the glacier and then developed lids as snowdrifts bridged over or the ice squeezed closed. The most common are probably moulins that started as crevasses. Water flows faster where the cracks are wider, making “frictional” heat that melts ice, while refreezing happens where cracks are thin. Boreholes through “wet” glaciers have found all sorts of water channels and cavities, many quite interesting, big and little, long and short, interconnected and not (and, up shallow or in the winter when the water drains, some become air channels, including ones that really skillful or really crazy people go caving in). So, an iceberg from an appropriate glacier starts with a lot of holes.

    Next, my experience is that the big channels in icebergs often are close to the water level, either at the water level or slightly above on a berg that seems to have been rising as ice calves or melts away above the water line faster than below. So the suggestion is that something occurring at or near the ocean surface is important.

    Often, there is a relatively thin layer of sun-warmed water near the ocean surface, so maybe waves moving this water are focused into the preexisting channels and crevasses in some places, enlarging them to give the beautiful features seen. At least, this seems like a good working hypothesis, although I suspect we could cook up a few others as well.
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