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One enjoyable aspect of school is the opportunity to explore new ideas which keeps your field of study fresh. Now that may seem like a funny statement, if only for its obviousness alone. Isn’t that what school is for? Well, sure, but in the grind of labs, term papers, presentations, and exams, the experience of discovery for its own sake is often put on the backburner for other things such as good grades and late-night coffee runs.

Geomorphology is a subfield of geology that I’ve not had much exposure to in the past few years, and I regret that. Not only is it useful for seeing first hand the way wind, water, and ice enact weathering and erosion to sculpt the land in a plethora of unique features to better our understanding as geoscientists, it just so happens to be interesting, too. For example, just this evening I was working on a chapter summary assignment on periglacial environments – high latitude or high altitude environments that are not permanently glaciated, but where seasonal ices and permafrost features act as a major control on landforms – and stumbled across the idea of nivation.

Simply stated, nivation is a feature of the periglacial environment where small snow patches not large enough to be considered glaciers act as a control on weathering and erosion (Fig. 1). Weathering occurs at the margin of the snow bank, and meltwater acts as the erosianl agent. It’s a slow and subtle process, but effective, forming so-called ‘nivation hollows’ in the side of hills.

Fig. 1. Idealized model of a nivation hollow in the side of a hill. Note the erosional alluvial fan at the base of the snowpatch. Adapted from Thorn and Hall (2002).

The reason this struck so pointedly was because it reminded me of the sort of features I saw while hiking the Bald Hills this summer near Jasper, Alberta:

 

(Nivation hollow with snow patch on the northeast face.)

Granted, it’s minimal in extent compared to the model in Figure 1, but it’s at the proper elevation for a periglacial setting above the treeline at approximately 2225 m. Secondly, keep in mind this photo was taken in early August with snow cover at a minimum. I would like to visit this site in late spring once the seasonal snow cover has melted. I can easily imagine the process of nivation going on; field confirmation would be the icing on the cake.

Additionally, just down slope is an impressive talus field:

(Looking east, downslope on a periglacial talus field. Nivation hollow to the right, Maligne Lake in the background.)

I cannot provide a date on this feature (I suspect the last glacial maximum) but I think it provides a pretty good case for a periglacial environment. In any event, it’s a veritable playground for any geomorphologist. I think I can even provide evidence for tors:

 

(Tors near the ‘summit’ of the Bald Hills at 2300 m – note the vertical and horizontal joints between close-packed, yet separate weathered blocks of rock, esp. near centre of photo.) 

References

Thorn, C.E., and Hall, K. (2002), Nivation and cryoplanation: the case for scrutiny and integration. Progress in Physical Geography, vol. 26, no. 4, p. 533-550

Since we’re on the theme of climate, an oldie but a goodie – Futurama explaining the vagaries of global warming:

The idea is straight-forward and, by this point, quite well-known: because the molecular structure of CO2 allows it to absorb infrared radiation (i.e. heat) as shown in Figure 1, an increase of CO2 in the Earth’s atmosphere will force a delay in the escape of longwave, infrared radiation back out into space. This results in the greenhouse effect, and along with sufficient levels of atmospheric oxygen, is one of the main reasons why planet Earth is habitable for human and animal life. 

 

(Fig. 1. Different vibrational modes of CO2 molecule from infrared absorption.)

So when Lindzen and Choi (2009) published a paper in Geophysical Research Letters  (GRL) last August suggesting that the effect of CO2 in the atmosphere is – for simplicity’s sake – overstated, some AGW critics were quick to jump on it. Can you blame them? Here’s a study that looks at Earth Radiation Budget Experiment (ERBE) data from NASA and finds that current model predictions are too sensitive. In other words, if we were to double the concentration of atmospheric CO2, it would have much less of a warming effect on the atmosphere than the AGW crowd would have you believe – amounting to a lot of environmental and political fuss for nothing. 

Except that chinks are now starting to appear in the armour of this paper. 

The first blow came last November when former NASA scientist Roy Spencer weighed in on the issue. He commended the authors on their methodology, agreeing that if you want to investigate the link between outgoing radiative change and temperature change, it makes sense to focus on periods of time where a temperature change is actually taking place. However, Spencer was unable to replicate their results under the same parameters, and was less forgiving with the study’s conclusions: 

“So, while I tend to agree with the Lindzen and Choi position that the real climate system is much less sensitive than the IPCC climate models suggest, it is not clear to me that their results actually demonstrate this.” 

The second look comes courtesy of the RealClimate blog with some guest commentary by the authors of a study (Trenberth et al., 2010) published in the past February issue of GRL. They ask the most obvious question of all: 

“Why would such a significant finding have gone undiscovered when these feedbacks are widely studied and recognised as central to the projections of climate change?” 

Indeed, if CO2 really is much less senstive to climate that we have thought all this time, why has it taken so long to figure that out? Climate models may be relatively new on the scene, but the greenhouse properties of CO2 have been known for over 100 years.

So what gives? A lot, apparently, considering the number of objections Trenberth et al. (2010) have to the paper concerning everything from results that are not robust, to misinterpretations, to comparing results to existing, incomplete, ‘test’ models – assumedly never intended for such rigorous attention. In the GRE paper they have this to say:

“While [Lindzen and Choi] adopt a procedure to avoid one of these pitfalls, they fail to recognize and account for several others, they do not account for external forcings, and their use of a limited tropical domain is especially problematic. Moreover their results do not stand up to independent testing.”

Now I’ll be the first to admit I don’t have the personal experience to back up my reaction on this, but nevertheless, having read  a number of scientific papers the past four years, them’s fighting words. Lindzen and Choi clearly have their work cut out for them if they want to continue down their present path. 

References

Lindzen, R. S., and Y.‐S. Choi, 2009. On the determination of climate feedbacks from ERBE data. Geophysical Research Letters, vol., 36, L16705. 

Trenberth, K. E., J. T. Fasullo, C. O’Dell, and T. Wong, 2010. Relationships between tropical sea surface temperature and top‐of‐atmosphere radiation. Geophysical Research Letters, vol. 37, L03702.

In what surely must be the first published paper to have a list of authors longer than the abstract, 41 scientists led by Peter Schulte recently concluded that the extinction of the dinosaurs was indeed the result of the Chicxulub impact off the Yucatan Penninsula 65.5 million years ago (abstract).

Wait a minute – hasn’t this idea been kicking around for at least 30 years now? How is this in any way ‘new’ news?

Well, one reason may stem from a name that isn’t included among the 41: Gerta Keller of Princeton University. Over the past several years she has written a number of both intriguing and controversial articles that call into question the assumed, prominant role of the Chicxulub impact: namely the double-edged sword of it predating the K-Pg boundary by 300,000 years, and Deccan volcanism playing the pivotal role in the mass extinction.

Though the general public is largely unaware of the debate, that has not had any bearing on the impact of Keller’s research within the scientific community. Given some of the reaction to it, I have to wonder if this latest paper is more of a public relations, ‘consensus’ tactic than anything else (certainly critics of Keller such as Philippe Claeys are among its authors).

If so, it’s working wonders. Consider headlines such as this one from Scientific American:

“A Theory Set in Stone: An Asteroid Killed the Dinosaurs, After All – A single asteroid impact near the Yucatan remains the best explanation for the massive Cretaceous-Paleogene extinction, scientists conclude in a new, deep review.”

Or how about quotes like this from the LA Times which proclaim a ‘Dream Team’ conclusion:

“It’s official: The extinction of the dinosaurs and a host of other species 65.5 million years ago was caused by a massive asteroid that crashed into the Gulf of Mexico, creating worldwide havoc, an international team of researchers said Thursday.”

That said, the review is an excellent one. My only complaint is that being a Science article it’s very short – a 15-20 pager would be nice! – though the supplemental material is a valuable addition. If you have access or are willing to toss down a few bucks, I urge you to check it out.

On a semi-related note, anyone else slightly disconcerted by seeing “K-Pg” instead of “K-T”?

..and nothing illustrates this fact more than the mighty, little gymnosperm:

Red Lake Baby Spruce(Baby spruce growing in Precambrian outcrop, Red Lake, Ontario.)

Mt. Edith-Cavell Conifer

(Young spruce sapling taking hold in a recently de-glaciated valley in the shadow of Mt. Edith-Cavell, near Jasper, Alberta.)

Take care to note, however, that the flowering angiosperms are not about to be shown up by their cone-bearing cousins:

Popular Sapling

(Poplar/aspen sapling flourishing on the side of a roadcut in northwestern Ontario.)

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