It is time to stop quivering in our boots in pointless fear of the future and just roll up our sleeves and build it.
- Ray Pierrehumbert

Sunday, January 18, 2009

The Arrogance of Anthropogenic Impact Theories

Many denialist groups, particularly those of religious persuasion, talk about the "arrogance" of believing that human impact is of a scale to affect the atmosphere. I leave the profile of the atmosphere up at the top right of this blog to emphasize that the atmosphere is really a thin film, and that it might well be within our capacities to alter it. This attitude may be more prominent in remote rural areas where the scope of human impact is less obvious on a daily basis.

Perhaps the visual impact of human impact on the land surface may cause people to reconsider their intuitions in this regard. Here for instance is a picture of some protected lands in Tunisia. Sidi Toui National Park is about 7 km wide, and lies surrounded by unprotected lands that have been destroyed by overgrazing.




Lifted from an amazing gallery at boston.com .

Then of course, there is Lake Chad, before and after:



And the Aral sea:



I referred to these massive anthropogenic changes briefly before, with a couple of interesting links.

I'm reminded of it in trolling the denialist sludge my RSS feeds pick up. The question is which way is the arrogant one. Is the presumption that we are "as gods", and capable of changing the surface and near-surface of a planet sacrilegious? (Note: surprisingly, that is the correct spelling, apparently.) Perhaps the refusal to look at plain evidence because of some pre-existing dogma is even more arrogant?

This arrogance is an ancient story, of course. You'd think folks might have learned something by now.

 

19 comments:

Belette said...

But ironically you can't spell "surprise" :-)

Michael Tobis said...

I need an editor.

Also, so far I can't seem to get a reasonable format for this article out of blogger.

Michael Tobis said...

all fixed now...

VangelV said...

How misleading. The fact that humans can empty a lake does not prove that they have been the primary driver of temperature since the end of the Little Ice Age. It is now clear that CO2 can't be a primary driver of temperature change because the ice core data shows that historically CO2 concentrations have lagged temperature changes by hundreds of years. We also know that over the short term we have had cooling periods during which CO2 concentrations went up significantly. Add to this the fact that last year's average temperature was very close to the 110 year mean and anyone with an unbiased approach can see that the AGW arguments have fallen apart.

I won't even comment on the recent divergence of the GISS data from satellite record or the poor state of the weather stations that provide the raw data that is used to make the AGW arguments because even with all of the manipulation and errors it is clear that there is no warming problem.

guthrie said...

You know, I'd like to say something more useful than we're fucked, but somehow I can't think of it.

eco101 said...

Hah, I thought "trolling" was a mistake too... I (Australian english) spell it "trawling". I think of Trolling as what arrogant deniers do...

-naught101

Michael Tobis said...

VangeIV, you are changing the subject.

My point was that it is not especially arrogant to believe that humans can have impacts on a grand scale.

You could either contest the point, elaborate the point, or be silent on it. Those would be polite and constructive responses.

"It is now clear that CO2 can't be a primary driver of temperature change because the ice core data shows that historically CO2 concentrations have lagged temperature changes by hundreds of years."

You should be clear about this. For "temperature" you should say "local temperature in Antarctica" of course.

Anyway, can you explain your reasoning here? It is as if you were saying "whiskey can't get you drunk because one time I got drunk on gin".

David B. Benson said...

VangelV --- I strongly recvommend you read W.F. Ruddiman's popular "Plows, Plagues and Petroleum". Then read David Archer's "The Long Thaw".

This will certainly dispell the notions you have obtained for misinformation web sites, which have gotten it all wrong.

Dano said...

David:

you really don't think Vange will read your recommendations, do you? These books have "facts" that don't comport with an ideology, so the "facts" contained in these "books" are suspect.

Best,

D

Michael Tobis said...

Dano, you are falling into the trap.

If there is no intention for a real discussion, likely the case here, the writer is not really addressing me or us, but the innocent passerby. The trap is to call him on it before the evidence is clear to the innocent passerby. It makes us look closed-minded and arrogant. Which is the purpose of the endeavor.

It is much more productive to pretend that the inquiry was honest, and ask politely "how do you account for this and that and the other". This tends to make them at least go away ion search of more fertile ground, and doesn't alienate the openminded reader.

Michael Tobis said...
This comment has been removed by the author.
EliRabett said...

The Aral Sea is recovering, at least the northern end, which has been damned.

Dano said...

at least the northern end, which has been damned.

Indeed. My take is most of the water has been damned, esp by eutrophication and salinization.

Dano, you are falling into the trap.

I agree Michael, and in my view (YMMV, and this is your blog) the innocent passerby may find useful a pointing out of a possible strategy.

IME the innocent question of 'where do you get your facts' can lead into either no response, or a long competing recitation of "facts", whack-a-mole-like.

Just a thought.

Best,

D

Michael Tobis said...

Regarding the whack-=a-mole strategy, one has to try to deal with one topic at a time. It's always tempting to go after the whole foul mess, though.

What I did on this thread was to 1) point out that the subject had been changed and 2) go after a particularly weak argument that they made. This may be a good approach. It is important not to let the denialist attack blossom into a herd of moles.

Anyway it worked this time, though in retrospect I allowed myself to get more contentious than I ought. It seemed a strong enough response that they went away, although "Vange" may be of the drive-by school anyway.

Steve said...

One question only, in two parts, and on topic. You mention the picture displaying the thin atmosphere.

1) What is the volume of the atmosphere as compared to the total oceans [something for comparison]

2) What would be an appropriate way, in your opinion, to compare the scale difference between the examples you gave and the thin shell of atmosphere (volume from part 1) that we are affecting?

Michael Tobis said...

Good question. To part 1, roughly equal by volume, and here's a nice illustration.

To part 2, I appreciate the way you phrased it. As a first pass, you would compare the volume of a large shallow lake to the ocean easily enough. Let's take the familiar example of Lake Erie: 3 meters deep by 333 km by 100 km, I think is close enough. So (1000/3)*(3/1000) * 100 = 100 cubic km. The total volume of the ocean according to wikipedia is 1.3 billion cubic km, so we are looking at a factor of something on the order of 13 million.

That is a tiny fraction of the ocean and so our ability to utterly destroy a large shallow lake is indeed not analogous to our ability to totally transform the atmosphere.

But wait; how many people did it take to destroy the shallow lake? Say, perhaps, a million? Ten million? But to damage the atmosphere everybody on earth is a participant. So there are a thousand or even ten thousand times as many participants. Now the ratio is down to thirteen thousand, or even thirteen hundred.

Oh, and one more thing. It turns out the radiatively active long lived gases in the atmosphere (mostly CO2 by volume) are a small fraction of the total. To be specific, about 1 part in 3000.

And that is what we are disrupting.

So our factor somewhere in the range of 1300 to 13000 is overstated by a factor of about 3000, and what do you know, we are right in the ballpark.

Which doesn't strike me as a coincidence, though to be honest I didn't work it out in advance. It's no surprise because I already knew we were doing significant damage.

That's the whole point, right?

Thanks, though. Nice question.

Your turn; do the same calculation by mass rather than volume.

Steve said...

Thanks for the thoughtful reply.

From the link you provided, it looks like they're concerned with mass, by weight (with the atmosphere condensed) not really volume.

The numbers I found were anywhere from 14 to 51 trillion Km3 - which is a big range, and one of the reasons I asked. I'd like to get a more accurate number.

I suppose for various things you would want volume and for other purposes mass. I've been thinking about this since I heard Al repeatedly refer to our "thin, thin shell of atmosphere" which, regardless of anything else, seems hard to swallow.

I had a nagging guess that the volume of the atmosphere had to dwarf the volume of the water on the planet. I think this is a useful mental thumbnail to consider.

BTW, on other unrelated stories, I'm just as dismayed by vaccine/autism robots and creationists as you. It's indeed a scary culture. Maybe I'm just as ignorant as they are?? But I don't feel that way, but I guess one never realizes their own ignorance.

Michael Tobis said...

Volume of the atmosphere is ill-defined because it doesn't really have a top; just trails out into space.

Weight of the atmosphere is something I always forget. I remember sea level pressure is 14 psi, then convert to metric.

Similarly, volume of the ocean is 3/4 of the surface of the earth covered to a depth of 4 km. Weight is exactly a metric ton per cubic meter.

Of course, most people nowadays would be too lazy for even that much math, and tonight, frankly, I am too.

Wikipedia gives 1.4 × 10^21 kg for the ocean ; 5.1480×10^18 kg for the atmosphere. So there is 200 times as much water as air by mass.

AdamW said...

Could you not restrict the section of atmosphere we are disrupting to just the troposphere? Or maybe add in the stratosphere too if you want to bring in CFCs? Both of which are more definitive in height.

Incidentally, air pressure at sea level is a about around 1000hpa (1 atm ~= 1013hpa) which might be easier to remember as it's a 1:1 with mbs and the figures are on meteo pressure charts. It might also be easier to convert to units of use, as it's 100,000pa (or 100,000 n/m2).

I notice that Canada uses kPa which means that slp is ~ 100kPa. Which gives you the same thing.