Dear Mr. Levitt,
The complaint of tellurian warming is so large which solving it will require creative meditative from most disciplines. Economists have most to contribute to this effort, quite with courtesy to a question of how assorted means of putting a cost upon CO emissions competence shift human behavior. Some of a lines of meditative in your initial book, Freakonomics, could good have had a bearing upon this issue, if brought to bear upon a CO emissions problem. we have unequivocally most enjoyed as well as benefited from a growing collaborations between Geosciences as well as a Economics dialect here during a University of Chicago, as well as had hoped someday to have a wish of making your acquaintance. It is some-more in disappointment than anger which we am essay to we now.
I am addressing this to we rsther than than your journalist-coauthor because a single has become all as well in a habit of to tendentious screeds from media personalities (think Glenn Beck) with a forward disregard for a truth. However, if it has come to pass which we cant expect a William B. Ogden Distinguished Service Professor (and Clark Medalist to boot) during a top-rated dialect of a respected university to consider obviously as well as overtly with numbers, we have been indeed in a sad way.
By now there have been most minute dissections of all which is wrong with a treatment of meridian in Superfreakonomics , yet what has been mislaid amidst all which endless contention is how unequivocally facile it would have been to get this things right. The complaint wasnt indispensably which we talked to a wrong experts or talked to as well few of them. The complaint was which we failed to do a most facile meditative indispensable to see if what they were observant (or what we suspicion they were saying) in actuality made any sense. If we were stupid, it wouldnt be so bad to have messed up such facile reasoning, yet we dont by any means consider! we have been stupid. That creates a disaster to do a meditative all a some-more disappointing. we will take Nathan Myhrvolds explain about solar cells, which we quoted prominently in your book, as an example.
As quoted by you, Mr. Myhrvold claimed, in effect, which it was purposeless to try to compromise tellurian warming by office building solar cells, because they have been black as well as catch all a solar appetite which hits them, yet modify usually a little 12% to physical phenomenon whilst radiating a rest as heat, warming a planet. Now, maybe we were dazzled by Mr Myhrvolds brilliance, yet dont we try to learn a students to consider for themselves? Lets go through a mathematics step by step as well as see how it comes out. Its not hard.
Lets do a suspicion experiment of office building a solar form to generate a entire worlds benefaction physical phenomenon consumption, as well as see what a additional fullness of object by a form does to climate. First we need to find a physical phenomenon consumption. Just do a Google search upon World physical phenomenon expenditure as well as here we are:
Now, thats a total electric appetite used up during a year, as well as we can spin which in to a rate of appetite expenditure (measured in Watts, usually like a world was a single large light bulb) by dividing kilowatt hours by a series of hours in a year, as well as multiplying by 1000 to modify kilowatts in to watts. The answer is dual trillion Watts, in turn numbers. How most area of solar cells do we need to generate this? On average, about 200 Watts falls upon any block scale of Earths surface, yet we competence preferentially put your cells in sunnier, clearer places, so lets call it 250 Watts per block meter. With a 15% efficiency, which is middling for benefaction jot down a area w! e need i s
or 53,333 block kilometers. Thats a block 231 kilometers upon a side, or about a size of a single dungeon of a typical ubiquitous dissemination model grid box. If we put it upon a globe, it looks like this:
So already we should be beginning to consider which this is a pretty pardonable partial of a Earths surface, as well as maybe doubtful to have most of an outcome upon a overall engrossed sunlight. In fact, its usually 0.01% of a Earths surface. The numbers we used to do this calculation can all be found in Wikipedia, or even in a good paperbound World Almanac.
But we should go further, as well as demeanour during a tangible volume of additional solar appetite absorbed. As most reviewers of Superfreakonomics have noted, solar cells arent essentially black, yet thats not a categorical issue. For a sake of argument, lets usually pretence they catch all a object which falls upon them. In my business, we call which zero albedo (i.e. zero reflectivity). As most commentators additionally noted, a albedo of genuine solar cells is no reduce than materials like roofs which they have been often placed on, so which solar cells dont indispensably enlarge engrossed solar appetite during all. Lets omit that, though. After all, we competence wish to put your solar cells in a desert, as well as we competence try to cold a world by painting your roof white. The albedo of desert sand can additionally be found simply by doing a Google search upon Albedo Sahara Desert, for example. Heres what we get:
So, lets contend which sand has a 50% albedo. That means which any block scale of black solar dungeon a! bsorbs a n additional 125 Watts which otherwise would have been reflected by a sand (i.e. 50% of a 250 Watts per block scale of sunlight). Multiplying by a area of solar cell, we get 6.66 trillion Watts.
That 6.66 trillion Watts is a rubbish feverishness which is a byproduct of generating physical phenomenon by regulating solar cells. All means of generating physical phenomenon engage rubbish heat, as well as hoary fuels have been not an exception. A typical coal-fired appetite plant usually is around 33% efficient, so we would need to recover 6 trillion Watts of feverishness to bake a spark to make a 2 trillion Watts of electricity. That creates a rubbish feverishness of solar cells vs. spark basically a wash, as well as we could stop right there, yet lets go upon a practice in meditative with numbers anyway.
Wherever it comes from, rubbish feverishness is not usually taken in to account in tellurian meridian calculations for a facile reason which it is utterly pardonable in comparison to a feverishness trapped by a CO dioxide which is expelled when we bake hoary fuels to supply energy. For example, which 6 trillion Watts of rubbish feverishness from spark blazing would volume to usually 0.012 Watts per block scale of a Earths surface. Without even meditative unequivocally hard, we can realize which this is a little series compared to a heat-trapping outcome of CO2. As a ubiquitous indicate of reference, a additional feverishness trapped by CO2 during a indicate where youve burned sufficient spark to double a windy CO2 concentration is about 4 Watts per block scale of a Earths aspect over 300 times a outcome of a rubbish heat.
The 4 Watts per block scale statistic gives us an easy indicate of anxiety because it is available from any series of simply permitted sources, such as a IPCC Technical Summary or David Archers facile textbook which came out of a Global Warming for Poets core course. Another facile approach to learn a nullity of a rubbish feverishness outcome is to spin it! in to a feverishness shift regulating a standard meridian sensitivity of 1 grade C of warming for any 2 Watts per block scale of feverishness combined to a appetite bill of a world (this sensitivity factor additionally being straightforwardly available from sources like a ones we usually pointed out). That gives us a warming of 0.006 degrees C for a rubbish feverishness from spark burning, as well as most reduction for a incremental feverishness from switching to solar cells. It doesnt take a lot of meditative to realize which this is a pardonable series compared to a bulk of warming approaching from a doubling of CO2.
With usually a little some-more calculation, its probable to do a some-more precise as well as informative comparison. For coal-fired generation,each kilowatt-hour constructed formula in emissions of about a entertain kilogram of CO in to a ambience in a form of CO dioxide. For a 16.83 trillion kilowatt-hours of physical phenomenon constructed any year, we then would evacuate 4.2 trillion kilograms of carbon, i.e. 4.2 gigatonnes any year. Unlike energy, CO dioxide accumulates in a atmosphere, as well as builds up year after year. It is usually solemnly private by fullness in to a ocean, over hundreds to thousands of years. After a hundred years, 420 gigatonnes will have been emitted, as well as if half which remains in a ambience (remember, serious estimates sufficient to make a indicate here) a windy batch of CO2 CO will enlarge by 210 gigatonnes, or 30% of a pre-industrial windy batch of about 700 gigatonnes of carbon. To get a feverishness trapped by CO2 from which volume of increase, we need to reach all a approach behind in to middle-school math as well as make use of a awesome apparatus of logarithms; a series is
or 1.5 Watts per block meter. In alternative words, by a time a hundred years have passed, a feverishness trapped any year from a CO2 issued by regulating spark instead of solar appetite to furnish physical phenomenon is 125 times a outcome of a hoary fuel rubb! ish heat . And recollect which a incremental rubbish feverishness from switching to solar cells is even not as big than a hoary fuel rubbish heat. Whats more, because any flitting year sees some-more CO2 amass in a atmosphere, a feverishness trapping by CO2 continues to go up, whilst a outcome of a rubbish feverishness from a hoary fuels or solar cells indispensable to furnish a given volume of physical phenomenon stays fixed. Another approach of putting it is which a meridian outcome from a rubbish feverishness constructed by any kind of appetite plant is a one-off thing which we incur when we set up a plant, whereas a warming outcome of a CO2 constructed by hoary fuel plants continues to amass year after year. The warming outcome of a CO2 is a legacy which will go upon for most centuries after a spark has run out as well as a hull of a appetite plant have been moldering away.
Note which we dont essentially have to wait for a hundred years to see a benefit of switching to solar cells. The same mathematics shows which even during a finish of a unequivocally initial year of operation, a CO2 emissions prevented by a solar form would have trapped 0.017 Watts per block scale if expelled in to a atmosphere. So, during a finish of a initial year we already come out ahead even if we slight a rubbish feverishness which would have been issued by blazing hoary fuels instead.
So, a bottom line here is which a heat-trapping outcome of CO2 is a 800-pound gorilla in meridian change. In comparison, rubbish feverishness is a pardonable contribution to tellurian warming either a rubbish feverishness comes from solar cells or from hoary fuels. Moreover, a incremental rubbish feverishness from switching from spark to solar is an even some-more pardonable number, even if we allow for a little alleviation in a potency of coal-fired appetite plants as well as omit any probable improvements in a potency of solar cells. So: trivial,trivial trivial. Simple, isnt it?
By a way, a emanate of either rubbish feverish! ness is an vicious factor in tellurian warming is a single of a questions most ordinarily asked by students who have been initial learning about appetite budgets as well as meridian change. So, there have been no necessity of places where we can learn about this sort of thing. For example, a facile Google search upon a difference Global Warming Waste Heat turns up several pages of correct references explaining a emanate in facile conditions for beginners. Including this essay from Wikipedia:
A some-more substantive (though in a finish roughly similarly trivial) emanate is a CO issued in a march of production solar cells, yet which is not a matter during palm here. The indicate here is which unequivocally facile arithmetic, which we could not be bothered to do, would have been sufficient to discuss it we which a explain which a blackness of solar cells creates solar appetite purposeless is complete as well as complete nonsense. we dont consider we would have accepted such laziness as well as sloppiness in a tenure paper from a single of your students, so because do we accept it from yourself? What does a disaster to do such facile meditative with numbers contend about a border to which anything we write can be trusted? How do we consider it reflects upon a contention of economics when a part of of which contention somebody who which contention seems to esteem rarely publicly as well as noisily shows which he cannot be bothered to do facile mathematics as well as facile credentials reading? Not even for a theme of such peerless importance as tellurian warming.
And its not as if a black solar dungeon gaffe was a usually bit of educational malpractice in your book: between alternative things, a display of insect poison geoengineering as a submissive as well as cheap quick fix for tellurian warmi! ng aband oned a good understanding of permitted as well as straightforwardly available element upon a serious risks involved, as Gavin remarkable in his recent post. The fault here is not which we dared to advocate geoengineering as a solution. There is a broad spectrum of perspective between scientists about a volume of insect poison geoengineering investigate which is justified, yet unequivocally few scientists consider of it as anything yet a unfortunate last-ditch attempt, or during best a strategy to be used in extreme moderation as partial of a basket of strategies dominated by emissions reductions. You due it to your readers to benefaction a satisfactory picture of a consequences of geoengineering, yet chose not to do so.
May we indicate which if we should occur to need a little friendly help subsequent time we take upon a subject of meridian change, or would like to have a chat about because insect poison geoengineering competence not be a cure-all, or usually need a vicious yet informed opponent to rebound ideas off of, we dont have to go unequivocally far. For example
But given a approach Superfreakonomics mangled Ken Caldeiras rsther than nuanced views upon geoengineering, lets keep it off a record, eh?
Your colleague,
Raymond T. Pierrehumbert
Louis Block Professor in a Geophysical Sciences
The University of Chicago
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