Gidon Eshel | Rethinking the American Diet || Radcliffe Institute


– All right. Thanks so much for coming. Thanks for this great
introduction, but let’s do it systematically, OK? That’s my family. And when I told Laura,
who you see in the middle, that I got this
phone call from Judy, she said, oh, we
have a big problem. And I thought, she’s nixing
the idea of my coming here. She said, you may have to
buy a button-down shirt, and wear it too. So this is it. You’re looking at it. I owe her big. So the fellow Fellows in whose
company I spent this year are truly amazing. I really don’t think I’ve
ever been in the company– such a rarefied company, so
that’s really quite an honor. And, of course, all of this
mountain of applications that we created, somebody
had to read that stuff. And such a valiant act
of selflessness cannot go unrecognized. So I really thank Liz,
Judy, and everybody at Radcliffe for making
such a great place to work. Similarly, in the Center
for the Environment, the two co-directors made
me at home pretty much from the beginning. And finally, my collaborators
at the Chan School of Public Health. So I really thank all of
them, and you, for coming. And let’s get going. Oh, sorry, sorry, sorry. Once I hit the deck, I got
acquainted with these two Harvard College pals. And we meet once a week, they
tell me what needs to be done, then they tell me how
they are doing it, and then we meet
the following week and they show me
how it was done. So, I mean, I taught at
the University of Chicago for almost a decade. I’ve never seen
anything like these two, so I feel very fortunate. So the plan for
today is as follows. I’ll start by
introducing the problem heuristically, the problem
that I’m interested in. I’ll highlight some
geophysical and societal costs of agriculture that
motivate this work. Then I’ll take you
on a short personal aside that kind of
augments a little bit the story that Judy
told a few minutes ago. And then I’ll share
key results that will be the crux of the talk,
and some concluding musings. And then it’ll be your turn. So that’s the idea. Now, what is rethinking
the American diet? So here are two meals that
I would be likely to eat, kind of betraying my
Middle Eastern origin. And here is
something a bit more, let’s say, American or European. The essence of my work, and
the essence of the talk that I prepared today, is to show
you how if you know it or you don’t. When you make a choice
between one of those meals, or between any two competing
ingredients, or any two competing meals,
you’re making, really, a whole cascade of
important choices that you may or may
not be aware of. So for example,
in that choice you determine very much the
nature of rural communities. How they are structured, how
densely populated they are, et cetera. You certainly– those
choices have a lot to say about greenhouse
gas emissions that are done on your behalf. And you also get to take sides
in things that we don’t often think about, that are kind
of like societal strifes. So here’s an example. This article discusses
this long picket line that farmers in the Klamath
Basin in Oregon formed, because for the
first time, they were told that the US
is actually going to honor its treaty
with the Klamath tribe, and share the water
between alfalfa growers– who got 100% of the
water up until now– and the Klamath tribe. And they didn’t like it one bit. You also get to make important
contributions, large or small, to water pollution on
land, like creeks, ponds, even as far up as
the Great Lakes. Lake Erie, every
10 years it seems that Lake Erie– Lake Erie’s
obituary appears in The New York Times, and then it
comes back to life ever so fleetingly. That has a lot to
do with choices such as choosing between
either of these or this. And it has a coastal
oceanic counterpart, which seems a lot
more devastating, but it happens with
great regularity every summer the entire northern
part of the Gulf of Mexico is dead to the world. But dead, I mean literally
dead, like that dead. And that is because
of dietary choices, as I’ll describe later. And finally, you also get
to decide, if by the time you are 82, you’re going to
be able– like this pal, right here, at 82– to ride
across Canada, from Nova Scotia to British
Columbia, or you will be warming the
rocking chair on the porch. Those alternatives also have
a lot to do with the choices that you’re making. So let’s look a
little bit at how geophysics and food and
dietary choices are related. This is actually a
farm, the closest thing to heaven on earth. It’s right near my house. And this is what it looks like. When I bike from
my home to work, this is the kind of
landscape that I traverse. But, of course, not all
agricultural communities are quite that beautiful. So here’s an
interesting example. There’s a million
dimension to this problem, and I don’t have time
to describe them all. I’ll just cherry pick a few, OK? So one of them is this
burgeoning field of geophysics called hydrobio-geochemistry. So it is what it sounds like. It’s concatenating four
different sciences into one. Now, geochemistry– of course,
geology and chemistry– that concatenation happened
half a century ago. So now we think of
it as a discipline. But now a lot of the
reactions that it addresses are mediated by life. So naturally, we appended
bio to that as a prefix. And finally, all of that is
done as aqueous chemistry, so hydrology is the
next obvious addition. So hydrobio-geochemistry
is actually a thing. And it determines the confluence
of hydrology, biology, geochemistry of the
Earth’s surface. Now, farmers do
a bunch of things to the surface to have
an impact on the rate at which hydrobio-geochemical
processes occur. So first of all, they fertilize. That just adds a larger source. Normally, the atmosphere,
which is 80% nitrogen, just deposits roughly half dry,
half wet nitrogen on the land, or on the ocean, on the surface. And that’s what the biosphere
has to contend with. Fertilization makes
that that much larger. Tilling and so on
aerate the soil, which is very important because
then the percolation of meteoric water in–
meteoric water means rain, or snow, any kind
of precipitation. So aeration of
the soil basically makes the percolation
of this water that much faster
into the subsurface. Now, they also do
something that’s called tiling, not
tilling– they do that, and that belongs here–
but they do tiling. It’s a little known
fact, but basically most agricultural provinces,
such as the Midwest, have about six feet
below the surface– it used to be literally tiles. It isn’t tiles anymore, it’s
just perforated plastic pipes. But the purpose of
that is basically to keep root systems
from being submerged. That’s the kiss of
death for crops. So, whereas it is well-known
that farmers, let’s say, pray for rain– but the
minute rain arrives, they become unhappy,
because now they see the root systems
gradually becoming submerged. That’s where tiling
comes in, and it totally alters– as I will show you
momentarily– the hydrology. And then they also degrade, by
chemical and physical means, the soil biota. And soil biota are extremely
important in taking any kind of reactive compound
brought down from the surface, and processing it
and rendering it benign, environmentally benign. So when you degrade soil
biota, you basically diminish the ecosystem’s
ability to render those otherwise dangerous–
or potentially dangerous– compounds harmless. So all of this,
like I said, happens in an aqueous environment. So this is, over
here, discharge, and over here you have
days after a rain event. Zero is when the rain occurs. And what we’re seeing here are
two– the discharge response to rain of two different,
but otherwise very similar in composition,
small drainage basins. One is highly
impervious, so it’s like, you can think
about it like pavement. But tiling is very much
taking a natural surface and rendering it
highly impervious. And the other is natural. And you see that what happens
is that the modified one, the modified basin, has an
extremely rapid response. And it is equally rapidly
decaying once the rain is over. So you can now picture on
the natural environment, the water comes down
in a stately manner, it is kind of assimilated
into the soil, and the soil biota
begins to handle it, et cetera, and gradually
percolates down. And over maybe a
week, order a week, it makes its way downstream. Conversely, in this case, the
highly-modified one, 12 hours and it’s gone. So because soil biota
have a limiting kinetics– in other words,
there’s only that much that they can handle
per unit time– the amount of time that the
aqueous solutions are resident over in that soil is extremely
important to the soil biota’s ability to process that. Well, if you hasten
that to such an extent, you basically make that
soil biota really unable to handle it, or
able very partially. And the end result,
you can see right here, this is the mouth of the
Mississippi right here, and this is the northern
part of the Gulf of Mexico. The contours right here–
you see right here, that’s bottom water dissolved
oxygen in milligrams per liter. And these are the
numerical values. So the point is,
natural upper-level sea waters will have, let’s say,
order 10 to 100 in those units. So these waters are
severely depleted in oxygen. Essentially,
just like if you leave a head of lettuce in the
fridge and forget about it. It’ll decay, decompose,
and it will consume oxygen because decomposition is the
opposite of photosynthesis, so it’ll consume oxygen. In the fridge there is
no limitation on oxygen, but in the bottom waters
of the Gulf of Mexico there’s only that much
oxygen to go around. If you invest all that oxygen
in decomposing dead algae, you have none left for the fish. And that’s the result, are those
dead fish that we saw earlier. Another aspect of the dietary
choices described earlier, really is impacting, very
strongly, the radiative balance of the Earth’s surface. It’s a zeroth order attribute of
the Earth, the degree to which it receives solar
radiation from the star it orbits– that’s the sun– and
then gets rid of it to space. That’s a fundamental attribute
of any particular planet, and ours is strongly modified
by the presence of agriculture. For example, since we are
in North America right now, let’s focus on North America. What we are looking
at is MODIS data. MODIS is a piece of hardware
that NASA put in orbit, and it has cameras
looking down on Earth in various wavelengths. And in this particular
case, you see the degree to which the vegetation–
anthropogenic vegetation– changes modified the
Earth’s reflectivity. So all of the eastern
part of the US increased between 2% to 5%. Now, that sounds, perhaps, not
that dramatic, but remember that the entire planetary mean
of that is something like 30%. 2% to 5% is a very
large perturbation. And sure enough, if you
ask what does it correspond to– the fact that I took
all of this part of the US, devoted it to crops,
and thereby made it that much more reflective
to solar radiation– what does that do? Well, here you see it in terms
of the net downward surface radiation, and you see
that that part is somewhere in the range of 2 to
10 watts per meter squared– that’s the currency of
global warming, watts per meter squared. So between 2 and 10 watts
per meter squared less are warming the
eastern part of the US, exclusively because
of food production. And that is something you
can– I know that most of you don’t think in watts
per meter squared, so let me help you here. The entire anthropogenic
perturbation to the planetary heat balance
that we have created by, in the longwave part
of the spectrum, so-called global warming
is one and a half watts per meter squared. This is significantly
larger than that, locally. That one and a half applies
to the planetary mean, this only applies locally. But still, these are
large, large provinces. Another one is
greenhouse gas emissions. So in the US, agriculture is
about 10% of all emissions. Putting food on our
tables is about 25%. So, in other words, that
9%, 10% is roughly doubled, or a little more than
that with all the things that happen post-production. Packaging, shipping,
cooking, all of that stuff. So that’s not
enormously important, but every little bit helps. Now, agriculture is, of
course, a huge land user. So, again, let’s
focus on the US. In the US, 47% of the
total national surface area is devoted to food production. 48%. And it’s broken down. In terms of crops,
corn and hay dominate, and other crops kind
of trail this bit to the tune of about 19% of
the natural surface area. And pasture range
and forested graze land, that’s a third of the
entire national surface area. And these two together work
out to just under half. Now, just to give you a
yardstick again, all the things that we actually eat
that are enumerated here, that’s under half a percent. That’s this green
bar right here. So how amazing is that, that all
the stuff that we actually eat is like a minuscule fraction
of the total, but all of this is basically entirely
devoted to animals? Of course, we eat those
animals, ultimately, but as I’ll show
you momentarily, it’s not a particularly
efficient metabolic pathway. Now, it’s important because
the environmental costs of diets scale roughly
as the land surface used. So one example is biodiversity. So the European, especially
in the Netherlands, they care a lot about
their songbirds, I guess. And they spent a
lot of money trying to preserve on farm songbirds,
only to realize this paper was supposed to be the
triumphant enumeration of tax money well-spent in
saving those birds. Instead, they concluded that
all that money, and still 50% to 90% of all
species are steadily declining despite all
of that hand-holding. Back in North America,
it’s about 100,000 coyotes that are killed in
the name of sparing ranchers the inconvenience
called coyotes. 100,000 a year. I mean, try to picture
100,000 dead German Shepherds. That’s what we’re talking about. It’s not a pretty sight. Now, this piece that
aired on NPR in 2014 put forth the statistics that
ranchers all but wiped out the Mexican Gray Wolf, the
most endangered wolf species in the world, in the US. And, of course, that
is to protect ranching. Now, one thing that the beef
industry– the beef industry is employing exactly
the same methodology that ExxonMobil employs, and
that The Heartland Institute, and all of those– this kind of
a front series of organizations that are in the business of
spewing this information. The beef industry is
very much in that milieu, and they always tell you,
oh, but graze land out west is a great means by which
we further biodiversity. Really? Let’s look at that a
little bit critically. So here is a paper
from PNAS in 2011 that scaled natural range-land
species abundance to be one. And then they progress down
the gradient of increasing human intervention. And what did they see? By the time you get to
moderately used or intensively used, you lost about a
half of all the species. By the time you got to this,
which they unfortunately named man-made grasslands, you
lost 70% of all the species. That doesn’t look,
to me, like grazing is a great means by which
we will further biodiversity in the semi-arid west. And so much so,
that this paper that came out just a few
weeks ago– this guy is the king of something
that ecologists called [? exclusia, ?] which is
basically take a landscape, exclude from it all the
ungulates, and wait 25 years, come back and write a
paper about what happened. And that’s what they do,
paper after paper after paper. These guys better
enjoy longevity, or else their number
of papers is limited. So they just concluded,
very clearly, that biodiversity
conservation key is reducing meat consumption. Therefore, it follows that
eating land-cheap food is one of the callings of our time. And that is added to
non-geophysical issues raised by food production. For example– this is from
the Times just the other day, a couple weeks
ago– showing how, in the Salinas
Valley in California, just southeast of
Santa Cruz, you have all of this
production of broccoli, and arugula, and all of
the great green stuff everywhere except on
the table of those who actually farm these fields. They can’t afford that. So that said, that’s not really
my department, I do geophysics. But I’m certainly
acutely aware of and mindful of these aspects. Now it’s time to define my work. This is, by the way, our forest. The backyard of our house. And here I am
beginning to prepare firewood for the winter. I come from geophysics,
that’s where I’m comfortable, and this is what I know best. Climate, meteorology, land
atmosphere interactions. This I wouldn’t call myself
an expert on, but I use it. That’s my comfort zone. Now, there’s the
societal issues. I will definitely not
manufacture new information, new knowledge, in this. I will just be aware
of what’s going on. Agricultural tax
and water policies, farm wages and conditions,
immigration, et cetera. Everything that affects farming. Crop science is
extremely important. What can be– I am condensing
crop sizes to a simple, to question a synopsis–
what can be grown where, and at what cost? Hugely important for my work. Nutritional science. Again, a whole body of
centuries-old discipline that I condense into
what extends or shortens healthy lives. Culture, cuisines,
preferences, all of that stuff that impact our dietary choices. So my work really conflates
all of those things, and the way it does
that is formally, not by hand-waving,
but formally. This is the objective. Devise diets and
agricultural policies that simultaneously minimize
environmental impacts and maximize health outcomes. That’s the idea. And the actual– when
I say a solution, I mean a vector,
comprising x1 grams of eggplant, x2 grams of
lentils, blah blah blah, like that. All of those masses
of individual foods that they can only
be positive and real, so that’s what this is saying. Finding a solution like
that, that’s what I do. But it is subject
to these conditions. It must minimize
the cost function. This is the linear term,
which is very simple. It’s just– suppose my cost
is greenhouse gas emissions. So eggplant emits that much,
and squash emits that much. I sum them up, and that’s
this term, right here. Some other things are better
described quadratically, and this is what is shown here. It’s not really super important. The point is that it’s
an optimization problem, minimizing the cost,
however defined. And you can add to
this– I mean, typically in a real problem, you will have
numerous terms, not just one. You will have
multiple linear terms and numerous quadratic terms
in the most general cases. This basically
says that this diet must satisfy a series
of constraints, as I will show you momentarily. And, of course, everything has
to be positive semi-definite. You can’t have a negative
amount of pork, let’s say. So let me give you kind of
a heuristic explanation, in the simplest possible
way, what’s going on. Suppose I want to devise a diet
that cares about two things. Not exceeding that amount of
fat, so this is maximum fat, and this axis here is
grams of fat in the diet. And not going below
minimum amount of protein, shown by the
vertical dashed line. As long as I’m in this
quadrant, all is well. I have more protein
than the minimum, I have less fat
than the maximum. I’m good to go. Suppose I’m trying to
do that with two foods. Let’s start with tofu,
always a good idea. And what is shown
right here, this is the arrow of
increasing mass of tofu. But because tofu has
more protein than fat, it’s kind of oblique. It adds little fat, while
adding a whole lot of protein. However, there is
a third dimension to this problem,
kind of emanating from the board toward you. And that is mass. You can’t expect the gal to
sit down and put away two pounds of tofu in one sitting. So think about this
as just lurking above this surface,
the glass ceiling that Hillary almost shattered. Now, we realize that by the
time we hit the ceiling, we’re still short of
the feasible region. In other words, we maxed out on
the amount of tofu permitted, and we are not in the
feasible space yet. Not good, not good. But avocados to the rescue. So here we are, we
add, now, avocado. We back off a little
bit, so you see that this arrow is a
little shorter than this, so as to go down relative
to the glass ceiling and allow the avocados
some mass to work with. And just by simple kind of
high school vector addition, we get to, with the
ample amount of avocado, we get inside the
feasible region. But you see that
I can be anywhere between this line and this. So the problem is
underdetermined. The indeterminacy
is exactly my chance to minimize, or maximize,
whatever the hell I want. So for example, you
see the shading, as this is showing right
here, is simply monetary cost. Obviously, the more tofu I
buy, the more I’ll pay, right? So the shading gets darker
as you go to the upper right. Now, as soon as we
added avocado, now the cost field is bent
that way, because now it’s avocado that is
calling the shots. But it’s still doing
the same thing. And if I were to simply
minimize monetary costs, this will be my
solution right here. There is a beautiful
theorem that tells us the solution is
always on one of the vertices. So we need not look
in the entire space, we only need to go vertex after
vertex, and we’re good to go. Now, on the other hand,
if monetary cost was not the only thing, but
suppose, for example, we wanted to maximize intake
of some protective fatty acid of which avocado
provides a whole lot of. Then, we would want to have
as much avocado as possible. So we will actually be here. Because we can’t go
any further than this, because then we will
have too much fat. But we can be there, and
that will maximize the intake of that protective fatty acid. That’s the– in a nutshell–
a highly truncated, simplified version of the
kind of optimization problems that I’m discussing. Now, here is the personal bit. And I get asked this a
million times a week, now is a good time to answer. I always shrug my
shoulders, but today I think I’m going to answer it. So let me show you this. This is my father, right there. And he was a seaman. I mean, when I was
born, he was a mate, and then he became a captain. And here he is leading
our ship into the Corinth Canal separating Greece
proper from the Peloponnese. And when he met my mother
and they became an item, and shortly thereafter, my
sister and I came along, we kept on sailing. And this is how I
grew up, on ships. I never went to
school to speak of, except whatever my mother kind
of squeezed in between storms. And that’s what it looked like. Now, I had this particular
spot on the right side of the bridge. On ships they call it
the starboard side. And that’s where I
would sit and worry if we’re going to make it
up the next wave or not. It was a great
childhood, and it took us to all kinds of nice places. This is Western Africa. We spent the better
part of a year there, and met somebody
smaller than us, which was uncharacteristic. But when my sister
was a teen and she had to go to the
military, I really didn’t want to continue
doing that by myself, just with my parents. And so both my parents
were born in Kibbutzim, and they continued sailing. I basically struck it on my own. I was 13, and I went to
live in this kibbutz, and that’s when I
first met cattle. And it was love at
first sight, and I still very much love cows, very much. So this was dairy. And, you see, in ’76 I
went to the military, then I biked around the
world for several years. All kinds of good stuff. But then I came back
to Israel in ’82. There was a war, that’s
what brought me there, to reserve service. But then after that, I stayed. And I said, what is
it that I want to do? Really, cattle is
what I love best. Let me raise cattle. So the mothers were living
in the Golan Heights, you see right here. They would give birth to calves,
they were all synchronized, all the mothers are
synchronized so it’s based on the availability of grass. So they would all give birth
to a calf, sometimes two, between late September
and early November, when the grass is actually green and
not this bleak yellow that it now is. And then they would
be brought over here to this place
called [INAUDIBLE], and that’s where they would
gain about a kilogram, sometimes a kilogram and a half
per day eating like that. During that time, I
availed myself of something that Israel, because of
its socialist past, had, which was a free– you can
think about this, essentially, like an undergraduate major
from Cornell in animal science. But it’s not academic. It’s meant for herd
managers, and that is what I suppose I was at that time. And I started and
graduated in this– it kind of looks like
a kibbutz, really, but it’s sort of a
pseudo-academic place. And it was extremely rigorous
and very, very wonderful. And finally, as Judy said, then
I switched to math and physics, I liked it, et cetera. And then I started the
Ph.D. This guy, Mark Cane, is my thesis advisor. He’s a professor of
applied math at Columbia, and now a good friend. So here is the answer. That’s the end of the aside. So how do you get there? Well, I think that maybe
early life dominated by ocean, atmosphere, and cattle. Having no K-12 schooling
always helps, I think. And so basically if
you learn anything, it’s not because your
teachers nag you, but it’s because
you saw something and you want to understand
what the heck is going on. That’s a very good motivation,
at least in my experience. And then once I stopped being
a bum and became serious, I enjoyed really
superb training, both courtesy of the
Israeli Ministry of Ag, and then in geophysics
with Mark Cane. And then I was a
post-doc, actually, across the common at
the Department of Earth and Planetary Phys–
then, it was called Earth and Planetary Physics. So it sort of makes
sense, I don’t know. If it doesn’t to you,
oh well, what can I say. Let’s do some homework here, OK? So this is a paper
in which we took the mean American
diet, which comprised– it has 3,800 kilocalories
per person, per day. That much from plant, and
all the rest is from animals. And we ask, what happens
if those calories, about 1,000 calories a
day from animal sources, what if it obeys
a certain pattern? For example, lacto-ovo
vegetarian, or purely red meat diet, or only
poultry, et cetera. The diets ended up
stacking up like this. Vegan was the least
greenhouse gas intensive, red meat was the most. MAD is– I’m very
proud of this– it’s the mean American diet. Very aptly acronym. And this was taken up by
pretty much every news outlet in existence. It was my first introduction
to this sort of– the mad house that science coverage
in the media is. But this is the upshot. If you take two Americans eating
the same number of calories and the same quality of diet,
but one only from plants, and the other like the
mean American diet, the difference between
those two is 1,500 kilograms of CO2 emitted per person,
per day– per year, excuse me. Now, being that
each one of us now is responsible for 21
metric tons per year, that’s 7% of the total that
can be eliminated by switching from the MAD to
plant-based diet, and that’s maybe why it caught
the attention of those media outlets. If you recall, that
7% is the lion’s share of what I showed
you earlier, the 9%. Remember the 9%? It’s this. This. So almost all of
it– let me speed this up a little bit–
almost all of this can actually be eliminated
by that dietary transition. Well, that was
pretty interesting. But then I realized,
well, I mean, if you’re looking at
something that’s, at most, 9%, that’s not really
that interesting. Let’s look at something
that actually dominates. And that is land use, over
here, and reactive nitrogen. NR is reactive nitrogen. Think
about this as contributions to water pollution. So here, this is something
called a Monte Carlo solution, which means you kind of
randomly envision people eating in various
idiosyncratic ways. And there are 2,000 people
eating the mixed diets, like the mean American
diet, and 2,000 people eating plant-based diets. Never mind the
difference between those, that’s optimization
or no optimization. It’s not really
supremely important. What is important is that we
devise 4,000 diets, half mixed, half pure plant. And we see, now, the difference
in terms of– over here, in the vertical– the
contribution to water pollution, and over
here, the contribution to demand for land, cropland. And we see the national scale
difference between those two. And by the way, there is nothing
in the way the problem is posed that will make these clouds,
and these clouds, mutually exclusive, non-overlapping. They could have overlap
if they so chose, but they chose not to. And that is because of the
stark, stark difference in land consumption
and in contributions to water pollution. So here’s the upshot. In terms of land,
you– excuse me, in terms of, yes, land, which
is this distance right here– you save something
like 130 million acres. National cropland
is just over 400. So that’s somewhere
between a quarter and a third of the total,
is saved by these choices. Now, in terms of contributions
to water pollution, you save 7 million metric tons
out of a total national of 11. Again, a very
significant difference. Now, let me speed
up here, because we don’t have that much time left. So let me just introduce you to
this guy, who I’ve been working with for a number of years now. It’s really an honor, almost
comparable to the honor that I feel being part
of the Radcliffe crew, but let me take you to the paper
that we’re about to submit, and I’ll wrap this up because
I am running out of time. So if you think switching from
whatever you’re eating now to plants is very hard,
this calculation asks, what happens if we
only replace beef? Beef contributes only about
65 grams per person, per day. That’s it. But it claims, depending
on the resource that you’re looking at, 80%
or 90% of the total national. So it contributes
almost nothing, and it uses almost everything. So for example, here, if
you just switch from beef to poultry, this is the
amount of concentrated feed and processed
roughage and pasture that are going into beef. This we treat as entirely free. So not contributing anything,
because chickens can’t graze, they are monogastric. So this is just free. And these two, if you reallocate
them to producing poultry, you will be able to increase
the output calories five-fold. 520% more calories
will be available if you just made that simple
switch from beef to poultry. And how many– check
this out– how many more Americans will be fully
sustained on that addition? 116 million out of a
320 million nation. Now, this is in energy. What about in protein? You will have four-fold
more output protein in this substitution. Look at how much
smaller the losses are. This red is the loss in
the beef route, this one. This is the lost protein
in the poultry route. And it’s, of course,
dramatically smaller. And it will add 140 million
additional Americans. When you look at results
like that, you say, really? You have to eat beef, no matter
those 140 additional million Americans that could
have been sustained on the same resources,
just because you think their beef is indispensable? That just doesn’t make sense. This paper refutes a commonly
repeated, but never correct, assertion that grass-fed
beef is somehow superior. I will skip that. And finally, this paper is now
working its way through review. The way we put it, nature
has not yet rejected it. So this is what we’re saying. We’re asking, OK, people,
you want your beef, fine. You want sustainable beef,
how much can we have? But, of course, what
is sustainable beef? No two Jane and John
will define it similarly, and I don’t claim
that our definition is by no means unique
or definitive, but here’s how we defined it. We said, there are two
things that beef currently eat that really have
no alternative use. And that is industrial
by-product, and pasture. No other– well, I
mean, lamb can graze, but that’s a minuscule amount. Forget lamb. So but other than
lamb, it’s cattle. So fine, let’s allocate the
entire pastureland currently used for beef, still
for beef, and all the by-products– you know
what I mean by by-products? For example, you squeeze
citrus for orange juice, the peel that’s left is very
high-quality cattle feed. So that’s an
industrial by-product. Mills, you make flour, it’s
the results– well, other than the flour, the
weakling, all the other is very high-quality cattle feed. So we allocate all the
by-products currently used for beef, still for beef,
and that’s shown right here. I’ll explain this in a minute. And increasing fraction of the
total current pastureland used. So this left-hand
means no grazing at all, only by-products. This means the full 670
million acres currently grazed by beef, still grazed by beef. And this is the percent
of today’s beef supply we can have with
those conditions. By-products alone
only give us something under 5%, almost nothing. But then when you start
adding pastureland, and you get to some
non-vanishingly small amount. By the time you get
to, let’s say, half, you get to– over here,
it’s somewhere like 35%– if you go from half of the
pastureland to full– remember, this is a vast area– going from
half to full is an enormously large area. 300 million acres of land. You only add– you only go
from 35% to 39%, that’s it. So it really seems like, if
in a sensible kind of resource allocation, you
will say, you know what, let me be
somewhere around here, claim the prime
pastureland for beef, fine. Let’s do that. But let’s not eke out every
last morsel of pasture at great environmental cost. For example, to riparian
buffers out west, or whatever. All the things that grazing
cattle does so much damage to. And you get oodles
more of nutrients. For example, right here, this
is alternative protein delivery. So for example, if you take
the 93 million acres of fine, high-quality cropland. Forget pastureland, that
we gave to the beef. But only high-quality
cropland that is currently used for feed for beef. And you plant in it, let’s
say, wheat, or spelt. How much more
protein will you get? Well, you will get
somewhere around nine times the supply of protein
beef currently delivers. Nine times. And what about nutrition? Let’s skip– this is the
environmental savings, and they are enormous. But let’s look– I don’t
know, let’s pick one. Soluble fiber. Look at this. What this means, for
example, is if I took those 93 million acres, and planted
them soybeans end-to-end, I will have gotten for each
one of us four and a half times the additional soluble fiber
than the entire soluble fiber delivery by your entire diet. That’s what it means, and
it goes on and on in terms of protective nutrients. I don’t want to
beat a dead horse, so let’s just get to the crux
of it and I’ll let you go. So here we go. Now I’m going to do something
the scientists do not do, and that is I’m
actually going to read. Eating is a personal,
cultural, culinary, social act. That we all know. We also know that it determines
your health-span as powerfully as genetics, or
exercise, or whatever. My work adds a
dimension to this, showing that in making
dietary choices, you get to tip the scale of
environmental, social, and political contests,
that right now, good luck if you think we
can tip any of those scales. For example, who wins? A hay farmer enabling growing
Chinese panache for beef– that’s an allusion to
the Klamath Basin– or salmon that depend on
these contested waters, and the native populations
that depend on them? Who wins? A Mississippi shrimper,
or the Iowa farmer who’s nitrogen-rich
effluent kills her catch? It’s our choice. Is what’s on your plate
furthering your health, or that of Archer Daniels? Again, that’s our choice. Importantly, health,
environmental, and societal considerations often,
but not always, lead in similar directions. It gets hairy, I’ll
grant you that. All right, thanks much.

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