This course introduces the academic approach of Sustainability and explores how today’s human societies can endure in the face of global change, ecosystem degradation and resource limitations. The course focuses on key knowledge areas of sustainability theory and practice, including population, ecosystems, global change, energy, agriculture, water, environmental economics and policy, ethics, and cultural history. This subject is of vital importance, seeking as it does to uncover the principles of the long-term welfare of all the peoples of the planet. As sustainability is a cross-disciplinary field of study, this foundation requires intellectual breadth: as I describe it in the class text, understanding our motivations requires the humanities, measuring the challenges of sustainability requires knowledge of the sciences (both natural and social), and building solutions requires technical insight into systems (such as provided by engineering, planning, and management).
Food Miles
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来自 University of Illinois at Urbana-Champaign 的课程
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从本节课中
Measuring Sustainability
In this module, we will examine what tools are available to measure sustainability. Finally, I will make some predictions on global sustainability for the 21st century, based on the models we have spoken about in this course and the trends that have been observed in the early part of this century.
与讲师见面
Dr. Jonathan TomkinAssociate Director
School of Earth, Society and Environment
I'm Jonathan Thomkin from the University of Illinois.
We've been speaking about how to measure individuals impact on the environment, and
this would logically lead us to think about what our own actions do.
In this lecture, I want to show how difficult it can be for us as individuals
to correctly assess what our impacts are. And I'm going to use the example of food
miles. Food miles quantify the distance food
travels from production to the consumer. Of course if you're not in the US, it
could be in the kilometers of course, but I'm going to refer to it as food miles for
this course. If food comes a long way, then we could
infer that a lot of fossil fuels were needed to transport it.
Since most of our transport systems rely on fossil fuels.
Since climate change is such a large concern, this would suggest that food
miles could be a measure of how unsustainable a food source is.
Possibly as a consequence we're often asked to buy local.
Now buying local food might have be done, might be done for many reasons.
For example local food might be fresher and so taste better, or maybe we'd like to
try and support the local community in some way.
Although of course every community is local to someone.
Here, we'll concentrate on the potential benefits to the environment that list
transport would bring. Let's consider the food miles that go into
a fruit salad. If we make our fruit salad from bananas,
apples, and honey, and we're making it say, in Chicago, we can measure the
distance from which the fruit comes from, and the honey comes from, and add that up
to determine the food miles of our fruit salad.
For this example. Apples often come from Washington state.
And bananas come from as far a field as Costa Rica.
The honey might be grown locally. If we add up these sort of miles, we find
that the travel distance is approximately two thousand miles for the apples, two and
a half thousand miles for the bananas and about a hundred sixty miles for the honey.
We could try to just then average the miles of each of these ingredients, but we
probably don't use equal amounts. If the recipe called for two pounds of
apple, two pounds of bananas and let's say, a quarter pound of honey, we could
then weight the different food stuffs to determine the average.
And in this cause, it would be just over 2,000 food miles per pound of fruit salad.
So we can use a calculation like this to try and determine our food mile impact if
you like. It turns out that this fruit salad is
pretty typical of foodstuffs that come in to Chicago.
Another study found that 1,500 food miles is typical for foods that come to Chicago
and are bought by consumers. So we might therefore conclude that the
smaller the food miles the lower the impact on the environment and so perhaps
we should source our fruit salad from more local ingredients.
The problem with this approach is that the transportation of the food is only a minor
part of the carbon footprint. The largest part at around 85% is the
production of the food. So we think about things like fertilizer
or diesel for the tractor. What's more, the wholesale transport of
food, which is what food miles measures, is less than half of the transport carbon
dioxide cost of food. On average driving to the store is a
bigger part of a carbon footprint of a foodstuff than the transport of that
foodstuff, in some cases from other continents, to that store.
And in fact the actual analysis is even worse than this.
There's probably a reason why that food is grown somewhere far away.
We grow apples in Washington state because it is very efficient for lots of apples to
be grown in Washington state. In many ways an efficient process can also
be a less carbon intensive process. In one study, for example, it was found
that transporting lamb from New Zealand to the United Kingdom, which is on the other
side of the planet, produced about a quarter of the carbon dioxide compared to
growing that lamb locally. Cuz in New Zealand they don't need to heat
the sheds that the sheep live in. There's lots of other examples of this
too. So for example, if we use heated
greenhouses, they're very much more carbon intensive than growing in the fields and
then transporting say, the tomatoes even thousands of miles.
So then there's two issues with using food miles.
The first one is it's hard to do in real life.
We need to know an enormous amount about the supply chain for a particular
foodstuff to accurately judge whether or not buying something that came from a long
way away is actually worse for the environment than buying something that was
made locally. Can you imagine trying to do this for
every single thing that you purchase? The calculations would be immense.
Can you think of all the components that go into a computer?
We have silicon chips, we have plastic, we have them, built in one place and have the
raw materials coming from many others. A house might be made of local stone, but
what about the copper wiring? Where does that come from?
And the insulation, where was that made? These sort of calculations are extremely
difficult for the individual to do for every single transaction that they make.
So in practice we don't make these calculations, it's too hard.
Instead we use heuristics. A heuristic is a simple efficient rule
that we use in place of these complex calculations.
You might think of it as common sense or a rule of thumb.
These are enormously valuable. In fact would couldn't live our lives
without using these simple shortcuts. We can't spend our entire lives
calculating every single action that we make.
We are not built to do that. The problem with environmental issues
though, is that so many of them are abstract.
And in fact this is one of the big problems with climate change.
It's so big and so far away that it's very difficult for the individual to see their
place in it and so if we use heuristics we don't get feedback that our heuristics are
accurate like we do in many other domains. Food miles is a misleading heuristic.
It makes logical sense but actually its benefit to the environment is either so
minor or negligible or even negative that as a way of helping the environment it
doesn't succeed. Food miles is more of a social concept, it
supports a type of community structure. This is true of many environmental ideas,
but we have to be at, be clear in our minds between what is affecting one system
and what's affecting another. On a personal level then, many heuristics
cannot be trusted because the problem is not something we get immediate feedback
on. That is, it's very difficult for us to
improve our rules of thumb. So, is there anything that we can do?
There are other general rules that you might use, true, but they also involve
tradeoffs. In practice, these calculations are very
difficult and the heuristics that we use are often somewhat inefficient.
Is there a better rule of thumb. Well if you don't do anything you can't
have an impact be it positive or negative. If we are worried about our carbon
footprint, a clear rule of thumb would be to do less.
We don't turn on that light switch, we have a smaller house, we heat less, we
drive less, we fly less, and so on. Here of course we have a clear tradeoff
between things that we value in our lives and things that have a negative
externality on the environment. Given that consumption will happen and
that it is unfeasible in most cases to ask individuals to do the calculation about
what their environmental impact is perhaps we need to embed the cost of environmental
damage in the transaction itself. In this way then consumer choices could be
neutral. The impact on the environment would be
balanced by the amount that the consumer paid for that impact.
So where does this leave the future of sustainability?
In the next lecture I'm going to talk about whether or not we are on a
sustainable path and what the likely future of human societies is.
Produced by OCE Atlas Digital Media at the University of Illinois, Urbana-Champaign.
