[MUSIC] I'm Jonathan Tomkin from the University of Illinois.
If the ecological footprint idea is too crude to help us with a policy debate,
which is where it would matter where we would decide on the changing of process,
perhaps by using a more specific footprinting idea we can actually make a,
make more progress in moving towards a sustainable future.
So one example of a more specific footprint idea is a carbon footprint.
Carbon footprinting is kind of a funny term actually, because really, when we
talk about our carbon footprint the meaning, and sometimes it's contested but
I'm going to use this definition here, a carbon footprint measures the total
greenhouse gas emissions caused directly and indirectly by a person, organization,
event or product. If we think about that, that doesn't
actually involve a land area. So why are we using this footprint
terminology? And I think that's because of the
importance of ecological footprinting in this idea of measuring our environmental
progress. And so indeed we see this footprinting
idea come in many other areas, for example energy footprinting.
So footprinting has become very much a metaphor.
It already was a metaphor of course because it's a, it's a footprint, it's,
that, that's a metaphor for our impact on the land and now it's, it's another step
removed from that so to speak. A further confusing thing about a carbon
footprint, is it's not just carbon. It's actually a greenhouse gas footprint.
But we can use other greenhouse gases, like methane for example, and turn them
into carbon equivalents. And so by adding together our other
impacts, so for example methane from farming, we can add that in and get a
single number which is the carbon footprint.
This concept is used for individuals, for companies, for countries and we can see
here an example of different processes. In this graph, we're looking at carbon
emissions for electricity generation for different types.
And we can see here, that coal, in three different countries has a much higher
carbon footprint than gas does or renewable energy sources do or nuclear
does. We can also do this with different
countries. The United States is famously high in that
it has a lot of carbon dioxide emissions per person.
If you look at this graph and you have good eyesight you might be able to find
your own country and see how you compare. And we can also use this idea of
individuals. So we can measure our carbon expenditure
and then determine our own carbon footprint, that is how much carbon dioxide
we put into the atmosphere each year. In the US, most of this carbon footprint
is directly in the form of energy use. But actually, that leaves a lot out right?
What's that other half? This is where we get to see that although
carbon foot printing is a relatively clean measure,
It's relatively straightforward, although there are complications to do with what if
we try to do carbon offsetting or we have forests or regrowth and so-on.
But there is a problem, in that many of the things that we use have carbon dioxide
emissions hidden within them, just in the same way we saw that food stuffs would
have large amounts of virtual water hidden within them.
The equivalent terminology in idea for energy is embodied, or sometimes embedded
energy. This is the sum of all the energy required
to produce goods or services, considered as if that energy was incorporated or
embodied in the product itself. So for example, buildings have lots of
embodied energy in them. It, it requires a lot of energy to make
steel, aluminum, brick, concrete. In fact, if we look at the entire life of
a building, about half of the energy in it's, in it's use is not actually from the
heating, the cooling, the lighting. It's just from the building and the
manufacture. So when we think about our own carbon
footprints it's not just a question of looking at how much gas we use or how much
oil we consume. It's also about other products that we use
that needed energy to be made. So to do a full assessment then we need to
look at the complete life cycle of a product.
Life cycle assessment is a way of measuring things like the amount of energy
used. So in any sort of foot printing analysis
be it water, energy, carbon dioxide but we have to look at it from every step.
This is sometimes known as cradle to grave analysis because it looks at it's
manufacture, it's use and what happens once it's disposed of.
There are four classic steps. First, you have to consider the
acquisition of the materials, so, for example the energy required in mining or
in recycling. We have to worry about the manufacturing,
refining and fabrication of that object. We have to worry about the use by
consumers. And then finally we have to worry about
how much energy, carbon dioxide, water and so on is required to decommission that
object. For most things,
Life cycle analysis really only focuses on one or two steps, because they often
dominate, which is the most important. So for example, for a car, it turns out
that the end use is the dominant factor in terms, in determining its energy output.
Manufacturing and fabrication does take up a significant amount but, compare to the
oil or gas that's being used to drive the car, it's relatively small.
On the other hand if we talk about an aluminum object, so a can for example for
soda. It's actually the first two steps that are
most important. Lots of energy is needed to extract the
bauxite and even more energy is needed to turn that mineral into aluminum.
So when we do a life cycle analysis, we can capture all of these ideas and life
cycle analysis is now pretty much the standard technique used by people who are
trying to measure the sustainability of their products or processes.
And so in the textbook, you will see lots of detail about how different people and
different companies use this idea to measure their impact on the environment.
If you do peruse the textbook on life cycle analysis you'll see how complicated
it is. There are many steps and there are many
assumptions that have to be made. Couple this with the knowledge that there
are literally millions of different products in the world today and of course
billions of consumers, We can see that accurately calculating the
life cycle impact of any object is actually quite difficult and in some cases
highly contentious. If you're relying on estimates that aren't
simple, so in other words you have a, an object that used And then recycled and
then used again. Where do we draw the line?
Where, where does the fabrication stop and where does the use of the next object
begin? Or the knowledge that some objects are
wasted so on some estimates, you know, a quarter of food in developed countries is,
is not used for eating, it's thrown out or it's wasted in other ways.
You can clearly see that actually this becomes quite a complicated calculation.
So in practice professionals are consulted when life cycle analyses are required.
There's actually a new field called sustainability consulting where experts
will go and try and determine these processes.
