The reason why we did this study was that years ago
there was some concern about how much of the planet's net primary production
people were demanding on an annual basis. In other words,
can the Earth keep up?
If you look at the planet, the land surface produces a certain amount of vegetation
based on all the agricultural inputs we have now, our natural climate
ecosystems - that's an amount that sort of constitutes the total
available amount of biomass that's present for consumption.
And the human appropriation component as we've measured it
is actually how much NPP, or plant growth, is required
to generate the products that are being consumed annually
by people all over the world in terms of food, fiber,
building materials, and also fuel for charcoal and wood-based fuels.
We used satellite data over a
long period of time to estimate how much plant material
the land surface generates and then compared that against the amount
plant material that humans need
in terms of food, fiber, and fabrication, and we found that two things are happening.
We are increasing our per-capita consumption, so as individuals
we are increasing how much we consume on an annual basis, and
we're also increasing our population, so both of those
factors have come together to move us from about
20 percent of the actual global supply to consuming
25 percent. And so what we're concerned about is that in the future
world where we've increased both populations and consumption
that we'll hit some tipping point where the ecosystems
where they are now and the current climate that we have will not be able to produce
the products that we need to keep the lifestyle that we have now.
If that future trend continues, we're going to be pushing
55 percent of the capability of the land surface by 2050.
If you bring into that now the conversion of
land to produce fuels to replace fossil fuels
then the pressure even becomes more severe.
So, what we're finding is that the biosphere doesn't really care
if you have a few people consuming a lot, or a lot of people
consuming a little, it's the total amount in the end that actually matters.
And so, we as a species we have two issues,
we have our per capita consumption to think about, and our overall numbers.
The implications of such high demand
come about in various ways.
One is that we are vulnerable to climate change and that we have to very carefully
manage our ecosystems so that they keep producing
the products that we require. Also we have to worry about the
loss of biodiversity from the natural ecosystems because there will be fewer
of those left as we have to convert more and more land
to uses that produce the products that we use on a daily basis.
[satellite: beep-beep, beep-beep, beep-beep]