《可持续发展的时代》旨在让你了解可持续发展 所面临的关键挑战和实践途径 即兼顾社会包容性和环境可持续性的经济发展
Towards a sustainable global food supply
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來自 Columbia University 的課程
可持续发展的时代
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從本節課中
Sustainable Food Supply and the End of Hunger
Professor Sachs provides an overview of food security, farm systems, and ecology and reviews what can be done to achieve a sustainable global food supply.
與講師見面
Jeffrey Sachs
Director, Earth Institute; Quetelet Professor of Sustainable Development; Professor of Health Policy and Management
[MUSIC]
Creating a sustainable farm system around the world
is absolutely vital to feed a growing world population.
And to reduce the tremendous pressures that our current farm
system, or systems around the world, are already placing
on the Earth and many of the key ecosystems on the planet.
We can think about what will happen if we continue with business as usual.
And contrast that with what we really need to do,
which is to reshape our own behavior with regard to
food and to reshape the farm systems that produce food
to create an alternative of trajectory, a trajectory of sustainable development.
What are the threats of the business as usual path?
The chart before you attempts to summarize those risks and to give an expert
assessment of how serious the particular risks
are in particular regions of the world.
The boxes that are shaded red are major alerts that these are places
in the world and kinds of challenges that are of the first order of significance.
The boxes that are yellow are like yellow warning signs, things
could get bad in these areas with regard to these particular threats.
Business as usual, for example, will mean increasing
food insecurity in some parts of the world.
The places at greatest threat are Sub-Saharan Africa
and South Asia, the two epicenters of under-nutrition.
But also one would add North Africa and the Middle East.
Why?
Because this is a place where all of
the climate evidence suggests there will be significant drying
in the future, and therefore, crop production will
be under even greater threat than it is today.
Certainly the business as usual course will put dangers in East Asia
and Southeast Asia as well because there will be places of tremendous water stress.
There will be places where higher
temperatures play havoc with the food supply.
Malnutrition in the sense of deep undernourishment, of course, will
continue to have it's intense epicenter in Sub-Saharan Africa and in South Asia.
But the other kind of malnutrition, obesity.
On a business as usual path is likely to worsen significantly in North
America, in many parts of Latin America, it's already epidemic
proportions in Mexico for example, in Europe, and with serious risks
in Southeast Asia, in in East Asia.
And in India and in other parts of South Asia as well.
Land use change we know will have
huge costs especially in the rain forest regions.
That means in Latin America, in Sub-Saharan Africa.
And in parts of Southeast Asia.
Soil degradation is already a major crisis in, in parts of Sub-Saharan Africa.
In many place in south and in east Asia, where the land has
already eroded the soils often have been swept away because
of trying to grow crops on steep slopes for example.
Or in places where the winds blow the topsoil
away, as is occurring in many parts of China.
We know that biodiversity loss is threatened pervasively.
One could say that the threats are moderately
or acutely high in every region of the world.
One can think about losses in the rain forest regions, one can think about losses
in the places likely to experience serious drying such as the Mediterranean basin.
One can think about losses of biodiversity in places
where population growth is so rapid that encroachments on land that are
bound to threaten and profoundly imperil
biodiversity as is occurring in Sub-Saharan Africa.
The chart in other words by region, by risk.
>> Is filled and while there are a few regions that escape some
of the risks, there are no regions that escape all of the risks.
And today's poor regions are of course as is usual
with poverty, at extreme peril because they're already living on the edge.
They're already people living in fragile environments, for
example in tropical ecosystems in dryland ecosystems, part
of the their poverty has come from the
fact that the, natural environment is already fairly inhospitable.
But with environmental change, what is now a difficult environment,
can be a, an impossible environment to support human life.
When that happens, not only will people suffer, will
people die, will there be conflict, there will be migration.
And there will be environmental refugees created by the
millions, the tens of millions, even the hundreds of millions.
And we know, sad to say in a world which does not do well with migration.
Where newcomers, especially poor newcomers that are forced to move
,uh, can face a very, very hostile environment to
when they arrive and so we're in for a lot
of trouble if we maintain this business as usual trajectory.
What to do?
How to move to a sustainable development trajectory?
Again, because of the complexity of the food system, the fact that
we're talking about land use, the fact that we're concerned about nitrogen use,
the fact that we're concerned about chemical pollutants, the fact that we're
concerned about the vulnerability of crops
to higher temperatures or more water stress.
Means that the kinds of responses that are needed, also are going to have be
varied, holistic in nature, and carefully tailored to local contexts.
Boy, that makes this among the toughest challenges
that we face because the world is in crisis.
The problems will get worse.
It's not easy to say that one region will
bail out the others because all regions will have stresses.
And also there will be no magic key that suddenly will
sweep the world, and make it possible to solve this problem.
Each region is going to have to
identify its own pathways to sustainable agriculture.
What are some of the things that can be done?
The first is to improve our ability to grow food.
And to be more productive in terms of higher yields, and more resilient in terms
of the ability of food crops to withstand
the shocks that we know are already coming.
Just as Norman Borlaug and his colleagues Emma Swaminathan and Minister Supranamian.
That triumvirate made possible the Indian Green Revolution and
comparable events in other parts of the world where
higher yields came because of the advent of high
yield varieties combined with fertilizer inputs and often with irrigation.
We're going to need another Green Revolution of new crop varieties that are
going to be especially propitious for the challenges that we face.
For some regions this will mean a special importance of drought resistant varieties.
Because the frequency of serious droughts is likely to become much higher.
We know that certain plants in nature have a high level of drought tolerance.
The plant scientists now are attempting to identify
those genes and through various means, conventional plant breeding or the
use of genetic modification as it's called, create new
crop varieties that also share, the drought resistance.
Partly the natural breeding has helped to
develop new seed varieties that are better able
to withstand bouts of of low rainfall, in
other words dry spells during the growing season.
GMOs, the genetically modified organisms, or GMO crops
have taken the experimental pathway of identifying
the gene complexes in naturally occurring, drought tolerant plants.
And transplanting those gene complexes into crops that for the food supply.
Now many, many people find this idea
of genetic modification to be very threatening,
very dangerous, and it poses risks to
the environment and potentially to human health.
So, whatever is done in this research domain of using
cutting edge genomics, both to identify potential genes that can add
to crop traits that are desirable, and then to transplant them
into food varieties to raise the resilience of those crops.
Needs to be tightly monitored and tightly regulated.
But I would argue, despite some critics of this technology, that we
should certainly test these technologies to see what they have to offer.
They seem very promising.
That by identifying genes for drought resistance or by
identifying genes for saline tolerance, for
saline soils, or for identifying genes as shown in this picture
for the ability of rice to resist submergence.
We can get major advances.
What you're looking at in this picture is a transplanted gene from a species of rice
that is able to tolerate being underwater for several days and still survive.
To the kinds of rice that are normally grown in Bangladesh, in India,
in Pakistan or other parts of Asia, that don't have that submergence trait.
Turns out, wonderfully, taking that gene for
submergence and putting it into popular, high yield traits for
rice, has led to high yield, submergence-tolerant
rice a wonderful breakthrough for farmers in
Bangladesh that suffer repeated episodes of submergence
of their rice.
Those who say don't even go that way
with technology aren't thinking, in my opinion, clearly
enough about the needs of that farm family
in Bangladesh to have this kind of variety.
We shouldn't dismiss a whole class of technology, because while it may pose
risks those risks are controllable, monitorable and
the technology itself can offer important breakthroughs.
Now, relatedly is a second step of what can be done.
And this is to make crop varieties more nutritious.
Not only to grow better in harsh
conditions, but to express more nutrients and
this is the idea that you're looking at, in this picture of so-called Golden Rice.
This is a, a crop that has been
developed by the International Rice Research, Rice Research
Institute, in Los Banos, Philippines the Rice Research
Institute that helped bring the Green Revolution in rice.
Now what scientists at IRRI, I-R-R-I, are doing is to
put in genes that express beta carotene, a precursor for vitamin A.
So the children who eat this rice, and you see how it's golden or looks more red, a
little bit more like a carrot carrot color then
have the vitamin A that they need for health.
And we've already identified that vitamin A deficiency
is one of the key kinds of hidden hunger.
How wonderful it will be if a nutritious rice that provides a basis
for vitamin A can successfully be diffused
and taken up by populations of rice eaters around the world.
A third direction for us, absolutely essential
is known as precision farming or information rich farming.
This is already being used in high income countries by relatively
wealthy farmers who can afford high tech approaches.
But in coming years, because of the declining costs of information technology,
it will increasingly be used by by poor farmers as well.
What precision farming means is having a
much more precise application of fertilizer, for example.
Just in the places where the soils require it.
Not in the places where it's not used and just in
the amounts that can be taken up by the plants without
experiencing the harmful side effects of the massive run off or
loss of that fertilizer, both into the waterways and into the atmosphere.
Precision agriculture depends on information technologies, on detailed
mapping of soil types, often on on global
positioning systems that can tell a farmer exactly where that farmer
is in the field, and what's happening in the soil in that part of the farm.
That relates more to, to a more general category of, better
nutrient management through better soil testing,
soil mapping using a, a local chemistry.
Even reading the qualities of the soil on handheld devices.
Or from satellite, it will be possible to
get a much more detailed resolution of soil needs.
What needs to be added here, what needs to be added
there, where's fertilizer not needed or needed only in very small amounts?
And that sort of nutrient management of
the soils offers places with soil nutrient depletion
a massive potential boost in yields, Africa
being number one in the line for that.
It also offers the chances for places that use far too much fertilizer, [COUGH]
like China, to cut down very, very sharply on the fertilizer use.
Another breakthrough is water management.
Of course, we need to apply less water to get more crop per drop, because
we're depleting the scarce water we have, and
the conditions will get tougher in the future.
Not only because of the depletion, but because of the climate change.
Another major breakthrough that offers us a real boost will
be better harvesting, storage, and transport of crops.
To avoid the very large losses, sometimes estimated as,
as much as a third, or even 40% of the crops to post-harvest loss,
to pests, to rotting to rodents, to physical
loss of the crops left to exposure to rains and so forth.
Simple means of more effective storage systems at very,very
low cost and better incentive systems and empowerment of local farmer
cooperatives to invest in community-based storage facilities offer a tremendous
hope for reducing losses in the value chain of agriculture.
With big gains not only for farm incomes,
but also big gains in effective productivity of the
farm systems, and our ability to ease up
on the big human pressures, on the farm systems.
Next I would argue that better business models for poor
smallholders is vital not only for ending extreme poverty but also
for making all of these investments in more efficient crop varieties, more
efficient irrigation more efficient water management, more efficient storage.
There is productivity through aggregation into farmer cooperatives.
Farmer based organizations, new kinds of models, new connections to local,
regional, and global value chains that are already proving their worth.
And finally, we have to take responsibility ourselves for our health.
And for the way we approach the issues of food.
When we have massive epidemics of obesity.
We know that something is seriously wrong.
A lot of it comes from the fact that
we have heavily subsidized the wrong kinds of foods.
We've heavily subsidized carbohydrates or trans fats, or other kinds of, of foods
stuff that are absolutely unhealthy in the
ways that they're being consumed right now.
And, our economic incentives have often played against
the very kinds of foods that are better for our diets, for our health.
We have subsidized in effect the feed grains that
have led to massive and the evidence shows from
a health point of view, an environmental point of
view, overconsumption of beef in the United States and Europe.
To the point where so much meat is eaten that it's bad for human health,
contributing to cardiovascular and other diseases, and it's
exceedingly bad for the environment when we are deploying ten or fifteen
kilograms of feed grain for every kilogram of beef that is consumed.
Tremendously multiplying the burdens on the land, on fertilizer
use, on water supplies, aggravating all of the natural problems.
We're also aggravating these problems by diverting food production,
or what should be food production, into the gas tank.
In the United States through absurd subsidies driven more by politics
than by any common sense or ecology, we've turned a
significant part of our annual food and feed grain production,
especially of maize into ethanol for automobiles.
It's a miserable deal because so much resources used to produce that ethanol.
It's creating no savings for the natural environment but what it is doing is
diverting a tremendous amount of food and feed grain away from the the food systems.
It's pushing up food prices.
It's putting extra pressures on the natural environment.
It is being done at the behest of
a few powerful companies with powerful lobbies in Washington.
And Europe isn't off the hook because it has
a similar problem of biofuels diverting valuable farmland in Europe.
The pathway to sustainable development involves behavioral change,
public awareness, taking responsibility, and the mobilization
of new systems and new technologies that can
dramatically reduce the pressures on the natural environment.
And help to make our economy and our way of
life more resilient to the environmental changes that are already underway.
It's a huge problem and a huge challenge.
It's an unsolved one.
It's one of the areas that will require the
most intensive kinds of problem solving, at local levels all
around the world, during the period of the sustainable development
goals from 2015 to 2030, the years that lie ahead.
