WEBVTT

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Yogi Berra, a US baseball player
and philosopher, said,

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"If we don't know where we're going,
we might not get there."

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Accumulating scientific knowledge
is giving us greater insights,

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greater clarity, into what our future
might look like in a changing climate

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and what that could mean for our health.

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I'm here to talk about a related aspect,

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on how our emissions of greenhouse gases
from burning of fossil fuels

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is reducing the nutritional
quality of our food.

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We'll start with the food pyramid.

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You all know the food pyramid.

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We all need to eat a balanced diet.

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We need to get proteins,

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we need to get micronutrients,

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we need to get vitamins.

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And so, this is a way
for us to think about

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how to make sure we get
what we need every day

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so we can grow and thrive.

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But we eat not just because we need to,

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we also eat for enjoyment.

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Bread, pasta, pizza --

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there's a whole range of foods
that are culturally important.

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We enjoy eating these.

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And so they're important for our diet,

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but they're also important
for our cultures.

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Carbon dioxide has been increasing since
the start of the Industrial Revolution,

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increasing from about
280 parts per million to over 410 today,

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and it continues to increase.

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The carbon that plants need to grow
comes from this carbon dioxide.

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They bring it into the plant,

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they break it apart
into the carbon itself,

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and they use that to grow.

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They also need nutrients from the soil.

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And so yes, carbon dioxide is plant food.

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And this should be good news,
of rising carbon dioxide concentrations,

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for food security around the world,

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making sure that people
get enough to eat every day.

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About 820 million people in the world
don't get enough to eat every day.

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So there's a fair amount written
about how higher CO2

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is going to help with
our food security problem.

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We need to accelerate our progress
in agricultural productivity

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to feed the nine to 10 billion people
who will be alive in 2050

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and to achieve the Sustainable
Development Goals,

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particularly the Goal Number 2,

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that is on reducing food insecurity,

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increasing nutrition,

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increasing access to the foods
that we need for everyone.

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We know that climate change
is affecting agricultural productivity.

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The earth has warmed
about one degree centigrade

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since preindustrial times.

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That is changing local temperature
and precipitation patterns,

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and that has consequences
for the agricultural productivity

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in many parts of the world.

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And it's not just local changes
in temperature and precipitation,

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it's the extremes.

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Extremes in terms of heat waves,
floods and droughts

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are significantly affecting productivity.

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And that carbon dioxide,

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besides making plants grow,

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has other consequences as well,

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that plants, when they have
higher carbon dioxide,

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increase the synthesis of carbohydrates,
sugars and starches,

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and they decrease the concentrations
of protein and critical nutrients.

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And this is very important for how we
think about food security going forward.

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A couple of nights ago
in the table talks on climate change,

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someone said that they're
a five-sevenths optimist:

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that they're an optimist
five days of the week,

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and this is a topic
for the other two days.

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When we think about micronutrients,

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almost all of them are affected
by higher CO2 concentrations.

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Two in particular are iron and zinc.

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When you don't have enough iron,
you can develop iron deficiency anemia.

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It's associated with fatigue,
shortness of breath

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and some fairly serious
consequences as well.

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When you don't have enough zinc,

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you can have a loss of appetite.

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It is a significant
problem around the world.

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There's about one billion people
who are zinc deficient.

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It's very important
for maternal and child health.

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It affects development.

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The B vitamins are critical
for a whole range of reasons.

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They help convert our food into energy.

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They're important for the functions

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of many of the physiologic
activities in our bodies.

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And when you have
higher carbon in a plant,

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you have less nitrogen,

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and you have less B vitamins.

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And it's not just us.

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Cattle are already being affected

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because the quality
of their forage is declining.

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In fact, this affects
every consumer of plants.

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And give a thought to, for example,
our pet cats and dogs.

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If you look on the label
of most of the pet and dog food,

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there's a significant amount
of grain in those foods.

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So this affects everyone.

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How do we know that this is a problem?

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We know from field studies

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and we know from experimental
studies in laboratories.

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In the field studies --

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and I'll focus primarily
on wheat and on rice --

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there's fields, for example, of rice

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that are divided into different plots.

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And the plots are all the same:

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the soil's the same,

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the precipitation's the same --

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everything's the same.

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Except carbon dioxide
is blown over some of the plots.

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And so you can compare

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what it looks like
under today's conditions

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and under carbon dioxide conditions
later in the century.

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I was part of one of the few studies
that have done this.

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We looked at 18 rice lines
in China and in Japan

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and grew them under conditions
that you would expect

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later in the century.

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And when you look at the results,

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the white bar is today's conditions,

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the red bar is conditions
later in the century.

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So protein declines about 10 percent,

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iron about eight percent,
zinc about five percent.

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These don't sound like really big changes,

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but when you start thinking
about the poor in every country

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who primarily eat starch,

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that this will put people
who are on the edge

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over the edge into frank deficiencies,

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creating all kinds of health problems.

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The situation is more significant
for the B vitamins.

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When you look at
vitamin B1 and vitamin B2,

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there's about a 17 percent decline.

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Pantothenic acid, vitamin B5,
is about a 13 percent decline.

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Folate is about a 30 percent decline.

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And these are averages over
the various experiments that were done.

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Folate is critical for child development.

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Pregnant women who don't get enough folate

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are at much higher risk
of having babies with birth defects.

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So these are very serious
potential consequences for our health

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as CO2 continues to rise.

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In another example,

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this is modeling work that was done
by Chris Weyant and his colleagues,

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taking a look at this chain
from higher CO2 to lower iron and zinc --

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and they only looked at iron and zinc --

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to various health outcomes.

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They looked at malaria,
diarrheal disease, pneumonia,

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iron deficiency anemia,

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and looked at what
the consequences could be in 2050.

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And the darker the color in this,

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the larger the consequences.

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So you can see the major impacts

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in Asia and in Africa,

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but also note that in countries
such as the United States

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and countries in Europe,

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the populations also could be affected.

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They estimated about
125 million people could be affected.

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They also modeled what would be
the most effective interventions,

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and their conclusion was
reducing our greenhouse gases:

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getting our greenhouse gas emissions
down by mid-century

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so we don't have to worry so much
about these consequences

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later in the century.

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These experiments, these modeling studies

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did not take climate change
itself into account.

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They just focused on
the carbon dioxide component.

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So when you put the two together,

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it's expected the impact is much larger
than what I've told you.

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I'd love to be able to tell you right now

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how much the food you had for breakfast,
the food you're going to have for lunch,

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has shifted from what
your grandparents ate

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in terms of its nutritional quality.

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But I can't.

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We don't have the research on that.

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I'd love to tell you how much
current food insecurity

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is affected by these changes.

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But I can't.

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We don't have the research
on that, either.

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There's a lot that needs
to be known in this area,

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including what the possible
solutions could be.

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We don't know exactly
what those solutions are,

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but we've got a range of options.

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We've got advancements in technologies.

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We've got plant breeding.
We've got biofortification.

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Soils could make a difference.

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And, of course, it will be
very helpful to know

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how these changes could affect
our future health

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and the health of our children
and the health of our grandchildren.

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And these investments take time.

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It will take time to sort
all of these issues out.

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There is no national entity
or business group

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that is funding this research.

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We need these investments critically
so that we do know where we're going.

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In the meantime, what we can do

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is ensure that all people
have access to a complete diet,

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not just those in the wealthy parts
of the world but everywhere in the world.

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We also individually and collectively need
to reduce our greenhouse gas emissions

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to reduce the challenges
that will come later in the century.

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It's been said that if you think
education is expensive, try ignorance.

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Let's not.

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Let's invest in ourselves,

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in our children

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and in our planet.

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Thank you.

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(Applause)