Yogi Berra, a US baseball player and philosopher, said,
"If we don't know where we're going, we might not get there."
Accumulating scientific knowledge is giving us greater insights,
greater clarity into what our future might look like in a changing climate
and what that could mean for our health.
I'm here to talk about a related aspect
on how our emissions of greenhouse gases from burning of fossil fuels
is reducing the nutritional quality of our food.
We'll start with the food pyramid.
You all know the food pyramid.
We all need to eat a balanced diet.
We need to get proteins.
We need to get micronutrients. We need to get vitamins.
And so this is way for us to think about how to make sure
we get what we need every day
so we can grow and thrive.
So we eat not just because we need to,
we also eat for enjoyment.
Bread, pasta, pizza,
there's a whole range of foods
that are culturally important.
We enjoy eating these.
And so they're important for our diet,
but they're also important for our cultures.
Carbon dioxide has been increasing since the start of the Industrial Revolution,
increasing from about 280 parts per million to over 410 today,
and it continues to increase.
The carbon that plants need to grow comes from this carbon dioxide.
They bring it into the plant, they break it apart
into the carbon itself,
and they use that to grow.
They also need nutrients from the soil.
And so yes, carbon dioxide is plant food.
And this should be good news, of rising carbon dioxide concentrations,
for food security around the world,
making sure that people get enough to eat every day.
About 820 million people in the world don't get enough to eat every day.
So there's a fair amount written about how higher CO2
is going to help with our food security problem.
We need to accelerate our progress in agricultural productivity,
to feed the nine to 10 billion people who will be alive in 2050
and to achieve the Sustainable Development Goals,
particularly the Goal Number 2,
that is on reducing food insecurity,
increasing nutrition,
increasing access to the foods that we need for everyone.
We know that climate change is affecting agricultural productivity.
The Earth has warmed about one degree Centigrade
since pre-industrial times.
That is changing local temperature and precipitation patterns,
and that has consequences for the agricultural productivity
in many parts of the world.
And it's not just local changes in temperature and precipitation,
it's the extremes,
Extremes in terms of heat waves, floods and droughts
are significantly affecting productivity.