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Yogi Berra, a US baseball player[br]and philosopher, said,

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

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Accumulating scientific knowledge[br]is giving us greater insights,

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greater clarity into what our future[br]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[br]from burning of fossil fuels

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is reducing the nutritional[br]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.[br]We need to get vitamins.

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And so this is way for us[br]to think about how to make sure

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we get what we need every day

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so we can grow and thrive.

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So 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

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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[br]for our cultures.

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

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increasing from about[br]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[br]comes from this carbon dioxide.

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They bring it into the plant,[br]they break it apart

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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,[br]of rising carbon dioxide concentrations,

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for food security around the world,

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making sure that people[br]get enough to eat every day.

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

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

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is going to help with[br]our food security problem.

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We need to accelerate our progress[br]in agricultural productivity,

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

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and to achieve the Sustainable[br]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[br]that we need for everyone.

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We know that climate change[br]is affecting agricultural productivity.

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The Earth has warmed[br]about one degree Centigrade

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since pre-industrial times.

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That is changing local temperature[br]and precipitation patterns,

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and that has consequences[br]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[br]in temperature and precipitation,

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it's the extremes,

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Extremes in terms of heat waves,[br]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[br]higher carbon dioxide,

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increase the synthesis of carbohydrates,[br]sugars and starches,

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and they decrease the concentrations[br]of protein and critical nutrients,

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and this is very important for how we[br]think about food security going forward.

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

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someone said that they're[br]a five-seventh optimist,

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

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and this is a topic for other two days.

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When we think about micronutrients,

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almost all of them are affected[br]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,[br]you can develop iron deficiency anemia.

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It's associated with fatigue,[br]shortness of breath,

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and some fairly serious[br]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[br]problem around the world.

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There's about one billion people[br]who are zinc-deficient.

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It's very important[br]for maternal and child health.

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It affects development.

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The B-vitamins are critical[br]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[br]activities in our bodies,

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and when you have[br]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[br]of their forage is declining.

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In fact, this affects[br]every consumer of plants.

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

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

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there's a significant amount[br]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[br]studies in laboratories.

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In the field studies --

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and I'll focus primarily[br]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 is the same,[br]everything's the same

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except carbon dioxide[br]is blown over some of the plots.

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And so you can compare

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what it looks like[br]under today's conditions

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and under carbon dioxide conditions[br]later in the century.

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

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We looked at 18 rice lines[br]in China and in Japan,

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and grew them under conditions[br]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[br]later in the century.

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So protein declines about 10 percent,

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iron about eight percent,[br]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[br]about the poor in every country

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who primarily eat starch,

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that this will put people[br]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[br]for the B-vitamins.

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When you look at[br]vitamin B1 and vitamin B2,

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there's about a 17 percent decline.

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Pantothenic acid, vitamin B5[br]is about a 13 percent decline,

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and folate is about a 30 percent decline,

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and these are averages over[br]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[br]of having babies with birth defects.

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So these are very serious[br]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 Wyant