YouTube

Teniu un compte YouTube?

New: enable viewer-created translations and captions on your YouTube channel!

English subtítols

← How climate change could make our food less nutritious

Obtén el codi d'incrustació
29 llengües

Showing Revision 10 created 09/16/2019 by Oliver Friedman.

  1. Yogi Berra, a US baseball player
    and philosopher, said,
  2. "If we don't know where we're going,
    we might not get there."
  3. Accumulating scientific knowledge
    is giving us greater insights,
  4. greater clarity, into what our future
    might look like in a changing climate
  5. and what that could mean for our health.
  6. I'm here to talk about a related aspect,
  7. on how our emissions of greenhouse gases
    from burning of fossil fuels
  8. is reducing the nutritional
    quality of our food.
  9. We'll start with the food pyramid.

  10. You all know the food pyramid.
  11. We all need to eat a balanced diet.
  12. We need to get proteins,
  13. we need to get micronutrients,
  14. we need to get vitamins.
  15. And so, this is a way
    for us to think about
  16. how to make sure we get
    what we need every day
  17. so we can grow and thrive.
  18. But we eat not just because we need to,

  19. we also eat for enjoyment.
  20. Bread, pasta, pizza --
  21. there's a whole range of foods
    that are culturally important.
  22. We enjoy eating these.
  23. And so they're important for our diet,
  24. but they're also important
    for our cultures.
  25. Carbon dioxide has been increasing since
    the start of the Industrial Revolution,

  26. increasing from about
    280 parts per million to over 410 today,
  27. and it continues to increase.
  28. The carbon that plants need to grow
    comes from this carbon dioxide.
  29. They bring it into the plant,
  30. they break it apart
    into the carbon itself,
  31. and they use that to grow.
  32. They also need nutrients from the soil.
  33. And so yes, carbon dioxide is plant food.
  34. And this should be good news,
    of rising carbon dioxide concentrations,

  35. for food security around the world,
  36. making sure that people
    get enough to eat every day.
  37. About 820 million people in the world
    don't get enough to eat every day.
  38. So there's a fair amount written
    about how higher CO2
  39. is going to help with
    our food security problem.
  40. We need to accelerate our progress
    in agricultural productivity
  41. to feed the nine to 10 billion people
    who will be alive in 2050
  42. and to achieve the Sustainable
    Development Goals,
  43. particularly the Goal Number 2,
  44. that is on reducing food insecurity,
  45. increasing nutrition,
  46. increasing access to the foods
    that we need for everyone.
  47. We know that climate change
    is affecting agricultural productivity.
  48. The earth has warmed
    about one degree centigrade
  49. since preindustrial times.
  50. That is changing local temperature
    and precipitation patterns,
  51. and that has consequences
    for the agricultural productivity
  52. in many parts of the world.
  53. And it's not just local changes
    in temperature and precipitation,
  54. it's the extremes.
  55. Extremes in terms of heat waves,
    floods and droughts
  56. are significantly affecting productivity.
  57. And that carbon dioxide,

  58. besides making plants grow,
  59. has other consequences as well,
  60. that plants, when they have
    higher carbon dioxide,
  61. increase the synthesis of carbohydrates,
    sugars and starches,
  62. and they decrease the concentrations
    of protein and critical nutrients.
  63. And this is very important for how we
    think about food security going forward.
  64. A couple of nights ago
    in the table talks on climate change,

  65. someone said that they're
    a five-sevenths optimist:
  66. that they're an optimist
    five days of the week,
  67. and this is a topic
    for the other two days.
  68. When we think about micronutrients,

  69. almost all of them are affected
    by higher CO2 concentrations.
  70. Two in particular are iron and zinc.
  71. When you don't have enough iron,
    you can develop iron deficiency anemia.
  72. It's associated with fatigue,
    shortness of breath
  73. and some fairly serious
    consequences as well.
  74. When you don't have enough zinc,
  75. you can have a loss of appetite.
  76. It is a significant
    problem around the world.
  77. There's about one billion people
    who are zinc deficient.
  78. It's very important
    for maternal and child health.
  79. It affects development.
  80. The B vitamins are critical
    for a whole range of reasons.
  81. They help convert our food into energy.
  82. They're important for the functions
  83. of many of the physiologic
    activities in our bodies.
  84. And when you have
    higher carbon in a plant,
  85. you have less nitrogen,
  86. and you have less B vitamins.
  87. And it's not just us.

  88. Cattle are already being affected
  89. because the quality
    of their forage is declining.
  90. In fact, this affects
    every consumer of plants.
  91. And give a thought to, for example,
    our pet cats and dogs.
  92. If you look on the label
    of most of the pet and dog food,
  93. there's a significant amount
    of grain in those foods.
  94. So this affects everyone.
  95. How do we know that this is a problem?

  96. We know from field studies
  97. and we know from experimental
    studies in laboratories.
  98. In the field studies --
  99. and I'll focus primarily
    on wheat and on rice --
  100. there's fields, for example, of rice
  101. that are divided into different plots.
  102. And the plots are all the same:
  103. the soil's the same,
  104. the precipitation's the same --
  105. everything's the same.
  106. Except carbon dioxide
    is blown over some of the plots.
  107. And so you can compare
  108. what it looks like
    under today's conditions
  109. and under carbon dioxide conditions
    later in the century.
  110. I was part of one of the few studies
    that have done this.

  111. We looked at 18 rice lines
    in China and in Japan
  112. and grew them under conditions
    that you would expect
  113. later in the century.
  114. And when you look at the results,
  115. the white bar is today's conditions,
  116. the red bar is conditions
    later in the century.
  117. So protein declines about 10 percent,
  118. iron about eight percent,
    zinc about five percent.
  119. These don't sound like really big changes,
  120. but when you start thinking
    about the poor in every country
  121. who primarily eat starch,
  122. that this will put people
    who are on the edge
  123. over the edge into frank deficiencies,
  124. creating all kinds of health problems.
  125. The situation is more significant
    for the B vitamins.

  126. When you look at
    vitamin B1 and vitamin B2,
  127. there's about a 17 percent decline.
  128. Pantothenic acid, vitamin B5,
    is about a 13 percent decline.
  129. Folate is about a 30 percent decline.
  130. And these are averages over
    the various experiments that were done.
  131. Folate is critical for child development.
  132. Pregnant women who don't get enough folate
  133. are at much higher risk
    of having babies with birth defects.
  134. So these are very serious
    potential consequences for our health
  135. as CO2 continues to rise.
  136. In another example,

  137. this is modeling work that was done
    by Chris Weyant and his colleagues,
  138. taking a look at this chain
    from higher CO2 to lower iron and zinc --
  139. and they only looked at iron and zinc --
  140. to various health outcomes.
  141. They looked at malaria,
    diarrheal disease, pneumonia,
  142. iron deficiency anemia,
  143. and looked at what
    the consequences could be in 2050.
  144. And the darker the color in this,
  145. the larger the consequences.
  146. So you can see the major impacts
  147. in Asia and in Africa,
  148. but also note that in countries
    such as the United States
  149. and countries in Europe,
  150. the populations also could be affected.
  151. They estimated about
    125 million people could be affected.
  152. They also modeled what would be
    the most effective interventions,
  153. and their conclusion was
    reducing our greenhouse gases:
  154. getting our greenhouse gas emissions
    down by mid-century
  155. so we don't have to worry so much
    about these consequences
  156. later in the century.
  157. These experiments, these modeling studies

  158. did not take climate change
    itself into account.
  159. They just focused on
    the carbon dioxide component.
  160. So when you put the two together,
  161. it's expected the impact is much larger
    than what I've told you.
  162. I'd love to be able to tell you right now

  163. how much the food you had for breakfast,
    the food you're going to have for lunch,
  164. has shifted from what
    your grandparents ate
  165. in terms of its nutritional quality.
  166. But I can't.
  167. We don't have the research on that.
  168. I'd love to tell you how much
    current food insecurity
  169. is affected by these changes.
  170. But I can't.
  171. We don't have the research
    on that, either.
  172. There's a lot that needs
    to be known in this area,
  173. including what the possible
    solutions could be.
  174. We don't know exactly
    what those solutions are,
  175. but we've got a range of options.
  176. We've got advancements in technologies.
  177. We've got plant breeding.
    We've got biofortification.
  178. Soils could make a difference.
  179. And, of course, it will be
    very helpful to know
  180. how these changes could affect
    our future health
  181. and the health of our children
    and the health of our grandchildren.
  182. And these investments take time.
  183. It will take time to sort
    all of these issues out.
  184. There is no national entity
    or business group
  185. that is funding this research.
  186. We need these investments critically
    so that we do know where we're going.
  187. In the meantime, what we can do

  188. is ensure that all people
    have access to a complete diet,
  189. not just those in the wealthy parts
    of the world but everywhere in the world.
  190. We also individually and collectively need
    to reduce our greenhouse gas emissions
  191. to reduce the challenges
    that will come later in the century.
  192. It's been said that if you think
    education is expensive, try ignorance.

  193. Let's not.
  194. Let's invest in ourselves,
  195. in our children
  196. and in our planet.
  197. Thank you.

  198. (Applause)