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← Emergency medicine for our climate fever

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Showing Revision 12 created 09/13/2019 by Brian Greene.

  1. I'm here to talk to you about something
    important that may be new to you.
  2. The governments of the world
  3. are about to conduct
    an unintentional experiment
  4. on our climate.
  5. In 2020, new rules will require ships
    to lower their sulfur emissions
  6. by scrubbing their dirty exhaust
  7. or switching to cleaner fuels.
  8. For human health, this is really good,
  9. but sulfur particles
    in the emission of ships
  10. also have an effect on clouds.
  11. This is a satellite image of marine clouds
  12. off the Pacific West Coast
    of the United States.
  13. The streaks in the clouds
    are created by the exhaust from ships.
  14. Ships' emissions include
    both greenhouse gases,
  15. which trap heat over long periods of time,
  16. and particulates like sulfates
    that mix with clouds
  17. and temporarily make them brighter.
  18. Brighter clouds reflect
    more sunlight back to space,
  19. cooling the climate.
  20. So in fact,
  21. humans are currently running
    two unintentional experiments
  22. on our climate.
  23. In the first one, we're increasing
    the concentration of greenhouse gases

  24. and gradually warming the earth system.
  25. This works something like a fever
    in the human body.
  26. If the fever remains low,
    its effects are mild,
  27. but as the fever rises,
    damage grows more severe
  28. and eventually devastating.
  29. We're seeing a little of this now.
  30. In our other experiment,

  31. we're planning to remove
    a layer of particles
  32. that brighten clouds and shield us
    from some of this warming.
  33. The effect is strongest
    in ocean clouds like these,
  34. and scientists expect the reduction
    of sulfur emissions from ships next year
  35. to produce a measurable increase
    in global warming.
  36. Bit of a shocker?

  37. In fact, most emissions contain sulfates
    that brighten clouds:
  38. coal, diesel exhaust, forest fires.
  39. Scientists estimate that the total
    cooling effect from emission particles,
  40. which they call aerosols
    when they're in the climate,
  41. may be as much as all of the warming
    we've experienced up until now.
  42. There's a lot of uncertainty
    around this effect,
  43. and it's one of the major reasons
    why we have difficulty predicting climate,
  44. but this is cooling that we'll lose
    as emissions fall.
  45. So to be clear, humans
    are currently cooling the planet
  46. by dispersing particles
    into the atmosphere at massive scale.
  47. We just don't know how much,
    and we're doing it accidentally.
  48. That's worrying,
  49. but it could mean that we have
    a fast-acting way to reduce warming,
  50. emergency medicine
    for our climate fever if we needed it,
  51. and it's a medicine
    with origins in nature.
  52. This is a NASA simulation
    of earth's atmosphere,

  53. showing clouds and particles
    moving over the planet.
  54. The brightness is the Sun's light
    reflecting from particles in clouds,
  55. and this reflective shield
    is one of the primary ways
  56. that nature keeps the planet
    cool enough for humans
  57. and all of the life that we know.
  58. In 2015, scientists assessed possibilities
    for rapidly cooling climate.
  59. They discounted
    things like mirrors in space,
  60. ping-pong balls in the ocean,
    plastic sheets on the Arctic,
  61. and they found
    that the most viable approaches
  62. involved slightly increasing
    this atmospheric reflectivity.
  63. In fact, it's possible that reflecting
    just one or two percent more sunlight
  64. from the atmosphere
  65. could offset two degrees Celsius
    or more of warming.
  66. Now, I'm a technology executive,
    not a scientist.

  67. About a decade ago,
    concerned about climate,
  68. I started to talk with scientists about
    potential countermeasures to warming.
  69. These conversations grew
    into collaborations
  70. that became the Marine
    Cloud Brightening Project,
  71. which I'll talk about momentarily,
  72. and the nonprofit policy organization
    SilverLining, where I am today.
  73. I work with politicians, researchers,
  74. members of the tech industry and others
  75. to talk about some of these ideas.
  76. Early on, I met British
    atmospheric scientist John Latham,
  77. who proposed cooling the climate
    the way that the ships do,
  78. but with a natural source of particles:
  79. sea-salt mist from seawater
  80. sprayed from ships into areas
    of susceptible clouds over the ocean.
  81. The approach became known
    by the name I gave it then,
  82. "marine cloud brightening."
  83. Early modeling studies suggested
    that by deploying marine cloud brightening
  84. in just 10 to 20 percent
    of susceptible ocean clouds,
  85. it might be possible to offset
    as much as two degrees Celsius's warming.
  86. It might even be possible
    to brighten clouds in local regions
  87. to reduce the impacts caused
    by warming ocean surface temperatures.
  88. For example, regions
    such as the Gulf Atlantic
  89. might be cooled in the months
    before a hurricane season
  90. to reduce the force of storms.
  91. Or, it might be possible to cool waters
    flowing onto coral reefs
  92. overwhelmed by heat stress,
  93. like Australia's Great Barrier Reef.
  94. But these ideas are only theoretical,

  95. and brightening marine clouds
    is not the only way
  96. to increase the reflection
    of the sunlight from the atmosphere.
  97. Another occurs when large volcanoes
    release material with enough force
  98. to reach the upper layer
    of the atmosphere, the stratosphere.
  99. When Mount Pinatubo erupted in 1991,
  100. it released material
    into the stratosphere,
  101. including sulfates that mix
    with the atmosphere to reflect sunlight.
  102. This material remained
    and circulated around the planet.
  103. It was enough to cool the climate
    by over half a degree Celsius
  104. for about two years.
  105. This cooling led to a striking increase
    in Arctic ice cover in 1992,
  106. which dropped in subsequent years
    as the particles fell back to earth.
  107. But the volcanic phenomenon
    led Nobel Prize winner Paul Crutzen
  108. to propose the idea that dispersing
    particles into the stratosphere
  109. in a controlled way might be
    a way to counter global warming.
  110. Now, this has risks
    that we don't understand,
  111. including things like
    heating up the stratosphere
  112. or damage to the ozone layer.
  113. Scientists think that there could be
    safe approaches to this,
  114. but is this really where we are?
  115. Is this really worth considering?
  116. This is a simulation

  117. from the US National Center
    for Atmospheric Research
  118. global climate model showing,
    earth surface temperatures through 2100.
  119. The globe on the left visualizes
    our current trajectory,
  120. and on the right, a world where particles
    are introduced into the stratosphere
  121. gradually in 2020,
  122. and maintained through 2100.
  123. Intervention keeps surface temperatures
    near those of today,
  124. while without it, temperatures rise
    well over three degrees.
  125. This could be the difference
    between a safe and an unsafe world.
  126. So, if there's even a chance
    that this could be close to reality,

  127. is this something
    we should consider seriously?
  128. Today, there are no capabilities,
  129. and scientific knowledge
    is extremely limited.
  130. We don't know whether these types
    of interventions are even feasible,
  131. or how to characterize their risks.
  132. Researchers hope to explore
    some basic questions
  133. that might help us know
    whether or not these might be real options
  134. or whether we should rule them out.
  135. It requires multiple ways
    of studying the climate system,
  136. including computer models
    to forecast changes,
  137. analytic techniques like machine learning,
  138. and many types of observations.
  139. And though it's controversial,
  140. it's also critical that researchers
    develop core technologies
  141. and perform small-scale,
    real-world experiments.
  142. There are two research programs
    proposing experiments like this.

  143. At Harvard, the SCoPEx experiment
    would release very small amounts
  144. of sulfates, calcium carbonate and water
    into the stratosphere with a balloon,
  145. to study chemistry and physics effects.
  146. How much material?
  147. Less than the amount released
    in one minute of flight
  148. from a commercial aircraft.
  149. So this is definitely not dangerous,
  150. and it may not even be scary.
  151. At the University of Washington,

  152. scientists hope to spray
    a fine mist of salt water into clouds
  153. in a series of land and ocean tests.
  154. If those are successful,
    this would culminate in experiments
  155. to measurably brighten
    an area of clouds over the ocean.
  156. The marine cloud brightening effort
    is the first to develop any technology
  157. for generating aerosols for atmospheric
    sunlight reflection in this way.
  158. It requires producing
    very tiny particles --
  159. think about the mist that comes
    out of an asthma inhaler --
  160. at massive scale -- so think
    of looking up at a cloud.
  161. It's a tricky engineering problem.
  162. So this one nozzle they developed

  163. generates three trillion
    particles per second,
  164. 80 nanometers in size,
  165. from very corrosive saltwater.
  166. It was developed by a team
    of retired engineers in Silicon Valley --
  167. here they are --
  168. working full-time for six years,
    without pay, for their grandchildren.
  169. It will take a few million dollars
    and another year or two
  170. to develop the full spray system
    they need to do these experiments.
  171. In other parts of the world,
    research efforts are emerging,
  172. including small modeling programs
    at Beijing Normal University in China,
  173. the Indian Institute of Science,
  174. a proposed center for climate repair
    at Cambridge University in the UK
  175. and the DECIMALS Fund,
  176. which sponsors researchers
    in global South countries
  177. to study the potential impacts
    of these sunlight interventions
  178. in their part of the world.
  179. But all of these programs,
    including the experimental ones,
  180. lack significant funding.
  181. And understanding
    these interventions is a hard problem.
  182. The earth is a vast, complex system
  183. and we need major investments
    in climate models, observations
  184. and basic science
  185. to be able to predict climate
    much better than we can today
  186. and manage both our accidental
    and any intentional interventions.
  187. And it could be urgent.

  188. Recent scientific reports
    predict that in the next few decades,
  189. earth's fever is on a path to devastation:
  190. extreme heat and fires,
  191. major loss of ocean life,
  192. collapse of Arctic ice,
  193. displacement and suffering
    for hundreds of millions of people.
  194. The fever could even reach tipping points
    where warming takes over
  195. and human efforts are no longer enough
  196. to counter accelerating changes
    in natural systems.
  197. To prevent this circumstance,

  198. the UN's International Panel
    on Climate Change predicts
  199. that we need to stop
    and even reverse emissions by 2050.
  200. How? We have to quickly and radically
    transform major economic sectors,
  201. including energy, construction,
    agriculture, transportation and others.
  202. And it is imperative that we do this
    as fast as we can.
  203. But our fever is now so high
  204. that climate experts say
    we also have to remove
  205. massive quantities of CO2
    from the atmosphere,
  206. possibly 10 times
    all of the world's annual emissions,
  207. in ways that aren't proven yet.
  208. Right now, we have slow-moving solutions
    to a fast-moving problem.

  209. Even with the most optimistic assumptions,
  210. our exposure to risk
    in the next 10 to 30 years
  211. is unacceptably high, in my opinion.
  212. Could interventions like these
    provide fast-acting medicine if we need it

  213. to reduce the earth's fever
    while we address its underlying causes?
  214. There are real concerns about this idea.
  215. Some people are very worried
    that even researching these interventions
  216. could provide an excuse to delay efforts
    to reduce emissions.
  217. This is also known as a moral hazard.
  218. But, like most medicines,
  219. interventions are more dangerous
    the more that you do,
  220. so research actually
    tends to draw out the fact
  221. that we absolutely,
    positively cannot continue
  222. to fill up the atmosphere
    with greenhouse gases,
  223. that these kinds of alternatives are risky
  224. and if we were to use them,
  225. we would need to use
    as little as possible.
  226. But even so,

  227. could we ever learn enough
    about these interventions
  228. to manage the risk?
  229. Who would make decisions
    about when and how to intervene?
  230. What if some people are worse off,
  231. or they just think they are?
  232. These are really hard problems.
  233. But what really worries me
    is that as climate impacts worsen,
  234. leaders will be called on to respond
    by any means available.
  235. I for one don't want them to act
    without real information
  236. and much better options.
  237. Scientists think it will take
    a decade of research

  238. just to assess these interventions,
  239. before we ever were
    to develop or use them.
  240. Yet today, the global level of investment
    in these interventions
  241. is effectively zero.
  242. So, we need to move quickly
  243. if we want policymakers
    to have real information
  244. on this kind of emergency medicine.
  245. There is hope!

  246. The world has solved
    these kinds of problems before.
  247. In the 1970s, we identified
    an existential threat
  248. to our protective ozone layer.
  249. In the 1980s, scientists,
    politicians and industry
  250. came together in a solution to replace
    the chemicals causing the problem.
  251. They achieved this with the only
    legally binding environmental agreement
  252. signed by all countries in the world,
  253. the Montreal Protocol.
  254. Still in force today,
  255. it has resulted in a recovery
    of the ozone layer
  256. and is the most successful
    environmental protection effort
  257. in human history.
  258. We have a far greater threat now,

  259. but we do have the ability
    to develop and agree on solutions
  260. to protect people
  261. and restore our climate to health.
  262. This could mean that to remain safe,
  263. we reflect sunlight for a few decades,
  264. while we green our industries
    and remove CO2.
  265. It definitely means we must work now
  266. to understand our options
    for this kind of emergency medicine.
  267. Thank you,

  268. (Applause)