1
00:00:00,877 --> 00:00:04,807
I'm here to talk to you about something
important that may be new to you.

2
00:00:05,434 --> 00:00:09,131
The governments of the world are about
to conduct an unintentional experiment

3
00:00:09,131 --> 00:00:10,655
on our climate.

4
00:00:10,909 --> 00:00:16,325
In 2020, new rules will require ships
to lower their sulfur emissions

5
00:00:16,325 --> 00:00:18,441
by scrubbing their dirty exhaust

6
00:00:18,441 --> 00:00:20,392
or switching to cleaner fuels.

7
00:00:20,905 --> 00:00:23,562
For human health, this is really good,

8
00:00:23,562 --> 00:00:25,952
but sulfur particles
in the emission of ships

9
00:00:25,952 --> 00:00:28,713
also have an effect on clouds.

10
00:00:29,221 --> 00:00:33,082
This is a satellite image of marine clouds

11
00:00:33,082 --> 00:00:35,008
off the Pacific West Coast
of the United States.

12
00:00:35,008 --> 00:00:38,339
The streaks in the clouds are created
by the exhaust from ships.

13
00:00:38,339 --> 00:00:41,096
Ships' emissions include
both greenhouse gases,

14
00:00:41,096 --> 00:00:44,050
which trap heat over long periods of time,

15
00:00:44,050 --> 00:00:47,120
and particulates like sulfates
that mix with clouds

16
00:00:47,120 --> 00:00:49,415
and temporarily make them brighter.

17
00:00:49,920 --> 00:00:53,187
Brighter clouds reflect
more sunlight back to space,

18
00:00:53,187 --> 00:00:55,619
cooling the climate.

19
00:00:55,619 --> 00:00:57,741
So in fact,

20
00:00:57,741 --> 00:01:01,019
humans are currently running
two unintentional experiments

21
00:01:01,019 --> 00:01:01,968
on our climate.

22
00:01:01,968 --> 00:01:06,102
In the first one, we're increasing
the concentration of greenhouse gases

23
00:01:06,102 --> 00:01:07,793
and gradually warming the Earth System.

24
00:01:07,793 --> 00:01:11,372
This works something like a fever
in the human body.

25
00:01:11,372 --> 00:01:14,535
If the fever remains low,
its effects are mild,

26
00:01:14,535 --> 00:01:18,037
but as the fever rises,
damage grows more severe

27
00:01:18,037 --> 00:01:20,020
and eventually devastating.

28
00:01:20,020 --> 00:01:22,654
We're seeing a little of this now.

29
00:01:22,654 --> 00:01:24,351
In our other experiment,

30
00:01:24,351 --> 00:01:26,736
we're planning to remove
a layer of particles

31
00:01:26,736 --> 00:01:29,970
that brighten clouds and shield us
from some of this warming.

32
00:01:30,546 --> 00:01:33,470
The effect is strongest
in ocean clouds like these

33
00:01:33,470 --> 00:01:39,433
and scientists expect the reduction
of sulfur emissions from ships next year

34
00:01:39,433 --> 00:01:42,284
to produce a measurable increase
in global warming.

35
00:01:43,633 --> 00:01:45,595
Bit of a shocker?

36
00:01:45,595 --> 00:01:50,034
In fact, most emissions contain sulfates
that brighten clouds:

37
00:01:50,034 --> 00:01:53,880
coal, diesel exhaust, forest fires.

38
00:01:53,880 --> 00:01:58,112
Scientists estimate that the total
cooling effect from emission particles,

39
00:01:58,112 --> 00:02:00,964
which they call aerosols
when they're in the climate,

40
00:02:00,964 --> 00:02:05,839
may be as much as all of the warming
we've experienced up until now.

41
00:02:06,068 --> 00:02:08,989
There's a lot of uncertainty
around this effect,

42
00:02:08,989 --> 00:02:13,387
and it's one of the major reasons
why we have difficulty predicting climate,

43
00:02:13,387 --> 00:02:17,396
but this is cooling that we'll lose
as emissions fall.

44
00:02:18,185 --> 00:02:21,917
So to be clear, humans
are currently cooling the planet

45
00:02:21,917 --> 00:02:26,778
by dispersing particles into
the atmosphere at massive scale.

46
00:02:26,778 --> 00:02:29,810
We just don't know how much,
and we're doing it accidentally.

47
00:02:30,387 --> 00:02:32,179
That's worrying,

48
00:02:32,179 --> 00:02:36,195
but it could mean that we have
a fast-acting way to reduce warming,

49
00:02:36,195 --> 00:02:39,763
emergency medicine for
our climate fever if we needed it,

50
00:02:39,763 --> 00:02:42,540
and it's a medicine
with origins in nature.

51
00:02:43,768 --> 00:02:47,340
This is a NASA simulation
of Earth's atmosphere

52
00:02:47,340 --> 00:02:50,168
showing clouds and particles
moving over the planet.

53
00:02:50,168 --> 00:02:54,508
The brightness is the Sun's light
reflecting from particles of clouds,

54
00:02:54,508 --> 00:03:01,643
and this reflective shield
is one of the primary ways

55
00:03:01,695 --> 00:03:03,165
that nature keeps the planet
cool enough for humans

56
00:03:03,838 --> 00:03:04,278
and all of the life that we know.

57
00:03:04,278 --> 00:03:08,754
In 2015, scientists assessed possibilities
for rapidly cooling the climate.

58
00:03:08,964 --> 00:03:11,408
They discounted things
like mirrors in space,

59
00:03:11,408 --> 00:03:14,255
ping-pong balls in the ocean,
plastic sheets on the Arctic,

60
00:03:14,255 --> 00:03:19,783
and they found that
the most viable approaches

61
00:03:19,783 --> 00:03:23,850
involved slightly increasing
this atmospheric reflectivity.

62
00:03:24,606 --> 00:03:28,990
In fact, it's possible that reflecting
just one or two percent more sunlight

63
00:03:28,990 --> 00:03:30,650
from the atmosphere

64
00:03:30,650 --> 00:03:34,348
could offset two degrees Celsius
or more of warming.

65
00:03:35,800 --> 00:03:39,459
Now, I'm a technology executive,
not a scientist.

66
00:03:39,459 --> 00:03:42,007
About a decade ago,
concerned about climate,

67
00:03:42,007 --> 00:03:46,432
I started to talk with scientists about
potential countermeasures to warming.

68
00:03:47,251 --> 00:03:50,130
These conversation grew
into collaborations that became

69
00:03:50,130 --> 00:03:54,810
the Marine Cloud Brightening Project,
which I'll talk about momentarily,

70
00:03:54,810 --> 00:03:58,863
and the non-profit policy organization
Silver Lining, where I am today.

71
00:03:59,723 --> 00:04:03,192
I work with politicians, researchers,

72
00:04:03,192 --> 00:04:05,294
members of the tech industry and others

73
00:04:05,294 --> 00:04:07,433
to talk about some of these ideas.

74
00:04:08,239 --> 00:04:11,445
Early on, I met British
atmospheric scientist John Latham,

75
00:04:11,445 --> 00:04:14,301
who proposed cooling the climate
the way that the ships do,

76
00:04:14,301 --> 00:04:16,775
but with a natural source of particles:

77
00:04:16,775 --> 00:04:19,132
sea salt mist from seawater

78
00:04:19,585 --> 00:04:23,232
sprayed from ships into areas
of susceptible clouds over the ocean.

79
00:04:23,583 --> 00:04:26,453
The approach became known
by the name I gave it then,

80
00:04:26,453 --> 00:04:28,251
marine cloud brightening.

81
00:04:28,251 --> 00:04:32,526
Early modeling studies suggested
that by deploying marine cloud brightening

82
00:04:32,526 --> 00:04:36,267
in just 10 to 20 percent
of susceptible ocean clouds,

83
00:04:36,267 --> 00:04:41,191
it might be possible to offset
as much as two degrees Celsius of warming.

84
00:04:41,400 --> 00:04:45,052
It might even be possible
to brighten clouds in local regions

85
00:04:45,052 --> 00:04:48,962
to reduce the impacts caused
by warming ocean surface temperatures.

86
00:04:48,962 --> 00:04:51,760
For example, regions
such as the Gulf Atlantic

87
00:04:51,760 --> 00:04:54,299
might be cooled in the months
before a hurricane season

88
00:04:54,299 --> 00:04:56,766
to reduce the force of storms.

89
00:04:56,766 --> 00:05:00,754
Or, it might be possible to cool waters
flowing onto coral reefs

90
00:05:00,754 --> 00:05:03,219
overwhelmed by heat stress,
like Australia's Great Barrier Reef.

91
00:05:03,219 --> 00:05:07,090
But these ideas are only theoretical,

92
00:05:07,090 --> 00:05:10,878
and brightening marine clouds
is not the only way

93
00:05:10,878 --> 00:05:14,263
to increase the reflection
of the sunlight from the atmosphere.

94
00:05:14,263 --> 00:05:19,756
Another occurs when large volcanoes
release material with enough force

95
00:05:19,756 --> 00:05:22,985
to reach the upper layer
of the atmosphere, the stratosphere.

96
00:05:22,985 --> 00:05:25,550
When Mount Pinatubo erupted in 1991,

97
00:05:25,550 --> 00:05:28,775
it released material into
the stratosphere including sulfates

98
00:05:28,775 --> 00:05:33,212
that mix with the atmosphere
to reflect sunlight.

99
00:05:33,212 --> 00:05:36,498
This material remained
and circulated around the planet.

100
00:05:36,498 --> 00:05:41,299
It was enough to cool the climate
by over half a degree Celsius

101
00:05:41,299 --> 00:05:44,282
for about two years.

102
00:05:44,282 --> 00:05:50,399
This cooling led to a striking increase
in Arctic ice cover in 1992,

103
00:05:50,399 --> 00:05:54,327
which dropped in subsequent years
as the particles fell back to the Earth,

104
00:05:54,327 --> 00:05:58,391
but the volcanic phenomenon
led Nobel Prize Winner Paul Crutzen

105
00:05:58,391 --> 00:06:01,970
to propose the idea that dispersing
particles into the stratosphere

106
00:06:01,970 --> 00:06:06,557
in a controlled way might be
a way to counter global warming.

107
00:06:06,557 --> 00:06:09,988
Now, this has risks
that we don't understand,

108
00:06:09,988 --> 00:06:11,867
including things like
heating up the stratosphere

109
00:06:11,867 --> 00:06:14,209
or damage to the ozone layer.

110
00:06:14,209 --> 00:06:17,487
Scientists think that there
could be safe approaches to this,

111
00:06:17,487 --> 00:06:20,958
but is this really where we are?

112
00:06:20,958 --> 00:06:22,807
Is this really worth considering?

113
00:06:22,807 --> 00:06:24,865
This is a simulation

114
00:06:24,865 --> 00:06:27,810
from the US National Center
for Atmospheric Research

115
00:06:27,810 --> 00:06:31,754
Global Climate Model showing
Earth surface temperatures through 2100.

116
00:06:31,754 --> 00:06:36,163
The globe on the left visualizes
our current trajectory,

117
00:06:36,163 --> 00:06:39,428
and on the right, a world where particles
are introduced into the stratosphere

118
00:06:39,428 --> 00:06:41,393
gradually in 2020

119
00:06:41,393 --> 00:06:43,315
and maintained through 2100.

120
00:06:43,315 --> 00:06:47,134
Intervention keeps surface temperatures
near those of today,

121
00:06:47,134 --> 00:06:53,144
while without it temperatures rise
well over three degrees.

122
00:06:53,144 --> 00:06:56,514
This could be the difference
between a safe and an unsafe world.

123
00:06:57,554 --> 00:07:01,885
So, if there's even a chance
that this could be close to reality,

124
00:07:01,885 --> 00:07:06,039
is this something
we should consider seriously?

125
00:07:06,039 --> 00:07:09,661
Today, there are no capabilities

126
00:07:09,661 --> 00:07:11,618
and scientific knowledge
is extremely limited.

127
00:07:11,618 --> 00:07:15,822
We don't know whether these types
of interventions are even feasible,

128
00:07:15,822 --> 00:07:19,152
or how to characterize their risks.

129
00:07:19,152 --> 00:07:22,004
Researchers hope to explore
some basic questions

130
00:07:22,004 --> 00:07:24,365
that might help us know

131
00:07:24,365 --> 00:07:26,307
whether or not these might be real options

132
00:07:26,307 --> 00:07:28,404
or whether we should rule them out.

133
00:07:28,404 --> 00:07:31,990
It requires multiple ways
of studying the climate system

134
00:07:31,990 --> 00:07:36,002
including computer models
to forecast changes,

135
00:07:36,002 --> 00:07:37,785
analytic techniques like machine learning,

136
00:07:37,785 --> 00:07:40,954
and many types of observations.

137
00:07:40,954 --> 00:07:42,377
And though it's controversial,

138
00:07:42,377 --> 00:07:46,907
it's also critical that researchers
develop core technologies

139
00:07:46,907 --> 00:07:51,275
and perform small-scale
real world experiments.

140
00:07:51,275 --> 00:07:57,117
There are two research programs
proposing experiments like this.

141
00:07:57,117 --> 00:08:00,715
At Harvard, the SCoPEx experiment
would release very small amounts

142
00:08:00,715 --> 00:08:04,059
of sulfates, calcium carbonate, and water
into the stratosphere with a balloon

143
00:08:04,059 --> 00:08:09,776
to study chemistry and physics effects.

144
00:08:09,776 --> 00:08:11,139
How much material?

145
00:08:11,139 --> 00:08:14,544
Less than the amount released
in one minute of flight

146
00:08:14,544 --> 00:08:15,747
from a commercial aircraft.

147
00:08:15,747 --> 00:08:17,806
So this is definitely not dangerous,

148
00:08:17,806 --> 00:08:21,386
and it may not even be scary.

149
00:08:21,386 --> 00:08:23,974
At the University of Washington,

150
00:08:23,974 --> 00:08:27,312
scientists hope to spray
a fine mist of salt water into clouds

151
00:08:27,312 --> 00:08:30,503
in a series of land an ocean tests.

152
00:08:30,503 --> 00:08:32,776
If those are successful,
this would culminate in experiments

153
00:08:32,776 --> 00:08:36,371
to measurably brighten
an area of clouds over the ocean.

154
00:08:37,018 --> 00:08:40,400
The marine cloud brightening effort
is the first to develop any technology

155
00:08:40,400 --> 00:08:45,067
for generating aerosols for atmospheric
sunlight reflection in this way.

156
00:08:45,067 --> 00:08:48,489
It requires producing
very tiny particles --

157
00:08:48,489 --> 00:08:52,614
think about the mist that comes
out of an asthma inhaler --

158
00:08:52,614 --> 00:08:55,814
at massive scale -- so think
of looking up at a cloud.

159
00:08:56,533 --> 00:08:58,937
It's a tricky engineering problem.

160
00:08:58,937 --> 00:09:04,065
So this one nozzle the developed generates
three trillion particles per second,

161
00:09:04,065 --> 00:09:06,012
80 nanometers in size,

162
00:09:06,012 --> 00:09:08,515
from very corrosive saltwater.

163
00:09:08,515 --> 00:09:12,652
It was developed by a team
of retired engineers in Silicon Valley --

164
00:09:12,652 --> 00:09:14,083
here they are --

165
00:09:14,083 --> 00:09:19,314
working full time for six years
without pay for their grandchildren.

166
00:09:19,645 --> 00:09:22,273
It will take a few million dollars
and another year or two

167
00:09:22,273 --> 00:09:26,748
to develop the full spray system
they need to do these experiments.

168
00:09:26,748 --> 00:09:30,617
In other parts of the world,
research efforts are emerging,

169
00:09:30,617 --> 00:09:34,262
including small modeling programs
at Beijing Normal University in China,

170
00:09:34,262 --> 00:09:37,287
the Indian Institute of Science,

171
00:09:37,287 --> 00:09:42,050
a proposed center for climate repair
at Cambridge University in the UK,

172
00:09:42,050 --> 00:09:44,231
and the ?? Fund,

173
00:09:44,231 --> 00:09:46,904
which sponsors researchers
in Global South countries

174
00:09:46,904 --> 00:09:50,026
to study the potential impacts
of these sunlight interventions

175
00:09:50,026 --> 00:09:52,090
in their part of the world.

176
00:09:52,090 --> 00:09:54,337
But all of these programs,

177
00:09:54,337 --> 00:09:56,203
including the experimental ones,

178
00:09:56,203 --> 00:09:58,801
lack significant funding.

179
00:09:58,801 --> 00:10:01,736
And understanding these
interventions is a hard problem.

180
00:10:01,736 --> 00:10:04,182
The Earth is a vast, complex system

181
00:10:04,182 --> 00:10:07,125
and we need major investments
in climate models, observations

182
00:10:07,125 --> 00:10:08,444
and basic science

183
00:10:08,444 --> 00:10:12,127
to be able to predict climate
much better than we can today

184
00:10:12,127 --> 00:10:16,945
and manage both our accidental
and any intentional interventions.

185
00:10:16,945 --> 00:10:19,387
And it could be urgent.

186
00:10:19,387 --> 00:10:24,328
Recent scientific reports predict
that in the next few decades

187
00:10:24,328 --> 00:10:26,892
Earth's fever is on a path to devastation:

188
00:10:26,892 --> 00:10:29,278
extreme heat and fires,

189
00:10:29,278 --> 00:10:33,139
major loss of ocean life,

190
00:10:33,139 --> 00:10:35,996
collapse of Arctic ice,

191
00:10:35,996 --> 00:10:39,832
displacement and suffering
for hundreds of millions of people.

192
00:10:40,477 --> 00:10:44,139
The fever could even reach tipping points
where warming takes over

193
00:10:44,139 --> 00:10:46,462
and human efforts are no longer enough

194
00:10:46,462 --> 00:10:50,104
to counter accelerating changes
in natural systems.

195
00:10:50,104 --> 00:10:52,339
To prevent this circumstance,

196
00:10:52,339 --> 00:10:55,007
the UN's International Panel
on Climate Change predicts

197
00:10:55,007 --> 00:10:59,081
that we need to stop
and even reverse emissions by 2050.

198
00:10:59,081 --> 00:11:03,896
How? We have to quickly and radically
transform major economic sectors,

199
00:11:03,896 --> 00:11:08,618
including energy, construction,
agriculture, transportation and others.

200
00:11:08,618 --> 00:11:13,667
And it is imperative that we do this
as fast as we can.

201
00:11:13,667 --> 00:11:15,739
But our fever is now so high

202
00:11:15,739 --> 00:11:17,945
that climate experts say
we also have to remove

203
00:11:17,945 --> 00:11:20,607
massive quantities of CO2
from the atmosphere,

204
00:11:20,607 --> 00:11:24,047
possibly 10 times all of
the world's annual emissions,

205
00:11:24,047 --> 00:11:26,801
in ways that aren't proven yet.

206
00:11:26,801 --> 00:11:32,184
Right now, we have slow-moving solutions
to a fast-moving problem.

207
00:11:32,184 --> 00:11:34,350
Even with the most optimistic assumptions,

208
00:11:34,350 --> 00:11:37,268
our exposure to risk
in the next 10 to 30 years

209
00:11:37,268 --> 00:11:40,377
is unacceptably high in my opinion.

210
00:11:40,826 --> 00:11:44,764
Could interventions like these
provide fast-acting medicine if we need it

211
00:11:44,764 --> 00:11:48,308
to reduce the Earth's fever while we
address its underlying causes?

212
00:11:48,821 --> 00:11:51,446
There are real concerns about this idea.

213
00:11:51,446 --> 00:11:54,708
Some people are very worried
that even researching these interventions

214
00:11:54,708 --> 00:11:59,100
could provide an excuse to delay efforts
to reduce emissions.

215
00:11:59,100 --> 00:12:01,875
This is also known as a moral hazard.

216
00:12:01,875 --> 00:12:04,118
But like most interventions,

217
00:12:04,118 --> 00:12:07,399
interventions are more dangerous
the more that you do,

218
00:12:07,399 --> 00:12:13,118
so research actually tends to draw out
the fact that we absolutely positively

219
00:12:13,118 --> 00:12:15,937
cannot continue to fill up
the atmosphere with greenhouse gases,

220
00:12:15,937 --> 00:12:18,305
that these kinds of alternatives are risky

221
00:12:18,305 --> 00:12:23,388
and if we were to use them we would need
to use as little as possible.

222
00:12:24,946 --> 00:12:27,211
But even so,

223
00:12:27,211 --> 00:12:29,728
could we ever learn enough
about these interventions

224
00:12:29,728 --> 00:12:31,328
to manage the risk?

225
00:12:31,328 --> 00:12:35,434
Who would make decisions
about when and how to intervene?

226
00:12:35,434 --> 00:12:40,937
What if some people are worse off,

227
00:12:40,937 --> 00:12:43,181
or they just think they are?

228
00:12:43,181 --> 00:12:44,550
These are really hard problems.

229
00:12:44,550 --> 00:12:46,497
But what really worries me

230
00:12:46,497 --> 00:12:48,696
is that as climate impacts worsen,

231
00:12:48,696 --> 00:12:52,424
leaders will be called on to respond
by any means available.

232
00:12:53,036 --> 00:12:55,890
I for one don't want them to act
without real information

233
00:12:55,890 --> 00:12:58,958
and much better options.

234
00:12:58,958 --> 00:13:00,996
Scientists think it will take
a decade of research

235
00:13:00,996 --> 00:13:03,370
just to assess these interventions

236
00:13:03,370 --> 00:13:06,299
before we ever were
to develop or use them.

237
00:13:06,299 --> 00:13:10,892
Yet today, the global level of investment
in these interventions

238
00:13:10,892 --> 00:13:13,463
is effectively zero.

239
00:13:13,463 --> 00:13:17,246
So, we need to move quickly

240
00:13:17,246 --> 00:13:20,040
if we want policymakers
to have real information

241
00:13:20,040 --> 00:13:22,244
on this kind of emergency medicine.

242
00:13:24,369 --> 00:13:26,737
There is hope!

243
00:13:26,737 --> 00:13:29,834
The world has solved
these kinds of problems before.

244
00:13:29,834 --> 00:13:33,085
In the 1970s, we identified
an existential threat

245
00:13:33,085 --> 00:13:35,336
to our protective ozone layer.

246
00:13:35,336 --> 00:13:38,628
In the 1980s, scientists,
politicians and industry

247
00:13:38,628 --> 00:13:42,697
came together in a solution to replace
the chemicals causing the problem.

248
00:13:43,137 --> 00:13:46,623
They achieved this with the only
legally binding environmental agreement

249
00:13:46,623 --> 00:13:48,878
signed by all countries in the world,

250
00:13:48,878 --> 00:13:50,611
the Montreal Protocol.

251
00:13:50,842 --> 00:13:52,876
Still in force today,

252
00:13:52,876 --> 00:13:55,684
it has resulted in
a recovery of the ozone layer

253
00:13:55,684 --> 00:13:58,468
and is the most successful
environmental protection effort

254
00:13:58,468 --> 00:14:00,080
in human history.

255
00:14:01,074 --> 00:14:03,827
We have a far greater threat now,

256
00:14:03,827 --> 00:14:08,177
but we do have the ability
to develop and agree on solutions

257
00:14:08,177 --> 00:14:09,703
to protect people

258
00:14:09,703 --> 00:14:12,535
and restore our climate to health.

259
00:14:12,741 --> 00:14:16,095
This could mean that to remain safe,

260
00:14:16,095 --> 00:14:17,863
we reflect sunlight for a few decades

261
00:14:17,863 --> 00:14:20,681
while we green our industries
and remove CO2.

262
00:14:21,896 --> 00:14:24,717
It definitely means we must work now

263
00:14:24,717 --> 00:14:29,804
to understand our options
for this kind of emergency medicine.

264
00:14:29,804 --> 00:14:31,594
Thank you,

265
00:14:31,594 --> 00:14:35,909
(Applause)