WEBVTT 00:00:00.877 --> 00:00:04.807 I'm here to talk to you about something important that may be new to you. 00:00:05.434 --> 00:00:09.131 The governments of the world are about to conduct an unintentional experiment 00:00:09.131 --> 00:00:10.655 on our climate. 00:00:10.909 --> 00:00:16.325 In 2020, new rules will require ships to lower their sulfur emissions 00:00:16.325 --> 00:00:18.441 by scrubbing their dirty exhaust 00:00:18.441 --> 00:00:20.392 or switching to cleaner fuels. 00:00:20.905 --> 00:00:23.562 For human health, this is really good, 00:00:23.562 --> 00:00:25.952 but sulfur particles in the emission of ships 00:00:25.952 --> 00:00:28.713 also have an effect on clouds. 00:00:29.221 --> 00:00:33.082 This is a satellite image of marine clouds 00:00:33.082 --> 00:00:35.008 off the Pacific West Coast of the United States. 00:00:35.008 --> 00:00:38.339 The streaks in the clouds are created by the exhaust from ships. 00:00:38.339 --> 00:00:41.096 Ships' emissions include both greenhouse gases, 00:00:41.096 --> 00:00:44.050 which trap heat over long periods of time, 00:00:44.050 --> 00:00:47.120 and particulates like sulfates that mix with clouds 00:00:47.120 --> 00:00:49.415 and temporarily make them brighter. 00:00:49.920 --> 00:00:53.187 Brighter clouds reflect more sunlight back to space, 00:00:53.187 --> 00:00:55.619 cooling the climate. 00:00:55.619 --> 00:00:57.741 So in fact, 00:00:57.741 --> 00:01:01.019 humans are currently running two unintentional experiments 00:01:01.019 --> 00:01:01.968 on our climate. 00:01:01.968 --> 00:01:06.102 In the first one, we're increasing the concentration of greenhouse gases 00:01:06.102 --> 00:01:07.793 and gradually warming the Earth System. 00:01:07.793 --> 00:01:11.372 This works something like a fever in the human body. 00:01:11.372 --> 00:01:14.535 If the fever remains low, its effects are mild, 00:01:14.535 --> 00:01:18.037 but as the fever rises, damage grows more severe 00:01:18.037 --> 00:01:20.020 and eventually devastating. 00:01:20.020 --> 00:01:22.654 We're seeing a little of this now. 00:01:22.654 --> 00:01:24.351 In our other experiment, 00:01:24.351 --> 00:01:26.736 we're planning to remove a layer of particles 00:01:26.736 --> 00:01:29.970 that brighten clouds and shield us from some of this warming. 00:01:30.546 --> 00:01:33.470 The effect is strongest in ocean clouds like these 00:01:33.470 --> 00:01:39.433 and scientists expect the reduction of sulfur emissions from ships next year 00:01:39.433 --> 00:01:42.284 to produce a measurable increase in global warming. NOTE Paragraph 00:01:43.633 --> 00:01:45.595 Bit of a shocker? 00:01:45.595 --> 00:01:50.034 In fact, most emissions contain sulfates that brighten clouds: 00:01:50.034 --> 00:01:53.880 coal, diesel exhaust, forest fires. 00:01:53.880 --> 00:01:58.112 Scientists estimate that the total cooling effect from emission particles, 00:01:58.112 --> 00:02:00.964 which they call aerosols when they're in the climate, 00:02:00.964 --> 00:02:05.839 may be as much as all of the warming we've experienced up until now. 00:02:06.068 --> 00:02:08.989 There's a lot of uncertainty around this effect, 00:02:08.989 --> 00:02:13.387 and it's one of the major reasons why we have difficulty predicting climate, 00:02:13.387 --> 00:02:17.396 but this is cooling that we'll lose as emissions fall. 00:02:18.185 --> 00:02:21.917 So to be clear, humans are currently cooling the planet 00:02:21.917 --> 00:02:26.778 by dispersing particles into the atmosphere at massive scale. 00:02:26.778 --> 00:02:29.810 We just don't know how much, and we're doing it accidentally. 00:02:30.387 --> 00:02:32.179 That's worrying, 00:02:32.179 --> 00:02:36.195 but it could mean that we have a fast-acting way to reduce warming, 00:02:36.195 --> 00:02:39.763 emergency medicine for our climate fever if we needed it, 00:02:39.763 --> 00:02:42.540 and it's a medicine with origins in nature. NOTE Paragraph 00:02:43.768 --> 00:02:47.340 This is a NASA simulation of Earth's atmosphere 00:02:47.340 --> 00:02:50.168 showing clouds and particles moving over the planet. 00:02:50.168 --> 00:02:54.508 The brightness is the Sun's light reflecting from particles of clouds, 00:02:54.508 --> 00:03:01.643 and this reflective shield is one of the primary ways 00:03:01.695 --> 00:03:03.165 that nature keeps the planet cool enough for humans 00:03:03.838 --> 00:03:04.278 and all of the life that we know. 00:03:04.278 --> 00:03:08.754 In 2015, scientists assessed possibilities for rapidly cooling the climate. 00:03:08.964 --> 00:03:11.408 They discounted things like mirrors in space, 00:03:11.408 --> 00:03:14.255 ping-pong balls in the ocean, plastic sheets on the Arctic, 00:03:14.255 --> 00:03:19.783 and they found that the most viable approaches 00:03:19.783 --> 00:03:23.850 involved slightly increasing this atmospheric reflectivity. 00:03:24.606 --> 00:03:28.990 In fact, it's possible that reflecting just one or two percent more sunlight 00:03:28.990 --> 00:03:30.650 from the atmosphere 00:03:30.650 --> 00:03:34.348 could offset two degrees Celsius or more of warming. NOTE Paragraph 00:03:35.800 --> 00:03:39.459 Now, I'm a technology executive, not a scientist. 00:03:39.459 --> 00:03:42.007 About a decade ago, concerned about climate, 00:03:42.007 --> 00:03:46.432 I started to talk with scientists about potential countermeasures to warming. 00:03:47.251 --> 00:03:50.130 These conversation grew into collaborations that became 00:03:50.130 --> 00:03:54.810 the Marine Cloud Brightening Project, which I'll talk about momentarily, 00:03:54.810 --> 00:03:58.863 and the non-profit policy organization Silver Lining, where I am today. 00:03:59.723 --> 00:04:03.192 I work with politicians, researchers, 00:04:03.192 --> 00:04:05.294 members of the tech industry and others 00:04:05.294 --> 00:04:07.433 to talk about some of these ideas. 00:04:08.239 --> 00:04:11.445 Early on, I met British atmospheric scientist John Latham, 00:04:11.445 --> 00:04:14.301 who proposed cooling the climate the way that the ships do, 00:04:14.301 --> 00:04:16.775 but with a natural source of particles: 00:04:16.775 --> 00:04:19.132 sea salt mist from seawater 00:04:19.585 --> 00:04:23.232 sprayed from ships into areas of susceptible clouds over the ocean. 00:04:23.583 --> 00:04:26.453 The approach became known by the name I gave it then, 00:04:26.453 --> 00:04:28.251 marine cloud brightening. 00:04:28.251 --> 00:04:32.526 Early modeling studies suggested that by deploying marine cloud brightening 00:04:32.526 --> 00:04:36.267 in just 10 to 20 percent of susceptible ocean clouds, 00:04:36.267 --> 00:04:41.191 it might be possible to offset as much as two degrees Celsius of warming. 00:04:41.400 --> 00:04:45.052 It might even be possible to brighten clouds in local regions 00:04:45.052 --> 00:04:48.962 to reduce the impacts caused by warming ocean surface temperatures. 00:04:48.962 --> 00:04:51.760 For example, regions such as the Gulf Atlantic 00:04:51.760 --> 00:04:54.299 might be cooled in the months before a hurricane season 00:04:54.299 --> 00:04:56.766 to reduce the force of storms. 00:04:56.766 --> 00:05:00.754 Or, it might be possible to cool waters flowing onto coral reefs 00:05:00.754 --> 00:05:03.219 overwhelmed by heat stress, like Australia's Great Barrier Reef. NOTE Paragraph 00:05:03.219 --> 00:05:07.090 But these ideas are only theoretical, 00:05:07.090 --> 00:05:10.878 and brightening marine clouds is not the only way 00:05:10.878 --> 00:05:14.263 to increase the reflection of the sunlight from the atmosphere. 00:05:14.263 --> 00:05:19.756 Another occurs when large volcanoes release material with enough force 00:05:19.756 --> 00:05:22.985 to reach the upper layer of the atmosphere, the stratosphere. 00:05:22.985 --> 00:05:25.550 When Mount Pinatubo erupted in 1991, 00:05:25.550 --> 00:05:28.775 it released material into the stratosphere including sulfates 00:05:28.775 --> 00:05:33.212 that mix with the atmosphere to reflect sunlight. 00:05:33.212 --> 00:05:36.498 This material remained and circulated around the planet. 00:05:36.498 --> 00:05:41.299 It was enough to cool the climate by over half a degree Celsius 00:05:41.299 --> 00:05:44.282 for about two years. 00:05:44.282 --> 00:05:50.399 This cooling led to a striking increase in Arctic ice cover in 1992, 00:05:50.399 --> 00:05:54.327 which dropped in subsequent years as the particles fell back to the Earth, 00:05:54.327 --> 00:05:58.391 but the volcanic phenomenon led Nobel Prize Winner Paul Crutzen 00:05:58.391 --> 00:06:01.970 to propose the idea that dispersing particles into the stratosphere 00:06:01.970 --> 00:06:06.557 in a controlled way might be a way to counter global warming. 00:06:06.557 --> 00:06:09.988 Now, this has risks that we don't understand, 00:06:09.988 --> 00:06:11.867 including things like heating up the stratosphere 00:06:11.867 --> 00:06:14.209 or damage to the ozone layer. 00:06:14.209 --> 00:06:17.487 Scientists think that there could be safe approaches to this, 00:06:17.487 --> 00:06:20.958 but is this really where we are? 00:06:20.958 --> 00:06:22.807 Is this really worth considering? NOTE Paragraph 00:06:22.807 --> 00:06:24.865 This is a simulation 00:06:24.865 --> 00:06:27.810 from the US National Center for Atmospheric Research 00:06:27.810 --> 00:06:31.754 Global Climate Model showing Earth surface temperatures through 2100. 00:06:31.754 --> 00:06:36.163 The globe on the left visualizes our current trajectory, 00:06:36.163 --> 00:06:39.428 and on the right, a world where particles are introduced into the stratosphere 00:06:39.428 --> 00:06:41.393 gradually in 2020 00:06:41.393 --> 00:06:43.315 and maintained through 2100. 00:06:43.315 --> 00:06:47.134 Intervention keeps surface temperatures near those of today, 00:06:47.134 --> 00:06:53.144 while without it temperatures rise well over three degrees. 00:06:53.144 --> 00:06:56.514 This could be the difference between a safe and an unsafe world. NOTE Paragraph 00:06:57.554 --> 00:07:01.885 So, if there's even a chance that this could be close to reality, 00:07:01.885 --> 00:07:06.039 is this something we should consider seriously? 00:07:06.039 --> 00:07:09.661 Today, there are no capabilities 00:07:09.661 --> 00:07:11.618 and scientific knowledge is extremely limited. 00:07:11.618 --> 00:07:15.822 We don't know whether these types of interventions are even feasible, 00:07:15.822 --> 00:07:19.152 or how to characterize their risks. 00:07:19.152 --> 00:07:22.004 Researchers hope to explore some basic questions 00:07:22.004 --> 00:07:24.365 that might help us know 00:07:24.365 --> 00:07:26.307 whether or not these might be real options 00:07:26.307 --> 00:07:28.404 or whether we should rule them out. 00:07:28.404 --> 00:07:31.990 It requires multiple ways of studying the climate system 00:07:31.990 --> 00:07:36.002 including computer models to forecast changes, 00:07:36.002 --> 00:07:37.785 analytic techniques like machine learning, 00:07:37.785 --> 00:07:40.954 and many types of observations. 00:07:40.954 --> 00:07:42.377 And though it's controversial, 00:07:42.377 --> 00:07:46.907 it's also critical that researchers develop core technologies 00:07:46.907 --> 00:07:51.275 and perform small-scale real world experiments. NOTE Paragraph 00:07:51.275 --> 00:07:57.117 There are two research programs proposing experiments like this. 00:07:57.117 --> 00:08:00.715 At Harvard, the SCoPEx experiment would release very small amounts 00:08:00.715 --> 00:08:04.059 of sulfates, calcium carbonate, and water into the stratosphere with a balloon 00:08:04.059 --> 00:08:09.776 to study chemistry and physics effects. 00:08:09.776 --> 00:08:11.139 How much material? 00:08:11.139 --> 00:08:14.544 Less than the amount released in one minute of flight 00:08:14.544 --> 00:08:15.747 from a commercial aircraft. 00:08:15.747 --> 00:08:17.806 So this is definitely not dangerous, 00:08:17.806 --> 00:08:21.386 and it may not even be scary. NOTE Paragraph 00:08:21.386 --> 00:08:23.974 At the University of Washington, 00:08:23.974 --> 00:08:27.312 scientists hope to spray a fine mist of salt water into clouds 00:08:27.312 --> 00:08:30.503 in a series of land an ocean tests. 00:08:30.503 --> 00:08:32.776 If those are successful, this would culminate in experiments 00:08:32.776 --> 00:08:36.371 to measurably brighten an area of clouds over the ocean. 00:08:37.018 --> 00:08:40.400 The marine cloud brightening effort is the first to develop any technology 00:08:40.400 --> 00:08:45.067 for generating aerosols for atmospheric sunlight reflection in this way. 00:08:45.067 --> 00:08:48.489 It requires producing very tiny particles -- 00:08:48.489 --> 00:08:52.614 think about the mist that comes out of an asthma inhaler -- 00:08:52.614 --> 00:08:55.814 at massive scale -- so think of looking up at a cloud. 00:08:56.533 --> 00:08:58.937 It's a tricky engineering problem. 00:08:58.937 --> 00:09:04.065 So this one nozzle the developed generates three trillion particles per second, 00:09:04.065 --> 00:09:06.012 80 nanometers in size, 00:09:06.012 --> 00:09:08.515 from very corrosive saltwater. 00:09:08.515 --> 00:09:12.652 It was developed by a team of retired engineers in Silicon Valley -- 00:09:12.652 --> 00:09:14.083 here they are -- 00:09:14.083 --> 00:09:19.314 working full time for six years without pay for their grandchildren. 00:09:19.645 --> 00:09:22.273 It will take a few million dollars and another year or two 00:09:22.273 --> 00:09:26.748 to develop the full spray system they need to do these experiments. 00:09:26.748 --> 00:09:30.617 In other parts of the world, research efforts are emerging, 00:09:30.617 --> 00:09:34.262 including small modeling programs at Beijing Normal University in China, 00:09:34.262 --> 00:09:37.287 the Indian Institute of Science, 00:09:37.287 --> 00:09:42.050 a proposed center for climate repair at Cambridge University in the UK, 00:09:42.050 --> 00:09:44.231 and the ?? Fund, 00:09:44.231 --> 00:09:46.904 which sponsors researchers in Global South countries 00:09:46.904 --> 00:09:50.026 to study the potential impacts of these sunlight interventions 00:09:50.026 --> 00:09:52.090 in their part of the world. 00:09:52.090 --> 00:09:54.337 But all of these programs, 00:09:54.337 --> 00:09:56.203 including the experimental ones, 00:09:56.203 --> 00:09:58.801 lack significant funding. 00:09:58.801 --> 00:10:01.736 And understanding these interventions is a hard problem. 00:10:01.736 --> 00:10:04.182 The Earth is a vast, complex system 00:10:04.182 --> 00:10:07.125 and we need major investments in climate models, observations 00:10:07.125 --> 00:10:08.444 and basic science 00:10:08.444 --> 00:10:12.127 to be able to predict climate much better than we can today 00:10:12.127 --> 00:10:16.945 and manage both our accidental and any intentional interventions. NOTE Paragraph 00:10:16.945 --> 00:10:19.387 And it could be urgent. 00:10:19.387 --> 00:10:24.328 Recent scientific reports predict that in the next few decades 00:10:24.328 --> 00:10:26.892 Earth's fever is on a path to devastation: 00:10:26.892 --> 00:10:29.278 extreme heat and fires, 00:10:29.278 --> 00:10:33.139 major loss of ocean life, 00:10:33.139 --> 00:10:35.996 collapse of Arctic ice, 00:10:35.996 --> 00:10:39.832 displacement and suffering for hundreds of millions of people. 00:10:40.477 --> 00:10:44.139 The fever could even reach tipping points where warming takes over 00:10:44.139 --> 00:10:46.462 and human efforts are no longer enough 00:10:46.462 --> 00:10:50.104 to counter accelerating changes in natural systems. NOTE Paragraph 00:10:50.104 --> 00:10:52.339 To prevent this circumstance, 00:10:52.339 --> 00:10:55.007 the UN's International Panel on Climate Change predicts 00:10:55.007 --> 00:10:59.081 that we need to stop and even reverse emissions by 2050. 00:10:59.081 --> 00:11:03.896 How? We have to quickly and radically transform major economic sectors, 00:11:03.896 --> 00:11:08.618 including energy, construction, agriculture, transportation and others. 00:11:08.618 --> 00:11:13.667 And it is imperative that we do this as fast as we can. 00:11:13.667 --> 00:11:15.739 But our fever is now so high 00:11:15.739 --> 00:11:17.945 that climate experts say we also have to remove 00:11:17.945 --> 00:11:20.607 massive quantities of CO2 from the atmosphere, 00:11:20.607 --> 00:11:24.047 possibly 10 times all of the world's annual emissions, 00:11:24.047 --> 00:11:26.801 in ways that aren't proven yet. NOTE Paragraph 00:11:26.801 --> 00:11:32.184 Right now, we have slow-moving solutions to a fast-moving problem. 00:11:32.184 --> 00:11:34.350 Even with the most optimistic assumptions, 00:11:34.350 --> 00:11:37.268 our exposure to risk in the next 10 to 30 years 00:11:37.268 --> 00:11:40.377 is unacceptably high in my opinion. NOTE Paragraph 00:11:40.826 --> 00:11:44.764 Could interventions like these provide fast-acting medicine if we need it 00:11:44.764 --> 00:11:48.308 to reduce the Earth's fever while we address its underlying causes? 00:11:48.821 --> 00:11:51.446 There are real concerns about this idea. 00:11:51.446 --> 00:11:54.708 Some people are very worried that even researching these interventions 00:11:54.708 --> 00:11:59.100 could provide an excuse to delay efforts to reduce emissions. 00:11:59.100 --> 00:12:01.875 This is also known as a moral hazard. 00:12:01.875 --> 00:12:04.118 But like most interventions, 00:12:04.118 --> 00:12:07.399 interventions are more dangerous the more that you do, 00:12:07.399 --> 00:12:13.118 so research actually tends to draw out the fact that we absolutely positively 00:12:13.118 --> 00:12:15.937 cannot continue to fill up the atmosphere with greenhouse gases, 00:12:15.937 --> 00:12:18.305 that these kinds of alternatives are risky 00:12:18.305 --> 00:12:23.388 and if we were to use them we would need to use as little as possible. NOTE Paragraph 00:12:24.946 --> 00:12:27.211 But even so, 00:12:27.211 --> 00:12:29.728 could we ever learn enough about these interventions 00:12:29.728 --> 00:12:31.328 to manage the risk? 00:12:31.328 --> 00:12:35.434 Who would make decisions about when and how to intervene? 00:12:35.434 --> 00:12:40.937 What if some people are worse off, 00:12:40.937 --> 00:12:43.181 or they just think they are? 00:12:43.181 --> 00:12:44.550 These are really hard problems. 00:12:44.550 --> 00:12:46.497 But what really worries me 00:12:46.497 --> 00:12:48.696 is that as climate impacts worsen, 00:12:48.696 --> 00:12:52.424 leaders will be called on to respond by any means available. 00:12:53.036 --> 00:12:55.890 I for one don't want them to act without real information 00:12:55.890 --> 00:12:58.958 and much better options. NOTE Paragraph 00:12:58.958 --> 00:13:00.996 Scientists think it will take a decade of research 00:13:00.996 --> 00:13:03.370 just to assess these interventions 00:13:03.370 --> 00:13:06.299 before we ever were to develop or use them. 00:13:06.299 --> 00:13:10.892 Yet today, the global level of investment in these interventions 00:13:10.892 --> 00:13:13.463 is effectively zero. 00:13:13.463 --> 00:13:17.246 So, we need to move quickly 00:13:17.246 --> 00:13:20.040 if we want policymakers to have real information 00:13:20.040 --> 00:13:22.244 on this kind of emergency medicine. NOTE Paragraph 00:13:24.369 --> 00:13:26.737 There is hope! 00:13:26.737 --> 00:13:29.834 The world has solved these kinds of problems before. 00:13:29.834 --> 00:13:33.085 In the 1970s, we identified an existential threat 00:13:33.085 --> 00:13:35.336 to our protective ozone layer. 00:13:35.336 --> 00:13:38.628 In the 1980s, scientists, politicians and industry 00:13:38.628 --> 00:13:42.697 came together in a solution to replace the chemicals causing the problem. 00:13:43.137 --> 00:13:46.623 They achieved this with the only legally binding environmental agreement 00:13:46.623 --> 00:13:48.878 signed by all countries in the world, 00:13:48.878 --> 00:13:50.611 the Montreal Protocol. 00:13:50.842 --> 00:13:52.876 Still in force today, 00:13:52.876 --> 00:13:55.684 it has resulted in a recovery of the ozone layer 00:13:55.684 --> 00:13:58.468 and is the most successful environmental protection effort 00:13:58.468 --> 00:14:00.080 in human history. NOTE Paragraph 00:14:01.074 --> 00:14:03.827 We have a far greater threat now, 00:14:03.827 --> 00:14:08.177 but we do have the ability to develop and agree on solutions 00:14:08.177 --> 00:14:09.703 to protect people 00:14:09.703 --> 00:14:12.535 and restore our climate to health. 00:14:12.741 --> 00:14:16.095 This could mean that to remain safe, 00:14:16.095 --> 00:14:17.863 we reflect sunlight for a few decades 00:14:17.863 --> 00:14:20.681 while we green our industries and remove CO2. 00:14:21.896 --> 00:14:24.717 It definitely means we must work now 00:14:24.717 --> 00:14:29.804 to understand our options for this kind of emergency medicine. NOTE Paragraph 00:14:29.804 --> 00:14:31.594 Thank you, NOTE Paragraph 00:14:31.594 --> 00:14:35.909 (Applause)