Note: I wrote up this summary when I finished reading Bill Gates’ book in March 2021, but I am only publishing it now because I wanted to share it with others. It is incomplete (I haven’t typed up highlights/summaries for all chapters), and some reflections might be a bit outdated (e.g. since then I have read this piece, which has influenced my thinking a fair amount)

Book Notes: How to Avoid a Climate Disaster

by Bill Gates Amazon link (affiliate)

The world is not exactly lacking in rich men with big ideas about what other people should do, or who think technology can fix any problem

The book in 3 sentences

1. Base assumption: We need to get to net zero emissions to avoid a climate disaster, which will be hard.
2. Ramping up the deployment of technologies we already have (like solar, wind, heat pumps, electric vehicles) is a necessary, but not sufficient, step towards net zero emissions; we also need a lot of innovations to be developed and spread around the world in the coming decades (e.g. advanced batteries, nuclear, biofuels, as well as geoengineering tech)
3. Dealing with climate change cannot come at the expense of human development and lifting the bottom billion out of poverty; we should not (and do not need to) place unrealistic expectations either on the world’s poorest or anyone else in order to get to net zero.

Impressions

• It’s not a long read: Just 230 pages (or 7 hours on Audible)
• Gates has written a book that can be read (and accepted) not just by those of us already on team Net Zero, but also by those who have reservations about climate change.
  • He appeals to the climate skeptics, by painting a very clear set of pictures of what the world might look like, even under what might appear to be mild scenarios
  • He appeals to businesspeople who, let’s face it, probably don’t care very much about climate change (or at least don’t care enough to change their behaviour at work as much as they might need to) by outlining the economic case for (1) loss aversion (2) new commercial opportunities.
  • He appeals to those who might see climate activists as a privileged elite asking developing countries to hit the brakes and stop lifting millions out of poverty by imposing a “green vs growth” tradeoff on them
• It is obviously both technocentric and technocratic in its ideas: While Gates makes reference to politics and political reform, the thrust of his plan for avoiding a climate disaster isn’t with governments (or with degrowth/de-consumerism ideas)

Who should read it?

• If you are looking for an accessible and (largely) holistic primer on climate change
• If you want a framework for understanding the many moving parts of the problem, and getting better at sniffing out misleading information about what e.g. a company or government is doing to be green
• If you question technocentric views on climate change, and want to challenge your perspective
• If you don’t buy into more radical solutions, like degrowth or anti-capitalism (with the caveat that I’d urge you to not just read within your echo chamber!)

Criticisms

After reading the book, I also read a few reviews/criticisms:

• Gordon Brown’s review on The Guardian, which felt rather self-serving, and acted as little more than a summary of the book while asking “why haven’t we done more yet?”
• Michael E. Mann, whose own book The New Climate War recently came out, lays out a few criticisms in this piece (while plugging his book, which, I mean, is fair enough in this case).
  • Unintended consequences, especially from the geo-engineering techniques Gates touches on (but are definitely not central to his book)
  • Moral hazard: If we are betting on big techno-fixes to come later, we’ll take the pressure off polluters now
  • Mann is more optimistic about already-existing renewable tech than Gates, citing this Popular Science article

Chapter-by-chapter highlights

Chapter 1: Why Zero?

This chapter goes through the basics of climate change: How global warming occurs, how it will lead to more extreme weather events (heatwaves, superstorms, hurricanes, floods, droughts), a rise in sea levels, and more wildfires

• We don’t absolutely know exactly what will happen due to rising temperatures; modelling the climate is really complicated. But what we can point to is an increase in extreme weather events, as well as an increase in their intensity
• There might be some positive consequences too (e.g. in colder areas, fewer people will die of hypothermia, and the cost of heating will go down), but the overall trend points towards trouble
• The consequences of climate change will, on balance, hurt the world’s poorest the most. For example sub-Saharan African farmers could see the growing season shrink by 20%, and millions of acres of land could become substantially drier.
  • In fact, a lot of the extreme weather events Gates describes as likely to occur are already taking place: Think back to the 2007-2010 Syrian drought, which caused 1.5 million farmers to migrate to the cities - and the catalytic role that mass migration played in sparking the uprising against Assad in 2011, and the ongoing conflict that’s created 13 million refugees and internally displaced Syrians.
• Negative effects compound each other: Any one of the negative effects of climate change is bad enough on its own, but nobody will just suffer from only floods, or only hot days.
  • Example: As it gets hotter and drier, mosquitoes will start living in new places that get more humid, meaning we’ll see cases of malaria and other diseases where they’ve never appeared before
• Comparison to COVID-19:
  • Loss of life: “By mid-century, climate change could be just as deadly as COVID-19, and by 2100 it could be five times as deadly”
  • Economic harms: “In the next decade or two, the economic damage caused by climate change will likely be as bad as having a COVID-sized pandemic every 10 years. And by the end of the 21st century, it will be much worse if the world remains on its current emissions path.”

Despite the seeming doom and gloom, Gates is quick to point out 2 things:

1. That we can still do something about it: Adaptation and Mitigation (the book focuses mostly on Mitigation strategies, but also touches on Adaptation, esp. for developing crops that can better withstand a hotter planet)
2. That this can be seen as an economic opportunity, especially for the world’s rich countries: “The countries that build great zero-carbon companies and industries will be the ones that lead the global economy in the coming decades”.

Gates highlights that rich countries are the ones best positioned to develop the innovative solutions required to get to zero thanks to research universities, labs, startups, access to highly-skilled workers, and government funding.

Chapter 2: This Will Be Hard

• Fossil fuels are everywhere.
  • We’ve built entire industries to extract, process, transport, and use fossil fuels, and innovated extensively to keep their prices low (partly because their price does not reflect the damage they cause)
  • As a result, fossil fuels are abundant, cheap, and over the past century we have reshaped our way of life to run on them.
  • Did you know oil is cheaper than Coke? At $66/barrel (I looked up the Brent Crude price today), that’s $0.42/litre. A 2L bottle of Diet Coke is £1.59 on Tesco ($1.11/litre).
• The key to transitioning to clean energy will be to make it cheap (or almost as cheap) as fossil fuels
• Energy use per person is going up, and thus so will emissions: All across the world, standards of living are rising as economies develop, which means more cars, more fridges, more buildings, more computers, and more energy required to power them all.
  • And population growth means even more energy use and GHG emissions
• Better standards of living is a good thing for the people who will be leading longer and healthier lives, but bad news for the climate. It would be both immoral and impractical to try and stop this - to try and kick people off the economic ladder as they climb up
  • “Instead, we need to make it possible for low-income people to climb the ladder without making climate change worse. We need to get to zero -producing even more energy than we do today, but without adding any carbon to the atmosphere- as soon as possible.”
• But history is not on our side: Energy transitions take a long time Source: Bill Gates (tweet here); originally Vaclav Smil’s Energy Transitions: Global and National Perspectives (2018)
• It’s not just that energy transitions take a long time: It’s also that the driving factor behind this transition doesn’t rely on selfishness. We moved from coil to oil and natural gas because they were cheaper and more powerful
• Gates cites Moore’s Law as an outlier in technical innovation: Computer chips might have gotten exponentially more powerful in the past few decades, but energy doesn’t quite work the same way
  • For example, the first Model T had a fuel efficiency of about 21 miles per gallon; 110 years later, the top hybrid gets 58 miles per gallon - less than 3x improvement
  • Solar panels have similarly gone from 15% conversion in the 1970s to 25% today Worth adding a relevant criticism from Bill McKibben at this point re: Moore’s Law:

But that’s not really the target here: In fact, as the analyst Ramez Naam pointed out last spring, the price of solar power has dropped astonishingly in the last decade, far outpacing even the most optimistic forecasts. The price drop is 50 to 100 years ahead of what the International Energy Agency was forecasting in 2010, mostly because we’re getting better at building and installing solar panels. Every time we double the number of panels installed, the price drops another 30 to 40 percent, and there’s plenty of runway left.

Gates identifies other barriers to rapid transition in energy:

• The industry is huge ($5 trillion a year) and complex, and complex things resist change
  • Gates doesn’t mention it, but obviously Big Oil etc. don’t just ‘resist change’. For example, the world’s five largest publicly-traded oil and gas companies spent over $1bn in the first three years since the Paris Agreement on misleading climate-related branding and lobbying (source: InfluenceMap Report, March 2019).
• We have built in inertia into the system in the form of regulations: Unlike software, you can’t ship a half-finished product, or have your customers sometimes deal with unpredictable downtime as you patch things up after breaking everything
• There are huge startup costs for each new plant or other piece of infrastructure - you can’t just spend millions writing a program or developing a vaccine and then churn out copies
• Outdated laws and regulations
  • Subsidies and tax breaks for fossil fuels
  • The US Clean Air Act was passed in 1970 to reduce local air pollution not deal with rising carbon emissions and temperatures
  • Fuel-economy standards were adopted in the 1970s to deal with skyrocketing oil prices
  • The good side of these outdated regulations? They were pretty effective at doing what they were designed to do: Cars got more efficient, and the air got cleaner
• While there is climate consensus on the problem, there is much less consensus about the solution
  • Really, this is why Gates wrote the book: He wants to push the idea that we need to invest large amounts of money in technological breakthroughs to deal with climate change
  • We need to act soon: “Unless we move fast toward zero, bad things (anmd probably many of them) will happen well within most people’s lifetime, and very bad things will happen within a generation”
  • We don’t have everything we need already (see chapters 4-8)
  • Global cooperation is really difficult. All the more true when you’re asking countries to incur a cost that others may want to avoid - good ol’ Tragedy of the Commons
    • In this light, the Paris Agreement was a huge achievement, not because of the emissions states pledged to curb (it only adds up to 12% of today’s emissions), but because it proved global cooperation to be possible.

Chapter 3: Five Questions to Ask in Every Climate Conversation

The Five Questions

Gates’ 5-question framework for assessing different (partial) solutions to solving climate change:

1. How much of the 51 billion tons are we talking about? Convert tons of emissions to a percentage of 51 billion
2. What’s your plant for cement? Remember that we need to find solutions for all five activities that emissions come from: Making things, plugging in, growing things, getting around, and keeping cool and warm.
3. How much power are we talking about? Kilowatt = house. Gigawatt = mid-sized city. Hundreds of gigawatts = big, rich country (rough shorthand to give you a sense of scale)
4. How much space do you need? Some energy sources, like wind, are much more space-intensive i.e. low watts per square metre
5. How much is it going to cost? What’s the premium for going green, and is it low enough for middle-income countries to pay

Key concept: Green Premiums

The Green Premiums are the additional costs involved with replacing an existing greenhouse gas-emitting activity with a greener one.

• For example, normal aviation fuel is $2.22 per gallon, while zero-carbon fuel (advanced biofuel) cost $5.35 per gallon. That means the Green Premium is $5.35-$2.22 = $3.13 (a premium of 140%)
• A Green Premium can sometimes be negative - meaning it would be cheaper to switch to than what we’re using at the moment
• Zero-carbon options with low or zero Green Premiums = the ones we should be deploying now. If we’re not, it’s not because of financial cost, but other factors (e.g. outdated policies, lack of awareness)
• R&D funding for early-stage innovation should be allocated towards areas where the Green Premium is currently too high, i.e. areas where the limiting factor right now is cost (think back to how renewable electricity is often the cheapest now, but was pricey before)
• Green Premiums can act as a measurement system that shows us the progress we’re making toward stopping climate change.
  • ‘Tons of CO2 equivalents’ tell us how far we are from net zero, but tell us nothing about how hard it will be to get there. Green Premiums help us answer this by measuring the cost of getting to zero, sector by sector, which highlights where we need to innovate (or adjust regulations).
  • If we were to use Direct Air Capture (DAC, i.e. sucking CO2 out of the atmosphere and storing it underground), a technology which is still in the experimental stage, assuming projected efficiency gains that took its cost down to $100/ton (it’s over $200/ton at the moment), that means that removing 51 billion tons per year would cost $5.1 trillion per year (6% of world GDP)

Chapter 4: How we plug in (27% of 51 billion)

• 2018 estimate from the IEA: Governments around the world spent around $400 billion in 2018 to subsidise the consumption of fossil fuels
• Between 2000 and 2018, China tripled the amount of coal power it uses
• For the US to eliminate its electricity-related GHG emissions, only a modest Green Premium is required - approximately $18 a month per household
  • A similar estimate for Europe puts +20% to energy bills to decarbonise 90-95% of electricity consumption (though the methodology is different to the one used for the US estimate)
  • But this will be harder for other countries: The US has a large supply of renewables, as well as the money to finance the high upfront costs of going green

Why is going green expensive?

Unlike natural gas or coal plants, renewable sources don’t need to continuously buy stuff to burn. And yet…

1. Fossil fuels are very cheap
   • We’ve spent decades building up our systems for extracting, processing, transporting, and burning fossil fuels
   • Their price doesn’t factor in the true cost of climate change
2. Renewable resources aren’t distributed evenly around the world
   • So we’d have to move clean energy from places that are sunny and/or windy, which would require significant investments in building transmission infrastructure
   • The more transmission lines you need, the greater the cost of your electricity
     • Transmission and distribution are responsible for more than a third of the final cost of electricity (Gates’ stat - in the UK,
   • This doesn’t just add up to a financial cost: There’s also geopolitical risk to consider (countries often don’t want to rely on their neighbours for power, unless if they’re really good friends…)
3. Our demand for network reliability
   • Kinda self-explanatory: Even a one-hour power cut is a big disturbance (no WiFi, no heating, no lights, no TV, no phone charges…)
   • Not much that can be done about this - at least not in Gates’ paradigm of not disturbing people’s way of life too much (or denying a similar QoL to those who are working towards it in developing economies right now)
4. The curse of intermittency
   • I think we’re all familiar enough with this by now: You need the sun to be out to collect solar power (and the difference between a sunny summer day and cloudy winter day can lead to as much as 12x more electricity generation)
     • It’s not just about day versus night: Length of day, cloudiness, distance from the Sun, distance from the equator all play a role. So nighttime intermittency isn’t as big a deal - you just need a battery that can store half a day’s worth of energy. But if you’re getting 5-10x more energy in the summer than in winter… You’ll need a pretty big battery to last through winter.
     • Thus, we need to keep fossil fuel sources like natural gas plants around, to plug the intermittency gap and/or use lots of batteries (which are still prohibitively expensive)
     • As we approach 100% clean electricity, intermittency thus becomes a bigger and more expensive problem
     • Not only is daytime and seasonal intermittency a challenge: You also need to plan for random disruptions. What if you have a cyclone coming, which will rip your wind turbines apart if you keep them running? You’ll have to keep them off for several days

• Because solar and wind are intermittent, our capacity to generate electricity will have to grow disproportionately to our average consumption

  • Completely decarbonising US power grid by 2050 will require adding around 75 gigawatts of capacity every year for the next 30 years
    • That’s 3x more annual capacity added than the US has managed over the past decade (avg 22 gigawatts a year)

• In the US (and, I’d assume, many other countries), electricity generation is done on a fairly decentralised basis: You build power plants close to cities, and ship fossil fuels via pipeline or train

  • This means that decarbonising the grid isn’t just about swapping fossil fuel plants with wind turbines and photovoltaic panels: You also need to build a lot of transmission lines to replace train tracks and pipes, because most of America’s sunlight supply is in the South West, and most of the wind is in the Great Plains.
  • To add to the challenge, the US doesn’t have one powergrid connecting all states. It’s a patchwork mess that doesn’t currently allow you to send power outside each region, broadly speaking.
  • So let’s build more transmission lines! Yes, but it won’t be easy: You need to bring together a lot of landowners, utility companies, local governments, and state governments.
  • Example: The TransWest Express is a transmission project designed to move wind-generated power from Wyoming to California and the Southwest. Planning begun in 2005, the initial application was filed in 2007, construction is expected to start at the end of 2021, and is due to conclude in 2024. That’s a lead time of nearly 20 years!
  • Another challenge is that reliance on fossil fuels isn’t just an electricity thing: If our car or heating will also be electrified, that means each household will have bigger electrical service requirements (at least 2x as much).
    • The impact of this will be extremely local, and thus felt by communities (with all the NIMBY or other backlash that comes with): Streets will be dug up, power lines will need to be heavier, and in many cases, the added load might mean you can’t rely on underground lines (which cost more anyway), and thus cause more backlash (powerlines are an eyesore)

Making carbon-free electricity

[todo]

Storing electricity

1. Batteries: Gates is pessimistic, at least about the incremental improvements we can make to existing battery designs like Li-ion.
   • Other types, like liquid metal and flow batteries, are in earlier stages of research and development - if successful, they could be the key to creating grid-scale batteries (i.e. you can store city-sized amounts of energy this way).
2. [[Pumped hydro]]: The biggest form of grid-scale electricity storage in the world.
   • You use cheap electricity (e.g. during peak solar/wind times) to pump water up a hill into a reservoir, and then let the water flow back down the hill and spin a turbine when demand for power goes up (e.g. 7pm when home usage peaks and the sun is almost set)
3. [[Thermal storage]]: Use cheap electricity to heat up a material (like molten salt), then use that heat when you need to convert it to electricity. Currently 50-60% efficient.
   • Commercially, this could mean squeezing more money out of a nuclear power plant (and not creating excess electricity) by using your output to heat molten salt, rather than compete with solar during the day, and then selling more overnight. Advanced nuclear design company TerraPower, which Gates is chairman of, is investigating this approach.
4. Cheap hydrogen: A potential ‘breakthrough’ technology that could be used to create cheap fuel cell batteries (typically hydrogen/oxygen batteries that only have water as a byproduct).
   • Why aren’t we converting clean electricity to fuel cell batteries today, if it means we can take excess power and store it for years? It’s too expensive to do so right now without emitting carbon in the process: (1) energy lost during each conversion step leads to lower efficiency; (2) storing hydrogen is hard, even when pressurised; (3) electrolyzer materials are quite costly

Other innovations

1. [[Carbon capture]]: Point capture and direct air capture
2. Using less: Improving energy efficiency and load shifting

Chapter 5: How We Make Things (31% of 51 billion)

1. Concrete
2. Steel
3. Plastics
4. Glass
5. Aluminium
6. Fertilizer
7. Paper

In short, we make materials that have become just as essential to modern life as electricity is. We’re not going to give them up. If anything, we’ll be using more of them as the world’s population grows and gets richer.

Gates makes it clear that he thinks this is a good thing - people are earning more money, getting a better education, are less likely to die young. It’s good news if you care about fighting poverty. But, these materials account for a third of emissions, and in some cases (notably concrete) we don’t currently have a practical way of making them without producing carbon. In other cases, like with steel, it’s a lot cheaper to make it in a very carbon-intensive way.

Useful reminder: When we make cement and steel, the carbon byproducts end up in the atmosphere. But when we make plastics, only around half the carbon gets into the atmosphere - the other half stays in the plastic. Plastic pollution is bad for many reasons, but worsening climate change isn’t one of them (since plastics take so, so long to decompose).

Three stages at which making things leads to emissions

1. When we use fossil fuels to generate the electricity that factories need to run their operations
2. When we use them to generate heat needed for different manufacturing processes, like melting iron ore to make steel
3. When we actually make these materials, like the way cement manufacturing inevitably creates carbon dioxide

Path to net zero emissions in manufacturing

1. Electrify every industrial processes possible
2. Get that electricity from a power grid that’s been decarbonised
3. Use carbon capture to absorb the remaining emissions
4. Use materials more efficiently

All of the above will take lots of innovation.

Gates briefly also mentions using less stuff, though he means it in the cost of a net reduction in inputs through recycling materials (not so much in terms of reducing aggregate demand)

Chapter 6: How We Grow Things (19% of 51 billion)

[todo]

Chapter 7: How We Get Around (16% of 51 billion)

[todo]

Chapter 8: How We Keep Cool and Stay Warm (7% of 51 billion)

[todo]

Chapter 9: Adapting to a Warmer World

4x return - the economic case is clear

Ch9 geoengineering as a “break glass” tour

• cheap and effects go away a week later

Chapter 10: Why Government Policies Matter

• historic examples of successful anti-air pollution (US clean air act, UK clean air act), as well as more recent ones (China’s 2014 anti-smog policies)
• many US efforts to improve efficiency and energy production were abandoned when oil prices crashed;

7 high-level goals Governments should aim for

1. Mind the investment gap. Absent policy interventions you can’t ensure the market will solve for green (dirty electricity is the same from a consumer pov; R&D outcomes uncertain at early stages so need blue skies). Also it’s a venue for exports.
2. Level the playing field. (Price in carbon’s true costs). You don’t want innovation to be deterred by artificially cheap fossil fuels
3. Overcome non-market barriers. (Educate on benefits; offer options/ensure there is supply; don’t ban ppl from doing it).
4. Stay up to date. Government policies sometimes out of date. Example: building performance standards also include chemical composition standards that rule out low-emission cement
5. Plan for a just transition. Don’t punish losers (e.g. US states that rely on oil jobs - need to give wats to replace jobs). Transition will often be difficult and requires funding, technical advice, and knowledge sharing (things that central govt can do). Understand the problems communities are facing.
6. Do the hard stuff too. Can’t just go after low-hanging fruit to show progress. Examples: Cement, storage
7. Work on technology, policy, and markets at the same time. Adopting eg zero-emissions standard if the tech and manufacturing capacity and supply chains don’t exist not useful. Need investment and financing strategies to bring to scale. Markets need certainty to take a tech from experimental to mainstream.

Example: Danish govt wanted to increase wind power and decrease oil use They paired R&D support with a feed-in tariff

Chapter 11: A Plan For Getting to Zero

Nuance: “reduce by 2030” and “get to zero by 2050” aren’t automatically compatible. Need to make the right reductions by 2030 and ensure

e.g. could replace coal plants with gas plants to reduce by 2030. We’d meet the 2030 goal, but fail to hit zero by 2050.

So we need to pursue a two-pronged approach:

1. Go all out to deliver zero electricity cheaply reliably
2. Electrify as widely as possible (even if SQ some areas use dirty electricity)

[Meaning electric cars running on fossil fuels not so bad? Add that crap ben garson comic here]

Innovation is not just a matter of coming up with new machines. Also business models, supply chains, markets, policies to help inventions come to scale.

Expand supply of innovations while also increasing the demand for them.

Technologies needed:

• Hydrogen produced without emitting carbon
• Grid-scale electricity storage that can last a full season
• Electrofuels
• Advanced biofuels
• Zero-carbon cement
• Zero-carbon steel
• Plan- and cell-based meat and dairy
• Zero-carbon fertilizer
• Next-generation nuclear fission
• Nuclear fusion
• Carbon capture (both direct air capture and point capture)
• Underground electricity transmission
• Zero-carbon plastics
• Geothermal energy
• Pumped hydro
• Thermal storage
• Drought- and flood-tolerant food crops
• Zero-carbon alternatives to palm oil
• Coolants that don’t contain F-gasses

What’s needed to take us there on government side:

1. 5x R&D into clean energy and climate. Only 0.02% of world GDP atm ($22bn). US spends $7bn. Follow NIH model ($37bn in US)
2. Make bigger bets on high risk high reward projects. Leave safe investments for private sector. [my thought/reflection: can we get VCs to also do this? e.g. indirect funding thru tax breaks?] Example = human genome project (13 years), which returned 141x returns (!). Commit to long-term funding
3. Match R&D to our greatest needs. Integrate applied research objectives to blue skies research. Integrated approach example: PV efficiency
4. Work with private sector from the beginning

Govts must commit to three priorities:

1. Make it a goal to get to zero
2. Develop specific plans for meeting this goal
3. Be on track to reduce costs of green energy by enough to make it affordable for middle-income countries

Chapter 12: What Each of Us Can Do

• As a citizen it’s natural to think of driving electric cars or eating less meat
• The bulk of our emissions comes from the larger system thru which we live our daily lives
• Most important = engage in political process

Citizens

1. Make calls, write letters, attend town halls - push representatives to do more
2. Look locally as well as nationally when it comes to scrutinising + voting
3. Run for office

Consumers

1. Sign up for a green pricing program with your electric utility
2. Reduce your home’s emissions
3. Buy an electric vehicle
4. Eat more plant-based food (doesn’t mean go fully vegan)

Companies

An idea I really liked: Internal (corporate) carbon tax on BUs, that corporates can then use to fund green-related R&D

Things companies should do:

1. Internal carbon tax
2. Spend more in R&D
3. Become early adopters
4. Engage in policymaking process
5. Connect with government-funded research
6. Help early-stage innovators get across the valley of death (eg provide facilities, data, fellowships)

Gates pushes for a Factfulness-style framing at the end of the chapter:

When we have a fact-based view of climate change, we can see that we have some of the things we need to avoid a climate disaster, but not all of them. We can see what stands in the way of deploying the solutions we have and developing the breakthroughs we need. And we can see all the work we must do to overcome those hurdles.

Afterword: Climate Change and Covid-19

• industry researchers and governments working together = vaccine
• resisting science = no masks or social distancing
• global self-interest: like limiting covid globally