How to Avoid a Climate Disaster: The Solutions We Have and the Breakthroughs We Need

by Bill Gates

The world needs to provide more energy so the poorest can thrive, but we need to provide that energy without releasing any more greenhouse gases. Now the problem seemed even harder.

Besides, making electricity accounts for only 27 percent of all greenhouse gas emissions. Even if we had a huge breakthrough in batteries, we would still need to get rid of the other 73 percent.

methane, 120 times more warming the moment it reaches the atmosphere. But methane doesn’t stay around as long as carbon dioxide.

The 51 billion tons I keep mentioning is the world’s annual emissions in carbon dioxide equivalents. You may see numbers like 37 billion elsewhere—that’s just carbon dioxide, without the other greenhouse gases—or 10 billion, which is just the carbon itself.

How do greenhouse gases cause warming? The short answer: They absorb heat and trap it in the atmosphere. They work the same way a greenhouse works—hence the name.

whenever your car is sitting outside in the sun: Your windshield lets sunlight in, then traps some of that energy. That’s why the interior of your car can get so much hotter than the outside temperature.

molecules with two copies of the same atom—for example, nitrogen or oxygen molecules—let radiation pass straight through them. Only molecules made up of different atoms, the way carbon dioxide and methane are, have the right structure to absorb radiation and start heating up.

The countries that build great zero-carbon companies and industries will be the ones that lead the global economy in the coming decades.

Whoever makes big energy breakthroughs and shows they can work on a global scale, and be affordable, will find many willing customers in emerging economies.

oil is cheaper than a soft drink. I could hardly believe this the first time I heard it, but it’s true. Here’s the math: A barrel of oil contains 42 gallons; the average price in the second half of 2020 was around $42 per barrel, so that comes to about $1 per gallon.2 Meanwhile, Costco sells 8 liters of soda for $6, a price that amounts to $2.85 a gallon.

Tip: Whenever you see some number of tons of greenhouse gases, convert it to a percentage of 51 billion, which is the world’s current yearly total emissions (in carbon dioxide equivalents).

Passenger cars represent less than half of all the emissions from transportation, which in turn is 16 percent of all emissions worldwide.

How much greenhouse gas is emitted by the things we do? Getting around (planes, trucks, cargo ships) 16% Growing things (plants, animals) 19% Plugging in (electricity) 27% Making things (cement, steel, plastic) 31% Keeping warm and cool (heating, cooling, refrigeration) 7%

Tip: Whenever you hear “kilowatt,” think “house.” “Gigawatt,” think “city.” A hundred or more gigawatts, think “big country.”

How much power can we generate per square meter? Energy source Watts per square meter Fossil fuels 500–10,000 Nuclear 500–1,000 Solar* 5–20 Hydropower (dams) 5–50 Wind 1–2 Wood and other biomass Less than 1 * The power density of solar could theoretically reach 100 watts per square meter, though no one has accomplished this yet.

Here’s a summary of all five tips: Convert tons of emissions to a percentage of 51 billion. 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. Kilowatt = house. Gigawatt = mid-size city. Hundreds of gigawatts = big, rich country. Consider how much space you’re going to need. Keep the Green Premiums in mind and ask whether they’re low enough for middle-income countries to pay.

It’s no secret that nuclear power has its problems. It’s very expensive to build today. Human error can cause accidents. Uranium, the fuel it uses, can be converted for use in weapons. The waste is dangerous and hard to store.

TerraPower’s reactor could run on many different types of fuel, including the waste from other nuclear facilities. The reactor would produce far less waste than today’s plants, would be fully automated—eliminating the possibility of human error—and could be built underground, protecting it from attack. Finally, the design would be inherently safe, using some ingenious features to control the nuclear reaction; for example, the radioactive fuel is contained in pins that expand if they get too hot, which slows the nuclear reaction down and prevents overheating. Accidents would literally be prevented by the laws of physics. We’re still years away from breaking ground on a new plant. So far, TerraPower’s design exists only in our supercomputers; we’re working with the U.S. government on building our first prototype.

But the key point is not that any one company has the single breakthrough idea we need in nuclear fission or fusion. What’s most important is that the world get serious once again about advancing the field of nuclear energy. It’s just too promising to ignore.

Cheap hydrogen could do that for storing electricity. The reason is that hydrogen serves as a key ingredient in fuel cell batteries. Fuel cells get their energy from a chemical reaction between two gases—usually hydrogen and oxygen—and their only by-product is water.

A solar farm needs between 5 and 50 times more land to generate as much electricity as an equivalent coal-powered plant, and a wind farm needs 10 times more than solar.

If a genie offered me one wish, a single breakthrough in just one activity that drives climate change, I’d pick making electricity: It’s going to play a big role in decarbonizing other parts of the physical economy.

To make steel, you need to separate the oxygen from the iron and add a tiny bit of carbon. You can accomplish both at the same time by melting iron ore at very high temperatures (1,700 degrees Celsius or over 3,000 degrees Fahrenheit), in the presence of oxygen and a type of coal called coke. At those temperatures, the iron ore releases its oxygen, and the coke releases its carbon. A bit of the carbon bonds with the iron, forming the steel we want, and the rest of the carbon grabs onto the oxygen, forming a by-product we don’t want: carbon dioxide. Quite a bit of carbon dioxide, in fact. Making 1 ton of steel produces about 1.8 tons of carbon dioxide.

As challenging as that may sound, concrete is even harder. (Sorry—no pun intended.) To make it, you mix together gravel, sand, water, and cement. The first three of these are relatively easy; it’s the cement that is a problem for the climate. To make cement, you need calcium. To get calcium, you start with limestone—which contains calcium plus carbon and oxygen—and burn it in a furnace along with some other materials. Given the presence of carbon and oxygen, you can probably see where this is going. After burning the limestone, you end up with the thing you want—calcium for your cement—plus something you don’t want: carbon dioxide. Nobody knows of a way to make cement without going through this process. It’s a chemical reaction—limestone plus heat equals calcium oxide plus carbon dioxide—and there’s no way around it. It’s a one-to-one relationship. Make a ton of cement, and you’ll get a ton of carbon dioxide.

cement is the toughest case of all. It’s hard to get around that simple fact—limestone plus heat equals calcium oxide plus carbon dioxide.

molten oxide electrolysis: Instead of burning iron in a furnace with coke, you pass electricity through a cell that contains a mixture of liquid iron oxide and other ingredients. The electricity causes the iron oxide to break apart, leaving you with the pure iron you need for steel, and pure oxygen as a by-product. No carbon dioxide is produced at all.

the path to zero emissions in manufacturing looks like this: Electrify every process possible. This is going to take a lot of innovation. Get that electricity from a power grid that’s been decarbonized. This also will take a lot of innovation. Use carbon capture to absorb the remaining emissions. And so will this. Use materials more efficiently. Same.

(Borlaug found that as he made the grains bigger, the wheat couldn’t stand up under their weight, so he made the wheat stalks shorter, which is why his varieties are known as semi-dwarf wheat.)

synthetic fertilizer was a key factor in the agricultural revolution that changed the world in the 1960s and 1970s. It’s been estimated that if we couldn’t make synthetic fertilizer, the world’s population would be 40 to 50 percent smaller than it is.

People cut down trees not because people are evil; they do it when the incentives to cut down trees are stronger than the incentives to leave them alone.

50 acres’ worth of trees, planted in tropical areas, to absorb the emissions produced by an average American in her lifetime. Multiply that by the population of the United States, and you get more than 16 billion acres, or 25 million square miles, roughly half the landmass of the world. Those trees would have to be maintained forever.

On average, after a car rolls off the assembly line, it runs for more than 13 years before reaching its final resting place in the junkyard.

We can also use zero-carbon electricity to combine the hydrogen in water with the carbon in carbon dioxide, resulting in hydrocarbon fuels. Because you use electricity in the process, these fuels are sometimes called electrofuels, and they have a lot of advantages. They’re drop-in fuels, and because they’re made using carbon dioxide captured from the atmosphere, burning them doesn’t add to overall emissions.

Shenzhen, China—home to 12 million people—has electrified its entire fleet of more than 16,000 buses and nearly two-thirds of its taxis.

the best lithium-ion battery available today packs 35 times less energy than gasoline.

the bigger the vehicle you want to move, and the farther you want to drive it without recharging, the harder it’ll be to use electricity as your power source

We should also be exploring nuclear-powered container ships. The risks here are real (for example, you have to make sure the nuclear fuel doesn’t get released if the ship sinks), but many of the technical challenges have already been solved. After all, military submarines and aircraft carriers run on nuclear power already.

It’s rare that you can boil the solution for such a complex subject down into a single sentence. But with transportation, the zero-carbon future is basically this: Use electricity to run all the vehicles we can, and get cheap alternative fuels for the rest.

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 Plant- 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

Geothermal energy Pumped hydro Thermal storage Drought- and flood-tolerant food crops Zero-carbon alternatives to palm oil Coolants that don’t contain F-gases

The demand side is a little more complicated than the supply piece. It actually involves two steps: the proof phase, and the scale-up phase.

Ideas currently in the proof phase include low-carbon cement, next-generation nuclear fission, carbon capture and sequestration, offshore wind, cellulosic ethanol (a type of advanced biofuel), and meat alternatives.

Put a price on carbon. Whether it’s a carbon tax or a cap-and-trade system where companies can buy and sell the right to emit carbon, putting a price on emissions is one of the most important things we can do to eliminate Green Premiums.

There are markets worth billions of dollars waiting for someone to invent low-cost, zero-carbon cement or steel, or a net-zero liquid fuel.

I hope you’ll spend more time and energy supporting whatever you’re in favor of than opposing whatever you’re against.

“When we have a fact-based worldview, we can see that the world is not as bad as it seems—and we can see what we have to do to keep making it better.”

China committed to the ambitious goal of being carbon neutral by 2060.