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

by Bill Gates

But then we started burning fossil fuels. These fuels are made of carbon that’s stored underground, thanks to plants that died eons ago and got compressed over millions of years into oil, coal, or natural gas. When we dig up those fuels and burn them, we emit extra carbon and add to the total amount in the atmosphere.

Although we can predict the course of broad trends, like “there will be more hot days” and “sea levels will go up,” we can’t with certainty blame climate change for any particular event. For example, when there’s a heat wave, we can’t say whether it was caused by climate change alone. What we can do, though, is say how much climate change increased the odds of that heat wave happening. For hurricanes, it’s unclear whether warmer oceans are causing a rise in the number of storms, but there is growing evidence that climate change is making storms wetter and increasing the number of intense ones.

We know that when the average temperature rises, more water evaporates from the earth’s surface into the air. Water vapor is a greenhouse gas, but unlike carbon dioxide or methane, it doesn’t stay in the air for long—eventually, it falls back to the surface as rain or snow. As water vapor condenses into rain, it releases a massive amount of energy, as anyone who has ever experienced a big thunderstorm knows. Even the most powerful storm typically lasts only a few days, but its impact can reverberate for years.

Air can contain only a certain amount of water vapor, and at some point it hits a ceiling, becoming so saturated that it can’t absorb any more moisture. Why does that matter? Because the human body’s ability to cool off depends on the air’s ability to absorb sweat as it evaporates. If the air can’t absorb your sweat, then it can’t cool you off, no matter how much you perspire.

Consider that nearly 40 percent of the world’s emissions are produced by the richest 16 percent of the population. (And that’s not counting the emissions from products that are made someplace else but consumed in rich countries.) What will happen as more people live like the richest 16 percent? Global energy demand will go up 50 percent by 2050, and if nothing else changes, carbon emissions will go up by nearly as much.

Consider that the first Model T that rolled off Henry Ford’s production line in 1908 got no better than 21 miles to the gallon. As I write this, the top hybrid on the market gets 58 miles to the gallon. In more than a century, fuel economy has improved by less than a factor of three.

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

Here’s a summary of all five tips: Convert tons of emissions to a percentage of 52 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.

some power plant; it has to be converted to electricity on the spot. But most of America’s sunlight supply is in the Southwest, and most of our wind is in the Great Plains, far from many major urban areas. In short, intermittency is the main force that pushes the cost up as we get closer to all zero-carbon electricity. It’s why cities that are trying to go green still supplement solar and wind with other ways to generate electricity, such as gas-fired power plants that can be powered up and down as needed to meet demand, and these so-called peakers are not zero-carbon by any stretch of the imagination.

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.

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.

We emit greenhouse gases (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; and (3) when we actually make these materials, like the way cement manufacturing inevitably creates carbon dioxide.

To sum up, 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.

With agriculture, the main culprit isn’t carbon dioxide but methane—which causes 28 times more warming per molecule than carbon dioxide over the course of a century—and nitrous oxide, which causes 265 times more warming.

As people get richer, they eat more calories, and in particular they eat more meat and dairy. And producing meat and dairy will require us to grow even more food. A chicken, for example, has to eat two calories’ worth of grain to give us one calorie of poultry—that is, you have to feed a chicken twice as many calories as you’ll get from the chicken when you eat it. A pig eats three times as many calories as we get when we eat it. For cows, the ratio is highest of all: six calories of feed for every calorie of beef. In other words, the more calories we get from these meat sources, the more plants we need to grow for the meat.

Around the world, there are roughly a billion cattle raised for beef and dairy. The methane they burp and fart out every year has the same warming effect as 2 billion tons of carbon dioxide, accounting for about 4 percent of all global emissions.

There’s one last way we can cut down on emissions from the food we eat: by wasting less of it. In Europe, industrialized parts of Asia, and sub-Saharan Africa, more than 20 percent of food is simply thrown away, allowed to rot, or otherwise wasted. In the United States, it’s 40 percent. That’s bad for people who don’t have enough to eat, bad for the economy, and bad for the climate. When wasted food rots, it produces enough methane to cause as much warming as 3.3 billion tons of carbon dioxide each year.

Why is fertilizer so magical? Because it provides plants with essential nutrients, including phosphorus, potassium, and the one that’s especially relevant to climate change: nitrogen. Nitrogen is a mixed blessing. It’s closely linked to photosynthesis, the process by which plants turn sunlight into energy, so it makes all plant life—and therefore all our food—possible. But nitrogen also makes climate change much worse.

Finally, after the fertilizer is applied to soil, much of the nitrogen that it contains never gets absorbed by the plant. In fact, worldwide, crops take up less than half the nitrogen applied to farm fields. The rest runs off into ground or surface waters, causing pollution, or escapes into the air in the form of nitrous oxide—which, you may recall, has 265 times the global-warming potential of carbon dioxide.

According to the World Bank, the world has lost more than half a million square miles of forest cover since 1990. (That’s an area bigger than South Africa or Peru, and a decline of roughly 3 percent.)

It’s a political and economic problem. 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. So we need political and economic solutions, including paying countries to maintain their forests, enforcing rules designed to protect certain areas, and making sure rural communities have different economic opportunities so they don’t have to extract natural resources just to survive.

Taking all these factors into account, the math suggests you’d need somewhere around 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. And that’s just for the United States—we haven’t accounted for any other country’s emissions.

The most effective tree-related strategy for climate change is to stop cutting down so many of the trees we already have.

Gas contains an amazing amount of energy—you’d need to bundle 130 sticks of dynamite together to get as much energy as a single gallon of gas contains.

Cars aren’t the only culprit. Passenger vehicles are responsible for nearly half of all transportation-related emissions. (International Council on Clean Transportation)

At one point in May 2020, the average price of gas in the United States had dropped to $1.77 per gallon; when gas is that cheap, EVs can’t compete—the batteries are simply too expensive. With the price of today’s batteries, EV owners save money only if gas costs more than around $3 per gallon.

We can also use zero-carbon electricity to combine the hydrogen in water with the carbon in carbon dioxide, resulting in hydrocarbon fuels.

But electrofuels also have a downside: They’re very expensive. You need hydrogen to make them, and as I mentioned in chapter 4, it costs a lot to make hydrogen without emitting carbon. In addition, you need to make them using clean electricity—otherwise, there’s no point—and we don’t yet have enough cheap, clean electricity in our power grid to use it economically for making fuel. It all adds up to a high Green Premium for electrofuels:

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—becomes a law. Barring some unlikely breakthrough, batteries will never be light and powerful enough to move planes and ships anything more than short distances.

Green Premiums to replace current fuels with zero-carbon alternatives Fuel type: Gasoline Retail price per gallon $2.43 $5.00 (advanced biofuels) Zero-carbon option per gallon $2.43 $8.20 (electrofuels) Green Premium 106% 237% Fuel type: Diesel Retail price per gallon $2.71 $5.50 (advanced biofuels) Zero-carbon option per gallon $2.71 $9.05 (electrofuels) Green Premium 103% 234% Fuel type: Jet fuel Retail price per gallon $2.22 $5.35 (advanced biofuels) Zero-carbon option per gallon $2.22 $8.80 (electrofuels) Green Premium 141% 296% Fuel type: Bunker fuel Retail price per gallon $1.29 $5.50 (advanced biofuels) Zero-carbon option per gallon $1.29 $9.05 (electrofuels) Green Premium 326% 601%

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.

If you live in a typical American home, your air conditioner is the biggest consumer of electricity you own—more than your lights, refrigerator, and computer combined.

Also, although A/C units demand the most electricity, they’re not the largest consumers of energy in American homes and businesses. That honor goes to our furnaces and water heaters. (This

They also contain refrigerants—known as F-gases, because they contain fluorine—that leak out little by little over time when the unit ages and breaks down, as you’ve no doubt noticed if you’ve ever had to replace the coolant in your car’s air conditioner. F-gases are extremely powerful contributors to climate change: Over the course of a century, they cause thousands of times more warming than an equivalent amount of carbon dioxide.

Together, furnaces and water heaters account for a third of all emissions that come from the world’s buildings. And unlike lights and A/C units, most of them run on fossil fuels, not electricity. (Whether you use natural gas, heating oil, or propane depends largely on where you live.) This means we can’t decarbonize hot water and air simply by cleaning up our electric grid. We need to get heat from something other than oil and gas.

Since the energy crisis of the 1970s, we’ve been trying to cut down on energy use, and so state governments created various incentives to favor natural gas furnaces and water heaters over less efficient electric ones. Some modified their building codes to make it harder for homeowners to replace their gas appliances with electric alternatives. Many of these policies that prize efficiency over emissions are still on the books, restricting your ability to lower your emissions by swapping out a gas-burning furnace for an electric heat pump—even if doing this would save you money.

Electrify as much as we can, getting rid of gas-powered furnaces and water heaters and replacing them with electric heat pumps. In some regions, governments will have to update their policies to allow—and encourage—these upgrades.

we can still make homes and offices more efficient at a low cost. They can be designed with what developers call a supertight envelope (not much air leaking in or out), good insulation, triple-glazed windows, and efficient doors.

Worldwide, there are 500 million smallholder farms, and about two-thirds of people in poverty work in agriculture. Yet despite their large numbers, smallholder farmers are responsible for remarkably few greenhouse gas emissions, because they can’t afford to use nearly as many products and services that involve fossil fuels.

As the climate gets warmer, droughts and floods will become more frequent, wiping out harvests more often. Livestock eat less and produce less meat and milk. The air and soil lose moisture, leaving less water available for plants; in South Asia and sub-Saharan Africa, tens of millions of acres of farmland will become substantially drier. Crop-eating pests are already infesting more acreage as they find more hospitable environments to live in. The growing season will also get shorter; at 4 degrees Celsius of warming, most of sub-Saharan Africa could see it shrink by 20 percent or more.

“Please don’t take away vaccine money and put it into electric cars. Africa is responsible for only about 2 percent of all global emissions. What you really should be funding there is adaptation. The best way we can help the poor adapt to climate change is to make sure they’re healthy enough to survive it. And to thrive despite it.”

Governments should also explore strengthening social-security systems and arranging for weather-based agriculture insurance that helps farmers recover their losses.

One study by a UN agency found that if women had the same access to resources as men, they could grow 20 to 30 percent more food on their farms and reduce the number of hungry people in the world by 12 to 17 percent.

Mangroves are short trees that grow along coastlines, having adapted to life in salt water; they reduce storm surges, prevent coastal flooding, and protect fish habitats. All told, mangroves help the world avoid some $80 billion a year in losses from floods, and they save billions more in other ways. Planting mangroves is much cheaper than building breakwaters, and the trees also improve the water quality. They’re a great investment.

In short, we can reduce Green Premiums by making carbon-free things cheaper (which involves technical innovation), by making carbon-emitting things more expensive (which involves policy innovation), or by doing some of both. The idea isn’t to punish people for their greenhouse gases; it’s to create an incentive for inventors to create competitive carbon-free alternatives.

Science tells us that in order to avoid a climate catastrophe, rich countries should reach net-zero emissions by 2050.

On the other hand, if our “reduce by 2030” goal is a milestone toward “zero by 2050,” then it makes little sense to spend a lot of time or money switching from coal to gas. Instead, we’re better off pursuing two strategies at the same time: First, going all out to deliver zero-carbon electricity cheaply and reliably; and second, electrifying as widely as possible—everything from vehicles to industrial processes and heat pumps, even in places that currently rely on fossil fuels for their electricity.

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

Use procurement power. Governments at all levels—national, state, and local—buy enormous amounts of fuel, cement, and steel. They build and operate planes and trucks and cars, and they consume gigawatts’ worth of electricity. This puts them in the perfect position to drive emerging technologies into the market at relatively low cost—especially if you factor in the social benefits of bringing these technologies to scale. Defense departments can commit to buying some low-carbon liquid fuels for planes and ships. State governments can use low-emissions cement and steel in construction projects. Utilities can invest in long-duration storage.

In addition to buying things themselves, governments can give the private sector various incentives to go green. Tax credits, loan guarantees, and other tools can help reduce the Green Premiums and drive demand for new technologies.