Quotes from Bill Gates

The average retail price for a gallon of jet fuel in the United States over the past few years is $2.22. Advanced biofuels for jets, to the extent they're available, cost on average $5.35 per gallon. The Green Premium for zero-carbon fuel, then, is the difference between these two prices, which is $3.13.

If we get a breakthrough in cheap hydrogen, for example, we might not need to worry as much about getting a magic battery.

I'm also a technophile. Show me a problem, and I'll look for technology to fix it.

In particular, Green Premiums are a fantastic lens for making decisions. They help us put our time, attention, and money to their best use. Looking at all the different premiums, we can decide which zero-carbon solutions we should deploy now and where we should pursue breakthroughs because the clean alternatives aren't cheap enough. They help us answer questions like these:

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.

Which zero-carbon options should we be deploying now? Answer: the ones with a low Green Premium, or no premium at all. If we're not deploying these solutions already, it's a sign that cost isn't the barrier. Something else—like outdated public policies or lack of awareness—is stopping us from getting them out there in a big way.

We already know the emissions number; it's 51 billion tons each year. As for the cost of removing a ton of carbon from the air, that figure hasn't been firmly established, but it's at least $200 per ton. With some innovation, I think we can realistically expect it to get down to $100 per ton, so that's the number I'll use. That gives us the following equation: 51 billion tons per year x $100 per ton = $5.1 trillion per year

We need to channel the world's passion and its scientific IQ into deploying the clean energy solutions we have now, and inventing new ones, so we stop adding greenhouse gases to the atmosphere.

CGIAR is the world's largest agricultural research group: In short, it helps create better plants and better animal genetics.

Tip: Keep the Green Premiums in mind and ask whether they're low enough for middle-income countries to pay.

To sum up: Rich and middle-income people are causing the vast majority of climate change. The poorest people are doing less than anyone else to cause the problem, but they stand to suffer the most from it. They deserve the world's help, and they need more of it than they're getting.

Making Carbon-Free Electricity Nuclear fission. Here's the one-sentence case for nuclear power: It's the only carbon-free energy source that can reliably deliver power day and night, through every season, almost anywhere on earth, that has been proven to work on a large scale.

The share of global power that comes from burning coal (roughly 40 percent) hasn't changed in 30 years. Oil and natural gas together have been hovering around 26 percent for three decades. All told, fossil fuels provide two-thirds of the world's electricity. Solar and wind, meanwhile, account for 7 percent.

With all the additional electricity we'll be using, and assuming that wind and solar play a significant role, completely decarbonizing America's power grid by 2050 will require adding around 75 gigawatts of capacity every year for the next 30 years.

A hotter climate means there will be more frequent and destructive wildfires.

If you like having an ozone layer, you can thank an international agreement called the Montreal Protocol.

Cities need to change the way they grow. Urban areas are home to more than half the people on earth—a proportion that will rise in the years ahead—and they're responsible for more than three-quarters of the world's economy. As they expand, many of the world's fast-growing cities end up building over floodplains, forests, and wetlands that could absorb rising waters during a storm or hold reservoirs of water during a drought.

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.

It's easy to feel powerless in the face of a problem as big as climate change. But you're not powerless.

It wasn't enough to deliver cheap, reliable energy for the poor. It also had to be clean.

If the vehicle you took to work or school today was powered by electricity, great—though that electricity was probably generated using a fossil fuel.

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

All these different types of plastics have one thing in common: They contain carbon. Carbon, it turns out, is useful in creating all sorts of different materials because it bonds easily with a wide variety of different elements; in the case of plastics, it's usually clustered with hydrogen and oxygen.

seawater expands when it gets warmer.