Scientists, politicians, youth activists and business leaders are talking about the dire consequences of climate change. But for the average person sitting on their couch, it can be hard to understand what is so urgent and why it matters to their life.
In his new book, "How to Avoid a Climate Disaster," billionaire Bill Gates shares five basic concepts that have helped to frame his understanding of the pending climate crisis. Gates says they can also help others grasp what's happening to the Earth.
"When I started learning about climate change, I kept encountering facts that were hard to get my head around," Gates writes in the book, which comes out Tuesday. "For one thing, the numbers were so large they were hard to picture....Another problem was that the data I was seeing often appeared devoid of any context."
Gates began to develop "a mental framework" organized around five concepts. "These are complex subjects that can be confusing," Gates writes. "This framework will help you cut through the clutter."
Here are the buckets of information Gates says can help you get your head around the importance of mitigating climate change.
51 billion tons of greenhouse gasses are added to the atmosphere each year
Though emissions for 2020 were a bit less than usual due to the coronavirus pandemic slowing travel and economic output, in a typical year, the world adds 51 billion tons of greenhouse houses (GHG) to the atmosphere, according to the book.
To help put that into perspective, each of those 51 gigatons (a gigaton is 1 billion tons) equals 2.2 trillion pounds. That is equivalent to 10,000 fully-loaded U.S. aircraft carriers, according to NASA (multiplied 51 times).
Gates writes that when considers any green technology or policy, he assesses its impact based on what percentage of 51 billion tons of GHG it can remove from the atmosphere.
"At Breakthrough Energy, we fund only technologies that could remove at least 500 million tons a year if they are successful and fully implemented," Gates writes, referring to the energy innovation investment fund in which he has money, along with other like Jeff Bezos. "That's roughly one percent of global emissions."
Making things, like cement and steel, is more of a culprit than cars or jets
Often, transportation and electricity get the lion's share of attention when it comes to addressing climate change. For instance, electric vehicles are super buzzy thanks to people like Elon Musk and his company, Tesla.
And while they are important, there is more to the story. Any comprehensive climate change strategy has to consider other sources of GHG, so Gates provides a breakdown of various categories and the percentage of total global greenhouse gas emissions each is responsible for:
Making things, like cement, steel and plastic: 31%
Growing things, including plants and animals: 19%
Transportation, including planes, trucks and cargo ships: 16%
Temperature regulation, meaning heating, cooling and refrigeration: 7%
It takes 5,000 gigawatts it takes to power the world
Gigawatts are an energy measurement: "If you were measuring the flow of water out of your kitchen faucet, you might count how many cups came out per second," Gates writes. "Measuring power is similar, only your measuring the flow of energy instead of water. Watts are equivalent to 'cups per second,'" he explains.
Gates shares key back-of-the-napkin measurements to help give context to how much energy it takes to power various things. (One billion watts equal one gigawatt; 1 million watts equals a megawatt; and 1,000 watts equals a kilowatt.)
The world: 5,000 gigawatts
The United States: 1,000 gigawatts
Mid-size city: 1 gigawatt
Small town: 1 megawatt
Average American household: 1 kilowatt
Some power sources take up more space
"Some power sources take up more room than others. This matters for the obvious reason that there is only so much land and water to go around," Gates writes. "Space is by far from the only consideration, of course, but it's an important one that we should be talking about more often than we do."
To measure how much space will be taken up to generate a given amount of power, scientists use a metric called power density, which is measured in watts per square meter.
It's important to consider the watts per square meter when discussing the viability of a particular energy solution for a particular location or situation. "If you want to use wind instead of solar, you'll need far more land, all other things being equal," Gates writes. "That doesn't mean that wind is bad and solar is good. It just means that they have different requirements that should be part of the conversation."
Here are the watts per square meter for some of the most commonly discussed power sources:
Fossil fuel: 500 to 10,000 watts per square meter
Nuclear: 500 to 1,000 watts per square meter
Solar: 5 to 20 watts per square meter (Gates says it's theoretically possible for this to get as high as 100.)
Hydropower, such as dams: 5 to 50 watts per square meter
Wind: 1 to 2 watts per square meter
Wood and other biomass: Less than 1 watt per square meter
It all comes back to money
"The reason the world emits so much greenhouse gas is that — as long as you ignore the long-term damage they do — our current energy technologies are by and large the cheapest ones available," Gates says.
Green or clean energy solutions, are more expensive than using fossil fuels. Gates calls it the "green premium." For each energy source, the green premium will be different. (In very rare cases, it can be negative. For instance, in some cities, intalling an electric heat pump will be cheaper than having a gas furnace and an air conditioner, Gates says.)
"During every conversation I have about climate change, Green Premiums are in the back of my mind," Gates writes.
And since carbon emissions are a global problem, it's key to consider what is affordable for all countries, not just the weatlhy ones, Gates says.