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  • For more than 10,000 years, the average global temperature

  • didn't change by more than 1 degree Celsius.

  • But then humans started burning fossil fuels,

  • around here.

  • Today, global temperatures have risen about 1 degree Celsius since pre-industrial times.

  • This is what that looks like so far:

  • Storms have gotten more intense,

  • wildfires are more common,

  • and ancient glaciers are melting faster and faster.

  • And that's just one degree of warming.

  • Without global action, the world is on track to warm at least 3 degrees Celsius by 2100.

  • This would be catastrophic.

  • That's why most scientists agree that we need to limit global warming to this range,

  • between 1.5 and 2 degrees Celsius.

  • Carbon dioxide, which is emitted when we burn fossil fuels,

  • accounts for most of the world's greenhouse gas emissions.

  • It's the main culprit behind climate change.

  • And to limit global warming to the degree that scientists are calling for,

  • we have to stop releasing it.

  • We have todecarbonize.”

  • The US doesn't currently emit the most carbon dioxide of any country.

  • But as one of the oldest industrial powers, it's emitted more carbon dioxide in total

  • than any other country or region.

  • So America has a big role to play in decarbonizing.

  • But how is the US supposed to do that?

  • And is it actually possible?

  • If you want to get halfway there by 2030, you have to start now.

  • Now. Going fast.

  • There is literally zero more time to waste.

  • Dave writes about energy and climate for Vox.

  • And he says the 2020 US election comes with fairly clear stakes.

  • If Trump is reelected, that's it. Like there's no chance for 1.5.

  • And probably all chances for 2 degrees are gone.

  • The United States will withdraw from the Paris climate accord.”

  • “...open up the coal mines.”

  • “...new offshore oil and gas leasing program.”

  • President Trump doesn't have a climate policy.

  • And his reelection will most likely continue policies designed to boost the fossil fuel industry.

  • They'd increase carbon emissions instead of decreasing them.

  • And the effects would be felt globally.

  • You just can't have the world's second biggest economy opting out,

  • moving kin the opposite direction, and expect the world to get there.

  • The other major candidate in the election does have a plan to address climate change.

  • And this part of it in particular is ambitious:

  • Biden has been convinced and pushed to the point that he's got a great climate plan.

  • What Biden's plan doesn't get into are the details on exactly how the US would actually do that.

  • But there are people who have thought about what it might look like to decarbonize by 2050.

  • And to understand that, it helps to get a picture of where America's energy comes from,

  • and where it goes.

  • [Scream]

  • Sorry, my son nearly stepped on a snake.

  • Do you want to say hi?

  • This is Saul Griffith. He's a physicist, and an engineer, but this is how Dave describes him:

  • Probably the person who knows more about energy as it's used in the United States

  • than any other human being.

  • A few years ago, Saul decided to make a model of America's energy use.

  • He ended up reading basically every available piece of data, from...

  • ...the Energy Information Administration,

  • Department of Transportation,

  • the National Highway Transit Authority,

  • the Census Bureau,

  • Bureau of Labor Statistics,

  • and NOAA.

  • And so we pulled all of those together to build a very comprehensive picture of the US energy economy.

  • That picture of the US energy economy?

  • It looks like this:

  • If you're just looking at the whole thing at once, it just looks like a big pile of spaghetti.

  • It's hard to make sense of, but it just traces energy, every unit of energy.

  • How does it enter the economy? How is it used throughout the economy?

  • This kind of chart is called a Sankey diagram. And it's easier to understand in 3 sections.

  • These columns here on the left are the sources of all the energy used in the US,

  • like natural gas, coal, solar, wind, nuclear, and oil.

  • This column in the middle is what those energy sources get converted into.

  • So a lot of it becomes electricity. Most oil becomes the fuel we use for transportation.

  • And here, you can see how much natural gas energy is being used to generate electricity,

  • versus being used directly to power things like cooking stoves.

  • And over here on the right? This is where all the energy is used,

  • broken down into incredible detail.

  • Like how much energy is used to light shopping malls in the US.

  • Or how much energy is used by vehicles driven for work.

  • So you start to get this incredibly detailed picture of all of the interconnections,

  • which is really, really important when you do the next exercise:

  • what happens if we decarbonize?

  • Remember that carbon emissions come from the burning of fossil fuels. This stuff.

  • And Saul says that means that to decarbonize, we just need to follow their path.

  • The first place that leads you is here, with electricity and the energy we use to generate it

  • the majority of which, in the US, comes from two kinds of fossil fuel: natural gas and coal.

  • If the US wants to decarbonize, it needs to stop getting electricity this way,

  • and replace it with other decarbonized energy sources.

  • That means coal power plants - gone.

  • Gas power — gone.

  • All electricity would come from renewable sources

  • wind, solar, geothermal, hydroelectric, and biomass. Or, nuclear energy.

  • Decarbonizing the way we get electricity would be a huge investment.

  • But it would also only eliminate 20% of emissions.

  • And that's because electricity and energy are not exactly the same thing.

  • That doesn't solve vehicles' emissions.

  • It doesn't solve your heating emissions from using natural gas or fuel oil in your basement.

  • All these other parts of the economy draw their energy directly from fossil fuels.

  • Like transportation: We use oil for fuel.

  • And commercial and residential buildings, where we use gas and oil for heat.

  • But Saul says there's a kind of elegant solution to this:

  • you decarbonize these sectors by switching their energy source

  • from here, to here.

  • Make all of it electric.

  • Because we already have almost all of the technology we need to do it.

  • Heat pumps, batteries, electric vehicles, wind turbines, nuclear power plants.

  • We know that that can work. We know we can do electric cars.

  • We know we can do electric heat for nearly everything.

  • It's all in the end just about machines, right?

  • We've got a bunch of machines that use fossil fuel energy.

  • We need to replace them with machines that use clean electricity.

  • And so it really just comes down to a matter of industrial capacity:

  • How fast can you build machines?

  • There are some things we'd have a harder time decarbonizing.

  • Air travel will rely on fossil fuels until alternative technologies get better.

  • And things like steel and concrete are really hard to manufacture without fossil fuels.

  • But if we decarbonized as much as possible with the technology that we have now,

  • it would end most of the US's carbon emissions.

  • This chart shows the country's carbon emissions broken down by economic sector.

  • If electricity, residential, commercial, and transportation were mostly decarbonized,

  • you'd have solved a lot of the problem.

  • All of this would be a huge undertaking. And it needs to happen fast.

  • Saul's research modeled different scenarios

  • for the transition from fossil fuel-based machines to electric ones:

  • From a market-driven transition, to carbon taxes,

  • to a much more direct and heavy-handed approach that would replace our machines with

  • their electric counterparts very quickly.

  • And he found that because we've delayed action for so long,

  • none of these slower approaches will be enough.

  • If you went back to 2000 and started then, you could just put like a modest carbon tax in place

  • and it would have just eased us down over the course of 30 years or whatever.

  • But emissions kept rising and rising and rising.

  • So now to get where we need to go, they got to fall off a cliff.

  • And that means zero delay.

  • We're just talking about a level of industrial mobilization that none of us alive have seen.

  • It would look like what FDR did to prepare us to prepare the US for war.

  • Literally, every single solitary fossil fuel machine that goes out of service

  • is replaced by a clean energy alternative.

  • Every furnace, car, factory, you name it.

  • Nearly everyone is buying an electric vehicle,

  • nearly everyone is buying rooftop solar, nearly every new power plant that comes online is

  • industrial scale solar, or industrial wind.

  • We need that level of effort to do a lot better than two degrees.

  • All of recorded human history has happened within an era of relative climate stability.

  • An era that's about to end.

  • But we still have control over what comes next.

  • And the global effort that'll require hinges in part on what the US decides to do.

  • America can decarbonize. We have the technology to do it. We have the resources.

  • The only question is whether we want to do it.

  • I have a six year old and an eleven year old, and I have to believe that's going to happen. Otherwise..

  • And I have to try to make that happen,

  • as long as possible,

  • because it's their future we're stealing by not doing it.

  • Thanks for watching this episode of our 2020 election series.

  • We're focusing on the issues that matter most to you. And we got this topic requested by a lot of people.

  • We want to know what you think the candidates should be talking about.

  • Tell us at Vox.com/ElectionVideos.

For more than 10,000 years, the average global temperature

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How America can leave fossil fuels behind, in one chart

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    林宜悉 posted on 2020/09/10
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