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  • People are always talking about the carbon footprint of cars and deforestation

  • but what about something simple like...

  • my lunch

  • this delicious BLT sandwich!

  • What path did it take to reach my plate?

  • What footprint did it leave on the planet?

  • GOOD QUESTION

  • Luckily, scientists have mapped every step of this sandwich's journey.

  • Let's start with the slices of bread

  • For this much bread you just need a ten by ten inch square of soil

  • A single-serving field!

  • A tractor plows that tiny field

  • burning a single drop of diesel

  • and releasing a puff of carbon dioxide

  • - about enough CO2 to fill a pint glass

  • The tractor comes back - this time to plant the seeds

  • Another drop of fuel,

  • another puff of CO2

  • And now the tractor smooths the soil

  • It's time to add a little fertilizer - about half a tablespoon

  • You'd probably use a tractor to spread that fertilizer

  • But there's more ... that fertilizer was brewed up in a factory

  • creating a couple gallons of CO2 in the process

  • Some of that fertilizer helps the wheat grow

  • but some of it is broken down by microbes in the soil

  • They belch out the equivalent of another gallon of CO2

  • Now it's harvest time!

  • Our little field has yielded ... a third of a cup of grain

  • Now come a bunch of steps that require electricity electricity that comes in part from burniing fossil fuels

  • Time to dry it

  • Drive it to the mill

  • And grind it into flour.

  • Then on to the bakery!

  • A little water, sugar, yeast - each with their own carbon journey

  • And into the oven!

  • Our slices are put in a plastic bag

  • (a plastic bag that was also made in a factory)

  • And shipped off to the store where I picked the up.

  • Every step took a little carbon that was in the form of fuel

  • and put it into the atmosphere as CO2

  • You can see the biggest chunk of carbon comes from the fertilizer.

  • But wait - that's just the bread!

  • We could follow our leaves of lettuce from their field

  • The tomatos from their nursery

  • All the ingredients in our mayo

  • Each journey puts a little more greenhouse gas into the atmosphere

  • But the biggest footprint comes from those four strips of bacon

  • Not only do we have to raise, process, and transport 1/1000th of a pig

  • We have to cultivate the plants to feed that pig

  • To get this one sandwich we've released

  • 800 grams of CO2 (equivalent)

  • That's enough gas to fill 100 of these gallon jugs

  • Eat one of these sandwiches every day for a year, and you'd release the same amount of CO2

  • as you would if you drove a car from New York to Chicago

  • It turns out this simple sandwich isn't so simple

  • Of course - nothing is.

  • You can ask Skunk Bear your science questions by following this link

  • Watch our last episode here

  • And please like, comment and subscribe to our channel.

People are always talking about the carbon footprint of cars and deforestation

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B1 中級 美國腔

碳足跡是什麼?一塊三明治|NPR的SKUNK熊 (The Carbon Footprint Of ... One Sandwich | NPR's SKUNK BEAR)

  • 228 9
    呂翠屏 發佈於 2021 年 01 月 14 日
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