Does the Amazon Rainforest Really Produce 20 Percent of the World's Oxygen?

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SL_Photography/iStock via Getty Images

Richard Muller:

No. In fact, under normal conditions (prior to human-caused fires) the Amazon [rain]forest is in a steady state. Oxygen is produced by photosynthesis and consumed by decay. If these were out of balance, then the mass of wood in the Amazon must change.

That means if the Amazon were to disappear today, instantly (e.g. we harvested all the wood and used it to build houses) then the oxygen and carbon dioxide in the atmosphere would continue on at the same level. Until, that is, the wood rots. Then the carbon dioxide levels would increase.

Except for the biomass decrease from human-caused fires, the biomass of the Amazon has not been changing. That means that no net carbon dioxide is being removed from the atmosphere, so no net oxygen is being released from carbon dioxide.

Recently the Amazon biomass has been changing due to fires. When that happens, the wood and other carbohydrates in the trees combine with oxygen and produce CO2 and H2O. Thus the burning of the rainforests contributes to global warming.

But under normal situations, when the biomass of the Amazon is not changing, there is no net production of oxygen or carbon dioxide.

Incidentally, many writers who don’t understand this—and mistakenly think that the Amazon produces net oxygen—double their error by using a backward metaphor. They refer to the Amazon basin the "lungs of the world," but lungs are the organ that remove oxygen from the air and replace it with carbon dioxide, not the other way around.

Where did the 20 percent figure come from? The best guess is that ecologists have calculated that 20 percent of the photosynthesis of the world takes place in the Amazon basin. But so does 20 percent of the consumption.

This post originally appeared on Quora. Click here to view.

This Course Will Teach You How to Play Guitar Like a Pro for $29

BartekSzewczyk/iStock via Getty Images
BartekSzewczyk/iStock via Getty Images

Be honest: You’ve watched a YouTube video or two in an attempt to learn how to play a song on the guitar. Whether it was through tabs or simply copying whatever you saw on the screen, the fun always ends when friends start throwing out requests for songs you have no idea how to play. So how about you actually learn how to play guitar for real this time?

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Why Are Common Graves Called Potter’s Fields?

Graves in potter's fields are sometimes marked with blank headstones or crosses.
Graves in potter's fields are sometimes marked with blank headstones or crosses.
vyasphoto/iStock via Getty Images

For centuries, regions around the world have maintained common graves called potter’s fields, where they bury unidentified victims and impoverished citizens who couldn’t afford their own cemetery plots. The term potter’s field has been around for just as long.

The earliest known reference to a potter’s field is from the Gospel of Matthew, which historians believe was written sometime during the 1st century. In it, a remorseful Judas gives the 30 silver coins he was paid for betraying Jesus back to the high priests, who use it to purchase a “potter’s field” where they can bury foreigners. It’s been speculated that the priests chose land from a potter either because it had already been stripped of clay and couldn’t be used for farming, or because its existing holes and ditches made it a particularly good place for graves. But Matthew doesn’t go into detail, and as the Grammarphobia Blog points out, there’s no evidence to prove that the original potter’s field was ever actually used for its clay resources—it could’ve just been a parcel of land owned by a potter.

Whatever the case, the term eventually caught on as English-language versions of the Bible made their way across the globe. In 1382, John Wycliffe translated it from Latin to Middle English, using the phrase “a feeld of a potter,” and William Tyndale’s 1526 Greek-to-English translation of the passage featured “a potters felde,” which was altered slightly to “potters field” in King James’s 1611 edition.

Around the same time, a new definition of potter was gaining popularity that had nothing to do with pottery—in the 16th century, people began using the word as a synonym for tramp or vagrant. According to the Oxford English Dictionary, it was first written in a 1525 Robin Hood tale, and William Wordsworth mentioned it in his 1798 poem “The Female Vagrant.” It’s likely that this sense of the word helped reinforce the idea that a potter’s field was intended for the graves of the unknown.

It’s also definitely not the only phrase we’ve borrowed from the Bible. From at your wit’s end to a fly in the ointment, here are 18 everyday expressions with holy origins.

[h/t Grammarphobia Blog]