Thread by @ncdave4life

1/14》Have you ever wondered…

Ｑ: Why is CO2 a trace gas in the atmosphere?

Ａ: Because of LIFE!

All life on planet Earth is carbon-based. The carbon is from CO2 in the air. Carbon-hungry living things used up nearly all of it, harvesting carbon and releasing oxygen as waste.

2/14》Every schoolchild learns that animals use O2 (oxygen) and produce CO2 (carbon dioxide), and plants do the opposite. But have you ever wondered why there are about five hundred O2 molecules in the Earth’s atmosphere for each CO2 molecule?

3/14》On Venus and Mars it's the other way around. On those planets, nearly all of the oxygen in the atmosphere is in the form of CO2, and almost none is O2.

But on Earth O2 is 21% of the atmosphere, and CO2 is only 0.04%.

Ｑ: Do you know why?

4/14》

Ａ: It is because Venus and Mars are dead planets, and the Earth is not. The difference is LIFE!

5/14》Carbon-hungry living things used up nearly all the CO2 to get carbon, discharging O2 as waste. All life is carbon-based, and CO2 is the source of that carbon. Photosynthetic plants get their carbon directly from the air, and animals get their carbon by eating those plants.

6/14》But, you might wonder, why aren't the CO2 and O2 levels similar? Why is there so little CO2, and so much O2?

Step outside and look around, and you'll have your answer: The plants outnumber us animals!
quora.com/Why-is-carbon-…

sealevel.info/forest-landsca…

7/14》In the CO2 / O2 tug-o-war between plants and animals, the plants pulled the rope all the way to the end.

8/14》The plants used up the CO2 until they ran out, practically speaking. They used up CO2 until the level got so low that the photosynthesis rate was reduced to rough equilibrium with the CO2 production rate.

9/14》It is a very fundamental, negative (stabilizing) climate feedback mechanism: the more CO2 there is, the faster plants and calcifying marine life use it up.
sealevel.info/feedbacks.html…

sealevel.info/co2_plant_nega…

10/14》The large amount of O2 (free oxygen) in Earth’s atmosphere, and the very low CO2 concentration, are both the result of LIFE.

11/14》What’s more, as CO2 levels have fallen, plants have become more and more adept at removing CO2 from the atmosphere. C4 grasses can continue to harvest CO2 from the atmosphere even at levels so low that most plants (C3 plants) die of CO2 starvation.
sealevel.info/Rice_C3_vs_Set…

12/14》BTW, that’s also how you can hope to detect life on exoplanets: look for an oxygen-rich atmosphere. If you find an atmosphere with a lot of free oxygen in it, you’ve found the fingerprint of carbon-based life.

13/14》To understand a highly politicized topic like #ClimateChange, you need balanced information. If you get information only from people working in the industry you'll surely be misled.

https://twitter.com/ncdave4life/status/1432810945017962505

14/14》The scientific evidence is compelling that manmade #ClimateChange is modest and benign, CO2 emissions are beneficial rather than harmful, and the "social cost of carbon" is negative.
sealevel.info/learnmore.html…

@ThreadReaderApp @Rattibha unroll

@threadreaderapp @rattibha 15/14》"Unrolled" compilations of this thread:
1. threadreaderapp.com/thread/1529098…
2. rattibha.com/thread/1529098…