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Greenhouse gases: Difference between revisions
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(Created page with "File:ghg-usa-2020.png <!-- TODO: find an equivalent pie chart for the world, not just USA --> <small>Total U.S. Emissions in 2020 = 5,981 Million Metric Tons of CO2 equivalent (excludes land sector). Percentages may not add up to 100% due to independent rounding.</small> The pie chart percentages are of total warming effect (CO2 equivalent), not the mass of the gases. ==Gases by potency== Some gases are far more potent than others, by mass. Luckily, the more pot...") |
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Luckily, the more potent gases are emitted in such vastly smaller quantities that they don't contribute as much to global warming as CO<sub>2</sub> does (see pie chart above). | Luckily, the more potent gases are emitted in such vastly smaller quantities that they don't contribute as much to global warming as CO<sub>2</sub> does (see pie chart above). | ||
{|class="wikitable" | {|class="wikitable sortable" | ||
! | ! | ||
!Name | !Name | ||
!GWP {{p|Global Warming Potential (per unit mass, 100-year timescale)}} | ![[Term:GWP|GWP]]<sub>100</sub> {{p|Global Warming Potential (per unit mass, 100-year timescale)<br /><br />Defined by question:<br />Emitting 1 ton of the gas is equivalent to emitting how many tons of CO<sub>2</sub>, when considering the warming effects over the next 100 years?}} | ||
!Relative potency {{p|This metric is not tied to a particular timescale.<br /><br />Defined by question:<br />1 ppm of the gas in the atmosphere, has the same warming effect as how many ppm of CO<sub>2</sub>?}} | |||
!Atmospheric longevity | !Atmospheric longevity | ||
|- | |- | ||
|CO<sub>2</sub> | |CO<sub>2</sub> | ||
|Carbon dioxide | |Carbon dioxide | ||
|1 | |||
|1 | |1 | ||
|300 to 1,000 years | |300 to 1,000 years | ||
| Line 25: | Line 27: | ||
|Methane | |Methane | ||
|25 | |25 | ||
| | |||
|12 years | |12 years | ||
|- | |- | ||
| Line 30: | Line 33: | ||
|Nitrous Oxide | |Nitrous Oxide | ||
|273 | |273 | ||
| | |||
|114 years | |114 years | ||
|- | |- | ||
| Line 35: | Line 39: | ||
|Tetrafluoromethane | |Tetrafluoromethane | ||
|7,380 | |7,380 | ||
| | |||
|50,000 years | |50,000 years | ||
|- | |- | ||
| Line 40: | Line 45: | ||
|Hexafluoroethane | |Hexafluoroethane | ||
|12,400 | |12,400 | ||
| | |||
|10,000 years | |10,000 years | ||
|- | |- | ||
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|[[Sulfur hexafluoride]] | |[[Sulfur hexafluoride]] | ||
|23,900 | |23,900 | ||
| | |||
|3,200 years | |3,200 years | ||
|} | |} | ||
<!-- TODO: elaborate on all this --> | <!-- TODO: elaborate on all this --> | ||
<!-- DRAFT: PFCs (CF4 and C2F6) have an even higher potency if looking at the ultra-long term (hundreds of thousands of years). If we emit too many PFCs,{{qn}} it might become impossible to maintain normal atmospheric temperatures without somehow removing so much CO2 from the atmosphere that plants can't grow (which would be bad, for obvious reasons). --> | <!-- DRAFT: PFCs (CF4 and C2F6) have an even higher potency if looking at the ultra-long term (hundreds of thousands of years). If we emit too many PFCs,{{qn}} it might become impossible to maintain normal atmospheric temperatures without somehow removing so much CO2 from the atmosphere that plants can't grow (which would be bad, for obvious reasons). --> | ||
<!-- TALK: ultra-longtermist perspective: | |||
We shouid define GWP<sub>longterm</sub> as: relative_potency * half_life / half_life_of_CO2 | |||
This would matter for the "immortal" fluoride compounds in thousands of years from now, if humanity never finds a way to scrub them faster from the atmosphere. | |||
--> | |||
==External links== | ==External links== | ||
* [https://www.epa.gov/ghgemissions/overview-greenhouse-gases Overview of Greenhouse Gases - US EPA] | * [https://www.epa.gov/ghgemissions/overview-greenhouse-gases Overview of Greenhouse Gases - US EPA] | ||