There isn't a great way to list all of the sources for a figure in the column.
This webpage provides links to sources and points to pages where the figures can be found. It also provides my calculations for figures I could not find online.
"In 2022, the majority of GHG emissions primarily consisted of CO2, resulting from the combustion of fossil fuels (71.6%). CH4 contributed 21% to the total, while the remaining share of emissions comprised N2O (4.8%) and Fgases (2.6%)"
21% of human-caused GHGs are methane. 37% of that is due to fossil fuel extraction, transportation, processing, and burning. (See below for the 37% figure)
37% of 21% is 7.8%.
71.6% (CO2) + 7.8% (methane) is 79.4% due to fossil fuel burning
"the global energy sector was responsible for nearly 135 million tonnes of methane emissions in 2022, a slight rise from the amount in 2021. Coal, oil and natural gas operations are each responsible for around 40 Mt of emissions and nearly 5 Mt of leaks from end-use equipment. Around 10 Mt of emissions comes from the incomplete combustion of bioenergy, largely from the traditional use of biomass. The energy sector is responsible for nearly 40% of total methane emissions attributable to human activity, second only to agriculture."www.iea.org/reports/global-methane-tracker-2023/overview
Calculations
10 Mt of the 135 Mt of energy sector methane emissions are from burning biomass.
125/135 of the energy sector methane emissions are from fossil fuel extraction, transportation, processing, and burning. 125/135 = 92.6%. 92.6% of 40% = 37%.
Data from www.iea.org/reports/methane-tracker-2021/methane-and-climate-change :
Waste 68 Mt
Total emissions: 570 Mt
60% emitted by people.
60% of 570 = 342.
68 / 342 = 20%
Data from www.iea.org/reports/methane-tracker-2021/methane-and-climate-change :
Agriculture emits 145 Mt
Total emissions: 570 Mt; 60% emitted by people. 60% of 570 = 342.
145 Mt / 342 Mt = 42% = Agriculture portion
42% of 21% = 9%.
On average, a pound of dry wood has roughly about a half-pound of carbon (www.woodworks.org/resources/calculating-the-carbon-stored-in-wood-products/, extension.psu.edu/conversions-commonly-used-when-comparing-timber-and-carbon-values)
A carbon dioxide molecule is created by adding two oxygen molecules, weighing 16 atom weight each, to a carbon molecule that weighs 12 in atomic weight. So the carbon weighs 12 and a carbon dioxide molecule weighs 44.
So, to translate from carbon to carbon dioxide, we multiply by 44/12.
44/12 is 3.667. Half of that is 1.83.
A pound of dry wood was created by pulling a half pound of carbon out of the air.
A half pound of carbon requires pulling 1.83 pounds of carbon dioxide out of the air.
A kilo of dry wood was created from 1.83 kilos of carbon dioxide.
"From the 50th year of age to 100th, an acre of Doug Fir forest in Western Washington adds about 40 to 500 cubic feet of wood each year"
A cubic foot of Douglas Fir wood weighs about 22 pounds
(https://images.thdstatic.com/catalog/pdfImages/73/73427c5c-1d81-4ffb-91be-08085cc63b60.pdf).
That's about 10 kilos. So an acre of mature (50 year to 100 year old) Doug Fir forest adds about 400 to 5,000 kilos of wood each year. That requires eating 2 to 9 metric tons of carbon dioxide each year per acre of forest.
Other sources:
"An acre of trees can sequester about two to five tons of carbon dioxide each year."
"on average one acre of slash pine forest offsets about 3.69 metric tons of CO2 emissions per year. In reality, there can be a lot of variation from site to site due to differences in stand age, site quality, silvicultural management, and planting density."
Oak forests probably sequester more carbon each year than forests in Western Washington.
"An approximate value for a 50-year-old oak forest would be 30,000 pounds of carbon dioxide sequestered per acre" [30,000 pounds is 13.6 metric tons]
"Counties west of the Cascade divide account for 93% of Washington's annual forest carbon sequestration from all pools (15.0 ± 8.2 MMT CO2e per year and 1.3 ± 0.7 MT CO2e/ac/yr)."
That is 1.3 metric tons of carbon dioxide per acre per year.
"Carbon sequestration as gross tree growth on an annual per acre basis is highest on private corporate and WA-DNR forests (4.9 ± 0.3 MT CO2e/ac/yr and 4.4 ± 0.4 MT CO2e/ac/yr, respectively), with slightly less carbon sequestration due to gross tree growth on other state and local government ownerships (4.2 ± 0.7 MT CO2e/ac/yr). Private non-corporate and USDA Forest Service ownerships have the lowest carbon sequestration from gross tree growth on an annual per acre basis at 2.8 ± 0.12 MT CO2e/ac/yr and 2.9 ± 0.05 MT CO2e/ac/yr respectively (Table 4.13, Figure 4.10)."
Burning a gallon of gasoline releases 8.887 kilograms of CO2 (https://www.epa.gov/energy/greenhouse-gases-equivalencies-calculator-calculations-and-references).
600 gallons release 5,332.2 kilograms (8.887 X 600), or 5.33 metric tons.
"Methane accounts for about 20 percent of global greenhouse gas... Besides agrifood systems, other human activities that generate methane emissions include landfills, oil and natural gas systems, coal mines and more. About 32 percent of global anthropogenic methane emissions result from microbial processes that occur during the enteric fermentation of ruminant livestock and manure management systems, while another 8 percent comes from rice paddies."
That is 32% of 20% is enteric fermentation. That is 6.4%.
8% of 20% is rice: that is 1.6%.
"Feeding livestock many seaweeds -- also known as red, green or brown marine macroalgae -- has been shown to reduce methane production, but with highly variable results (9–12). For example, in vitro analysis suggested that the tropical/subtropical red seaweed Asparagopsis taxiformis can reduce methane production by 95% when added to feed at a 5% organic matter inclusion rate (13)."
A report from 2014: www.greencarreports.com/news/1093560_1-2-billion-vehicles-on-worlds-roads-now-2-billion-by-2035-report
How many of them have a say over what the cattle get fed? Maybe 1 out of 5? If one out of five have a say over what the cattle are fed, that’s 153,000 cattle bosses in the U.S.
The U.S. produces about 18% of the beef in the world (https://www.beefresearch.org/programs/beef-sustainability/sustainability-quick-stats/us-vs-global-in-efficiency-and-production).
If each pound of beef involved the same number of decision makers everywhere in the world, you would have possibly 852,000 million cattle-feed decision makers.
There's a lot of uncertainty here, so estimate between 100,000 and 2 million.
100,000 / 1.5 billion = 15,000
If every rancher opts for seaweed, and there are 2 million feed-deciding ranchers, that would be something like 2 million people creating 6% improvement. That is 6 / 2 million percentage points per person. That is 0.000003 percentage points per person, 57 times as much impact per decision maker as the car shoppers.
If there are 100,000 feed-deciding ranchers, that is 6 / 100,000 percentage points per person: 0.00006 percentage points per person. That is 1,139 times the impact of the car shoppers.
Fossil fuel opportunity: 79% of current GHG emissions.
Remaining opportunity after stopping all fossil fuel burning: 21%.
Cattle seaweed portion of the remaining opportunity = 6.4% / 21% = 30.48%.