Sources and Calculations for April 2024 MyEdmondsNews Climate Protection column: Seaweed for Cows

My April Climate Protection column for My Neighborhood New Network has a lot of figures. Some of them come from large reports, and I can't link to the specific page where you would find the source. I calculated other figures myself, and it would be tedious to include all the calculations in the column.

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.

Globally, 79% of greenhouse gas emissions are from people burning fossil fuels... 21% of human-created greenhouse gases are methane.

"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%)"
(Page 13 of Crippa, M., Guizzardi, D., Pagani, F., Banja, M., Muntean, M., Schaaf E., Becker, W., Monforti-Ferrario, F., Quadrelli, R., Risquez Martin, A., Taghavi-Moharamli, P., Koykka, J., Grassi, G., Rossi, S., Brandao De Melo, J., Oom, D., Branco, A., San-Miguel, J., Vignati, E., GHG emissions of all world countries, Publications Office of the European Union, Luxembourg, 2023, doi:10.2760/953332, JRC134504.)

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

Altogether, if we stopped burning natural gas, gasoline, and coal, we would stop 37% of the methane releases.

"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."


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%.

Sewage treatment and landfills produce 20%.

Data from :

Waste 68 Mt

Total emissions: 570 Mt

60% emitted by people.

60% of 570 = 342.

68 / 342 = 20%

Agricultural releases 42% of global warming from methane... agricultural methane is 9% of the global greenhouse gas emissions.

Data from :

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%.

An acre of mature forest in Western Washington eats up about 2 to 5 metric tons of carbon dioxide each year.

The amount of carbon dioxide eaten up by a forest acre depends on how many trees are in the acre, how fast the trees is currently growing, how large they are currently, and what kind of trees they are.

On average, a pound of dry wood has roughly about a half-pound of carbon (,

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"
(, page 14).

A cubic foot of Douglas Fir wood weighs about 22 pounds


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)."
(, page 3)

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)."
(, Page 13)

Five tons is how much is released when a gasoline car that gets 25 MPG drives 15,000 miles

A 25-MPG car burns 600 gallons of gasoline to drive 15,000 miles.

Burning a gallon of gasoline releases 8.887 kilograms of CO2 (

600 gallons release 5,332.2 kilograms (8.887 X 600), or 5.33 metric tons.


Altogether, cattle gas produces 6.4% of the greenhouse gas heating of human activities.

"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%.


It turns out that supplementing cattle feed with seaweed can almost completely eliminate cattle gas.


"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)."

There are about 1.5 billion cars and trucks in the world.


A report from 2014:


There are probably somewhere between 100 thousand and 2 million people worldwide who decide whether to feed seaweed to cattle.

In the U.S., there are about 767,000 people working in the cattle industry (

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 (

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.


1 cattle boss for every 750 to 15,000 car shoppers

2 million / 1.5 billion = 750

100,000 / 1.5 billion = 15,000


Each rancher who chooses seaweed will have over 50 times the impact on greenhouse gas emissions as a car buyer who chooses electric... Maybe over 1,000 times the impact.

If every car shopper bought an EV, something like 1.5 billion people would have together created a 79% reduction in greenhouse gases. That is a 79 / 1.5 billion percentage points per person. That is 5.2666E-8 percentage points per person.

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.


If all we did was stop burning fossil fuels, cattle gas would go from 6.4% of greenhouse gas emissions up to 30%.

Cattle gas: 6.4% of current GHG emissions.

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%.