This also depends on what you count as carbon dioxide production. For example, cattle produce methane through gut fermentation, which is a strong greenhouse gas. However, it contributes to warming only to the extent the cattle stocks are growing. If cattle numbers are stable for some amount of time, than the methane produced by them does not contribute to new warming, as it forms closed cycle: methane decomposes to CO2 in atmosphere in a decade or two, which is then captured by grass, which is eaten by cattle. The result is a steady state of stable fraction of CO2 and CH4 in atmosphere, and no warming.
What really does contribute to climate change though is emissions that come from fossils, like fuel for machines, electricity for processing and storage, and gas for artificial fertilizer. The variation in reported numbers is caused by agenda, ie whether one wants to accurately assess impact of beef production, or whether they want to paint beef as worst thing ever.
I keep seeing this and I don't understand it because it literally doesn't matter.
There is a total amount of emissions in a year and it leads to a certain amount of atmospheric forcing.
Let's say the algae food amendment works out and cattle methane can be eliminated with it. Some cattle are completely pastured, let's say you can get a 70% reduction in total methane emission from cows, just mandate that lot-fed cattle must receive this feed amendment and maybe subsidize it.
That's huge. That reduces a big source of emissions. It's less atmospheric forcing in total for the year. That's the only thing that matters.
It's an open-and-shut scenario for "shut up and calculate".
Firstly you are presuming cattle are grass fed with no fertilizer used. Nitrogen fertilizer and stock feeds use petrochemicals directly or indirectly.
> If cattle numbers are stable for some amount of time
Cattle numbers are mostly static. The amount of methane produced is not trivial, although as you point out not the same class of problem as CO² since CO² is cumulative. Was your 40 year figure the half-life?
For comparison, CFCs break down over many decades (I couldn't find reliable figures) but the ozone hole is still a serious problem (it seriously affects us in New Zealand where I live).
> methane decomposes to CO2 in atmosphere in a decade or two, which is then captured by grass
But methane is a worse greenhouse gas than CO2, so it's not neutral at all.
You're also assuming that cattle are fed naturally occurring grass rather than industrial livestock feed, which I don't have numbers for but I assume is not carbon-neutral.
But methane is a worse greenhouse gas than CO2, so it's not neutral at all.
It is worse, but it doesn’t matter: as long as cattle population stays at constant levels, so will the amount of methane in the atmosphere that resulted from cattle emissions. You only get climate change from growing amount of greenhouse gases.
> You're also assuming that cattle are fed naturally occurring grass rather than industrial livestock feed, which I don't have numbers for but I assume is not carbon-neutral
In fact, I’m not; I explicitly mention artificial fertilizer, for example, which is typically not used to produce hay. The point is that to assess the effect of cattle on warming, you should focus on fossil inputs into it, not on methane. I think is quite likely that methane production from gastric fermentation in North America these days is lower than, say, in 1500s, where 60 millions bisons alone roamed the plains, along with another tens of millions of deer and other ruminants.
Can’t you apply this logic to other things too though? We have two ICE cars for the household, and as long as that remains stable the CO2 produced will be used by the plants in our garden.
No, because cows run on biofuel that is recently captured carbon, while your car is burning fossil fuel that is long ago captured carbon. Your houseplants aren't recapturing anywhere near that much.
And that methane does not stay in the atmosphere forever, but only for a decade or two. It’s all part of a cycle.
If it makes it easier to think about it, here is one way: imagine a world with no humans, no fossil fuels, but stable population of 10 billion cows. These 10 billion cows produce tremendous amounts of methane. Do you expect this methane to warm the climate over next 1000 years? If you do, you’re wrong: if the population has been and will stay stable, the methane that cows emit is just enough to replace the methane decomposing to CO2 and H2O that was previously emitted by the cows. As long as population numbers are constant, the amount of methane in the atmosphere is also constant, and you’ll see no climate warming.
No, because almost all of the CO2 that comes out of your tailpipe used to be buried underground in stable forms. The plants in your garden both won't absorb enough, and even if it did it would never end up in any long-term storage separate from the atmosphere.
The CO₂ produced by cars is proportional to their use. You could have 100 cars sitting in your massive garage and they wouldn't emit CO₂ beyond what was used for their manufacturing.
What really does contribute to climate change though is emissions that come from fossils, like fuel for machines, electricity for processing and storage, and gas for artificial fertilizer. The variation in reported numbers is caused by agenda, ie whether one wants to accurately assess impact of beef production, or whether they want to paint beef as worst thing ever.