I feel like the question asked in the survey and the conclusion regarding the prevalence of the eat local myth aren't quite aligned. The question (as I understand it) is about the effectiveness of government interventions, not the effectiveness of changes in consumer practice. As you mention in relation to the Overton window, it might be that public responses to your survey are focused on the perceptions of what the public might positively respond to - if going plant based is widely seen as almost 'unthinkable' the maybe the government's promotion of a plant based diet might not be the most effective intervention to reduce emissions from the animal agriculture industry, as such an intervention could be perceived as having very little impact on actual consumer behavior.
I worry that, for beef in particular, a lot of this discussion is slanted by the strange way in which methane emissions are scaled to "equivalent" CO2 emissions. There isn't really any non-arbitrary way to do this, because methane affects the climate in such a different way to CO2 (and N2O, the 3rd-most-important GHG).
Most GHGs are so long-lived in the atmosphere that their effect of emissions is effectively independent of time or rate of emissions. What matters is how much total carbon you've emitted. If the world emits X tonnes/yr for Y years, that's no different to X/2 tonnes/yr for 2Y years from the perspective of what the climate will be like at the end of that emission and ongoingly. What matters is how much carbon (or other long-lived GHGs) have been emitted total.
This is very nasty. It takes so long for the global carbon cycle to come to equilibrium that, on human-relevant timescales, adding CO2 to the atmosphere warms the planet up *and it doesn't cool down when you stop adding it*. It stops *heating up more* (give a decade or so for it to equilibrate), but then you're at that temperature. If you want to *undo* that warming, you have to *take CO2 out* (or wait millions of years).
Methane is much, much nicer. It has a much more aggressive warming effect per unit mass than CO2, but it's re-absorbed within a decade or two. This means that, if methane were the only relevant GHG, the temperature would depend on the *rate of emissions* rather than the total amount emitted. That would mean that, with a decade or two to equilibrate baked in again, if you had a methane-based warming problem, if you stopped emitting methane, the earth would *cool back down again to how it was before you started*.
These are entirely different dynamics, and you can't really just convert one to the other with a simple multiplier. For CO2, very roughly, you can say X tonnes emitted total will make the earth Y degrees hotter than the baseline. Zero emissions means constant temperature. For methane, very roughly, you can say X *rate of emissions* will give you an earth Y degrees hotter than baseline, and zero emissions means you return to that baseline.
Put another way, a constant rate of methane emissions equals a constant temperature. A constant rate of CO2 emissions means a constant *rate of temperature increase*.
In my mind, this means methane is just barely an issue long-term. It's like we're pouring water into a leaky tub with holes all up the side that we don't want to go above a certain level. We pour faster, the level rises, but then comes to equilibrium again with a faster leak rate. We reckon it's too high, we slow down the pour, the level drops again until it comes to equilibrium at a lower level with a lower leak rate. CO2 is like a sealed tub we don't want to go above a certain level. If you want to never go above that level, you gotta *stop pouring entirely before you reach it* and if you overshoot you've got to *remove some manually*.
So, we have to get CO2 emission to *net zero* to sort climate change. But we have to get methane emissions to *some level where we're comfortable with the temperature that *rate* of emissions implies*. Over-emitting methane is a problem you can correct by cutting methane emissions. Over-emitting CO2 is a problem you have to correct with carbon-removal tech (a big hassle slash basically impossible depending on who you talk to).
So why on earth would we put almost any marginal GHG-reduction efforts into methane, at almost any conversion factor, where this is an option?!?! Cutting methane emissions will have a sort of zero-order step-down effect on global temperatures which are still inexorably rising, whereas cutting CO2 emissions will *slow down the rate of increase*. That's so much better unless we're in some extremely well-defined "tipping-point" scenario and need some more time.
I'm not saying don't cut methane! I'm saying trying to compare the "equivalent" impacts of CO2 and methane with some conversion factor is nonsense, because they just aren't comparable. The IPCC realised this eventually and dropped the eCO2 metric, and now talks about CO2 and methane as two separate drivers with different modes of action. But a huge amount of the climate advocacy and financing industry has got stuck on "eCO2", which is a silly metric that tries to compare the incomparable by setting a particular time threshold (normally 100 years) and integrating under it. But that's far, far too short-sighted! Cutting almost any amount of methane in preference to almost any amount of CO2 is banking a little short-term gain for catastrophic long term loss!
I would almost advocate a strict policy dominance - get CO2 to *zero* before you compromise that effort *at all* in favour of cutting methane. Of course on the margin less methane is better, but in areas like ag, where methane, NO2, and CO2 emissions are all important, and often we have this exact choice of saying emit more of one than the other, then I say just measure CO2 and N2O (and the minor long-lived GHGs, all of which can safely be put into an eCO2 metric based on their relative warming effects as they all have this time-independent warming action) and care about that, and then consider methane as something totally separate and much less important.
I'd also say care about animal welfare way more than either because there's so much more value on that margin, but nobody's out there trying to roll chicken suffering into eCO2 terms so I don't have to have that fight!
But upshot of this is that it does mean beef just isn't nearly as overwhelmingly bad for the climate as eCO2 metrics make it seem, because a disproportionate amount of that comes from methane, which I really think we could stand to basically ignore in the short-term in preference to cutting CO2 and N2O.
Very interesting - lots of 'food' for thought!
I feel like the question asked in the survey and the conclusion regarding the prevalence of the eat local myth aren't quite aligned. The question (as I understand it) is about the effectiveness of government interventions, not the effectiveness of changes in consumer practice. As you mention in relation to the Overton window, it might be that public responses to your survey are focused on the perceptions of what the public might positively respond to - if going plant based is widely seen as almost 'unthinkable' the maybe the government's promotion of a plant based diet might not be the most effective intervention to reduce emissions from the animal agriculture industry, as such an intervention could be perceived as having very little impact on actual consumer behavior.
Great article, well evidenced and broken down.
Valuable post. I eat local for the regional landscape and socioeconomic sustainability, not climate. Keep up the good work.
I worry that, for beef in particular, a lot of this discussion is slanted by the strange way in which methane emissions are scaled to "equivalent" CO2 emissions. There isn't really any non-arbitrary way to do this, because methane affects the climate in such a different way to CO2 (and N2O, the 3rd-most-important GHG).
Most GHGs are so long-lived in the atmosphere that their effect of emissions is effectively independent of time or rate of emissions. What matters is how much total carbon you've emitted. If the world emits X tonnes/yr for Y years, that's no different to X/2 tonnes/yr for 2Y years from the perspective of what the climate will be like at the end of that emission and ongoingly. What matters is how much carbon (or other long-lived GHGs) have been emitted total.
This is very nasty. It takes so long for the global carbon cycle to come to equilibrium that, on human-relevant timescales, adding CO2 to the atmosphere warms the planet up *and it doesn't cool down when you stop adding it*. It stops *heating up more* (give a decade or so for it to equilibrate), but then you're at that temperature. If you want to *undo* that warming, you have to *take CO2 out* (or wait millions of years).
Methane is much, much nicer. It has a much more aggressive warming effect per unit mass than CO2, but it's re-absorbed within a decade or two. This means that, if methane were the only relevant GHG, the temperature would depend on the *rate of emissions* rather than the total amount emitted. That would mean that, with a decade or two to equilibrate baked in again, if you had a methane-based warming problem, if you stopped emitting methane, the earth would *cool back down again to how it was before you started*.
These are entirely different dynamics, and you can't really just convert one to the other with a simple multiplier. For CO2, very roughly, you can say X tonnes emitted total will make the earth Y degrees hotter than the baseline. Zero emissions means constant temperature. For methane, very roughly, you can say X *rate of emissions* will give you an earth Y degrees hotter than baseline, and zero emissions means you return to that baseline.
Put another way, a constant rate of methane emissions equals a constant temperature. A constant rate of CO2 emissions means a constant *rate of temperature increase*.
In my mind, this means methane is just barely an issue long-term. It's like we're pouring water into a leaky tub with holes all up the side that we don't want to go above a certain level. We pour faster, the level rises, but then comes to equilibrium again with a faster leak rate. We reckon it's too high, we slow down the pour, the level drops again until it comes to equilibrium at a lower level with a lower leak rate. CO2 is like a sealed tub we don't want to go above a certain level. If you want to never go above that level, you gotta *stop pouring entirely before you reach it* and if you overshoot you've got to *remove some manually*.
So, we have to get CO2 emission to *net zero* to sort climate change. But we have to get methane emissions to *some level where we're comfortable with the temperature that *rate* of emissions implies*. Over-emitting methane is a problem you can correct by cutting methane emissions. Over-emitting CO2 is a problem you have to correct with carbon-removal tech (a big hassle slash basically impossible depending on who you talk to).
So why on earth would we put almost any marginal GHG-reduction efforts into methane, at almost any conversion factor, where this is an option?!?! Cutting methane emissions will have a sort of zero-order step-down effect on global temperatures which are still inexorably rising, whereas cutting CO2 emissions will *slow down the rate of increase*. That's so much better unless we're in some extremely well-defined "tipping-point" scenario and need some more time.
I'm not saying don't cut methane! I'm saying trying to compare the "equivalent" impacts of CO2 and methane with some conversion factor is nonsense, because they just aren't comparable. The IPCC realised this eventually and dropped the eCO2 metric, and now talks about CO2 and methane as two separate drivers with different modes of action. But a huge amount of the climate advocacy and financing industry has got stuck on "eCO2", which is a silly metric that tries to compare the incomparable by setting a particular time threshold (normally 100 years) and integrating under it. But that's far, far too short-sighted! Cutting almost any amount of methane in preference to almost any amount of CO2 is banking a little short-term gain for catastrophic long term loss!
I would almost advocate a strict policy dominance - get CO2 to *zero* before you compromise that effort *at all* in favour of cutting methane. Of course on the margin less methane is better, but in areas like ag, where methane, NO2, and CO2 emissions are all important, and often we have this exact choice of saying emit more of one than the other, then I say just measure CO2 and N2O (and the minor long-lived GHGs, all of which can safely be put into an eCO2 metric based on their relative warming effects as they all have this time-independent warming action) and care about that, and then consider methane as something totally separate and much less important.
I'd also say care about animal welfare way more than either because there's so much more value on that margin, but nobody's out there trying to roll chicken suffering into eCO2 terms so I don't have to have that fight!
But upshot of this is that it does mean beef just isn't nearly as overwhelmingly bad for the climate as eCO2 metrics make it seem, because a disproportionate amount of that comes from methane, which I really think we could stand to basically ignore in the short-term in preference to cutting CO2 and N2O.