- Should we stop eating meat to combat climate change? Maybe not. White and Hall worked out what happened if the US stopped using farm animals:
The modeled system without animals only reduced total US greenhouse gas emissions by 2.6 percentage units. Compared with systems with animals, diets formulated for the US population in the plants-only systems resulted in a greater number of deficiencies in essential nutrients. (source: PNAS)
Of concern when considering farm animals are methane emissions. Methane is a potent greenhouse gas, with the caveat that it is short-lived in the atmosphere unlike CO2. Should we be worried about methane despite its short life? According to the American EPA (Environmental Protection Agency), total methane emissions have been falling consistently for the last 20 years. That should not surprise us: greenhouse gas emissions in most developed countries (including the US) have peaked some time ago. Not emissions per capita, but total emissions.
So beef, at least in the US, is not a major contributor to climate change. But we could do even better. Several studies like Stanley et al. report that well managed grazing can lead to carbon sequestration in the grassland. Farming in general could be more environmentally effective.
Of course, if people consume less they will have a smaller environmental footprint, but going vegan does not imply that one consumes less. If you save in meat but reinvest in exotic fruits and trips to foreign locations, you could keep your environmental footprint the same.
There are certainly countries were animal grazing is an environmental disaster. Many industries throughout the world are a disaster and we should definitively put pressure on the guilty parties. But, in case you were wondering, if you live in a country like Canada, McDonald’s is not only serving only locally-produced beef, but they also require that it be produced in a sustainable manner.
In any case, there are good reasons to stop eating meat, but in the developed countries like the US and Canada, climate change seems like a bogus one.
There also good reasons to keep farm animals. For example, it is difficult to raise an infant without cow milk and in most countries, it is illegal to sell human milk. Several parents have effectively killed their children by trying to raise them vegan (1, 2). It is relatively easy to match protein and calories with a vegan diet, but meat and milk are nutrient-dense food: it requires some expertise to do away with them.
Further reading: No, giving up burgers won’t actually save the planet (New York Post).
(Special thanks to professor Leroy for providing many useful pointers.)
- News agencies reported this week that climate change could bring back the plague and the black death that wiped out Europe. The widely reported prediction was made by Professor Peter Frankopan while at the Cheltenham Literary Festival. Frankopan is a history professor at Oxford.
- There is a reverse correlation between funding and scientific output, meaning that beyond a certain point, you start getting less science for your dollars.
prestigious institutions had on average 65% higher grant application success rates and 50% larger award sizes, whereas less-prestigious institutions produced 65% more publications and had a 35% higher citation impact per dollar of funding. These findings suggest that implicit biases and social prestige mechanisms (…) have a powerful impact on where (…) grant dollars go and the net return on taxpayers investments.
It is well documented that there is diminishing returns in research funding. Concentrating your research dollars into too few individuals is wasteful. My own explanation for this phenomenon is that, Elon Musk aside, we have all have cognitive bottlenecks. One researcher might carry fruitfully two, three major projects at the same time, but once they supervise too many students and assistants, they become a â€œnegative managerâ€, meaning that make other researchers no more productive and often less productive. They spend less and less time optimizing the tools and instruments.
If you talk with graduate students who work in lavishly funded laboratories, you will often hear (when the door is closed) about how poorly managed the projects are. People are forced into stupid directions, they do boring and useless work to satisfy project objectives that no longer make sense. Currently, â€œsuccessâ€ is often defined by how quickly you can acquire and spend money.
But how do you optimally distribute research dollars? It is tricky because, almost by definition, almost all research is worthless. You are mining for rare events. So it is akin to venture capital investing. You want to invest into many start ups that have a high potential.
- A Nature columns tries to define what makes a good PhD student:
the key attributes needed to produce a worthy PhD thesis are a readiness to accept failure; resilience; persistence; the ability to troubleshoot; dedication; independence; and a willingness to commit to very hard work â€” together with curiosity and a passion for research. The two most common causes of hardship in PhD students are an inability to accept failure and choosing this career path for the prestige, rather than out of any real interest in research.
6 thoughts on “Science and Technology links (October 20th, 2018)”
There was a recent story about a study that suggested that eating meat has a very big impact. So it very much contradicts the study you posted. I wonder which one I should trust more.
Is there really a contradiction?
That is, does the research you link to says that stopping the use of animals in US farming would reduce greenhouse gas emissions by a lot more than 2% in that country?
“For the United States, where per capita meat consumption is three times the global average, dietary change has the potential for a far greater effect on food’s different emissions, reducing them by 61-73%. See supplementary text for diet compositions and sensitivity analyses and fig. S14 for alternative scenarios. ” 
In the study by White & Hall they mention “decreased agricultural US GHGs (28%)”. So if this is wrong and it’s actually 61-73%, it would mean the total US GHGs would be reduced by 5.5-6.6 percentage units instead of 2.6.
it would mean the total US GHGs would be reduced by 5.5-6.6 percentage units instead of 2.6.
Ok. So stopping the use of animals in farming for the US would, one conjectures, reduce greenhouse gas emissions by about 6 percent.
What are the emissions due to agriculture as a whole? Maybe the EPA is a trusted source on this?
Right. So agriculture as whole is responsible for 6.1 percent of all US greenhouse gas emissions.
So, no, I don’t think it is credible that we could see a drop of 5.5 to 6.6 as you suggest. That’s if you stop all agriculture, entirely.
You have to watch the math also, because if, say, animals are responsible for, say 3.5% of greenhouse gas in the US, if you stopped it, it would not lead to a 3.5% reduction. Because, obviously, if you stop eating meat, you are going to eat more of something else. I think that the 2.6% is quite credible. You can argue on details… maybe it is 2.8% or 2.5%… But it is not 6%, 10% or 30%…
From the White & Hall Paper:
“Assuming agricultural emissions account for 9% of total US emissions (47), and assuming that emission estimates here are representative of national emissions, eliminating animal agriculture would decrease total US emissions by an estimated 2.6 percentage units.”
They also use the EPA as a source for that number. In a more recent report (yours used a number for 2008) you find 8.6% for CO2. I guess other greenhouse gases have been reduced since 2008?
So yes it can be reduced by about 6% if we assume 9% for total agriculture emissions.
This argument, that you would eat something else instead is correct and has been carefully considered in the study by Poore. If you look at the supplementary materials you will find a table where they looked at different diet scenarios.
I wonder what the upper and lower bounds for those estimates actually look like. There’s a lot of assumptions stacked on assumptions, numbers from different sources combined etc. And different people get wildly different results.
Now should we be concerned about 6%? I think so. It’s a big chunk of agriculture. Transport is also about 9% and if we could reduce that by 2/3 it would be considered a big achievement.
If you believe that 70-80% or so of CO2 emissions due to agriculture are due to farm animals, then I would agree that a reduction of 6% of the total CO2 emissions could be in the realm of possibilities… but that’s an extraordinary claim.
But let us suppose we believe this extraordinary claim.
Note that the whole plan implies all of the US population goes vegan. Even if you believe in the 6% figure, it relies on an extraordinary social transformation the like of which we have never seen.
As for the diet prescriptions, as explained by White and Hall, you cannot merely count proteins and calories. That’s obviously wrong. Maintaining a healthy diet made of tofu and soy milk is possible, but it is tricky, especially at the kind of scales we are talking about.
But let us assume that the US undergoes this transformation… everyone in the US forgoes meat, milk, cheese, and fish tomorrow. We somehow manage to make it so people don’t get sick in the process. Done deal. But then, are we assuming that the money that people do not spend on meat is spent on carbon-neutral activities? This is very likely wrong.
Transport is also about 9%
Let us eyeball it, will we? (EPA numbers, again.)
Transportation, electricity and industry are much bigger contributors than agriculture:
Agriculture is closer to residential and commercial.
I want to stress again that I think that there are good arguments for going meatless. I just don’t think that climate change passes the common sense test as a justification for becoming vegan.
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