So I have read this paper. The authors argue that the emphasis right now should lie on eliminating animal agriculture, rather than on eliminating fossil fuel use. Fossil fuel use needs to end, but to preserve a habitable planet, it is much more urgent to end animal agriculture, which they estimate to be responsible for 87% of greenhouse gas emissions.
The authors raise an important argument: The impact on CO2 concentrations in the atmosphere from no longer using fossil fuels is something that reveals itself over multiple decades.
But the impact when we stop using fossil fuels of no longer releasing the sulfate aerosols that block sunlight reveals its temperature impact almost overnight. And to make matters worse: The aerosols mostly cool the planet where people live. Their effect is concentrated. The effect of CO2 is diffuse.
Note, this problem does not apply for air travel. We can end air travel overnight, it would directly reduce temperatures. The reason is because at the high height the planes fly on, the soot they release generates contrails, which warm up the sky. There are no truly free lunches, but when it comes to our climate, ending air travel is one of the cheapest lunches: It is a hobby for rich people and ending it would immediately reduce global temperatures, concentrated in the exact places where most people live.
You can see above the ocean waters of the Northern hemisphere right now what happens when you stop those aerosols. Temperatures shoot up:
You can see where the temperature anomaly in the ocean is highest: It’s where we have the most ships. All those ships were cooling the ocean’s surface with their sunlight blocking emissions, but now they don’t.
If we try replicating this above places home to millions of people, the impact will be nightmarish. As I have illustrated before, we can end the lethal summer heatwaves that destroy our harvests, through rapid and widespread reforestation:
So how can they arrive at this figure of 87%? Well, the number you arrive at will depend on the numbers you want to include. If you look at a timescale since 1850, most carbon emissions have come from fossil fuels. But humans began influencing the climate much earlier. If you look at the past 8,000 years, most carbon emissions come from the removal of vegetation, mostly for animal agriculture.
Additionally, you have to take into consideration the relevant timescale you want to look at it. On a long timeline, CO2 has a much greater greenhouse potential. But in the short term, methane is the bigger villain. Methane is a short-lived pollutant, the atmosphere breaks it down after a few years.
And so because we are in an emergency situation, they argue we need to look at the greenhouse impact on a 10 year timescale. By looking at a 100 year timescale, the authors argue the IPCC underestimates the impact of methane five-fold.
But I think even these authors, who attribute 87% of the annual greenhouse gas emissions to animal agriculture, are underestimating the severity of what we’re dealing with. By removing forests and growing grain that we feed to animals, we’re destroying the tools that life has, to self-regulate its environment.
The atmosphere destroys methane using the hydroxyl radical. When the atmosphere has less of the hydroxyl radical, methane takes longer to be broken down, allowing it to build up. It is thought that some of the recent buildup of methane in the atmosphere, is caused by a decline of the hydroxyl radical in our atmosphere.
Where does this hydroxyl radical originate? It ultimately originates from plants. Water in the atmosphere (released by plants) along with terpenes (released by plants) interact with sunlight, to generate reactive oxygen species. These reactive oxygen species include the hydroxyl radical. The hydroxyl radical is difficult to measure, because it does not last very long before reacting with other chemicals.
Here is a map of the total hydroxyl radical reactivity in the atmosphere:
It’s very clear from this how the planet breaks down atmospheric methane: Through rain forests. By making sure there’s always enough water vapor and terpenes in the air to enable generation of the hydroxyl radical, these forests massively increase the atmosphere’s ability to break down methane.
The worst possible thing you can do, is to destroy these rain forests to grow food for humans. And additionally, if you allow the forests to regrow by abandoning land that we now use for agriculture, you will increase the atmosphere’s capacity to break down methane.
But this is not all. We divide methane emissions between “natural emissions” and “human emissions”. We call 363 million ton “anthropogenic” and we call 233 million ton “natural”. Of the human emissions, we attribute about 10% to rice production. But the underwater rice fields tend to produce methane because they’re continually fertilized with manure from cows, which contains methane producing bacteria. We know this because they don’t see the methane when the manure is sterilized.
Of the 233 million ton we call natural, 194 comes from wetlands. But the 194 million ton from wetlands is probably not really “natural” either. There is increased growth and decay of vegetation in these wetlands, from eutrophication. This depletes oxygen in the water. These are the exact conditions under which methane is produced by the bacteria in the water. And so it’s thought that reducing eutrophication would also reduce the emission of methane from these wetlands. With high nutrient inputs from manure, you get floating plants in the water, which deplete oxygen in the water and lead to the highest methane emissions.
Meeting the 1.5 degree warming target by reducing fossil fuel use has become effectively impossible, when you look at the speed of the change necessary. In addition, the sudden end of global dimming cessation of fossil fuel use would cause would mean you shoot above 1.5 degree after all.
You can’t expect people to stop heating their homes during freezing weather. You can’t stop driving trucks to the supermarket (and electric trucks are crap). There’s just no realistic path to rapidly bring down fossil fuel use to zero. Even building our solar panels and electric cars would require up-front fossil fuel sue.
On the other hand, you can end animal agriculture almost overnight. You would thereby reforest large parts of the Earth’s surface. This vegetation would immediately start reducing the heatwaves, in the exact places where humans live. These plants would immediately start sequestering carbon. The methane emissions from the animals would end. The bacteria in their manure would no longer cause the rice paddies to emit methane.
The lack of animal manure ending up in wetland ecosystems would reduce eutrophication. The reduced eutrophication would reduce “natural” emissions of methane. The increase in natural vegetation around the world, would accelerate the breakdown of methane, by increasing hydroxyl radical concentrations.
But you have no mercy for non-human animals. And so what will happen instead unless you develop mercy for them is that humans are just going to be removed from the Earth’s surface by viruses and the bacteria these viruses invite into your organs. Humans will just be removed until they stop causing this destruction and suffering. All the farms where animals are kept are breeding grounds for these viruses, just as prisons for humans are breeding grounds for viruses and bacteria like tuberculosis.