I saw this question in a writer’s discussion forum, and I can’t help myself.
As someone who’s been involved in livestock climate mitigation science, here is my official science advice on the question: Are dragons carbon neutral?
The Science
Let’s start with cows. It’s easier. This is the real world reason this question exists. On a cow farm (official terminology), you’ll have three main sources of emissions:
Methane from ruminant digestion (grass fermenting in the cow’s stomach)
Nitrous Oxide from nitrogen going on to soils (via cow urine and dung, or nitrogen fertilizer)
Carbon Dioxide from fossil fuels (e.g. to run a farm bike, or electricity)
You also might have a bunch of other stuff to consider.
If you put cow poo in a big tank it will ferment, releasing methane (this happens if you bring the cows inside a building and they poo on the floor – you need to clean that up).
All the products used on a farm (e.g. supplemental feeds, bits of string, the farmer’s gumboots) also have “embodied emissions”. That’s all the emissions involved with making that stuff.
Land use change can be an issue too, if, say, you burnt down a forest to create your cow farm.
Now, of these emissions, ruminant methane is by far the main one. Then comes a small amount of Nitrous Oxide. And then a tiny amount for Carbon Dioxide. At least, that’s the case in New Zealand.
To complicate things, all these gases behave differently.
That tiny amount of fossil carbon is very bad. That’s a permanent addition of carbon to the biosphere. Fossil fuels are the Big Bad Wolf of climate change. Nitrous oxide also sticks around a very long time, so not great.
The methane is temporarily supercharged carbon. If you stop emitting it then it goes away. So it’s more a question of bad timing. Now is a terrible time to be supercharging large amounts of carbon.
All up a cow farm is significant source of greenhouse gas emissions. In New Zealand ruminant agriculture makes up roughly half our emissions. It’s not good.
On a happier note, on-farm trees and soils might be sequestering carbon. That’s good. However, it’s best to think of emissions and sequestration as separate things, rather than as “cancelling out”. Burning fossil fuels, or supercharging carbon into methane just isn’t equivalent to planting a tree (because life is complicated).
Anyway, for context, that’s life in the real world.
Dragon Emissions
So then... dragons!
A lot depends on dragon physiology and... ah... dragon farm management practices.
Methane
How do dragons breath fire?
A) Magic? Probably zero emissions (unless you’re a Dark Lord).
B) Squirting funky combustion chemicals? Probably zero emissions too.
C) Squirting funky combustion chemicals for ignition... plus one gigantic sack of fermented methane as a fuel source? Well then...
If it’s C, dragons are a nightmare for climate change. Take all the problems for cows and scale it up to dragon size. Seeing as dragons don’t breathe fire 24/7, they’d be constantly burping out excess methane. And that is methane from fermented meat, not grass. Not exactly resource efficient.
Nitrous Oxide
Do dragons urinate like mammals?
If yes, we have a serious problem. Cows are worse than sheep because they are bigger than sheep. When a cow urinates it dumps a lot of urine in one spot. That overwhelms the soil’s capacity to deal with that much urine. More of the nitrogen gets turned into nitrous oxide as a result.
Dragons are much bigger than cows.
That’s going to be a lot...
Also, soil nitrogen chemistry gets horribly complicated. Please be careful about where and when your dragon dumps that mega-bladder load. As a simple rule, avoid urinating on wet soils.
Consider a dragon breeding program for less urinary nitrogen, and dietary changes.
Fossil Carbon
Standard dragon handling practice seems to favour medieval level technology. That’s great news for the climate. Zero emissions from fossil fuels. Hooray for 100% organic dragons!
Embodied Emissions
Unfortunately, half-remembered scenes from Game of Thrones suggest that dragons are typically fed on goats.
Goats are ruminants, like cows. Refer above. Consider switching your dragon’s diet to horses, rabbits, fish, unbelievably large amounts of mealworms, or other non-ruminants.
Land Use Change
Dragons hunt by fire.
Therefore the presence of dragons is likely to favour land use shifts from forests to grasslands. Large numbers of dragons could be a major driver of deforestation, as they go around literally torching everything.
Are Dragons Carbon Neutral?
Best case scenario:
Limited numbers of dragons are probably okay. Focus on Exxon-Mobil. Those guys are a real problem.
Worst case scenario:
Dragons are climate nightmares, burping out gigantic quantities of methane, urinating out enough nitrogen to drown a village, eating vast quantities of meat, and burning down the world’s forests.
We have no choice but to outlaw dragons immediately. The dragon-industrial complex must be stopped. Someone call Greta.