Rice paddies heat the planet about as much as every aeroplane in the sky, and nobody has made a documentary about your pilau. A flooded paddy is a man-made swamp. Under the water, with no oxygen, the same family of microbes that live in a cow's rumen break down plant matter and give off methane. It is a rumen with the cow taken out. Rice accounts for around a tenth of all the methane humans cause, and about 1.5% of all greenhouse gases, which puts it level with global aviation. The response so far: - Streaming exposés on rice: none - Celebrities going rice-free for January: none - Rice-free Mondays in school canteens: none - Carbon labels on a bag of basmati: none - Countries taxing it: none Denmark, meanwhile, will bill its farmers for every cow and pig from 2030. The cow's methane comes from grass, which pulled that carbon out of the air last spring, on ground too wet or too steep to plough, and it arrives with beef, milk, leather and a fertilised field. The paddy's methane arrives with a bowl of starch. The chemistry is identical. One of them is a plant, and plants do not get prosecuted. The climate case against your dinner depends on only ever pointing the instrument at the animal. Who decided which methane counts?

University debate, "Were humans built to eat meat?", same two chairs, same clock. Vegan: "Anatomically we're closer to the gorilla than the lion. Flat molars, long gut. A gentle plant-eater with delusions." Paleoanthropologist: "Then explain the acid." Vegan: "Which acid?" Paleoanthropologist: "Your stomach runs at a pH of about 1.5. A lion's sits nearer 3.6. Yours is stronger than the animal you've just been contrasted with, by a factor of about a hundred." Vegan: "Stomach acid digests food." Paleoanthropologist: "A cow's rumen sits at about 6.5. That's a compost heap with a pulse. Yours strips the zinc off a coin. Why would a gentle plant-eater carry that?" Vegan: "Protection." Paleoanthropologist: "From what? Lettuce doesn't fight back." Vegan: "Bacteria." Paleoanthropologist: "Which bacteria live in a leaf at a level that needs a pH of 1.5? Name the salad." Vegan: "..." Paleoanthropologist: "The animals that run acid as low as ours are the scavengers. Vultures. Things that arrive at a carcass on the second day and need to kill what's already living in it. We're not built like the lion. We're built like the bird that waits for the lion to finish." Vegan: "Flattering." Paleoanthropologist: "It's a picture of a species with a rock, a sharp flake and no claws. You don't get the fresh kill. You get the femur nobody could open, forty hours late, and you'd better have the acid for it." Vegan: "Acid that strong is dangerous. Look how many people are on tablets for it." Paleoanthropologist: "The only animal on earth that pays to switch its stomach off. You've spent sixty years pouring cereal onto a carcass digester and now you're medicating the digester for doing its job." Vegan: "So your argument is that we're vultures." Paleoanthropologist: "My argument is a number. Yours is a feeling about gorillas. The gorilla eats for most of the day and its gut is a fermentation tank. Yours is done in a few hours and runs on acid. One of you is designed for leaves." Moderator: "Thirty seconds." Paleoanthropologist: "She can keep them. I'm still waiting on the salad."

Korea was one people until 1945. Today the men of the South stand up to three inches taller than the men of the North. Same ancestry, same language, the same height at the start. The border is 160 miles long and 2.5 miles wide. In the North, food comes through the state ration. Rice when there is rice, maize when there is not, and meat on a few holidays a year. In 2012 the army cut its minimum height for a recruit to 4ft 8in, because too few 17 year olds could reach the old one. In the South, meat consumption rose about tenfold in 50 years. Beef, pork, eggs and milk went from luxuries to every day. South Korean women gained 8 inches in height over the 20th century. It is the largest increase recorded for any population on earth. Children who escape from the North are visibly smaller than Southern children of the same age. Fed in the South, the young ones catch up. The older ones are too late. Nobody designed the experiment. But it has 75 million subjects, a genetic control and a hard border, and it has run for 80 years. One side of the wire was fed grain by a government, and the other side ate meat.

Activist: "Farmers pump their cows full of antibiotics. It's in every glass of milk." Dairy farmer: "Do you know what happens if it is?" Activist: "People drink it." Dairy farmer: "The tanker gets tested at the gate. One cow's worth of antibiotic in 20,000 litres and the whole load goes down the drain. Every farm on the run that morning gets their milk tipped, and the farm that did it pays for all of it." Activist: "So you're saying it never happens." Dairy farmer: "I'm saying a treated cow on this farm gets red tape round her leg, goes to the back of the parlour, and her milk goes in a bucket for 6 days. I treat her like she's radioactive, because financially she is." Activist: "You still use them." Dairy farmer: "On a cow that's ill. Same as you. The vet writes it up, the date goes on the wall, and the wall's checked. Use on this farm is about half what it was 10 years ago, and that's every dairy I know." Activist: "Routine use in feed, then." Dairy farmer: "Illegal for years. Growth promoters went 20 years ago. You're describing a chicken shed in a country I don't farm in." Activist: "You can't prove it's not in the milk." Dairy farmer: "I can prove it 3 times a week, because they test it 3 times a week and send me the sheet. When did you last get a sheet on your oat drink?" Activist: "That's different." Dairy farmer: "It is. Nobody tests it. Mine's the most inspected liquid in your kitchen and it's the one you're scared of."