The global price of corn is up more than 60pc in six months and wheat prices are up nearly 40pc. This is adding to fears about a surge in global inflation, which has already prompted an incredible rise in Bitcoin prices. In addition, there are enough Marie Antoinette “let them eat cake” examples in history to tell us that political unrest often follows a jump in food prices. Why is this happening and how worried should we be?

We have been here before. In the 2000s, food prices rocketed due to three trends. A few poor harvests hit supply. On the demand side, China’s middle classes started swapping vegetable chow mein for Pork Sichuan. As anyone with a “vegetarian for environmental reasons” teenage daughter will know, meat requires far more cereal inputs to produce calories than a vegetarian diet. At the same time, booming oil prices to 2008 also encouraged the use of bio-fuels – a product that turns plants into fuel for cars.

For a while we wondered if one of the most infamously wrong economists in history, Thomas Malthus, might have actually had a point. Perhaps global agricultural supply couldn’t keep up with demand from a richer, meat-eating world? Then the oil price slumped, agricultural bulls recognised that India was unlikely to follow China’s meat-eating habits, and better harvests saw global wheat and corn stocks recover.

None of these factors are at play this time. Global harvests have been good, and stocks have risen in most recent years.

Yet China does seem to be responsible for the food price surge. In 2020 China, and to a lesser extent India, seem to have bought up the entire global wheat surplus. China has increased its wheat stockpiles from 152m tons to 164m tons. It was already a total far in excess of US stocks at just 24m and India at 31m tons.

The Chinese currency strengthened by about 10pc in 2020 and it seems that China took advantage of this to go on a buying spree for every dollar-priced commodity out there. It is not just wheat and corn. Copper prices have doubled from March lows. Iron ore prices jumped too.

This should be good news for agricultural exporters, from wheat farmers in east Anglia to the giant producers in Australia, Canada or Russia and Ukraine. But so closely does the domestic price of food track the global price, even in a country like Russia, that in Moscow domestic pasta prices are up 20pc in 12 months.

Russia is introducing export restrictions next month to crash local prices. The last thing Putin wants to see is an unhappy electorate before parliamentary elections in December (he cares about those results more than you might guess). In Turkey, domestic wheat prices are up 48pc. It is even harder for a country like Egypt, the world’s biggest wheat importer, where food prices are often cited as reason for the Arab spring of 2011.

For those worried about rising inflation, the good news is that in recent weeks China’s currency seems to have stopped strengthening. It looks like China may have finished stockpiling commodities, at least for now, and prices can stabilise. Providing global harvests remain good, this food price shock may soon be over.

But if we get bad harvests, perhaps exacerbated by the climate change my daughter fears so much, the challenges facing the poorest in the world will get harder still. China won’t be the only country scrabbling to build up agricultural stockpiles. There will be a global competition for food supplies in coming years to echo the battle for vaccines today. Let’s hope that unlike the rapidly mutating Covid virus, nature is on our side this time.

Charlie Robertson is the global chief economist at Renaissance Capital, the emerging and frontier markets investment bank.