Russia’s army is attempting to starve the people of Mariupol into submission in an act of barbarity that almost certainly constitutes a war crime. But the knock-on effects of Vladimir Putin’s invasion of Ukraine threaten hunger, even starvation, for millions of people beyond the immediate theatre of war.

Russia and Ukraine are major food producers, accounting for roughly 30 per cent of global exports of wheat and barley. Russia alone exports 15 per cent of global fertiliser, while Belarus, also under sanctions, is an important producer of potash, crucial for growing soyabeans that in turn go into animal feed. If farmers around the world use less fertiliser, next year’s harvests in Brazil, Argentina and other agricultural powerhouses could collapse.

Ukraine’s wheat exports are being blockaded by Russian ships. Ukrainian farmers don’t have seeds or fuel for their tractors. Grain prices are a third higher than when the war began and two-thirds above where they were a year ago.