One year on: Could negative oil prices ever return?

In April 2020, something unprecedented happened in the oil markets: the price of West Texas Intermediate plunged below zero. The slump was due to a combination of oversupply, plunging demand and a shortage of storage space in the United States. Oil prices have since recovered, but could it ever happen again? Also today, we find out how some of Greece's smaller islands are preparing for tourists to return, as the country lifts quarantine requirements for travellers from the EU and US.