News that Pfizer-BioNTech’s vaccine needs to be at –70 °C, which is best done with dry ice, has raised awareness of a new challenge. Dry ice is made by compressing and cooling liquid carbon dioxide. It accounts for about 20% of US demand for CO2. The trouble is, CO2 is in short supply. Most CO2 in the US is captured from ethanol and ammonia production, both of which are down right now due to depressed ammonia prices in the US. On top of that, demand for dry ice is already up because of an increase in home delivery of frozen groceries. As a result, scientists and businesses that rely on dry ice or other forms of CO2 are being urged to get their orders in soon and plan for longer wait times.