Because less then 20% of the global primary energy consumption comes from low carbon sources. So if we cut off all fossil fuels we have as much energy available as the average person in Cambodia or Mauretania today. So we have to develop and deploy green technologies on scale to keep a decent quality of life for everybody. Transporting food to countries that can not grow enough of their own, like for example Egypt, is going to be necessary. For that these types of ships are a good start.