The Northern European Enclosure Dam (NEED) is a proposed solution to the problem of rising ocean levels in Northern Europe. It would be a megaproject, involving the construction of two massive dams in the English Channel and the North Sea; the former between France and England, and the latter between Scotland and Norway. The concept was conceived by the oceanographers Sjoerd Groeskamp and Joakim Kjellsson. Groeskamp estimates that the NEED will cost 250 to 500 billion euros and will take 50 to 100 years to complete.