The National Academies have released Oil in the Sea IV, which updates estimates of oil entering North American seas. This is the third update since the publication of Oil in the Sea in 1985.
The updated inputs and seeps summary tables are pasted below. Some comments:
- The Oil in the Sea reports are important in that they provide perspective on natural inputs and those associated with man’s activities. The estimates generate informed discussion about the relative significance of the various inputs.
- The estimate for land-based sources, which far outweigh all other sources, increased dramatically from the previous report.
- The oil seepage estimate was reduced by 37.5%, owing to methodology.
- The difference between the itemized seepage total in Table 3.2 (109,000 mta) and the seepage total in Table 3.1 (100,000 mta) is not explained.
- The authors assume zero oil seepage in the entire US and Canadian Atlantic, and Arctic offshore. This is highly unlikely given the widespread presence of methane seeps in the Atlantic, the numerous oil seeps identified offshore Labrador, and the MMS/BOEM report on Arctic seepage.
- The estimate for platform spills (excluding Macondo and the MC-20 seepage) was significantly and inexplicably increased from the previous report, and is well above what BSEE data indicate for that period. No data or justification are provided.
- The statement (p. 58) that “spills occurred more frequently in offshore waters than nearshore waters” is puzzling and unsubstantiated.


