The notion of cumulative impacts relating to seismic surveys and exploration activities has been raised in various jurisdictions around the world as something which must be accounted for in exploration access. As defined under the United States’ National Environmental Policy Act (NEPA) regulations, cumulative impact or cumulative effect is the impact on the environment resulting from incremental impacts of an action over time. Specifically, it is “the impact on the environment which results from the incremental impact of the action when added to other past, present, and reasonably foreseeable future actions regardless of what agency (Federal or non-Federal) or person undertakes such other actions (40 CFR, 1508.7).
To date, there has been no demonstration of population-level effects, cumulative or direct on marine life from seismic or other geophysical survey activity despite the long history of seismic surveying in various parts of the world. This remains the case even where there are well-documented examples of long-term exposures of acoustically sensitive species; no biologically significant chronic or cumulative impacts have occurred.
For example, oil and gas seismic exploration activities have been regularly conducted in the Beaufort and Chukchi Seas of the Arctic Ocean for decades. During this period of acoustic exposure and in spite of being the subject of traditional subsistence hunting during that same time, bowhead whales have consistently increased in abundance to the point that they are believed to have reached the carrying capacity of the environment. Similarly, between 1960 and 1985 eastern Pacific gray whales went from endangered status to removal from the endangered species list in 1991, while interacting with extensive seismic survey activity from southern California to Alaska during that same time period (Malme, 1985).
The U.S. Department of the Interior, Bureau of Ocean Energy Management (BOEM) expressly recognizes this fact in its August 22, 2014 Science Note, stating, “there is a long-standing and well-developed [Outer Continental Shelf (OCS)] Program (more than 50 years); there are no data to suggest that activities from the preexisting OCS Program are significantly impacting marine mammal populations.” BOEM similarly concluded in its March 9, 2015, Science Note asserting that there has been, “no documented scientific evidence of noise from air guns used in geological and geophysical (G&G) seismic activities adversely affecting animal populations.”
Moreover, BOEM has spent more than $50 million USD on protected species and sound-related research without finding evidence of adverse effects. The geophysical and oil and gas industry, the National Science Foundation, the U.S. Navy and others have spent a comparable amount on researching impacts of seismic surveys on marine life and have found no evidence of significant effects, either direct or cumulative. The best available data strongly support a conclusion that there is an extremely low likelihood that cumulative impacts result from seismic survey activity.