WASHINGTON — Oil in runoff, primarily from cities and vehicles, is the top source of oil entering the ocean, says a new report from the National Academies of Sciences, Engineering, and Medicine. In North American waters, estimated ocean oil pollution from land-based runoff is up to 20 times higher than it was 20 years ago, and oil spills, natural oil seeps, and discharge from oil and gas operations remain major sources of pollution. The report recommends actions that government and others should take to minimize oil pollution, and calls for sustained research funding to better understand how oil reaches and affects ocean environments.

Although many economies worldwide are transitioning to more sustainable forms of energy, oil and other fossil fuels are still primary energy sources. Population growth in coastal areas and improved vehicle fuel efficiency are changing how and in what volume oil reaches the ocean. Aging infrastructure and the impacts of climate change — including more intense storms and sea level rise — are increasingly important factors affecting the amount of oil in the ocean.

“Since the last time the National Academies examined this issue in 2002, little progress has been made in terms of sustained investment in research that could help us understand how much oil is entering the ocean and precisely where it is coming from,” said Kirsi Tikka, independent non-executive director at Pacific Basin Shipping and Ardmore Shipping, and chair of the committee that wrote the report. “We need this data to ensure efforts to prevent harm to marine life and coastal communities are effective.”

Sources of Oil in the Ocean

The report says not all sources of oil in the ocean are equal in terms of their impact; for example, continuous inputs have very different effects on marine life than accidental spills do. The committee found:

The top source of oil in the ocean is land-based runoff, at an estimated volume up to 20 times higher than was reported two decades ago. Most of this pollution occurs through water from rain or snowmelt carrying oil, primarily from cities and vehicles, to rivers and ultimately into the ocean. Runoff from highways, parking lots, vehicle washing, and vehicle fluid leaks all contribute. Quantifying exact amounts and the contribution of specific activities remains difficult due to a lack of data.

The second largest source is natural oil seeps, or places where oil naturally enters the ocean without human interference, such as through faults and fractures in the seafloor sediment.

The third largest is oil spills. Over the last 20 years in North America, oil spills occurred more frequently in offshore waters than nearshore waters, predominantly in the Gulf of Mexico. The volume of spills decreased significantly for pipelines, ships carrying oil, and coastal refineries.

Another major source is discharge from oil and gas operations, which includes water from offshore oil and gas production operations and discharges from machinery operations on commercial vessels. These commercial vessel discharges are relatively small, assuming full compliance with regulations.

Preparing for Climate Change Impacts

The report recommends that the U.S. government conduct a comprehensive review of the integrity of coastal and offshore energy infrastructure to ensure it can withstand more frequent and more intense weather events due to climate change. This includes reviewing and updating design criteria to withstand extreme events, assessing the modifications that will need to be made to existing structures to prevent spills, and developing response plans and capabilities for extreme weather events. Agencies should inventory inactive or abandoned oil and gas infrastructure and prioritize salvage or capping based on the impact of their potential failure.

Deepwater Horizon and Future Oil Spill Responses

The report also summarizes lessons from the 2010 Deepwater Horizon oil spill, and says the government should review whether technical recommendations following the spill’s investigation have been implemented. Changes in U.S. regulations governing offshore oil operations and an increased focus on safety in the oil and gas industry have occurred since Deepwater Horizon, but the report notes complacency often follows periods of time when spills have decreased, and advises government and industry to maintain vigilance. The report commends progress made in oil spill science in the last two decades, and recommends oil spill planning by government agencies give greater priority to the impacts on human health and community disruption.

Preventing and Minimizing Oil Pollution in the Ocean

Although significant progress has been made in some areas, there have been decades of inaction in improving how to measure sources of ocean oil pollution. The report recommends a group of researchers, working independently from the federal government, should identify the responsibilities of specific government agencies to collect data that can better quantify where, how, and in what volume oil is entering the ocean. This information is critical for identifying and reducing specific sources of oil pollution, especially in higher-risk areas, such as heavily trafficked shipping routes or areas with offshore energy exploration.

The report also recommends actions to improve measurement of sources of oil in the ocean, and further research to address knowledge gaps, for example:

• Federal agencies should work with state and local authorities to regularly monitor oil from land-based sources; refine measurement of oil from the atmosphere; and, working with industry, quantify oil entering the sea from natural seeps, offshore exploration, and production activities.
• Controlled ocean field trials using real oils should be planned, permitted, and funded to better understand how oil in the ocean behaves and improve response effectiveness.
• Information should be gathered about oil in Arctic marine ecosystems, in advance of further development of Arctic regions.
• The National Oceanic and Atmospheric Administration should reinstate its National Status and Trends Mussel Watch Program to better measure and assess pollution in coastal waters, and evaluate the implications for seafood safety.
• Government should assess the impacts that changes to marine vessel transportation — such as increased vessel size, new types of cargo, and new shipping patterns — may have on oil pollution.

The study — undertaken by the Committee on Oil in the Sea, IV: Inputs, Fates, and Effects — was sponsored by the American Petroleum Institute; U.S. Bureau of Ocean Energy Management; U.S. Bureau of Safety and Environmental Enforcement; Fisheries and Oceans Canada; Gulf of Mexico Research Initiative; and the National Academies of Sciences, Engineering, and Medicine Presidents’ Circle Fund.

The National Academies of Sciences, Engineering, and Medicine are private, nonprofit institutions that provide independent, objective analysis and advice to the nation to solve complex problems and inform public policy decisions related to science, technology, and medicine. They operate under an 1863 congressional charter to the National Academy of Sciences, signed by President Lincoln.

Contact:
Megan Lowry, Media Officer
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202-334-2138; e-mail news@nas.edu