According to a new report from the National Academies of Science, Engineering and Medicine.
From 2010 to 2019, these land-based sources leaked about 1.2 million metric tons of oil each year that ended up in the sea, according to the report, compared to 380 tons a year from pipeline spills, 200 tons from spills of tankers. , and 66,500 tonnes from rigs and other extraction activities. Most of the latter figure – 57,000 tonnes – comes from the 2010 Deepwater Horizon disaster in the Gulf of Mexico.
“The main source of oil in the ocean is land-based runoff, at an estimated volume up to 20 times greater than reported two decades ago,” according to a press release accompanying the report. “Most of this pollution occurs through water from rain or snowmelt carrying oil, primarily from cities and vehicles, to rivers and eventually into the ocean. Runoff from highways, parking lots, vehicle washing and vehicle fluid leaks all contribute.”
The second largest source is natural oil seeps, at around 100,000 tonnes per year.
The report warns that government agencies, including the EPA, are not monitoring rivers and harbors for runoff from “non-point sources,” such as cars and gas stations, making it difficult to quantify the impacts. quantities that can actually reach the sea and the resulting effects.
Land-based pollution appears to be much worse than 20 years ago, when the previous edition of the same report estimated it at 54,000 tonnes per year. However, the report sees scope for improvement over the next 20 years through motor oil recycling, improved energy efficiency and electrification of transport.
These “personal and industrial non-point source pollution control practices…will have the added benefit of reducing land runoff.”