(CNN) Few sights prompt such dispiriting gut punches as an oil spill casting a blackened pall on pristine waters, beaches, and wildlife. I'm a scientist who has studied oil spills all over the world for more than three decades, including the Deepwater Horizon disaster in 2010. I've learned that the way an oil spill unfolds is not always simple or straightforward, and the worst-case scenario isn't a fait accompli. The Deepwater Horizon oil spill spread some 160 million gallons of crude oil along more than 1,300 miles of coastline. Despite our efforts, of course, there are lingering environmental impacts from Deepwater Horizon and many uncertainties about long-term effects.