These are the dunes of the Namib Desert, taken by Korea's Kompstat-2 satellite. The blue and white area is the dried riverbed of the Tsauchab river. (Photo by The European Space Agency)

A swimmer stops short of a red algae bloom at Sydney's Clovelly Beach on November 27, 2012, which closed some beaches for swimming including Bondi Beach for a period of time. While the red algae, known as Noctiluca scintillans or sea sparkle, has no toxic effects, people are still advised to avoid swimming in areas with discoloured water because the algae, which can be high in ammonia, can cause skin irritation. (Photo by William West/AFP Photo)

Models present creations during the Monse and Oscar de la Renta Autumn/Winter 2017 collection during New York Fashion Week in the Manhattan borough of New York, U.S., February 13, 2017. (Photo by Brendan McDermid/Reuters)

A woman dressed in a costume poses for a photograph at Tokyo Comic Con at Makuhari Messe in Chiba, Japan December 2, 2016. (Photo by Issei Kato/Reuters)

Indonesian activists covered with sludge from the mud volcano hold a protest during five year anniversary of the Sidoarjo mud eruption on May 29, 2011 in the subdistrict of Porong in Sidoarjo, East Java, Indonesia. (Photo by Ulet Ifansasti/Getty Images)