Dead zones are low-oxygen areas in the world’s oceans, the observed incidences of which have been increasing since oceanographers began noting them in the 1970s. These occur near inhabited coastlines, where aquatic life  is most concentrated. The size and number of marine dead zones—areas where the deep water is so low in dissolved oxygen that sea creatures can’t survive—have grown explosively in the past half-century. NASA just released the map above, which shows a quite disturbing image. According to Treehugger:

The good news is that dead zones are reversible. Fertilizer is often used in much greater quantities than required because farmers have no way to know exactly what the right quantity is, so they prefer to put more than not enough, leading to a lot of the extra finding its way to the sea. Better ways to monitor crop fields with sensors and satellites can help farmers reduce their fertilizer use and thus reduce runoffs.