The nature of these changes, and their implications, are at present unpredictable. Fisheries and agriculture were affected across the globe. Global sea level is currently rising at 1- 2 cm every ten years as the oceans warm and expand. That increase is predicted to double in the next century, with greater effects where land is naturally sinking, or where human activities have damaged coastal protection. Nutrient discharges and chemical wastes from industry and agriculture on land reach the sea via rivers, groundwater and the atmosphere.
Pollution can kill living organisms directly and selectively, affecting biodiversity in the oceans.
Some chemicals, such as hormone-mimics, affect the physiology and reproduction of invertebrates and fish. Human sewage and nutrients from agriculture can stimulate blooms of marine algal, some of which produce toxins which kill shellfish, fish, sea birds and sea mammals. Litter from coasts and dumping of rubbish at sea cause pollution, particularly by plastic materials. Fish farms cause pollution with organic wastes, which use up oxygen and kill seafloor communities, and with pesticides used to treat parasites and diseases of farmed fish. Oil spills from tankers cause acute pollution to coastal communities and chronic pollution to the marine environment generally.