Scientific consensus concludes that the world has been warming over this period, debates as to the degree contributed by either humans or natural variability notwithstanding. There are increasing concerns about the biological health of the oceans. Bellwether marine ecosystems, such as coral atolls, kelp forests, and estuaries are threatened. Important fisheries around the world are in decline, and many scientists believe that marine biodiversity overall is in serious decline. This is most unfortunate when one remembers that the oceans are thought to harbor a biocomplexity unrivaled in any other Earth system.
Humans come into closest contact with the ocean in the coastal region.
As much as 85 percent of U.S. shorelines are eroding due to a combination of factors including sea level rise, river damming, and storms. As the human population along our coasts increases, the net economic and public health risk due to natural hazards, from hurricanes to earthquake-generated tsunamis, naturally increases. Changing climate and rising sea level may further stress the coastal environment. There is increasing evidence that these stressors on the ocean and coastal environment can have significant impacts on the human populations that live along the shores. Not only are oceans the major driving force of the planet's climate, generating major natural hazards such as hurricanes and harmful algal blooms, but the oceans provide a vector for infectious diseases such as cholera and malaria and harbor toxic organisms which can poison important seafood sources and those that consume them.