Nearly three quarters of our planet is covered by oceans because Earth retained the water that rained down from space in the form of icy comets billions of years ago. Global warming could melt the polar ice caps and flood coastlines everywhere-but it might also have the opposite effect. The plant nutrients in sewage and agricultural runoff create dire environmental problems for many coastal waters. The extent of the worry and the effectiveness of some remedies are just now becoming clear. The Promise and Perils of Aquaculture Fish farming could relieve the pressure on wild fish populations, unless its detrimental effects on the environment offset the gains.
Experts debate the pros and cons.
Although the oceans harbor fewer species than the continents, the overall biodiversity in the sea is arguably much greater than on land. As entrepreneurs consider mining valuable metals from the floor of the ocean near Papua New Guinea, scientists weigh both the economic potential and the threat to deep-sea life. The Evolution of Ocean Law Jon L. Jacobson and Alison Rieser Bit by bit, the nations of the world have largely come to agreement on a scheme to govern the seas and divide up the resources they contain. Exploring the Ocean Planet Michael Menduno Dive into the fun with this guide to the top aquariums, scuba trips, films, Web sites and more. World Tour Bikini's Nuclear Ghosts Glenn Zorpette, staff writer Nuclear testing ravaged Bikini Atoll during the 1940s and 1950s.