Oceans and Seas Overview & Information

Overview

The oceans and seas cover 71 percent of the earth’s surface and are the habitat for thousands of species of marine life including phytoplanktons and planktons, corals, fish, dolphins and whales comprising a food chain essential to the health of the ecosystem.

The ocean habitats and ecosystem are principally under threat from:

1. Warming of the oceans, which can reduce phytoplankton, krill, and other marine life at the bottom of the food chain.

2. Absorption of CO2 from the atmosphere, which decreases seawater alkalinity causing potential detrimental effects on skeletal sea life including coral reefs.

3. Pollution from fertilizer run-off, untreated sewage, toxic chemicals, and garbage (especially plastics), which contribute to dead zones.

4. Overfishing, which reduces fish populations such as cod in the Grand Banks off the coast of Newfoundland.

Supporting Viewpoints

The amount of overall temperature rise in oceans is contentious, but in some localized areas is more evident than others. According to the IPCC 4^th Assessment report as summarized by the UCCS, “since 1961, the world’s oceans have been absorbing more than 80 percent of the heat added to the climate”. Marine life at the bottom of the food chain, such as phytoplankton, are most susceptible to warmer waters.

In addition to warming, the oceans have absorbed about half of the atmospheric CO2 in the past 200 years, resulting in the surface ocean pH dropping from approximately 8.25 to 8.14. The potential detrimental effect of continued ocean acidification on the biodiversity of the food chain could reduce the food fish population to extremely low levels.

Fertilizer run-off from farms and lawns stimulate algal blooms that result in oxygen depleted dead zones in places like the Gulf of Mexico, offshore California and the Baltic Sea. Land based solid garbage, especially plastics, often reaches the oceans. A sea of plastic by one estimate “twice the size of Texas” is floating in the Pacific Ocean 800 miles north of Hawaii. Toxic chemicals, including pesticides and heavy metals such as lead and mercury, affect marine life and enter the food chain for ultimate human consumption. Untreated or under-treated sewage disposal in parts of the world such as the Mediterranean Sea flows into the ocean or major seas.

Over-fishing has become more acute with the use of giant high tech factory ships that use sonar devices and planes to locate schools of fish, giant nets to encircle and trap the schools, and giant hoses to “vacuum them up”. The practice removes essential fish from the food chain and is devastating to the fish population in some areas. A 2003 global study by Myers and Worm concluded that 90 percent of the world's large fishes have disappeared over the last half-century by industrial overfishing; these practices can have a serious effect on the ecosystem of the oceans. The Marine Stewardship Council “promotes environmentally responsible stewardship of the world's most important renewable food source”.

Supporting Websites
Mongabay.com
Union of Concerned Scientists (IPCC Summary)
World Wildlife Fund WWF
RealClimate
Greenpeace
Marine Stewardship Council

Opposing Viewpoints

The anti-global warming advocates take issue with the linkage of human generated green house gases as the cause of global warming and ocean warming. Global warming and cooling periods have been a part of earth’s natural cycles for thousands of years.

Another view is that the build-up of CO2 in the atmosphere and the absorption of CO2 by the oceans will mitigate over time as fossil fuels are slowly used up and alternative clean energy supplies become more dominant.

The fisheries industry is generally supportive of monitoring control and surveillance as a means of protecting fish populations from illegal fishing and overfishing, but locally some disagreements have arisen.

Opposing Websites
GlobalWarmingSkeptics