They not only serve as the planet's largest habitat,

but also help to regulate the global climate.

- The ocean is a continuous body of salt water that

surrounds the continents.

It is divided into four major regions:

the Pacific, Atlantic, Indian and Arctic.

The ocean contains traces of all chemical elements found

on Earth.

But it tastes salty because sodium and chloride ions in

rainwater runoff, and minerals from geothermal vents on the

sea floor.

Climate change is altering the ocean in three major ways.

First, the ocean is getting warmer. The greenhouse effect

not only warms the planet, but also raises the temperature

of the world's oceans.

Over the past century, the ocean's surface temperature

rose at an average rate at about .13 degrees fahrenheit

per decade. And during the past 30 years, sea

surface temperature has been consistently higher than at any

other time on record.

This warmer water vaporizes quickly, fueling stronger and

more frequent storms.

Higher temperatures also threaten delicate ocean life like

coral reefs. And disrupt the food chain.

From krill, to penguins, to seals.

Second, since 1993, the seas have been rising at a rate

that's twice as fast as the long-term trend.

Sea levels rise not only because water expands when it heats

up, but also due to melting glaciers and ice sheets.

Rising seas contribute to flooding on once dry lands in

coastal regions.

A third consequence of climate change is

ocean acidification.

Sea water absorbs CO2 from the atmosphere, which lowers

its Ph and results in higher acid content.

This reduces the concentration of calcium carbonate

which makes it difficult for species like oysters, clams

and corals to form shells or skeletons.

The only way to stop the damage to our oceans is to

dramatically reduce greenhouse gas emissions.

But even emissions stop tomorrow, the gases currently in the

atmosphere would take decades to dissipate.

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