Without the greenhouse effect, the planet would be an uninhabitable, frozen wasteland. So the atmosphere has a natural supply of greenhouse gases. They capture heat and keep the surface of the Earth warm enough for us to live on. Earth has a natural balance between the amount of carbon dioxide and other greenhouse gases released into the atmosphere, Natural emissions of heat-trapping gases matches with what could be stored on Earth. However with industrialisation large amounts of greenhouse gases are being added daily to this natural supply of greenhouse gases. These gases are building up beyond the Earth's capacity to remove them and, in effect, creating an extra-thick heat blanket around the Earth. The result is that the globe has heated up by about one degree Fahrenheit over the past century, at a much faster rate especially in the past two decades. The difference in global average temperatures between modern times and the last ice age, when much of North America and Europe was covered under thick ice is only about 9 degrees Fahrenheit.

One of the ocean's most important climate functions is absorbing this heat and carbon dioxide, one of the gases that cause global warming. The oceans have already absorbed huge amounts of heat and carbon dioxide due to the industrialisation of the world. Thus slowing the atmospheric warming but it cannot stop it. Once the oceans come to equilibrium with a greenhouse-gas warmed earth, the excess heat will remain in the atmosphere and earth will get hotter at a much faster rate. However the prolonged absorption over the last two centuries is already affecting the ocean, by changing the ocean circulation patterns and in turn affecting the nutrient delivery system for marine life.

Colder waters are more productive than warm waters. The warming of the oceans may be starting to break the ocean's food chain. The system of currents replenishes deep waters with oxygen and carries nutrients to surface waters where microscopic plants known as phytoplankton can use them. When cold, nutrient-rich waters rise to the surface seasonally and mix with sunlit surface waters, the upwellings trigger the growth of phytoplankton. The areas where these upwellings occur are areas where the marine life flourishes, the fishing grounds.

As oceans absorb more heat, upwellings of cold, nutrient-rich waters can become less frequent. Without this nourishment, plankton blooms, a critical link in the marine food chain, are disrupted and so food for sea life up the food chain is cut off. Further phytoplankton use carbon dioxide for photosynthesis. With less plankton, the oceans could not remove as much carbon dioxide from the atmosphere.

The world's seas are naturally alkaline and many of the marine creatures that have been around for thousands of centuries will not survive in an acidic sea. But the oceans are acidifying because of increased absorption of atmospheric carbon dioxide. When carbon dioxide dissolves in ocean waters, it produces carbonic acid, which corrodes the limestone structures of coral reefs and seashells. Thus posing a threat for shell-forming species, which are essential parts of the marine food chain. With the present rates of pollution, carbon dioxide levels will only increase even more, causing further acidification of the ocean.

Corals get both their food and their spectacular colour from tiny algae called zooxanthellae that live in them. Corals are very sensitive to temperature and thrive within a narrow range of heat and cold. An increase of just 2 degrees Fahrenheit above the typical maximum summer temperature can cause corals to expel their algae, or "bleach." After prolonged bleaching, they often die. Warmer waters, more acidic oceans and stronger storms are taking their combined toll on coral reefs. Loss of coral reefs will result in huge economic losses, in many billions of dollars, in coastal regions dependent on reefs. However this will be a very small compared to the impact on the environment. Damage to reefs is an ecological catastrophe, coral reefs are home to a rich diversity of marine life.

With the destruction of the shell-forming species and the disruption of phytoplankton blooms – the most essential parts of the marine food chain is being completely destroyed. Thus questioning the future survival of the entire marine life as we presently know it. Significant changes loom for seabird and fish communities, ocean circulation patterns and basic processes of ocean chemistry. The debate over global warming has shifted from whether it is happening to how to avoid catastrophic damage.