Our Oceans Are in Dire Shape, But Without Them All Life on Land -- Human, Plant and Animal -- Is Totally Screwed
Global warming has often been discussed with regard to its effects for life on land: increased temperatures and heat waves, increased weather extremes, less but more intense rainfall, drought and forest fires.
Water, however, remains less considered. Even discussions of floods or rising sea levels, which focus on water, study mainly their consequences for land inhabitants.
Yet oceans, it is well known, cover three quarters of the earth's surface. And oceans have absorbed about a quarter of all carbon dioxide (CO2) emissions, one of four main greenhouse gases causing global warming. This absorption of CO2 is integrally related to the three major factors impacting the oceans: global warming, ocean acidification and decreasing amounts of oxygen. As a result, the current situation of the oceans is dire. And its impact will be severe not only for marine life but also for all life -- plant, animal and human -- on land.
Carbon dioxide (CO2) exists naturally in the air. But through the use of fossil fuels, in particular coal and oil, the amount of CO2 in the air has increased exponentially since the Industrial Revolution began.
As the oceans absorb carbon from the air, their chemistry changes. This process is known as ocean acidification, and it has brutal consequences for marine and land life.
Oceanographers estimate that before the use of fossil fuels, the ocean's PH balance, which measures its acidity, had been relatively stable for the past 20 million years. During the last great extinction of marine life, which occurred 55 million years ago, 50 percent of some groups of deep sea animals were wiped out.
But the current levels of carbon being absorbed by the oceans is far higher than the levels being absorbed then.
A United Nations Environment Program (UNEP) report released in 2010 on the "Environmental Consquences of Ocean Acidification" and based on studies conducted over the past two decades off the coast of Hawai'i has confirmed that the increased CO2 concentration levels in the ocean mirror the increased CO2 levels in the atmosphere.
Ocean Acidification and Phytoplankton
Already the increased levels of ocean acidification have led to a loss of phytoplankton and of coral reefs. And losses of phytoplankton and of coral reefs have a ripple effect.
First, much marine life relies on them for nourishment. Flounder, haddock, pollock, salmon and shrimp all eat phytoplankton. Humans eat many of these fish. Krill eat phytoplankton and whales eat krill. So a decrease in one threatens the liveilhood of the other.
Second, phytoplankton also absorbs carbon dioxide. Phytoplankton floats along the ocean's surface absorbing CO2 as land plants do in photosynthesis. As the CO2 is absorbed, the plant dies and sinks to the ocean floor, releasing CO2 along the way. Cold water can hold higher levels of CO2 than warmer water, so most of the CO2 released, which turns water acidic, is to be found along the ocean floor. But this acidic water does not stay at the ocean's floor. During an upswell, it rises to the surface and even the shore. Its acidity is deadly for the shells of marine life, such as shrimps, clams and oysters.
If the smallest part of the food chain is affected by ocean acidification, it ripples all the way up the food chain, making the largest part of the food chain vulnerable.
"Since the time before the industrial revolution," says the National Resource Defense Council's Lisa Suatoni, "ocean acidity has increased 30 percent."
And the bad news does not end there: According to oceanographers, the water rising from the ocean's depths holds CO2 that has accumulated over the past decades. Thus, in coming years, the increased levels of CO2 absorbed by the oceans will re-emerge as increased ocean acidification reaching the shores. Higher levels of cean acidification have already led to tremendous problems for the oyster industry. In the summer of 2007 oyster harvests began to plummet in the Pacific Northwest. The situation was extreme. The oyster hatcheries were keen to find the culprit, which turned out to be ocean acidification.
Ocean Acidification and Coral Reefs
Increasing ocean acidification also threatens coral reefs. Recent estimates suggest that coral reefs might disappear altogether by the end of the century.
Coral reefs have been referred to as the "rainforests of the sea." They make up only 10 percent of the world's oceans yet they contain some of the world's most diverse ecosystems. Coral reefs provide a home for and feed about 25 percent of the world's marine life, including crustaceans such as crabs, lobsters and shrimp; echinoderms, such as sea cucumbers, sea urchins and starfish; fish; mollusks; sea turtles; sponges and worms; and also sea birds like albatroses, herons, pelicans and boobies.
Typically located in shallow and warm ocean waters, coral reefs also provide shoreline protection. For example, the reefs near the Maldives help this island create a barrier against rising sea levels.
The extinction of coral reefs would not only jeopardize the lives of marine species that rely on them for shelter and food, but threaten the shorelines of low-lying island states already suffering the impacts of rising sea levels.
Global Warming: Air and Ocean
Global warming is typically talked about in terms of air temperature or earth surface temperature. Recently, NASA's Goddard Institute for Space Studies reported that 2010 was the hottest year on record.
A new study conducted by the National Center for Atmospheric Research (NCAR) found that the ocean has been absorbing much of increased temperatures. As with the CO2 absorbed by the oceans, these temperatures are soaked up and moved toward the bottom of the oceans. And again, as with the CO2, the warmer temperatures do not disappear but will eventually return to the surface. The earth's temperatures would then be doubly impacted: first, by the greenhouse gas emissions already in the air and causing global warming; second by the temperatures and CO2 returning from the ocean.
What Can We Do?
The only way to reduce ocean acidification is to reduce the level of CO2 emissions. Increased efficiency of buildings could help reduce the amount of energy needed, and producing the energy needed through solar and wind energy would emit less greenhouse gas emissions.
Marine biologists and chemists have argued for a Clean Air Act for the seas at the federal level. Last year, President Obama announced the first National Ocean Policy and created a National Ocean Council to establish it. One of its numerous duties, including managing the spatial planning of marine areas, the policy would seek to preserve ocean quality.
Oceanographers also recommend that when the international negotiations of the United Nations Framework Convention on Climate Change discuss the reduction of CO2 emissions, they explicitly consider the presence of CO2 in the oceans. Given how stalled movement has been in the federal and the international arena on passing legistlation and reaching an international agreement to reduce greenhouse gas emissions, it remains to be seen how long it will take for the effects of CO2 on oceans to be recognized, taken into account and addressed.