Oceans and Climate
Global warming is caused by the emission of greenhouse gases like carbon dioxide into the atmosphere. Carbon dioxide is removed from the environment through photosynthesis, a process in which plants use water, sunlight and the gas to produce energy. Photosynthesis, therefore, reduces the amount of carbon dioxide in the Earth’s atmosphere. Oceans are filled with photosynthetic marine organisms that remove the greenhouse gas from the environment.
Water itself absorbs enormous quantities of carbon dioxide. More than half of the greenhouse gases emitted by the combustion of fossil fuels are absorbed by ocean water. Carbon dioxide, for instance, is first absorbed by the water, and then it is dissolved in the icy waters near the Antarctic and Arctic regions. During winter, the cold water sinks, carrying the gas into the ocean’s deepest layers. Over time, the water is pulled back to the surface due to tides and winds. The carbon dioxide is then released back into the Earth’s atmosphere as the water warms.
In addition to absorbing large quantities of greenhouse gases, ocean water also absorbs high amounts of heat. Some of the heat built up in the atmosphere due to greenhouse gases is transferred to the ocean. In this way, the Earth’s oceans can slow the rate of climate change.
In the last 100 years, the levels of greenhouse gases emitted by human activities have exceeded the natural ability of oceans to transfer the gases into their deepest levels. As a result, high concentrations of dissolved carbon dioxide are causing the oceans to acidify at rapid rates. If climate change continues at its going rate, the pH level of the Earth’s oceans will decrease by 150 to 200 percent by 2100. The change will profoundly disrupt oceanic food chains and will be detrimental to marine life like shellfish, coral reefs and crustaceans.
Global warming may also cause catastrophically rising sea levels. The planet’s seas have already risen due to warmer global temperatures that melt glaciers and ice sheets, but if climate change continues, the result could be massive rises in levels by up to ten meters. If that occurs, entire coastal areas will be swept away by oceans, and many of the Earth’s islands will be completed submerged in water.