Climate Change Indicators in the United States
The oceans and atmosphere interact constantly—both physically and chemically—exchanging energy, water, gases, and particles. This relationship influences the Earth's climate on regional and global scales. It also affects the state of the oceans.
Covering about 70 percent of the Earth's surface, the oceans store vast amounts of energy absorbed from the sun and move this energy around the globe through currents. The oceans are also a key component of the Earth's carbon cycle. Oceans store a large amount of carbon, either in dissolved form or within plants and animals (living or dead).
What is happening?
As greenhouse gases trap more energy from the sun, the oceans are absorbing more heat, resulting in an increase in sea surface temperatures and rising sea level. Although the oceans help reduce climate change by storing one-fifth to one-third of the carbon dioxide that human activities emit into the atmosphere, 1 increasing levels of dissolved carbon are changing the chemistry of seawater and making it more acidic.
Why does it matter?
Changes in ocean temperatures and currents brought about by climate change will lead to alterations in climate patterns around the world. For example, warmer waters may promote the development of stronger storms in the tropics, which can cause property damage and loss of life. Other impacts come from increased ocean acidity, which reduces the availability of some types of minerals, thus making it harder for certain organisms, such as corals and shellfish, to build their skeletons and shells. These effects, in turn, could substantially alter the biodiversity and productivity of ocean ecosystems.
Changes in ocean systems generally occur over much longer time periods than in the atmosphere, where storms can form and dissipate in a single day. Interactions between the oceans and atmosphere occur slowly over many years, and so does the movement of water within the oceans, including the mixing of deep and shallow waters. Thus, trends can persist for decades, centuries, or longer. For this reason, even if greenhouse gas emissions are stabilized tomorrow, it will take many more years—decades to centuries—for the oceans to adjust to changes in the atmosphere and the climate that have already occurred.