The Oceans and Global Climate Change
The previous discussion of global warming and melting sea ice gives you one example of how the atmosphere and the oceans are connected. They exchange gases and are both affected by the composition and quality of the other. As we begin to research ways of mitigating the effects of global warming, the oceans are especially important. They have the capacity to store large amounts of carbon dioxide, but only up to a certain point. As the oceans get warmer and sea ice melts, more greenhouse gases may be released to the atmosphere—only advancing the problem of global warming.
The oceans also hold clues about Earth’s past climate. Understanding how climate has responded to environmental changes in the past helps us predict how the climate might change in response to the large scale change that humans are inducing on the atmosphere.
For example, we can study the nature of carbon isotopes in the bodies of microscopic sea organisms to gain information about how the oceans are absorbing carbon and how that capacity has changed through time. From this study we have learned that the oceans today are releasing more carbon than ever before. We can also study seafloor sediments, which are much like the rings in a tree in that they record annual changes in the ocean composition. These studies also show that the oceans’ ability to store carbon may be reaching its maximum capacity and that the oceans are releasing carbon back to the atmosphere. This disrupts Earth’s natural carbon balance and worsens global warming.
The diagram shows how carbon normally cycles between the atmosphere and the oceans. Note that huge amounts of carbon are in the oceans. Imagine if the oceans lose their ability to store that carbon and begin releasing it instead. The entire carbon cycle would be disrupted.
