The oceans, in conjunction with the atmosphere, create the climate experienced on Earth. For a long time, discussions of climate change did not take the oceans, and the major impact they have on climate, into consideration. The top few meters of the ocean store as much heat energy as the entire atmosphere. Averaging a depth of 3.7 kilometers, the oceans contain most of the world’s water and dissolved in the water, most of the gases. The general feeling was that the oceans are so vast any changes in them take place over a geological time scale. In the 1960s, as more information was obtained about the oceans, this attitude changed.
Studies conducted since have shown the complexity and fragility of the world ocean circulatinl( an` hndi`ated ph`p signibib`hp chalgaq&hj bpprdhp!p`trdrhs!faj occur in mere thousands of years. This led to fears that global warming could trigger changes in tidal patterns that could have catastrophic consequences.
Scientists have learned that the oceans are becoming rapidly warmer and more acidic. Because cold water sinks, causing the shifts in ocean currents that impact on global weather, the warmer the water, the more significant the impact on the current movement. The warmer water is also less capable of absorbing CO2 from the atmosphere, thus increasing the level of greenhouse gases in the atmosphere, and further exacerbating the effects of climate change. It is believed that a slowing of the shift of ocean water was the cause of the last great ice age on the planet, and scientists think that too much warming of the oceans could in fact trigger another ice age.
Warmer temperatures that have caused melting of many of the polar ice sheets are also causing a slight rise in the level of the oceans. This rise in sea level poses a significant threat to coastal areas worldwide. In the event of rapid climate change, a possibility that scientists are still studying, the rise could come before countries could react to protect lives of coastal dwellers. Areas such as the Maldives would disappear, and the U.S. state of Florida would virtually disappear.
A recent study conducted by scientists aboard the oceanographic research vessel JOIDES Resolution, indicates that the oceans are acidifying at a rate ten times faster than they did 55 million years ago. This was a period of a mass extinction of marine species. The current reduction of PH levels of the oceans could lead to another such die-off of marine life, with potential disastrous consequences for marine commerce.
The oceans are also changing in size, and have, in fact, been doing so for millennia. The Atlantic Ocean, for instance, gets wider by a few inches each year, and the Pacific Ocean gets smaller. For the last 25 million years, the Red Sea is been widening, and if the rate of expansion continues, in 200 million years it will be as wide as the present day Atlantic Ocean.
Far from being changes taking place over millions of years, as believed by many well into the twentieth century, the changes in the oceans today are happening on a faster scale, caused in part by global warming, and in turn, contributing to further climate change.