The oceans and our atmosphere work together to form the Earth's climate. Throw humans into the group and the debate begins. While the atmosphere quickly adjusts to our changes, the oceans are the world's great moderator.
Short-wave radiation (energy from the sun) passes nearly untouched through the atmosphere. When the sun is high in the sky, its radiation is almost all absorbed by the oceans. Not only are the oceans good at absorbing energy, they are good at doing it while keeping their cool. That is, relative to the atmosphere, it takes much more energy to change the temperature
Did you know? The amount of thermal energy required to raise the temperature of a substance by a given amount is called heat capacity. The heat capacity of water is about four times that of air.
People who live on the coast know the oceans mediate their climate. In winter, when the atmosphere is relatively cold and the oceans are relatively warm, heat is radiated from the water into the air, keeping the coast warmer. The opposite is true in summer. The oceans absorb heat from the atmosphere, keeping the air cool.
It is difficult for the oceans to keep the atmosphere cool when we insist on warming it up. Due to our carbon emissions, the increased greenhouse effect is acting to trap more energy in the Earth's atmosphere. However, the atmosphere would be much warmer than it is if it weren't for the oceans. They absorb much of the excess heat. In 2007 the Intergovernmental Panel on Climate Change reported that from 1961 to 2003 the oceans warmed on average 0.1°C. The energy required for that change is approximately 8x1022 joules (or 1.9 x 1022 calories). To use that much energy, you would likely have to bench-press your car four billion billion times.
The oceans' mediation of climate isn't limited to heat – they also absorb carbon dioxide. As we add to the atmosphere, we add to the oceans. Although the atmospheric concentration of carbon dioxide is increasing over time, the concentration would be higher than it is if there were no oceans. The only problem is that carbon dioxide acidifies the oceans, which can be detrimental to marine life.
Did you know? Carbon dioxide molecules in the ocean react with water molecules to form carbonic acid.
The oceans are doing their best to keep the Earth's climate steady, but they can only do so much. It's up to us to continue our own debate, to discuss climate change and its effects, and to look to the wisdom of the moderating oceans.
Specified Heat and Heat Capacity
How the Ocean Affects Climate
Carbon Dioxide in the Ocean and Atmosphere
Article first published March 21, 2011.