Role of the Global Hydrological Cycle

1. Global Oceans

Global oceans participate in the global energy balance by transporting heat energy, which is preferentially received in the tropics by solar radiation, toward the polar regions. Over half of the solar energy reaching the earth is first absorbed by oceans and then transmitted to other regions. Global oceans take excess CO₂ from the atmosphere at a rate that depends on ocean temperature. The partial pressure of CO₂ in cold water is depressed by enhanced solubility and (in the spring bloom) phytoplankton growth (Figure 9), making cold water a sink for atmospheric CO₂ . Global oceans are rich media for biological growth and contribute substantially to the global carbon cycle as was presented in the unit on the Carbon Cycle.

These surface water biological processes support a full spectrum of the food chain from phytoplankton to whales. Global oceans play a significant role in determining where and how much water vapor enters the atmosphere, which in turn influences the global energy balance. The massiveness of the global oceans also introduces a thermal inertia into the climate system: ocean processes are slow in comparison to atmospheric processes, so changes in ocean structure can introduce slow changes of climate. This fact has become more evident to us in recent years as we have come to understand the El Nino/Southern Oscillation (Climate Variability) which we now know causes perturbations of weather in certain regions for several successive months.

PREVIOUS: Components of the Global Hydrological Cycle

NEXT: --Ice Masses and Snow