CLIMATE TRENDS AND PROJECTIONS FOR THE GLOBAL OCEAN

Oceans and Atmospheric Weather System

Climate change is expected to have an impact on a variety of different climate dependent services, including agriculture, water supply, ecosystem health, human health, and weather. Climate is of prime importance in the economic, social and environmental health of our cities, coastal states and oceans. The ocean drives our planet's climate systems. Temperature differences between the ocean (which both heats and cools more slowly) and land create winds, and winds move air masses and their weather systems with them. Most of the precipitation that falls comes from evaporated seawater. The water we use to drink, wash, and water is linked to the ocean.

This excerpt from the 1998 Year of the Oceans report on the impacts of climate change explains the physics governing the behavior of the atmosphere and the ocean, thus how the ocean influences weather and climate:

The Earth’s weather and climate are the result of the redistribution of heat. The major source of heat to the surface of the Earth is the sun, principally through incoming visible radiation most of which is absorbed by the Earth’s surface. This radiation is redistributed by the ocean and the atmosphere with the excess radiated back into space as longer wavelength, infrared radiation. Clouds and other gases², primarily water vapor and carbon dioxide, absorb the infrared radiation emitted by the Earth’s surface and remit their own heat at much lower temperatures. This "traps" the Earth’s radiation and makes the Earth much warmer than it would be otherwise.

Most of the incoming solar radiation is received in tropical regions while very little is received in polar regions especially during winter months. Over time, energy absorbed near the equator spreads to the colder regions of the globe, carried by winds in the atmosphere and by currents in the ocean. Compared to the atmosphere, the ocean is much denser and has a much greater ability to store heat. The ocean also moves much more slowly than the atmosphere. The ocean moderates seasonal and longer variations by storing and transporting, via ocean currents, large amounts of heat around the globe, eventually resulting in changing weather patterns.

In short, without the oceans to "bank" the heat from the sun and redistribute it globally, the Earth would be freezing by night, and unbearably hot during the day. The ability of the oceans to absorb and transfer heat thus moderates the global environment.

²The primary gasses which contribute to the greenhouse effect are: water vapor (H20), carbon dioxide (CO2), ozone (O3), methane (CH4), nitrous oxide (N2O), and chlorofluorocarbons (CFCs). Developed countries produce roughly 70 percent of the CO2 emissions (mostly from burning fossil fuels). The United States, with only 5 percent of the world’s population, accounts for 22-26 percent of global CO2 emissions from human activities, and 20 percent of methane.