Where Have All the Ice Sheets Gone?

The deep circulation of the ocean has important influences on Earth's heat budget and climate. The deep circulation varies over periods from decades to centuries to perhaps a thousand years, and this variabililty is thought to modulate (change) climate over such time intervals. The ocean may be the primary cause of variability over times ranging from years to decades, and it may have helped modulate ice-age climate.

Two aspects of the deep circulation are especially important for understanding Earth's climate and its possible response to increased CO2 , an important greenhouse gas.

• The oceans are the primary reservoir of readily available carbon dioxide (CO2), an important greenhouse gas. CO2 dissolves more quickly in cold water than in warm water. New CO2 is released into the atmosphere when fossil fuels and trees are burned. Roughly half of the CO2 released into the atmosphere quickly dissolves in the cold waters of the ocean which carry it to the abyss (deepest part of the ocean). Forecasts of future climate change depend strongly on how much carbon dioxide is stored in the ocean and for how long. How much and how long CO2 is stored in the ocean depends on the thermohaline circulation.
• The oceans carry about half the heat from the tropics to high latitudes required to maintain Earth's temperature. Heat carried by the Gulf Stream and the north Atlantic drift warms Europe. Norway, at 60¡ N is far warmer than southern Greenland or northern Labrador at the same latitude; and palm trees grow on the west coast of Ireland, but not in Newfoundland which is further south. The oceanic component of the heat-transport system is called the Global Conveyor Belt.

Understanding causes and consequences (what happens) of variations in climate throughout history is important. Knowledge of this may provide an understanding of the effects and conseqeunces of extremely rapid (geologically speaking) global warming that many scientists believe has been brought on by human interaction with the atmosphere. The greenhouse effect is a much studied, discussed, and debated topic.

Questions that come to mind are:

1. What causes an ice age?

2. What effect, if any, do periods of glaciation (ice age) have on sea level?

3. Has Earth experienced its last glaciation (ice age)?

4. How is snow transformed into glacial ice?

5. How do scientists study paleoclimates?