The current factors are:
1) Natural cycles of ocean currents that tend to act on a short scale of a few months to a few decades. Anything less than a few months is a weather pattern. Anything greater than a few decades would require longer monitoring with good tools than has been available so far to discover. However, it can take a thousand years for water to complete a cycle , making its way around the globe. There is nothing to indicate that longer cycles are not possible.
2) Continental Drift.
3) Pole Reversal
4) Change in solar output.
5) Sun Spots: Do not confuse this theory with change in solar output. Sun spots have been correlated with global warming. Warmists assume that the only possible explanation for this is a greater solar output coinciding with sun spots. However, proponents of the theory do not claim to fully understand the mechanism. Generally, the most popular mechanism among the proponents is an increase in cosmic radiation affecting high altitude clouds, which has nothing to do with the infrared/visible/uv light spectrum that warmists use as their straw man to explain away this theory.
6) High Altitude Dust: http://en.wikipedia.org/wiki/Nuclear_win
7) Greenhouse Gases: http://en.wikipedia.org/wiki/File:Atmosp
8) Geothermal energy
9) Milankovitch cycles: http://en.wikipedia.org/wiki/Milankovitc
10) The Iris Effect: http://en.wikipedia.org/wiki/Global_warm
11) The disappearance of glaciers
12) The thinning of the atmosphere
13) A change in the albedo: http://en.wikipedia.org/wiki/Albedo
14) Still to be determined other causes
The ocean has a number effects on climate change.
1) The ocean is a great heat sink that provides momentum to the current climate state. It slows down changes, and provides stability in the climate.
2) The ocean is the source of humidity and thus, precipitation and clouds. This affects cloud formation.
3) The ocean is a sink for many minor gases that so much has been attributed to in terms of climate change lately. This includes CO2, SOx, NOx, H2S, halogens, and others. Some, such as CO2 are deposited on the bottom of the ocean and absorbed by the rocks at the bottom to become part of the earth's mantle and then be released by volcanoes eons later. Some, such as CO2 exist in a liquid state at temperatures and pressures found in the ocean, and have a heavier density than water. If, like CO2 they tend to form a separate layer, they can fall to the bottom of the ocean and form a layer on the bottom in pools there. The ocean sequesters them.
The equilibrium between the ocean and the atmosphere is determined by the temperature and pressure mainly at the surface of the ocean. For some gases like CO2, not only does the ocean inorganically absorb it, but also biologically. The longevity of CO2 in the atmosphere is ~5 years.
http://www2.canada.com/components/print.
In theory, as if sea levels were to fall enough, pockets of the gases stored beneath the ocean could bubble up as the pressure due to the water above drops below the natural vapor pressure of the liquefied gases. Sudden releases of gases are theoretically possible, and could affect the climate as well. http://www.sciencemag.org/cgi/content/ab
4) Salinity is not always uniform in every layer of the ocean. The Mediterranean Sea is an excellent case in point. Higher concentrations of salt at the bottom makes the deepest depths of the sea stable with respect to vertical mixing. That means that the heat trapped in the deepest depths of the Mediterranean tends to stay there longer.
5) As glaciation sucks the water out of the ocean, sea levels retreat, changing the earth's albedo.
6) Volcanoes have more difficulty affecting the climate by spewing ash and gases to high altitude when they erupt under water. The ocean covers nearly three quarters of the earth's surface, and most of the volcanoes. The ocean is directly responsible for most of the earth's albedo.
7) Precipitation provided by the oceans give rise to vegetation, and change the albedo of the land. Transpiration and shade from the vegetation changes the temperature and humidity of the land.
The above is not comprehensive, but should be comprehensive enough to provide an sense of the complexity involved, and the reasons why good computer models that have been proven do not yet exist.How and why does climate change and how does the ocean participate in and respond to climate change?The ocean is the primary heat sink on the planet. It is the source of most atmospheric moisture. It is the primary absorber of solar radiation.This radiation absorption is modified by the seasonal freezing near the poles - ice reflects most radiation. The ocean is the primary CO2 sink on the planet. Currently it absorbs about 1/2 of the excess CO2 that humanity is putting into the atmosphere by fossil fuel burning. This fossil fuel burning is currently the most important climate changer on the planet - far outweighing any of the non-human variables.
Our planet could more accurately be called Ocean rather than Earth.
