What property of water allows the earth's oceans to act as heat reservoirs which moderate earth's climate?

Answer 1

Boy with a name like Ecolink you think they would have nailed this one…

The concept is called a thermocline / halocline.
http://en.wikipedia.org/wiki/Thermocline
http://en.wikipedia.org/wiki/Halocline

As water heats it expands and becomes less dense. A distinct layer occurs in the oceans where the water goes from surface temperature down to temperatures closer to freezing (thermocline). As you swim down through this it feels like a distinct layer, but it actually transitions over a few feet.

At the equator water evaporates from the top layer. And the two layers are basically equal density (though the top layer has a far higher salt concentration – called a halocline). The heating of the top layer basically causes the top “skin” of the ocean to expand away from the equator of the earth and towards the poles. As this warm water reaches the poles it cools slightly. At some point the density of the top layer becomes greater than the water underneath and warm water is carried down, cold water is carried up.

So the oceans act like big heat exchangers. They take heat out of the atmosphere and re-circulate cold water up to the surface to absorb more heat.

Answer 2

Water resists temperature change.

Water is much slower to heat up and cool down than anywhere surrounded by air.

Answer 3

heat capacity------ how much energy it takes to increase the temperature of a substance. Mainly due to waters hydrogen bonding, it takes more energy for the water molecules to increase their motion and increasing motion increases temperature, so water can store more energy without drastic temperature increase when compared to air.

Answer 4

High boiling point