Water is key to the earth being warm and inhabitable. I am concerned that the current climate models, that fixate on a few green house gases, but does not also stress the importance of water, is half baked and misleading.
For example, water is the only natural substance on earth that exist in all three phases at the same time; gas, liquid and solid. Green house gases, besides water, are one trick ponies; only gases. They lack all the extra features of water, by also being a liquid and a solid. These extra phases bring extra things to the climate table. Water vapor absorbs more heat over a wider spectrum than does CO2. It there was no water in the atmosphere, the earth would freeze, with only CO2, N2 and O2. Clouds, which are part gas and part liquid reverse this, helping cool the solar heating.
For example, hurricanes, which are very powerful weather events, are connected to the phase change of water from gas to liquid. Gaseous water takes up about 1000 time's more volume than does liquid water. When lot of water vapor; gas, condenses into rain; liquid, a vacuum is created in the local atmosphere and a low pressure area forms. This low pressure can then pull more moist air into the atmospheric void, for a self feeding storm.
CO2 is stuck as a gas and is not part of these daily weather dynamics. All the high and low pressure systems in the earth's weather are connect to liquid to gas and gas to liquid phase transitions of water. Cloud, which are the bridge for the transition of water vapor to liquid water, can block the sun and bring down cool water and ice to help offset and cool the earth; hail in the summer.
One of the key solid state tricks of water, that also allows our planet not to become an ice ball, is the unique property of solid water expanding when it freezes. This is the most commonly known anomaly of water, that we all have seen; ice cubes in a drink. Most materials in the universe contract when they freeze into a solid. What this expanding of freezing water brings to the table, is it prevents the oceans from freezing solid, preventing the earth from becoming a cold ice ball.
If water contracted when it froze, like most materials, as the early winter water chilled, the cold water would sink downward by convection as warmer water rose up by convection. Once the surface water froze, it too would sink, exposing more liquid water to the surface cold, while snowing down ice, sealing the bottom, that would kill the fish. Over time, the snow and ice on the bottom of the water, would accumulate to where the summers would not be able to melt it, since the warm water of summer would float on the surface and not sink.
However, since water will expand when it freezes, you get an igloo affect that keeps the cold on the surface so it can be reversed by summer. Water has a density maximum at 4C. This is another anomaly of water. At 4C water will expand, whether you chill it or heat it at 4C, since 4C is the maximum density. In the winter, we will also get an initial cold water convection, until the surface water drops to below 4C. The even older 3C water will want to float on the 4C water, ands then freeze to becomes a solid that floats as ice, glaciers and ice bergs. This igloo affect keeps the bulk oceans always above freezing, with the summer heat able to catch up and melt the cold stored in the surface ice.
An important colligative property of water is connected to freeing point depression, which occurs in the salty oceans. The 4C is for pure water, with this number lower in the oceans, than in fresh water lakes. The oceans shifts the density maximum curve downward; lower temperature, allowing the cold to have more affect. However, water still expands, with the igloo affect still active.
When the glaciers melt and fresh water is added to the oceans, since fresh water is lighter; no salt, The freeing point depression reverses causing the igloo affect to occur sooner, so the oceans can warm a few degrees over time. We may be able to cool the earth simply by mixing the surface ocean water from the glacier melt, with the denser deeper ocean water, to reverse the freezing point depression on the surface. This will not require any major change to culture other than large pumps for recirculation and mixing.