When energy is used to heat something up, the temperature does not increase smoothly as the energy is put in. Most significantly, this is because causing matter to change states takes energy in itself, above and beyond the energy that goes into warming. Imagine a big block of ice at 0Â°C. A lot of energy has to go into it before it becomes a pool of water at 0Â°C. The same is true for turning 100Â°C water into 100Â°C steam. Latent heat has been discussed here before.
Because of climate change, the overall trend in global air temperatures is going upward. As anyone who has visited a steam room or had a camera fog up when coming inside on a cold day knows implicitly, warmer air can hold more water. As well as being an important feedback effect (since water vapour is a greenhouse gas), warmer more air-laden water contains more of the latent heat that provides the energy for thunderstorms, tornadoes, and hurricanes. The increase in the average amount of latent heat in a body of air increases the probable strength of future storms, a fact that becomes especially worrisome when you acknowledge how the damage caused by storms increases in a non-linear way. Winds that are 10% faster have a third more destructive potential.
The extra water in the air will also increase the quantity of precipitation and the likelihood of floods. Furthermore, melting ice sheets will cool sea water, increasing the temperature differential between the equatorial and polar regions. This will increase the strength of mid-latitude cyclones, as air currents cooled by melting ice sheets (latent heat, again) collide with ever-warmer masses of air, containing ever-more water. The level of melting in the ice sheets is already significant enough to measure using sensitive gravitational data from satellites like GRACE. Greenland is losing about 100 cubic kilometres of ice per year, while West Antarctica is losing it at a somewhat smaller rate. The ‘wet’ process of ice sheet disintegration suggests that the rate of ice loss could increase dramatically, one the ice sheets are pushed past a critical point by warming.