Last updated December 5, 2017

Increased Air Mass Temperature

Major heat sources for the air include solar radiation and the ocean. The ocean is storing 93 percent of the extra heat due to global warming, which has many cascading consequences on the climate system as a whole. One effect is on the exchange of heat and water between the ocean and the atmosphere. As sea surface temperatures warm, the hydrological cycle is expected to intensify and additional heat is available for pick-up by air masses passing over the ocean and onto land.

Physical considerations

The air and ocean are two major vessels of heat energy and moisture in the climate system, and the exchange of heat and moisture between the air and ocean affects circulation patterns that determine the weather we experience.

The ocean is storing 93 percent of the extra heat due to global warming, which has many cascading consequences on the climate system as a whole.[1] One effect is on the exchange of heat and water between the ocean and the atmosphere. As sea surface temperatures warm, the hydrological cycle is expected to intensify and additional heat is available for pick-up by air masses passing over the ocean and onto land, with implications for extreme rainfall and heat events.


Clausius-Clapeyron: the capacity of the air to hold moisture increases with temperature

As the temperature of the air increases, its water-holding capacity also increases by about 7 percent per °C of warming globally, according to the Clausius-Clapeyron relationship.[1] Consequently, precipitation in the form of rain and snowfall also increases with air temperature.

Changes in extreme precipitation from fully saturated air masses have been postulated to occur at the Clausius-Clapeyron rate, or even higher if local moisture convergence takes place, but changes in precipitation over the Earth's surface are typically smaller (approximately 2 to 3 percent per °C of warming[2]) than the Clausisus-Clapeyron rate, due to a difference in behavior over land and ocean.[3]


Global trends

Global observation records show the troposphere has warmed and the stratosphere cooled since 1958 but with uncertainty that grows with height and is much greater outside the better-sampled Northern Hemisphere extra-tropics, where warming is of the order 0.1°C per decade.[1]