A pair of dumb *****.
Warmer Oceans | A Student's Guide to Global Climate Change | US EPA
Ocean Warming
Since 1955, over
90% of the excess heat trapped by greenhouse gases has been stored in the oceans (Figure from IPCC 5thAssessment Report). The remainder of this energy goes into melting sea ice, ice caps, and glaciers, and warming the continents's land mass. Only the smallest fraction of this thermal energy goes into warming the atmosphere. Humans thus, living at the interface of the land, ocean and atmosphere, only feel a sliver of the true warming cost of fossil fuel emissions.
This 90% of extra heat taken up by the ocean is mostly in the upper 700 meters (m) layer (about 60% of total excess heat), while 30% is stored in layers deeper than 700 m
(IPCC 5th Assessment Report). The ocean absorbs most of this "anthropogenic heat" because:
- Water has a high heat capacity: It takes much more heat to warm 1 liter of water than it does to warm the same volume of air (or most other substances).
- The ocean is deep: The world's oceans cover 71% of the earth surface and are about 4 km deep on average. This represents a tremendous reservoir of heat.
- The ocean is dynamic: Heat, carbon, oxygen and various other quantities exchanged with the atmosphere are mixed throughout the ocean through currents, internal waves, eddies, and various other circulation mechanisms.
The largest changes in ocean temperatures were observed in the upper 75 m, due to closer proximity to the atmosphere and the large mixing within this layer (IPCC 5th Assessment Report). As we trap more energy in the earth climate system, heat penetrates further into the ocean. Two important geographic areas where the atmosphere "communicates" with deeper layers of the ocean are the North Atlantic and the Southern Ocean. Because of their distinct atmospheric conditions and geographic settings, surface waters near the poles can be buried into deeper layers, bringing along their heat signatures, thus warming the interior of the ocean.