Changes in Ocean
The capacity of the ocean to absorb the heat content is much higher than any other store of energy in the earthâ€™s system, and accounts for more than 90% of the possible increase in the heat content of the earth system. The oceanâ€™s capacity to absorb heat is about 1000 times higher than that of the atmosphere. Warming is widespread over the upper 700 m of the global ocean level.
- The oxygen concentration in the upper layer of the oceans has been observed to decrease during 1970â€“95 due to the warming of the oceans and/or changes in biological activity.
- Apart from this, variations have also been observed in the salinity levels of the oceans. In the tropics, almost all ocean basins show an increase in the salinity in the more evaporative regions.
Thermal expansion of oceans is partly responsible for the variation in the global sea level. The oceans play an important role both as a sink (any process or activity that removes GHGs) and a source (any process or activity that releases GHGs) of GHGs, depending on the changes in their biogeochemistry.
The increase in carbon dioxide concentrations influences the uptake by oceans and leads to the formation of a weak acid. This makes the oceans more acidic. This has an impact on the distribution of carbon species in the ocean (that is the balance between CO2, carbonates, and bicarbonates). Increase in the acidity of the oceans, along with the increase in sea surface temperatures, reduces the rate at which oceans absorb CO2 from the atmosphere.