Temperature changes

In response to increases in atmospheric temperatures a steady rise in ocean surface temperatures has also been observed. This change has not immediately been transferred across the water column, and so the differences between surface water temperatures and deeper waters have increased in many areas.

It is highly likely that changes to the stratification of the ocean surface layers could impact mixing and, in turn, alter patterns of ocean productivity. Proximity to light means that surface layers are the most productive parts of the ocean, but under normal conditions the nutrients in the surface layers are rapidly depleted. There is considerable dependence on the season breakdown of these surface layers, or on the mixing of these layers with deeper waters through storms and upwellings in order to provide nutrients to support surface productivity.

Changes in surface temperatures also directly impact the metabolism of particular species, and observed changes in the biomass of particular fish species, and in the movements of migratory species have been clearly linked to changes in temperatures.