Temperature

Temperature increases is detrimental to many species due to the fact that many of them have a narrow thermal range.  The most alarming scenario from global warming is the disruption of oceanic currents.  If the ocean currents were to cease, the world would end up in another ice age.  However, a more practical and recent scenario is that species are migrating poleward.  The reason is partially because of species’ optimal thermal ranges, but another reason is because food resources are dwindling in tropical oceans.

Warmer waters create less turbulence and become more stratified.  As a result less nutrients are upwelled from the deeper ocean waters.  Because there are less nutrients, the number of phytoplankton also decrease.  This leads to an overall decrease in fish populations.  In cooler waters, the turbulence is much higher and nutrients cycle through the ocean current.  This allows plankton to bloom, which also allows other species to proliferate.  It is easily evident that polar waters are much more productive.  Most of the ocean’s biomass resides in the polar regions of the world, which allows large animals, such as whales, to thrive in the abundance of food.