Impacts of sea water temperature

Earth is the only planet to have the life supporting systems to support the vast number of species. Though the richness of biodiversity is same in both water and land, the degree of sensitivity to changes is more in water compare to land. Apart from water, air, and soil, temperature is the most essential element for many reasons. Not only does it play the role in the metabolic and biological activities of the organisms; but it also regulates the global climatic phenomenon. However, in case of abnormal rise, it could prove detrimental for entire biotic world. Nowadays, with the increase in green house gases, it is heading to become a potential threat for the existence of flora and fauna. In this post, “Impacts of sea water temperature” I am going to explore the potential impacts of temperature in the marine environment.

Temperature distribution in space and time in the oceanic water

As a part of basic knowledge, specific heat capacity of water is more than the capacity of landmass as the water is poor conductor of heat. As a result, the degree of rise and fall in the temperature of water bodies is slow compare to landmass.

In the oceanic waters, temperature and heat hardly penetrate beyond 200 to 300 m. However, its degree may be vary in the continental shelf and abyssal plain. Due to land mass effect, oceanic water is more warm at the proximity of land compare to deepest open oceanic plains.

Apart from this, consideration of seasonal changes in the water temperature from place to place is indispensable, regarding marine or aquatic life. In the summer or spring season due to longer duration of days, there is no dearth of light and temperature in the “Photic zone.” Whereas, opposite happens when there is winter season in the either of hemispheres. Nevertheless, these changes are very instrumental in the marine world.

Ocean currents product of global heat imbalance

You know that temperature in the marine environment is vary in space and time due to seasons, landmass, and latitudinal position. Besides, it is the most vital  determinant of density and salinity the two major properties of oceanic waters.

In summer in the either of hemispheres, when the temperature rises, density of sea water declines but salinity concentration increases with greater evaporation. On the other hand, in winter all the phenomenon reverses.

 Ocean currents-heat balancing mechanism

Ocean currents are natural heat balancing mechanism of nature, flowing from higher temperature to lower and lower to higher. Accordingly, warm currents flow polewards, whereas cold in the direction of equator.

Upwelling and downwelling  density difference

In case of density difference, denser water sinks, replacing lighter and vice-versa. For clearity, denser cold water from either of poles find its way to replace lighter in the tropical regions in the form of under-currents. Moreover, upwelling and downwelling are the direct outcomes of density differences.

Ocean currents and climate

If we look at the rainfall map of the world; then, we easily notice that there is a close relationship between cold current and deserts. Whereas,  in case of warm currents, higher degree of rainfall is observed. That’s why we call it a major climatic factor.

Impacts of sea water temperature on gases dissolveability

All the spheres including hydro, litho, bio, and atmosphere are interconnected. Likewise, atmospheric gases dissolve in the surface sea waters. But, its degree depends on the nature of temperature of the waters. Scientificly, colder water is more favourable to dissolve more. Whereas, warmer water release more, instead to absorb.

In the winter season, waters remain colder. So, these waters absorb more carbon dioxide and oxygen. On the other hand, opposite happens in the spring or summer season.

It is well known that both gases are vital for aerobic animals and photosynthetic plants. In short, seasonal changes in the water temperature is very essential for photosynthesis, as well as survival of the aerobic organisms in the marine ecosystem.

Seasonal intermixing of sea water and nutrients cycle

Intermixing or upwelling and downwelling are attributed to the seasonal changes of sea water temperature. In the winter, upwelling is observed in the tropical, sub-tropical regions.

In this process, cold nutrients rich water mass replaces comparatively less denser. Cold water mass of the bottom is very rich in nutrients. Benthic part of the oceans continuously receives organic material of dead organisms. And, while upwelling, it enriches surface waters in the winter season. You know that upwelling places are the best fishing grounds of the world.

In the summer season, with abundant sunlight and carbon dioxide, phytoplankton  produce lots of food through photosynthesis for the rest of the animals. Definitely, this is the best epitome of nature’s babalancing act for its creatures

Impacts of higher or abnormal sea water temperature

Unlike terristorial organisms, as I mentioned earlier that marine organisms are too sensitive for changes in the  sea water temperature. These marine organisms cannot bear even the slightest change in the normal level. Let’s see the negative impacts of sea water temperature.

Release in gases

As per the scientific research, oceans are the biggest storehouse of the atmospheric carbon. However, it happens when there is a normal level of temperature. These gases are more dissolveable in the cold water compare to warm. But, in the higher level of temperature, oceans release the absorbed gases in the atmosphere. Consequently, the chances of further rise in global temperature increases more rapidly.

Loss of oxygen threat for aerobic animals

This is one of the most detrimental impacts of sea water temperature. Because, the quantity of oxygen is already less in the sea waters. But, its importance for aerobic animals is beyond value. Deoxygenating water isn’t less than poison for these precious organisms.

Ocean acidification

Ocean acidification is yet another negative impacts of sea water temperature. You might have heard about the chemical reactions of carbonic acid with calcium carbonate. In this reaction, carbonic acid transforms calcium carbonate into calcium bicarbonate which is easily dissolveable in the water, posing great threat for shell forming animals.

Shell forming animals such as corals, extract calcium dissolved in the water to form protective cover. Without this protective cover, these animals will become too vulnerable or will become extinct eventually.

Coral bleaching

Corals are the reef building tiny polyps live in the big colonies. For theirs survival, symbiotic relationship with Zooxanthellae is inevitable as the latter have photosynthetic pigment. In this way, corals receive 90 percent of food from this algae.

But, this algae cannot survive in the higher level of temperature. In the situation of higher temperature ,it becomes colourless and separates from corals. At the present, in this way, we are losing precious corals due to rise in temperature.

Furthermore, the prediction of rising level is also scaring. Hope it is a myth; Otherwise, the future of more than one billion would be in danger along rich rice belt to feed another billion.


So far, we have learnt about the negative, as well as positive impacts of sea water temperature on marine environment. According to the given logic, normal temperature is inevitable for the survival for many reasons, including survival of the marine biodiversity.

But, abnormal temperature will inflict irrepairable damage for the total life supporting systems. Today, we are witnessing just  symptoms in the form of lethal cyclones, loss of species and coral bleaching; then, what would be the nature of disease in the future.

Marine ecosystem

Coral reef ecosystems

Impacts of climate change

Growing cyclones in the Arabian sea

Conjunction of time and condition

Conjunctions for alternative choices



•Oceanography–K. Siddhartha.