Why Warmer Oceans are Bad

Most of us realise that warmer oceans cause polar ice to melt and raise water levels. That obviously reduces the land mass, in particular threatening low lying island; but there are far more wide reaching implications.  

With damaged marine ecosystems, we can also suffer other problems associated with fishing, tourism, and other marine dependant industries.

Global warming is the gradual increase in the lower atmosphere of the earth, due to a man-made enhancement of the naturally occurring greenhouse effect.

Any increase in the amount of greenhouse gases in the atmosphere means that the surface temperature of the Earth is likely to increase. In the last 150 years the amount of carbon dioxide has increased by about 25%. Other gases that have also increased include methane, chlorofluorocarbons, nitrous oxide, and ozone. 

Methane remains in the atmosphere for between 9 and 15 years. It is over 20 times more effective than CO2 at trapping heat in the atmosphere over a 100 -year period. It occurs naturally and because of human activities such as landfills, gas and petrol systems, agricultural activities, coal mining, combustion and wastewater treatment.

Chlorofluorocarbons (CFCs) are man-made chemicals that have been used since the 1930s in industry, in particular as refrigerants, solvents and non-flammable foaming agents for plastics. CFCs are mainly responsible for depleting the earth’s stratospheric ozone layer. The intense ultraviolet radiation at this level causes CFCs to break up and release chlorine which in turn reacts with ozone. 

Nitrous oxide (N₂O) emissions have increased significantly, primarily due to the use of agricultural nitrate fertilisers, which contribute to microbial processes in the soil. Smaller contributions come from the burning of coal and oil. Ozone in the lower atmosphere (troposphere) is formed in heavily polluted areas through photochemical reactions involving nitrogen oxides, volatile organic compounds (VOCs), and sunlight. Nitrous oxide is estimated to account for approximately 6% of the total greenhouse gas-induced heating effect in the atmosphere. 

Ocean Warming and Sea Levels
The warming of the oceans affects atmospheric moisture, precipitation, and circulation. As the atmosphere warms, it can hold more moisture and this influences the frequency and duration of rainfall, as well as the intensity and amount. However, the precipitation trends vary from region to region around the globe.
As the oceans warm, sea levels rise due to two primary factors: thermal expansion (warmer water expands, increasing ocean volume) and melting ice sheets and glaciers, which add water to the oceans. Projections suggest that global sea levels could rise by 0.28 to 1.01 meters by the end of the 21st century, depending on greenhouse gas emissions. Sea levels have been rising since at least 1961, with rates accelerating in recent decades. Regional variations in sea level rise occur due to differences in ocean temperatures, local winds, currents, salinity, and gravitational redistribution from melting ice.

Shifting Marine Ecosystems
Marine ecosystems are changing as a result of rising sea water temperatures. This can have larger consequences on marine biodiversity and food webs. Some examples include:
•    Changes in ocean stratification and thereby affecting distribution of nutrients and dissolved gases. This can in turn affect primary productivity and marine food webs.
•    Migration of animals to cooler waters, and may lead to imbalances in some ecosystems
•    Loss of nursery habitats and breeding grounds, particularly those in shallow waters
These shifts highlight the need for adaptive management strategies, along with a global efforts to mitigate climate change.
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Learning more about Marine Ecology can be a critical step toward understanding the earth and how to mitigate or adapt to the impacts that are coming from ocean warming.

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