Ajda Lotric Water covers 71% of the whole earth surface and roughly about 96% of that water are oceans. So fairly simply stated, oceans are the majority of everything in the world. It is a deep, dark, enigmatic and never-ending desert that is hiding many unbelievable secrets and most of it hasn't yet been explored. Oceanography or the science of oceans is the area of science covering oceans. It covers many aspects, from waves and currents to the tectonics of the earth’s crust at the very bottom. But this post is not going to go deep into the mysterious world of oceans at unimaginable depths and all the secrets, but it is going to stay more or less on the surface. The vast and mysterious ocean horizon (Source: https://www.globalcitizen.org/en/content/ocean-dead-zones-quadrupled-1950/) Not a lot of people think that there are impacts from our everyday environmental problems that affect a surface as vast as the oceans as much as the atmosphere and land. Not many even know how much the global climate change is affecting all the aspects of the oceans’ nature. Climate change is not a terrible thing to happen – it happened in the past and it will happen in the future. But the effect that human activity has on the speed of climate change is significant for the environment. In every aspect. In general, when talking about atmospheric changes in the environment, in the past few decades, the springs have come earlier, and winters are shorter. The temperature has been increasing 0.7 °C per decade. The biggest impact these temperature changes play on ice caps in the northern parts. More ice from the Arctic Circle region is melting and the water levels are slowly increasing (about 3 mm per year). The temperatures aren’t only affecting the melting of the ice but likewise so-called North Atlantic Oscillation (NAO) index. NAO index is a gradient of pressure differences between the Arctic region of Iceland and subtropical region of Azores. When the NAO index is positive, there has been a strong Icelandic low and Azores have had a high pressure. If the NAO index is negative, there has been an Icelandic high and low Azores pressure. NAO index of the period from 1864 to 2018 (Source: https://climatedataguide.ucar.edu/sites/default/files/styles/node_lightbox_display/public/key_figures/climate_data_set/naots2_3.gif?itok=W9z0fewZ) In the recent years, the NAO index is growing so greatly that the growth of the last 20 years has been 8 times higher than in the past 100 years which clearly corresponds to the fact that the arctic regions are warming up. The amount of ice that is covering the northern seas is decreasing and according to the reports in the next 30 years, we could face the periods of no ice in the summertime in the arctic regions. Such changes would dramatically affect the characteristics of the Arctic and the physical structure of the ocean. The ecosystems formed around the conditions where ice is present all year would disappear which would play a major role in the environment. The next important point in ocean changes would be the acidification. Since the industrial revolution in the 18th Century, the pH of oceans has already dropped by 0.11 units and it is predicted that by the start of 22nd Century the pH gradient would decrease for 0.4 more. Changes like that haven’t happened at any point in the last 300 million years. While the water is becoming less saturated in calcium carbonate and more in CO2 since the pH is decreasing, it could lead to the total disappearance of carbonated ions in some Arctic and Antarctic regions in the next 150 years. A number of organisms and ecosystems would have to undergo colossal changes since calcium carbonate is important for their growth and body structures (e.g. shells). It has already been observed by marine biologists that the shells have a thinner, weaker structure when kept in water with lower pH. The occurrence of such effects in nature would play a great impact on the populations who depend on calcium carbonate. Acidification is also playing a role in development of fish species. Atlantic cod (Gadus morhua) is facing the problem when the lower gradient of pH damages larvae’s tissue and consequently their development. That will have a significant effect on the stocks of cod in the future. Algal bloom, also known as eutrophication, is a global problem on water surfaces all over the world and even oceans, especially the parts near shores where human activity is strong, are affected by it. The nitrogen and phosphorus amount that has been used for agricultural production has increased dramatically in the past two decades. When the runoff of those two inorganic compounds enters rivers, it is in no time that they reach oceans as well. The nitrogen and phosphorus are an advantageous nourishment for phytoplankton, the microalgae, and therefore result in increased growth of algae colonies. Forming of phytoplankton on the top sea layer reduces the amount of light that penetrates through to lower layers for the photosynthesis of aquatic organisms at the very bottom. Water organisms need oxygen for their living and production and without it, the sea floor becomes anoxic or depleted of oxygen. Beautiful but toxic algae blooms in Baltic Sea between Sweden and Finland (Source: http://www.environmentalhumanities.ed.ac.uk/eh-seminar-jesse-petersen-kth-environmental-humanities-laboratory-algal-contamination-monitoring-networks-disgust-swedish-waters/) An algal bloom is a big problem of the Baltic Sea. The number of phytoplankton species has increased, and the sinking blooms have caused the oxygen reduction on the seabed so critically that some parts of the Baltic have even become dead of organisms on the seafloor. There are numerous other issues that the oceans are facing and are going to face in the future years. People spent too many decades thinking only about their own good that they didn’t think of the effect it is going to have on the environment. It might be too late to stop all the effects of global warming but at least we could try to soften them.
References: Thomas, D., Bowers D. 2012. Introducing Oceanography. Edinburgh: Dunedin Academic Press. |
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May 2019
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