When most people think of global warming, they think of icecaps melting, sea levels rising, and huge smokestacks pumping out noxious black smoke. When most people think of the ocean, they see a beautiful blue expanse of water, sandy beaches, and the sounds of seagulls and crashing waves. Now, put those two together and what do you have? A very big problem.
A recent study in the journal Proceedings of the National Academy of Sciences analyzed and explained how global warming and greenhouse gas emission will affect the oceans’ ecosystems, a problem made worse by overfishing and localized pollution. The report focused on increased carbon dioxide levels in the ocean, and how this will affect ocean temperatures and acidity.
The rising CO2 levels in the oceans will increase the acidity of the water. Oceans naturally absorb CO2, taking in approximately 2.5 billion metric tons each year and helping keep atmospheric temperatures down (NOAA Ocean Acidification Program). However, the amount of carbon dioxide and other gases have increased to a point where it is extremely detrimental to the oceans. Excess carbon dioxide is detrimental to any organism containing calcium, since calcium cannot form in highly acidic environments. Shells and coral will be affected, as will the bones of organisms. Increased acidity would also lead to a decrease in dimethylsulfide gas, (produced by ocean plankton) which encourages cloud formation. Any change in cloud formation will affect the heat of the earth, and a reduction in the cloud cover would increase heat.
The overall rise of ocean temperature is expected to cause a drastic change in species numbers. Plankton will thrive in warmer waters (some develop into toxic algae blooms) and microbes will increase as well. Further up the food chain, the effects will be negative. Warmer water means metabolism rates rise, so all species will require and have to compete for more food. This will eventually decrease their populations as this lack of sustenance travels up the food chain.
The warmer water also negatively impacts coral reefs by bleaching and killing them. It has been predicted that “By the end of this year 38% of the world’s reefs will have been affected. About 5% will have died” (The Guardian).
Global warming effect everything in the ocean from the species that live in it, to the people that depend on it, to the land it touches. Marine life will suffer as “expected ocean acidification and warming is likely to produce a reduction in diversity and numbers of various key species that underpin marine ecosystems around the world” (University of Adelaide). Hundreds of millions of people rely on the seas for food, income, medicine, among other things. The warming of the ocean could even have impacts beyond the waters—coral die off, for example, could exacerbate costal erosion because reefs protectshorelines from storms. The changes in the ocean environment have also led to an increase in hypoxia (an oxygen deficiency). These factors, combined with overfishing and direct pollution, have prevented species from adapting to the changes to the ocean.
In Steinberg’s Down to Earth, he mentions how water pollution was apparent even in the 19th century. After the decline of organic cities, waste was flushed into rivers, streams, lakes, etc. This caused a massive increase in algae, a decrease in the oxygen content of the water as the bacteria broke down the waste, and a subsequent decline in species of fish such as whitefish, herring, and trout because of the lack of oxygen. The species of fish that were negatively effected by the pollution were also the most commercialized, which hurt the industry as well as people who depended on fish for food. While a different type of pollution caused this, the impacts on the organisms in the water and the people who depended on them are similar to today.
The problem of the pollution of the oceans is a difficult one. Even if all global emissions stopped, the effects would still continue. The study does not explain provide all the answers—there is still much that scientists don’t know. A solution was not provided by this report; however, stopping pollution and overfishing would give species more time to adapt. Scientists also plan on studying organisms that live on the ocean floor near natural CO2 vents, to observe how other creatures might react.
For more information, see:
Koronowski, Ryan. “How Climate Change Could Cause an Epic Collapse of Ocean Ecosystems”. Climate Progress, 26 Oct. 2015. Web. 28 Nov. 2015.<http://thinkprogress.org/climate/2015/10/16/3712964/simplifying-the-oceans/>
Milman, Oliver. “Marine food chains at risk of collapse, extensive study of world’s oceans finds”. The Guardian, 13 Oct. 2015. Web. 28 Nov. 2015.<http://www.theguardian.com/environment/2015/oct/13/marine-food-chains-at-risk-of-collapse-extensive-study-of-worlds-oceans-reveals>
Steinberg, Ted. Down to Earth: Nature’s Role in American History. New York: Oxford University Press, 2013. Print.
University of Adelaide. “Global marine analysis suggests food chain collapse.” ScienceDaily. SUcienceDaily, 12 October 2015. <http://www.sciencedaily.com/releases/2015/10/151012181037.htm>
“What is Ocean Acidification?”. NOAA Ocean Acidification Program. Web. 28 Nov. 2015 <http://oceanacidification.noaa.gov/Home/WhatisOceanAcidification.aspx >