Ocean Acidification Demonstration
Ocean acidification is the ongoing absorption of carbon dioxide from the atmosphere causing a decrease in the pH and increase in acidity of the Earth’s oceans. About half of the carbon dioxide in the atmosphere goes into the sea, and as the amount of carbon rises in the atmosphere there is a corresponding rise of carbon going into the ocean.
Human activities such as the combustion of fossil fuels and land use changes have led to a new flux of CO2 into the atmosphere. About 50% has been taken up by the oceans, with most of the rest remaining in the atmosphere. Between 1750 and 1990 the world’s oceans have seen an increase of around 30% acidity.
18th century 0%
1990s +18.9%
Present +28.8%
2050 +69.8%
2100 +126.5%
Natural seawater has an abundance of calcium carbonate minerals, which are building blocks for calcifying organisms to build their skeletons and shells. When carbon dioxide is absorbed by seawater, chemical reactions occur that reduce seawater pH, carbonate ion concentration, and saturation states of biologically important calcium carbonate minerals. Continued ocean acidification is causing many parts of the ocean to become undersaturated with these minerals, which is likely to affect the ability of some organisms to produce and maintain their shells. The degree of change to ocean chemistry, including ocean pH, will depend on the mitigation and emissions pathways society takes.
Ocean Acidification and Phytoplankton
Water is moved around the globe by the great ocean conveyor belt. As warm surface water is moved away from the tropics, it cools and releases its heat to the atmosphere. The further north this water moves, the cooler and heavier it becomes, eventually sinking to the lower level of the conveyor belt. This cooler water is then carried along the depths of the ocean, picking up nutrients that have gathered there.
As winds move the top layers of the oceans, cold, nutrient rich waters from the depths are brought to the top at “up-welling sites”. These areas are important feeding grounds for phytoplankton — microscopic plants that float in the light filled waters at the top of the ocean. Phytoplankton feed on the nutrients that come from the deep ocean waters and many other species then feed on them. They are the primary producers of the ocean and form the base of many marine food chains.
Scientists predict many ecosystems will be greatly altered or may collapse altogether as a response to global warming. Fresh water is less dense than sea water. Therefore, the addition of significant amounts of fresh water from melting ice caps and glaciers may result in a slowing of the ocean conveyor belt, leading to cooler winters in Western Europe and a disruption of the circulation of vital nutrients to phytoplankton.
Phytoplankton may also be cut off from their food supply as surface temperatures warm, causing the mixing between the warmer top layers and cooler bottom layers to diminish. A decrease in phytoplankton can lead to a collapse of marine food webs, affecting marine mammals (whales, seals and dolphins), sea birds (albatross) and important commercial fish species (cod, salmon and tuna).
Ocean Acidification and Marine Life
Marine life ranging from the smallest plankton to the largest whale may be affected by ocean acidification. Coral reef ecosystems will be some of the first casualties of ocean acidification. Impacts to these beautiful and important habitats could have huge consequences for a quarter of the entire biological diversity of the oceans that depend on coral reefs for food and shelter. Shellfish such as sea urchins, lobsters, sea stars and brittle stars are some prime examples of creatures that could be affected. More acidic oceans are expected to lead to a shortage of carbonate, a key building block that these animals need to build their shells and skeletons.
In addition to coral reefs and shellfish, animals without shells or skeletons such as squid and various types of fish may be negatively affected in a variety of ways. Impacts to individual species may ultimately disrupt entire food webs. For example, pteropods are tiny swimming sea snail that forms a large base of the food chains and their shell building is particularly vulnerable to increasing ocean acidity. If pteropod populations plummet from acidified waters, this will affect the population numbers of animals that eat them, like salmon. If salmon numbers drop due to a loss of pteropods, it could further impact predators that eat salmon, such as killer whales.
The changing acidity of the oceans threatens to throw off the delicate chemical balance upon which marine life depends for survival. Corals are the framework builders of reefs, by far the most diverse ecosystems of our oceans. However, the effects of acidification are not going to stop with reefs. Like dominoes, the impacts are going to be far-reaching throughout the oceans.
Ocean Acidification and Sea Levels
The oceans play an important role in regulating the Earth’s temperature. As the levels of heat and carbon dioxide rise in the atmosphere, so do their levels in the oceans. Rising sea levels are caused by both the warming oceans and melting ice. As water heats above 39.2 F), it expands through a process known as “thermal expansion”. Global warming is causing the oceans to heat up and expand and therefore rise. The melting of glaciers, ice caps, and the Greenland and Antarctic ice sheets are also contributing to the rising seas.
In 2006, the first inhabited island was lost to rising sea levels in the Bay of Bengal. The island of Lohachara sank beneath the surface of of the ocean, and some 10,000 people became the world’s first global warming refugees. This Indian island was situated in an area which has some 70,000 people living on a dozen islands who are all facing the same fate as those of Lohachara. Unlike the area’s human inhabitants, its unique wildlife, including 400 endangered Bengal tigers, are unlikely to survive the rising tides.
Scientists have suggested that by 2080, millions of people are likely to be flooded every year and hundreds of millions more may be displaced by rising seas. Whole island nations could disappear off the map altogether and large swaths of low lying areas are likely to be inundated. Even some of the world’s most important and heavily populated cities, such as New York, London and Bangkok, are at risk of disappearing under the rising waters.
Increasing sea surface temperatures also increases evaporation and the amount of moisture in the atmosphere, which acts as the fuel for thunderstorms. As storms move across the open ocean, they pick up energy from the warm ocean surface and become more powerful. The more heat in the ocean’s surface, the more potential exists for strong winds and heavy rains to be created. It is these winds, rains, and storm surges that can devastate lives and cause billions of dollars of damage.
Organic Matters
Organic farming was the original type of agriculture, and has been practiced for thousands of years. After the industrial revolution had introduced inorganic methods, some of which were not well developed and had serious side effects, an organic movement began in the 1940s as a reaction to agriculture’s growing reliance on synthetic fertilizers. Organic farming is the form of agriculture that relies on techniques such as crop rotation, green manure, compost, and biological pest control to maintain soil productivity and control pests on a farm.
“Organic agriculture is a production system that sustains the health of soils, ecosystems and people. It relies on ecological processes, biodiversity and cycles adapted to local conditions, rather than the use of inputs with adverse effects. Organic agriculture combines tradition, innovation and science to benefit the shared environment and promote fair relationships and a good quality of life for all involved.”
- International Federation of Organic Agriculture Movements
Since 1990, the market for organic products has grown from nothing to $55 billion in 2009. This demand has driven a similar increase in organically managed farmland, with approximately 91,000,000 acres worldwide now farmed organically. Although organic farming is prehistoric in the widest sense, the modern organic movement is a revival movement in the sense that it seeks to restore balance that was lost when technology grew rapidly in the 19th and 20th centuries.
Ocean Acidification
Our oceans are being overwhelmed by the massive amounts of carbon dioxide they are absorbing. Since the Industrial Revolution, we have added about to 1.5 trillion metric tons of carbon dioxide to the atmosphere and the oceans have absorbed about a third of that amount. Without the oceans, global warming would be far worse than it already is. They also help to mitigate human caused climate change. But the unprecedented amount of carbon dioxide being created by human activity has surpassed what the oceans can healthfully absorb, changing ocean chemistry and making them more acidic.
Global warming is increasing ocean temperatures and raising sea levels, creating a host of problems for the oceans and ocean wildlife. Recent discoveries have revealed that global warming is not the only problem for the oceans resulting from the massive amounts of carbon dioxide we are releasing into the atmosphere. The impacts of absorbing such huge amounts of carbon dioxide and heat include ocean acidification, sea level rise, disrupted marine food webs, depleted ecosystems and more.
These excessive amounts of carbon dioxide are actually changing the chemistry of the oceans, making them more acidic. Ocean acidification will have major adverse effects on tropical as well as cold-water corals and other marine life, especially those that produce shells. Even small changes in the acidity of the oceans can result in severe ramifications. As they become more acidic, corals and other organisms will find it increasingly difficult to build new skeletons and shells and those that already exist may begin to dissolve. The loss of many coral species will negatively impact the oceans and ocean-dependent economies, such as fishing and tourism.
