1. Related phenomena - Why is it important?
Following two phenomena are problems of Climate Change which are directly related with increasing the greenhouse gases emission and carbon dioxide concentration. These climate change problems are accompanied by ‘natural fluctuations’, which occurs through internal procedures of the Earth system. Therefore, it is important to understand natural fluctuations like ‘El Niño’ with continuous collected data for the long term.
1) Ocean Acidification
(Images from http://www.oceanacidification.org.uk/Oarp/media/images/oa_800.jpg)
Ocean acidification is directly caused by the increase of carbon dioxide (CO2) levels in the atmosphere. When CO2 enters the ocean it rapidly goes through a series of chemical reactions which increase the acidity of the surface seawater (lowering its pH). The ocean has already removed about 30% of anthropogenic CO2 over the last 250 years, decreasing pH at a rate not seen for around 60 million years.
This effect can be considered beneficial since it has slowed the accumulation of CO2 in the atmosphere and the rate of global warming; without this ocean sink, atmospheric CO2 levels would already be greater than 450 ppm. However, the continuation of such a fundamental and rapid change to ocean chemistry is likely to be bad news for life in the sea; it will not only cause problems for many organisms with calcium carbonate skeletons or shells (such as oysters, mussels, corals and some planktonic species) but could also impact many other organisms, ecosystems and processes with potentially serious implications for society.
The average acidity of the upper ocean has already declined by around 0.1 pH unit (30% increase in acidity) since the industrial revolution and it is expected to further decline by about 0.3 pH units by the end of this century if CO2 emissions continue at the current rate.
2) Ocean Deoxygenation
Ocean deoxygenation is the reduction of dissolved oxygen (O2) in seawater. Climate change can influence oxygen levels in the ocean in several ways. This is certain to occur in a warmer ocean since higher temperatures reduce oxygen solubility. Warming is also likely to create a more stratified ocean, decreasing the downward oxygen supply from the surface. Ocean acidification and nutrient run-off from streams and rivers can also contribute to deoxygenation.
Fish and many other marine organisms depend on sufficient levels of oxygen to function, and may therefore be stressed by declining oxygen concentrations. Extended zones of low oxygen may result in the exclusion of such organisms. However, other organisms tolerant of low oxygen, particularly microbes are likely to flourish, altering the balance of communities. Low oxygen levels in the ocean may also increase the amount of greenhouse gases in the atmosphere by changing feedback mechanisms involving methane and nitrous oxide.
Current ocean models project declines of 1 to 7% in the global ocean oxygen inventory over the next century. However, there are considerable uncertainties regarding the scale and location of oxygen changes, and their ecological impacts.
1) Ocean Acidification
(Images from http://www.oceanacidification.org.uk/Oarp/media/images/oa_800.jpg)
Ocean acidification is directly caused by the increase of carbon dioxide (CO2) levels in the atmosphere. When CO2 enters the ocean it rapidly goes through a series of chemical reactions which increase the acidity of the surface seawater (lowering its pH). The ocean has already removed about 30% of anthropogenic CO2 over the last 250 years, decreasing pH at a rate not seen for around 60 million years.
This effect can be considered beneficial since it has slowed the accumulation of CO2 in the atmosphere and the rate of global warming; without this ocean sink, atmospheric CO2 levels would already be greater than 450 ppm. However, the continuation of such a fundamental and rapid change to ocean chemistry is likely to be bad news for life in the sea; it will not only cause problems for many organisms with calcium carbonate skeletons or shells (such as oysters, mussels, corals and some planktonic species) but could also impact many other organisms, ecosystems and processes with potentially serious implications for society.
The average acidity of the upper ocean has already declined by around 0.1 pH unit (30% increase in acidity) since the industrial revolution and it is expected to further decline by about 0.3 pH units by the end of this century if CO2 emissions continue at the current rate.
2) Ocean Deoxygenation
Ocean deoxygenation is the reduction of dissolved oxygen (O2) in seawater. Climate change can influence oxygen levels in the ocean in several ways. This is certain to occur in a warmer ocean since higher temperatures reduce oxygen solubility. Warming is also likely to create a more stratified ocean, decreasing the downward oxygen supply from the surface. Ocean acidification and nutrient run-off from streams and rivers can also contribute to deoxygenation.
Fish and many other marine organisms depend on sufficient levels of oxygen to function, and may therefore be stressed by declining oxygen concentrations. Extended zones of low oxygen may result in the exclusion of such organisms. However, other organisms tolerant of low oxygen, particularly microbes are likely to flourish, altering the balance of communities. Low oxygen levels in the ocean may also increase the amount of greenhouse gases in the atmosphere by changing feedback mechanisms involving methane and nitrous oxide.
Current ocean models project declines of 1 to 7% in the global ocean oxygen inventory over the next century. However, there are considerable uncertainties regarding the scale and location of oxygen changes, and their ecological impacts.