Ocean Acidification
Ocean and coastal regions under stress
- Triple trouble -
Rising seawater temperature,
Ocean acidification
Ocean deoxygenation
Multiple stressors Steps ahead The ocean covers nearly three quarters of the Earth’s surface, contains 96% of its living space, provides around half of the oxygen we breathe and is an increasing source of protein for a rapidly growing world population.
However, human activity is having an impact on this precious resource on local, regional and global scales. 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.
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.
Over the coming decades and centuries, ocean health will become increasingly stressed by at least three interacting factors.
Rising seawater temperature,
ocean acidification
and ocean deoxygenation
will cause substantial changes in marine physics, chemistry and biology.
These changes will affect the ocean in ways that we are only beginning to understand. It is imperative that international decision-makers understand the enormous role the ocean plays in sustaining life on Earth, and the consequences of a high CO2 world for the ocean and society.
- Triple trouble -
Rising seawater temperature,
Ocean acidification
Ocean deoxygenation
Multiple stressors Steps ahead The ocean covers nearly three quarters of the Earth’s surface, contains 96% of its living space, provides around half of the oxygen we breathe and is an increasing source of protein for a rapidly growing world population.
However, human activity is having an impact on this precious resource on local, regional and global scales. 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.
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.
Over the coming decades and centuries, ocean health will become increasingly stressed by at least three interacting factors.
Rising seawater temperature,
ocean acidification
and ocean deoxygenation
will cause substantial changes in marine physics, chemistry and biology.
These changes will affect the ocean in ways that we are only beginning to understand. It is imperative that international decision-makers understand the enormous role the ocean plays in sustaining life on Earth, and the consequences of a high CO2 world for the ocean and society.
Some of the above notes are From Oceans Under Stress booklet-
( Plymouth Marine Laboratory )
For more detailed information see link to the leaflet
-Hot -Sour and Breathless -Oceans under Stress
Oceans Under Stress
http://oceanessence.weebly.com/oceans-under-stress.html
To understand more of the whole picture of how crucial it is to respect and take care of the deeper reality of our watery body and waters of the Earth, we can then begin to make conscious changes for the future, changes which support a harmonious, healthier sustainable way forward for the health and future of Humanity, the Oceans and for the Earth as a whole.
A smarter future is one where we reduce carbon dioxide emissions, transition to cleaner, renewable sources of energy and prevent the need for such large-scale adaptation. Commitment to respect and nurture the waters of our bodies, and the waters of the Earth’s Oceans as once we acknowledge the deeper truth of the part we all play in the well being of our own personal health and the health of the Waters of the Earth.
Only then will we individually and collectively become guardians of our Oceans and alleviate some of the environmental stress from ourselves, from the global Ocean and from this beautiful Earth, we all call home.