Ocean Acidity.
Ocean acidity is potentially one of the biggest threats to humanity. Small changes in the numerical scale of acidity can have big changes in acidity of our ocean. Creatures that live in the oceans are used to a certain, slightly alkaline level, but as the seas are absorbing CO2 and becoming more acidic many marine creatures are getting stressed.
A scale of acidity to alkaline.
This is a simple pH gauge. The higher number is more alkaline and the lower number more acidic.
The scale is not linear but logarithmic and therefore small changes have a big effect
In pre-industrial levels the sea had a pH of 8.179 and today it is 8.069 which is a change of 0.11 and a 29% increase in acidity.
The simple cause of this is that CO2 moves easily between the atmosphere and the sea and as we have increased the CO2 level in the atmosphere from 280ppm to 400ppm, more CO2 has moved into the oceans.
In a normal world the rate of change would not be fast and would be spread over 100,000 years but the burning of fossil fuels has had a bigger effect in only 100 years and is expected to double again in the next 50 years. Nature simply can not keep up.
The scale is not linear but logarithmic and therefore small changes have a big effect
In pre-industrial levels the sea had a pH of 8.179 and today it is 8.069 which is a change of 0.11 and a 29% increase in acidity.
The simple cause of this is that CO2 moves easily between the atmosphere and the sea and as we have increased the CO2 level in the atmosphere from 280ppm to 400ppm, more CO2 has moved into the oceans.
In a normal world the rate of change would not be fast and would be spread over 100,000 years but the burning of fossil fuels has had a bigger effect in only 100 years and is expected to double again in the next 50 years. Nature simply can not keep up.
The modern records of CO2 are shown in the Keeling curve from records at Loa Mauna Hawaii. This chart shows how the rapid increase in CO2 (Red line) has resulted in an increase in CO2 (Blue line) in the oceans and a corresponding increase in acidity. (The green line shows a reducing pH number)
This is how nature normally removes CO2 from the seas.
In simple terms, Phytoplankton uses photosynthesis in the same way that a plant does to split CO2. The phytoplankton uses the carbon part of CO2 to make its calcium carbonate shell or skeleton, and oxygen is released to the atmosphere for us to breath. The carcass of marine life containing the carbon sinks to the seabed when it dies and the carbon is locked up for ever.
50% of the oxygen we breath comes from the sea.
50% of the oxygen we breath comes from the sea.
The base of the marine food chain are pteropods and phytoplankton whose structure is made of calcium carbonate. Although they are very small they multiply in vast quantities and are absolutely fundamental to the health of the oceans and the base of the food chain.
Their calcium carbonate structures are very sensitive to changes in the acidity of the oceans.
Their calcium carbonate structures are very sensitive to changes in the acidity of the oceans.
Aquatic life with calcium carbonate structures include plankton as discussed above but also all shell fish such as mussels and oysters and lobsters, crayfish and of course coral.
Calcium carbonates dissolve in acid water and there is plenty of current evidence that these creatures are having deformed shell structures and also problems with reproduction.
The newly hatched spat have delicate forms and quickly perish.
Calcium carbonates dissolve in acid water and there is plenty of current evidence that these creatures are having deformed shell structures and also problems with reproduction.
The newly hatched spat have delicate forms and quickly perish.
The The illustration above shows how a pteropod with a calcium carbonate shell becomes deformed with more acidic water and most likely perish in its few first days of life.
Coral reefs are a vital part of the marine ecosystem and provide habitat for a wide range of marine life. Their carbonate structure relies on a stable pH level of the oceans and they are sensitive to excessive acidity.
Coral is a refuge and breeding ground for many types of fish.
Coral is a refuge and breeding ground for many types of fish.
The thermohaline circulation system or ocean conveyor moves heat and nutrients around the world.
Warm water is taken from the tropics and transferred to the Poles and as it travels on the surface it absorbs CO2 from the atmosphere which it then takes into the deep oceans when it sinks.
The water that goes into the deep oceans could be there for thirty to forty years or even a thousand years before it rises at a turnover point bringing the nutrients and CO2 to the surface.
Warm water is taken from the tropics and transferred to the Poles and as it travels on the surface it absorbs CO2 from the atmosphere which it then takes into the deep oceans when it sinks.
The water that goes into the deep oceans could be there for thirty to forty years or even a thousand years before it rises at a turnover point bringing the nutrients and CO2 to the surface.
Sea water resurfacing now holds CO2 from the 1970's when CO2 was only 320 parts per million and we are already seeing oysters mussels and coral suffering. The current level of CO2 is 400 parts per million so we clearly can expect much more devastating effects in the years to come.
The chart shows a large (in green.) optimal area for coral.
The chart shows a large (in green.) optimal area for coral.
This chart shows how the green area has disappeared in the tropical and mid latitudes to be replaced by areas that are not hospitable to coral growth.
Bleached coral. The polyps that form coral are small and delicate and like most aquatic creatures have a low level of tolerance when it comes to temperature or acidity, They have taken millions of years to develope their life form for the location they are in. .
In normal ice age cycles they would migrate over thousands of years to a more suitable climatic location but in modern conditions it is all happening in an exceptionally short period of time. Perhaps less than one hundred years.
In normal ice age cycles they would migrate over thousands of years to a more suitable climatic location but in modern conditions it is all happening in an exceptionally short period of time. Perhaps less than one hundred years.
It can not be a coincidence that all round the world there are reports of coral bleaching and although this is mostly due to increased temperatures the big increase in acidity must also play a part.
There are also repeated cases of the collapse of mussel and oyster farming which is often put down to local pollution which may be true.
As it is happening simultaneously in North East USA, France, Ireland and many other producing areas including New Zealand it can not be considered a coincidence.
There are also repeated cases of the collapse of mussel and oyster farming which is often put down to local pollution which may be true.
As it is happening simultaneously in North East USA, France, Ireland and many other producing areas including New Zealand it can not be considered a coincidence.
The creatures with carbonate calcium shells are the early indicators of the condition of the oceans and if they are having problems now then it can only get worse.