Posts Tagged ‘Ocean Acidification’
I’ve just finished a major report on ocean acidification. I have published the executive summary below. You can click here to download the ocean acidification report as a pdf (approx 3.8Mb).
Executive Summary
Ocean acidification has been called “the other CO2 problem” and even “global warming’s evil twin”. It occurs when carbon dioxide dissolves in seawater, producing carbonic acid (H2CO3).
Carbonic acid rapidly dissociates to produce hydrogen (H+) and bicarbonate ions (HCO3-). The hydrogen ions so produced combine with carbonate ions(CO3), sourced from calcium carbonate (CaCO3) to form more bicarbonate. This reduces the amount of available calcium carbonate.
Ocean acidification must be recognized for what it is – A global challenge of unprecedented scale and importance that requires immediate action to halt the trend of increasing acidification (EPOCA 2009).
Calcium carbonate is used by many marine organisms (including coral, oysters, mussels and many types of plankton) to form shells and skeletons. Less calcium carbonate makes it harder for these organisms to precipitate calcium.
As the oceans have absorbed about one-third of all anthropogenic carbon dioxide, they are now 30% more acidic than in pre-industrial times. This drop in pH is already reducing calcification rates of some marine calcifiers, especially those in colder waters (which can absorb more CO2 than warmer seawater).
Many ocean species rely on calcium to make shells and skeletons.
If CO2 emissions continue on their current trajectory, oceans will be 3x – 5x more acidic than pre-industrial levels by 2100. This will be more acidic than at any time in t he last 300 million years. The effects of this are unprecedented, but likely to be overwhelmingly negative – major impacts that will probably ramify upwards through marine food chains to apex predators, and be accompanied by the widespread extinction of some ocean species (especially benthic plankton).
Ocean acidification could trigger a chain reaction of impacts through the marine food web, beginning with larval fish and shellfish, which are particularly vulnerable (EPOCA 2009)
Coral reefs will be placed under increasing threat as acidification progresses. If present emission rates continue it is thought that they will start to dissolve (ie calcium carbonate will be reabsorbed into solution) by 2050.
Because of major inertia in the system, the acidification process is essentially irreversible over any time frame meaningful to us (ie > 10,000 years). Likewise, even if we were to stop all CO2 emissions tomorrow, ocean pH would continue to drop for some time (at least decades) as it reached a new carbon equilibrium with the atmosphere.
Because acidification is independent of carbon dioxide’s effect as a greenhouse gas, geo-engineering strategies that aim to cool the planet without removing atmospheric CO2 will have no effect on ocean acidification. Approaches to offset acidification (such as the application of crushed limestone to the oceans) would need to be at such massive scales that they would be prohibitively expensive (both economically and environmentally).
The only real way to fix this problem is to stop emitting carbon dioxide.
Acidification will have impacts on key Australian marine ecosystems such as those of the Southern Ocean, marine protected areas on the southern margins of the Australian continent (the Great Australian Bight and Tasmanian seamounts) and, eventually the Great Barrier Reef (ACE-CRC 2008)
Now take action.
- We don’t have long to change things around.
- Ocean acidification is already making the calcified parts of some sea creatures thinner and lighter. It is happening right now, independent of global warming.
- Coral reefs are going to start disappearing by 2050 at the latest.
- Acidification has the same solution as global warming – rapid emissions reduction.
- Due to the long lag-times in the system, the quicker we reduce carbon dioxide emissions, the more effect it will have in the future.
Here’s what you can do – Tell someone about this problem. Do something today!!!Visit my ocean acidification resources page for videos and links to major learned reports on this topic. Watch this video:
More on ocean acidification and climate change. I actually think that this issue will shortly overtake global warming as the focus of reducing greenhouse gas emissions.
Why do I say that?
Because it’s happening rapidly, has definite and measurable ecological and economic effects, and is harder for the climate change deniers to disprove (although I’m sure that they’ll try and think of something!).
Watch this space – Remember you heard it here first!!!
Polar bears increasingly endangered by the Arctic impacts of climate change
Arctic seas turn to acid putting vital food chain at risk
Carbon-dioxide emissions are turning the waters of the Arctic Ocean into acid at an unprecedented rate, scientists have discovered. Research carried out in the archipelago of Svalbard has shown in many regions around the north pole seawater is likely to reach corrosive levels within 10 years. The water will then start to dissolve the shells of mussels and other shellfish and cause major disruption to the food chain. By the end of the century, the entire Arctic Ocean will be corrosively acidic.
Oceans May Soon Be More Corrosive Than When The Dinosaurs Died
Increased carbon dioxide emissions are rapidly acidifying the world’s oceans and, if unabated, could cause a mass extinction of marine life similar to one that occurred when the dinosaurs disappeared. By comparing computer model predictions of changes in ocean chemistry with evidence from the fossil record, researchers have found a glimpse of the possible future for ocean life if society does not drastically curb carbon dioxide emissions.
Ocean Becoming More Acidic, Potentially Threatening Marine Life
A dramatic increase in carbon dioxide levels is making the world’s ocean more acidic, which may adversely affect the survival of marine life and organisms that depend on them, such as humans.
A modest new lab at the Rosenstiel School is the first of its kind to tackle the global problem of climate change impacts on corals. Fully operational this month, this new lab has begun to study how corals respond to the combined stress of greenhouse warming and ocean acidification. The lab is the first to maintain corals under precisely controlled temperature and carbon dioxide conditions while exposing them to natural light conditions.
Ocean acidification has emerged as an extreme threat to marine ecosystems and fisheries – it may be the real threat from climate change, ready to blind-side us in just a few decades.
Why do I say that?
Our oceans have absorbed around one-third of the CO2 emitted so far. This (along with heat-absorption from the atmosphere) has had a moderating effect on temperature increases measured so far – climate change to date could have been worse than it is.
An unexpected problem has emerged, however.
When carbon dioxide dissolves in seawater it forms a weak acid (carbonic acid) – as CO2 has accumulated in oceans around the world, they have slowly but surely become more acidic (so far about one-tenth of one pH unit). Although the increase in acidity to date doesn’t seem like much, it is already having measurable biological and physical effects.
The main issue relates to the hardening (or calcification) of marine shells. Shell-forming organisms need a fairly narrow pH range to allow them to get calcium out of solution in seawater and deposit it in their shells.
But as the water becomes more acidic, shell calcification decreases, and at some point actually begins to reverse, causing shells and related structures (like coral reefs) to start dissolving – one study estimates that ALL coral reefs may cease to grow and start to dissolve when atmospheric CO2 reaches 560ppm. It is also likely that most regions will be inhospitable to coral reefs by 2050 (including Australia’s Great Barrier Reef).
This issue does not just affect oceans.
It affects all of us because it will cause major changes to marine food chains.
And if ocean ecosystems collapse, what happens to us?
Ocean acidification due to climate change
Further Reading
Acid In The Oceans: A Growing Threat To Sea Life
Can Corals Survive In A Warming World?
Report Warns about Carbon Dioxide Threats to Marine Life – download a PDF of “Impacts of Ocean Acidification on Coral Reefs and Other Marine Calcifiers.”
Ocean acidification: the other CO2 problem
According to an online report from The Sydney Morning Herald, climate change-related damage to Australia’s Great Barrier Reef will cost us some $37.5 billion during this century.
If greenhouse gas emissions are not reduced globally, the Great Barrier Reef is expected to be one of the first of Australia’s World Heritage sites seriously damaged. But chairman of the Great Barrier Reef Foundation Dr John Schubert warned that with climate change happening much faster than predicted, Australia must plan to ”adapt” the reef to save it from some level of damage scientists say is inevitable.
According to the article:
”There needs to be extra emphasis on the adaptation side,” said Dr Schubert, who is also the outgoing chairman of the Commonwealth Bank and sits on the board of BHP-Billiton and Qantas. He said the report by Oxford Economics was a conservative assessment of the losses if the reef was damaged by permanent bleaching.
Anemone Fish - Great Barrier Reef
Bleaching (due to higher water temperatures) is not the only threat facing coral reefs. With atmospheric CO2 levels rising fast, ocean acidification is fast becoming THE major threat to all marine ecosystems.
The oceans absorb a lot of the CO2 emitted by human activities. When it dissolves in seawater it forms carbonic acid – this makes the oceans more acidic.
Shell-forming sea creatures (including coral polyps) can only deposit calcium in their shells when pH is between a certain critical range (see diagram).And if they can’t harden their shells they can’t survive, or form coral reefs for that matter.
As the oceans become more acidic, it is likely that large areas will become less hospitable to marine life – this will damage ocean food webs significantly as many crustaceans (and related species) are food for fish and other animals higher up the food chain.
More about ocen acidification coming soon…
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