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Wednesday, October 20, 2021
Verena Schälter interviews ALEX DAVID ROGERS, Scientific Director of the International Programme on the State of the Ocean
UNITED NATIONS, Jul 13 2011 (IPS) - The health of the world’s oceans is much worse than is widely believed, but it is not too late to change tack and help this critical ecosystem recover, at least in part, experts say.
Marine scientists from all over the world recently came together at Oxford University to review new research under the auspices of the International Programme on the State of the Ocean (IPSO) and the International Union for Conservation of Nature (IUCN).
Their results, outlined in a report released in June, came to an alarming conclusion: If the current course of damage continues, marine species are at high risk of entering a phase of extinction unprecedented in human history.
Professor Alex David Rogers, IPSO’s scientific director, spoke to IPS about the reasons for the disastrous situation and what actions must be taken to avoid the worst. Excerpts from the interview follow.
Q: The report warns that the “worst-case scenario” is more or less imminent. What would it look like? A. It is difficult to predict exactly what the future will look like but the report highlights some of the things we may expect over the short to medium term and then over longer time frames.
Modelling the effects of climate change, particularly temperature, on marine communities suggests that species may shift in their distribution towards the poles or into deeper water. There are likely to be extinctions at both the tropics and in polar ecosystems.
We will also continue to see the spread of “dead zones”, areas of the oceans where agricultural and other runoff cause high levels of algal production in coastal waters that in turn trigger high levels of bacterial activity, using up oxygen in the water column.
Other effects of this are the increased occurrence of harmful algal blooms, increased incidence of pathogens in coastal waters and an increased likelihood of plagues of gelatinous zooplankton.
This will be happening against a background of increasing reliance on animal protein from aquatic systems by humans because of population growth.
There is also likely to be an increased frequency of increasing storm events and sea level rise to contend with.
Q: What are the main causes? A: One of the central themes of the meeting we had was the impact of climate change on marine ecosystems. Many people think about this as something that will happen in the future. But we are already seeing the effects of climate change in many ecosystems mainly caused by elevated sea surface temperatures.
These include mass coral bleaching and changes in the distribution of marine species.
The cause is mainly elevated CO2 in the atmosphere caused by human activities. CO2 is a greenhouse gas and it causes warming of the atmosphere and therefore also the oceans.
We have recently become aware of another phenomenon associated with CO2 emissions, ocean acidification. The oceans absorb about a third of our CO2 emissions, where it forms carbonic acid, reducing the pH of the oceans.
An effect of this is to reduce the concentration of carbonate in seawater, a major component of the skeletons and shells of many types of marine organisms including reef-forming corals. Studies of natural CO2 vents, usually associated with volcanic areas, suggests that this will negatively impact many organisms, including corals and molluscs.
Q: The die-off of coral reefs is often mentioned as a prime example of the ocean’s disastrous condition. What is special about coral reefs? A: Coral reefs are the most diverse ecosystems in the ocean. We do not know how many species are associated with them – a sad reflection on our state of knowledge of these and many other marine ecosystems – but there are estimates between 0.5 and nine million.
However, these ecosystems are also extremely important in socioeconomic terms. About 30 million people are completely dependent on reefs for their livelihoods; perhaps 500 million derive goods and services from them.
It has been estimated that reefs may be worth up to 375 billion dollars per annum, with goods and services including the provision of fish, coastal protection, tourism and other less tangible services.
Q: What else has a negative impact on the ocean’s ecosystems? A: Overfishing has had a major impact on marine ecosystems. Serious depletion of marine resources has occurred in many instances and the latest figures from the U.N. FAO with regards to the state of the world’s fish stocks show that these problems continue to worsen, not improve.
Overfishing has many knock-on effects on marine ecosystems, often known as cascade effects, where the removal of target species effects the abundance of other species in the ecosystem.
Q: What would be the consequences for humankind? A: That is very hard to predict and depends on where in the world you live.
The impacts of depletion of fish stocks, shifts in fisheries resources resulting from climate change effects, destruction of fish habitat, increasing frequency of powerful cyclones and sea level rise are likely to all be worse in parts of the developing world.
Here, populations have a greater dependence on fish for animal protein and for the livelihoods of large numbers of people, so there is naturally a higher vulnerability to impacts on fish stocks.
In the longer term the oceans are critical parts of the Earth system.
There are likely to be important feedback effects of climate change on the ability of the oceans to absorb CO2, something that will accelerate climate change.
Q: Is there a way to stop this development? A: There are many levels of action that can be taken.
These range from our actions as individuals, whether that is reducing our own CO2 emissions, choosing only fish from sustainable sources, getting involved in conservation action for the marine environment or making ourselves aware of these issues and writing to policy makers to ask for action.
At the level of national and international policy urgent action on the reduction of CO2 emissions is critical.
The longer this is left, the worse the impacts will be on marine ecosystems and the more expensive will be the measures to reduce our CO2 emissions and take remedial action on the environment.
Some of these issues, such as overfishing, are clear and the answers to them relatively straightforward although they appear to be politically difficult.
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