Marinet Briefing Paper considers the “sixth mass extinction” facing the ocean

In the Marinet film WTF? – Where’s the Fish?, produced by Sarah Mallabar and narrated by Chris Packham, Marinet makes the forecast that the ocean could be facing a new mass extinction by 2050 where 94% of marine species have become extinct unless there is a fundamental change in mankind’s actions which impact on the global environment.

This Briefing Paper notes and explains that there have been five earlier mass extinctions in the history of the planet and that there is now a substantial body of scientific opinion, including Nobel Prize winners within its ranks, which believes that we have initiated a new mass extinction, the sixth.  The levels of species mass extinction in the previous five events range between 60% and 95%.

In the previous five events the cause has been considered to be external (e.g. meteorite collision with Earth or extreme volcanic activity), but in the case of this sixth event it is mankind and our actions which are now the cause.  It is believed that the current rate of extinction of species could be at a rate from 100 to 1000 times greater than would be normally expected and that mankind’s use of fossil fuels and its consequential impact on the global environment is the driving cause, although other factors such as deforestation and an ever-increasing human population are associated drivers of similar force.

The Briefing Paper notes that mass extinction is not just a phenomenon where a significant swathe of life is eliminated. It is also a phenomenon with a cause; and that cause, whilst having an active agent (e.g. meteorite), is delivered by a profound alteration in the physical and chemical systems that support life on the planet.

It is the alteration in these physical and chemical systems within whose boundaries life is adapted to live which is the disruptive factor(s) that actually means that life finds its ability to survive insufficient and thus impossible.

The Briefing Paper observes that the ocean is acting as a crucial sink for the excess heat created in the atmosphere due to carbon dioxide emissions.  Scientists have measured and calculated that around 90% of this excess heat has been absorbed by the ocean and that it is affecting ocean temperature to the extent of a 0.1°C warming each decade (regionally variable) and also that a large part of the extra heat in the ocean is buried deep underwater with 35% of the additional warmth found at depths below 700 metres.

These changes in ocean temperatures are driving polar ice melt and threaten to disrupt the established currents which drive the circulation of water in the oceans which are, in turn, one of the principal drivers in global weather systems.

The Briefing Paper also observes that the ocean has absorbed around 30% of the excess carbon dioxide which has been released by fossil fuel burning into the atmosphere.  This absorption of CO2 converts into carbonic acid which, in turn, is reducing the alkalinity of the ocean (also known as “acidification”).  Measurements have revealed that ocean alkalinity has fallen by 0.1 pH [equivalent to a 30% fall] since the early 1800s, with a further reduction of this magnitude and perhaps even greater (0.2 to 0.3 pH) being predicted by the end of the present century if current trends continue.

This is of serious concern because many organisms are very sensitive to seemingly small changes in pH — for example, for humans a drop of 0.1 pH in human blood can cause profound health consequences including seizures, heart arrhythmia and even coma. In the case of marine organisms, many are very sensitive to a change of this magnitude (0.1 pH) because it can affect fundamental physiological processes such as respiration, calcification [shell/skeleton building], photosynthesis and reproduction which means that even tiny marine plants — phytoplankton, which are single celled algae at the base of the food chain, many of which have calcareous shells — will also be affected. Acidification of the ocean is therefore a profoundly disrupting phenomenon to marine ecosystems. This reduction in alkalinity of the ocean (acidification) is increasing and the origin of it all is mankind’s activities – namely, the increased CO2 levels we are releasing into the atmosphere.

These profound shifts in the chemical and physical parameters of the ocean are, in extinction terms, intensified by us by the harvesting of marine species and by pollution of the ocean.

In the case of marine mammals, the impact of whaling is well catalogued. The introduction of factory ships along with the concept of large-scale commercial whale harvesting in the first half of the 20th century has meant that by the late 1930s more than 50,000 whales were being killed annually. In 1986, the International Whaling Commission banned commercial whaling because of the extreme depletion of most of the whale stocks.

In the case of wild fish stocks, particularly commercial species, the intensity of wild harvesting has grown throughout the 20th Century.  Today fishing intensity is very severe due to the development of sonar which can pin-point the location of stocks to great exactitude in conjunction with larger engines in larger factory vessels which now have the mechanical and storage capability for effectively removing located shoals in their near entirety.  Where line-fishing is employed, lines now often extend several miles. Not only are fish stocks heavily impacted, but so also are non-commercial fish species, marine reptiles and sea birds which all fall prey in large numbers as unwanted by-catch.  The scale of this harvesting, intentional or otherwise, is now very intense and in the case of fish stocks it is estimated by the UN’s FAO that 33% in 2015 are now over-fished (i.e. their spawning stock threatened with collapse) whereas 40 years ago (in 1974) this level of over-fishing of stocks was 10%.  Meantime, human population continues to grow relentlessly — 1990 : 5 billion, 7.2 billion : 2018, with a projection of between 9.6 and 12.3 billion by 2100.

In the case of pollution, consider a single example.  Marine animals in the deepest ocean now contain man-made fibres and plastic; and by 2050 it is predicted that the weight of all waste plastic in the ocean will equal the weight of all fish in the ocean.  Man-made plastic contains a complex range of chemicals, the persistence of which in the body of marine organisms is still wholly unassessed in terms of impact.

It has been argued by those resistant to Marinet’s hypothesis of a possible 94% extinction of marine species by 2050 that this is a doomsday scenario with no scientific basis.  In other words, pure scaremongering.  Naysayers point out that the current rate of extinction is, at worst, at a rate of around 1000 species per annum whereas natural background levels record a rate of around 1 species per annum.  Hence no way will the ocean arrive at a 94% extinction level by 2050, even assuming that the sixth mass extinction is actually underway which many naysayers assert is not the case.

However Marinet believes that an argument over statistics is an instance of the proverbial red herring.  A mass extinction occurs when the normal chemical and physical parameters of life shift quickly and significantly.  Life in its present form is adapted to live within these parameters and its ability to adapt, which is relatively slow for most species, is outpaced by this rate of change.  This mismatch — the slower rate of evolution relative to the faster rate of environmental change — is the primary driver. The key point is that we are witnessing these changes and this mismatch now.

When the extinction rate accelerates then a biological parameter also comes into play — namely, a collapse in ecosystem structures whose primary characteristic is interdependence.  When one species disappears this impacts on other species and, if this process is repeated frequently and excessively, the impact and consequences intensify. Under these circumstances systemic stress begins to become a factor which, if it grows in intensity, can arrive at the point where that stress can become exponential i.e. become a cascading phenomenon where the event itself is self-reinforcing, known colloquially as a doom-loop phenomenon.

In this scenario an argument over a predicted 94% extinction level by 2050 or another % figure by another date becomes rather beside the point because, crucially, the process can no longer be put into reverse.

Marinet argues that we are now in the Age of Consequences.  This means we are now confronted by the fear that the damage has already been done, cannot be undone — or at least, not sufficiently. So we are now having to live with the consequences.  In the Age of Consequences processes and events have become irreversible. When climate change and ocean acidification and other factors cross over the tipping point then the consequences, by definition, become both inescapable and brutally severe.

Marinet’s film WTF? – Where’s the Fish? is a warning as much as a hypothesis.

`Our message is not one of “doom”.  On the contrary, it is a severe reminder that we have to accept responsibility for the present events. Only by accepting responsibility do we find the motivation to act.  Others in both the orthodox and the new versions of the environmental movement are now beginning to respond to the urgency of the fast mounting evidence.

Can we turn away and not act, seriously?

 


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