Our fate is also wrapped up in the ocean – another cause for tears.

In a very real sense, this Post continues from my writings of yesterday concerning James Hansen.

A year ago, the BBC reported the shocking state of our oceans.  It included this:

“The rate of change is vastly exceeding what we were expecting even a couple of years ago,” said Ove Hoegh-Guldberg, a coral specialist from the University of Queensland in Australia.

“So if you look at almost everything, whether it’s fisheries in temperate zones or coral reefs or Arctic sea ice, all of this is undergoing changes, but at a much faster rate than we had thought.”

But more worrying than this, the team noted, are the ways in which different issues act synergistically to increase threats to marine life.

Some pollutants, for example, stick to the surfaces of tiny plastic particles that are now found in the ocean bed.

This increases the amounts of these pollutants that are consumed by bottom-feeding fish.

Plastic particles also assist the transport of algae from place to place, increasing the occurrence of toxic algal blooms – which are also caused by the influx of nutrient-rich pollution from agricultural land.

In a wider sense, ocean acidification, warming, local pollution and overfishing are acting together to increase the threat to coral reefs – so much so that three-quarters of the world’s reefs are at risk of severe decline.

As Callum Roberts explains in a forthcoming book The Ocean of Life,

We have always been fish eaters, from the dawn of civilization, but in the last twenty years we have transformed the oceans beyond recognition. Putting our exploitation of the seas into historical context, Roberts offers a devastating account of the impact of modern fishing techniques, pollution, and climate change, and reveals what it would take to steer the right course while there is still time. Like Four Fish and The Omnivore’s Dilemma, The Ocean of Life takes a long view to tell a story in which each one of us has a role to play.

That book was recently reviewed in The Economist, from which I reproduce the following extracts,

The Ocean of Life: The Fate of Man and the Sea. By Callum Roberts.

Traditional attitudes towards the sea, as something immutable and distant to humanity, are hugely out of date. The temperature change that harmed the corals was not caused by human activity; yet it was a foretaste of what man is now doing to the sea. The effects of overfishing, agricultural pollution and anthropogenic climate change, acting in concert, are devastating marine ecosystems. Though corals are returning to many reefs, there is a fair chance that in just a few decades they will all be destroyed, as ocean temperatures rise owing to global warming. The industrial pollution that is cooking the climate could also cause another problem: carbon dioxide, absorbed by the sea from the atmosphere, turns to carbonic acid, which is a threat to coral, mussels, oysters and any creature with a shell of calcium carbonate.

The reviewer explains that, “The enormity of the sea’s troubles, and their implications for mankind, are mind-boggling. Yet it is equally remarkable how little this is recognised by policymakers—let alone the general public.” and then adds, to the author’s credit, ” There is also a dearth of good and comprehensive books on a subject that can seem too complicated and depressing for any single tome. Callum Roberts, a conservation biologist, has now provided one.”

The book review then continues,

He [Callum Roberts] starts with a bold claim: that anthropogenic stresses are changing the oceans faster than at almost any time in the planet’s history. That may be putting it too strongly. Yet there is no quibbling with the evidence of marine horrors that Mr Roberts presents.

Take overfishing. The industrialisation of fishing fleets has massively increased man’s capability to scoop protein from the deep. An estimated area equivalent to half the world’s continental shelves is trawled every year, including by vast factory ships able to put to sea for weeks on end. Yet what they are scraping is the bottom of the barrel: most commercial species have been reduced by over 75% and some, like whitetip sharks and common skate, by 99%. For all the marvellous improvements in technology, British fishermen, mostly using sail-power, caught more than twice as much cod, haddock and plaice in the 1880s as they do today. By one estimate, for every hour of fishing, with electronic sonar fish finders and industrial winches, dredges and nets, they catch 6% of what their forebears caught 120 year ago.

Overfishing is eradicating the primary protein source of one in five people, many of them poor. It also weakens marine ecosystems, making them even more vulnerable to big changes coming downstream.

For example, there is the matter of chemical pollution, mostly from agricultural run-off. This has created over 400 dead-zones, where algal tides turn the sea anoxic for all or part of the year. One of the biggest, at the mouth of the Mississippi Delta in the Gulf of Mexico, covers 20,000 square km (7,700 square miles) of ocean. An annual event, mainly caused by the run-off of agricultural fertilisers from 40% of America’s lower 48 states, it makes the one-off Deepwater Horizon oil-spill look modest by comparison.

Global warming is another problem. Hitherto, the sea has been a buffer against it: because the heat capacity of water is several times that of air, the oceans have sucked up most of the additional heat, sparing the continents further warming. Yet this is now starting to change—faster than almost anyone had dared imagine.

One effect of the warming ocean, for example, is to increase the density difference between the surface and the chilly deep, which in turn decreases mixing of them. That means less oxygen is making it down to the depths, reducing the liveability of the oceans. Off America’s west coast, the upper limit of low-oxygen water is thought to have risen by 100 metres. Where strong winds bring this water nearer to the surface, there are mass die-offs of marine life. Such events will proliferate as the climate warms.

This is a poor lookout for already put-upon fish. “Fish under temperature and oxygen stress will reach smaller sizes, live less long and will have to devote a bigger fraction of their energy to survival at the cost of growth and reproduction,” writes Mr Roberts. And that is before he gets to the effects of ocean acidification, which could be very bad indeed. Without dramatic action to reverse these processes, he predicts a catastrophe comparable to the mass extinctions of the Palaeocene-Eocene Thermal Maximum, when carbon-dioxide levels, temperature and ocean acidity all rocketed. He writes: “Not for 55m years has there been oceanic disruption of comparable severity to the calamity that lies just a hundred years ahead.” That would be hard to prove; it would be better not to try.

So what is to be done? Mr Roberts provides a hundred pages of answers, occupying roughly a third of the book. They range from the obvious—curbing carbon emissions—to technical fixes, like genetic improvements to aquaculture stocks. None is impossible; and Mr Roberts, almost incredibly, describes himself as an optimist. He writes, “We can change. We can turn around our impacts on the biosphere.” We had better do so.

Amen to that!

So want to know where to start?  Here’s a snippet of advice in terms of protecting our fish stocks,