If the land can’t sustain us properly, we can always catch fish to survive, right?
But before we get to the question of fish in the rivers and oceans, we need to look at the general state of water on our planet. Water is the cradle of life but – as many of us have experienced – it is also a rather invasive and destructive thing. It wears down rocks, it damages buildings, it floods us, or it stays away and dehydrates us.
Clean water is essential to health, and one of the major achievements of public health has been the ongoing provision of clean water and the processing or removal of dirty water in many urban areas, as the world’s population has grown.
As far as availability of freshwater is concerned, we are apparently still within the boundaries of sustainability, at least at the global level. In other words, there’s enough freshwater on the planet as a whole to keep us going. And, of course, it recycles.
Planetary Boundary 7 – freshwater use – green zone: The framework uses two variables to estimate the sustainability of our use of freshwater. The first is the overall global consumption of available clean freshwater. At 2,600 cubic kilometres (km3) a year, this is well inside the estimated Boundary of 4,000 km3.
The second variable used is the withdrawal of water in each river basin as a percentage of mean monthly flow. This varies enormously between river basins – some are in the red zone, some in the yellow or the green. The Planetary Boundaries group points out that 25% of our previously large rivers no longer reach the ocean. And great lakes such as the Aral Sea (once the fourth largest lake in the world) and the Dead Sea are drying up – the Aral Sea covers less than 10% of the area it covered only 50 years ago[i], and the Dead Sea is projected to vanish by 2050[ii]. The main cause of all of this is withdrawal of water for agricultural purposes.
But the Planetary Boundary group’s view is that there are so many existing and potential innovations, and opportunities for efficiency and increased productivity, that humanity can stay within a safe operating space at global level, and return to it at most regional levels.
Despite the group’s optimism, when we look at our current activities on a regional basis, freshwater remains extremely problematic. Many areas are natural drylands or deserts, and can only naturally sustain a low level of population density of any sort. Other areas vary from the temperate (in water terms, reasonable rainfall and ground water levels) to the tropical (over-abundance of water).
Many regions are already in severe water difficulties, while others have an abundance. So we apparently have the options of moving the people or the water. In poor countries, the people move, or they die. In wealthy countries, the water is moved, through aqueducts or tankers, and the drier lands are irrigated for agriculture or direct consumption by people.
Wealthy countries spend vast amounts of money moving the water to feed and support the people. California, which has a naturally dry climate, and a lot of desert, is currently experiencing a thousand year drought, and its ground water levels are being rapidly depleted. Much is often made of the fact that major cities such as Los Angeles owe their size, and perhaps even their existence, to the Colorado River[iii]. And these days even Hollywood stars are being castigated for maintaining green lawns during the drought.
But while Los Angeles ranks first in the world at moving water across basins (ie piping it hundreds of kilometres from the Colorado, as well as using other rivers in central and northern California), the core issue is the cost and efficiency of doing this, not LA’s overall level of water use.
The real villain is agriculture, not the urban areas. About two-thirds of the water flowing in the Colorado River and its tributaries is used for irrigation, and the other third evaporates or supports river-side vegetation or supplies urban areas such as Los Angeles, Las Vegas, Phoenix and Tucson[iv].
California maintains a large agricultural industry (the “fruit basket of America”) which is water-intensive and uses 80% of its water consumption to produce 2% of its Gross Domestic Product. Only in 2015 has the possibility that agriculture should take its share of water rationing been seriously discussed!
In New Zealand, Canterbury (dryland) and Central Otago (dryland and desert) are being rapidly converted to dairy farming, a highly water-intensive industry, in the pursuit of profit. This is nonsense.
In both cases, the inappropriate use of both land and water is unsustainable in the long run – California is simply not designed to be a fruit orchard, nor are Canterbury and Central Otago designed for dairy farms.
The novel and movie, “Salmon Fishing in the Yemen”, in which an incredibly wealthy person persuades others to attempt this unnatural feat, is simply an extreme illustration of how humanity can get things wrong in terms of working against natural states and processes.
The poor have it right. We should move the people to the water. Or, more accurately, we should work with nature to plant crops and graze animals fit to their local conditions, as far as possible. Of course we need irrigation, but only where it is supporting “fit” forms of agriculture. And we should carefully consider where we build or extend our towns and cities, in relation to both their impact on agricultural land and also the natural or easy availability of freshwater.
The recycling of freshwater is also problematic, as a result of global warming. The vast storage vaults of the world’s glaciers are shrinking and this has a number of impacts, two of which I will mention here. First, the level of natural run-off, which previously provided steady (more or less – spring floods are not exactly “steady”, but they have their own function in renewal and revitalisation) flows of freshwater, is shrinking or becoming more erratic, so putting pressure on both agriculture and direct consumption downstream. As noted above, many of our great rivers are shrinking, and some are drying up.
Second, when the water recycles from the oceans, it is increasingly coming down as rain not snow, so we have heavier monsoons and extreme weather events, which our infrastructures are not equipped to cope with. So, we have too little water flowing along the ground, and too much flooding us from the sky.
It’s also worth remembering that groundwater (pumped up from aquifers) does not regenerate nearly as quickly as surface water. It is also under increasing pressure, as dropping water-tables in California[v] and elsewhere illustrate.
The oceans (and the fishes)
Turning now to the oceans, which cover about 70% of the earth’s surface, and contain 97% of its water (albeit a bit salty). My first observation is on the oceans’ scale – as it only takes 3% of the Earth’s water to sustain the human race and all land species, then if we could directly use a tiny fraction more of the water in the oceans, freshwater need never again be a problem for humanity.
Currently, about 80 million cubic metres of fresh water a day is produced worldwide by desalination[vi]. This sounds a lot, but it represents about only 1% of total water use (about 29 km3 per year). Israel is the largest user proportionately in the world, producing 40% of its water for domestic use from desalination. But desalination is expensive and energy intensive, and disposal of the salt removed is problematic. It would be wonderful to have truly economical and environmentally friendly methods of bulk desalination of saltwater.
Life came from the oceans originally, and they remain the most abundant source of life. Thousands, and perhaps millions of species of fishes and plants remain undiscovered in the oceans, and they live and thrive at all depths. Humans have barely begun to understand the variety of life in the oceans.
But we are very good at harvesting it, particularly close to land and when it’s big and slow enough and close enough to the surface for us to find and catch it. There have been numerous collapses of fish stocks over the last few hundred years, and figures suggest that as much as 85% of the world’s fisheries have been over-exploited[vii].
With the bigger sea animals, many of you will be aware of the very public reactions against the harvesting of various species of whales, and the collateral damage done to other species by industrial harvesting of smaller fish. To this can be added the more recent outcries against bottom trawling, which destroys the local ecology by scraping heavy nets along the ocean floor.
We’re putting serious pressure on the abundance of accessible fish life in the oceans, by both the quantity and the methods of our harvesting.
But fish stocks can (mostly) rebound, if we reduce our harvest to something more sustainable, or stop fishing them altogether. Even totally collapsed fisheries such as the Newfoundland cod fishery can recover within a human generation or less[viii].
Our more serious long term problem is that we are using the oceans as a rubbish bin and sink for what we do onshore.
We dump everything from nuclear waste to plastics to agricultural run-off in the ocean. Plastics now form large “garbage patches” in various areas of the oceans, and are altering the life balances wherever they are. A recent report by the World Economic Forum notes that 95% of plastic packaging material (worth about $100 billion) is used only once – and most of this ends up in the ocean. The report projects that, by weight, there will be more plastics than fish in the ocean by 2050.
And, invisibly, plastic “microbeads” which are endemic in household products are being washed to sea and entering the marine chain of life, with numerous species already affected. Surveys show that in the 1960s only 5% of seabirds had bits of plastic in their gut – now 90% do[ix].
Also invisibly, we are dumping vast amounts of carbon into the ocean. As carbon concentration in the atmosphere increases, carbon dioxide is slowly absorbed by the ocean to balance out the concentration between air and water. This is very useful in the short term, as it reduces the amount of carbon in the atmosphere, and slows global warming. The ocean acts as sink for carbon by dissolving it and letting it sink, and absorbs about a third of our current human production of carbon.
The immediate effects of this are to warm the ocean up, and to acidify it. The ocean surface has warmed by about 0.3 degrees in the last 45 years[x] – it doesn’t sound like much, but when you consider the vast volume of water involved, it is a huge amount of warming.
And its acidity has increased, by a reduction in “pH value” of about 0.1. Again, this might not sound like much in a 14 point scale, but it represents a 30% increase in hydronium ion concentration (a direct measure of ocean acidity) in the water[xi]. This is starting to create problems for marine life, particularly shellfish, whose shells are softening or not growing. A recent study estimates that large regions of the Southern Ocean may be “inhospitable” to key organisms in the food chain by 2030 as a result of acidification, which has been called the “evil twin” of global warming[xii].
Planetary Boundary 4 – ocean acidification – green zone: The framework uses as its control variable the saturation state of “aragonite”, a form of calcium carbonate formed by many marine organisms. The Boundary is 80% of pre-industrial levels of saturation, the current state is 84%.
While we are still inside the Boundary, we are getting closer to it. However, the Planetary Boundary group says that if the climate change Boundary (350 ppm atmospheric CO2) were respected, the acidification Boundary would not be transgressed. This is also an initial illustration of the interconnected nature of the Planetary Boundaries, which we will return to in Chapter 11.
Both these changes – warming and acidification – are reducing the oceans’ capacity to store further carbon, and also rapidly altering their ecology, threatening fish stocks and plant life. The Great Barrier Reef in Australia is not only the largest living thing on the Earth, but also a “canary in the mine” for this particular problem. It has lost about half its coral in the last 30 years[xiii]. The general consensus is that its rapid bleaching and deterioration is being caused by the rising sea temperatures, helped by pollution caused by agricultural run-off. But, just as with fish populations, coral reefs can show remarkable resilience, and regenerate if left alone[xiv].
You may have noticed that nothing has been said about possible sea-level rises yet. This will be discussed in the next chapter, under global warming.
In summary, the oceans are vast, and have huge capacity to absorb unusual invasions of one sort or another. But we humans are definitely starting to change how life in the oceans is generated and sustained.
[ii] See “$1B pipeline project…” Dominion Post, 3/12/2015
[iii] See for example, http://www.waterencyclopedia.com/Ce-Cr/Colorado-River-Basin.html
[iv] See for example, from the National Geographic, http://voices.nationalgeographic.com/2014/06/06/worlds-large-cities-move-water-equivalent-to-ten-colorado-rivers-to-meet-their-annual-water-needs/
[viii] See Canadian study quoted in Dominion Post, page B3, 30/10/2015
[ix] Surveys quoted in Dominion Post, page A12, 26/10/2015
[xii] See study quoted in Dominion Post, page B3, 04/11/2015