Water Security

Geographer Anson Mackay on the ecosystem services, the demands on freshwater around the Earth and the decline in biodiversity

videos | August 6, 2020

I’m mainly going to focus on freshwater security that comes from surface waters, from lakes and rivers: I won’t touch on groundwater because that has its own implications and problems in different parts of the world. Freshwater security is important in terms of, for example, what we call ecosystem services. An ecosystem is a group of microorganisms, plants, animals that live together in, for example, a water body, and they interact together with the chemistry and the climate. An ecosystem service is the benefit that ecosystem provides humanity for wellbeing. For example, lakes will provide benefits in terms of fish for protein, for food (which is economy), they’ll provide fresh water for drinking. Lakes also help to clean up water, they help regulate the carbon cycle, regulate climate change etc.

If we start to disrupt the ecosystem functioning of lakes and rivers, then we also pose major threats for freshwater security. An excellent example of that is the Aral Sea. The Aral Sea was once the fourth largest lake in the world: it exists in the former Soviet Union between Kazakhstan and Uzbekistan. In the 1950s the governments there thought they would want to promote further cotton irrigation in the catchment of the Aral Sea. The Aral Sea basically exists in the desert, so it’s very sensitive to changes in precipitation, it’s very sensitive to evaporation and the rivers flowing into it especially.

Geographer Anson Mackay on freshwater pollution, acid rains and the dangers of invasive species and algal blooms
So in the 1950s and especially the 1960s water was averted from the Aral Sea for the cotton irrigation, and that meant the less water was flowing into the Aral Sea itself because it was all going into the cotton plantations. So between the 1960 and the 1980 the Aral Sea lost about 90% of its volume and shrunk to a really small size. That meant that all the hundreds of species that lived there all died out. The Aral Sea shrunk to such an extent that it caused major health problems with local populations because they lost the fishing industry basically, so the freshwater security they had from the fishing industry which has been the biggest in the former Soviet Union just disappeared within a matter of decades. This caused their health to become compromised which meant that they are much more susceptible to disease. So again, we can see that kind of a very extreme example of how human impact on lakes can really affect freshwater security.

The World Economic Forum has recognized that freshwater security is one of the most important concerns going into the future. Because of population increases around the world, we’re making more demands on freshwater for both drinking but also industry and factories etc. But one of the problems is that freshwater itself is very unevenly distributed, so in North America there is over half the world’s freshwater, for Southeast Asia it has only about sort of 10% of permanent surface freshwater. The 60% of the world population live in Southeast Asia, so the demands there are very large and very extreme and that’s why it is of a great concern.

There are some very nice studies done that looked at freshwaters around the world, and it is estimated that at about any one month of the year about four billion people are exposed to a threatened freshwater security, and that’s defined by, say, people taking water out of a river where there’s moor actually flowing through the river. About half a billion people on the planet are exposed to very dangerous levels of freshwater security throughout the year, so you can see how it’s an extremely important problem.

Climate change is having some impact on that as well. You might think that there’s actually more freshwater in the world today than there was thirty years ago as the amount, the volume is actually increasing but it is increasing in certain regions of the world which perhaps aren’t needing it so much. So again, that has its own implications.

One of the major things we’re seeing with freshwater security now and into the future is linked to biodiversity. Freshwater covers about 3% of the land surface of the planet. Yet, fresh waters contain 6% of the world’s biodiversity, they contain over a third of the world’s vertebrates and over 40% of the world’s fishes. That means at a very small amount of area they contain a very high proportion of biodiversity, and that makes freshwater security and biodiversity very very important.

There’s been this really nice study done called the Living Planet Index that’s done by the World Wildlife Fund and also the Zoological Society of London. They’ve looked at tens of thousands of populations of thousands of species from 1970 up to the present day. The 1970 act as a baseline.

What they found for freshwater vertebrates is that they’ve declined in population by over 83%, so 4/5 of the world’s freshwater vertebrates have disappeared.

We’re relying on vertebrates for food, for recreation, for ecosystem health, so it’s really really damaging. I think things like pollution of lakes can damage freshwater security but we can clean that up, we can clean that up through international legislation, for example, for acid rain; we can clean it up through local and regional legislation, for example, for farming impacts on lakes and rivers. But when we look to biodiversity, it’s very hard to regain those populations, and if populations keep getting less and less, that means that they could go into extinction, and when you lose a species to extinction, you’re never going to get it back.

So there’s been a lot of talk about whether the Earth in general is moving into sixth mass extinction, we’re going to be losing all these species. The population decline, especially in freshwaters, is not negating that hypothesis of the sixth mass extinction. So we could be moving towards this sort of tipping point in the Earth, and that in a sense is why freshwater security is extremely important not just for human health and well-being in terms of freshwater: it’s important for biodiversity in general around the planet. Biodiversity is important for regulating carbon cycle, nitrogen cycle, so again all these things in the planet are all interrelated and interconnected, and we started damaging one to such an extent that it will have impacts elsewhere in the world as well.

Glaciologist Martin Siegert on the ice sheets in Greenland and in Antarctica, the Larsen Ice Shelf and how the glaciers melt
So in the last ten years a lot of the research has been using, for example, remote sensing from satellites just to actually characterise where is the water and where is it disappearing from and potentially where to. Some studies have come out in the last couple of years that have shown that there is a lot of freshwater decline, for example, both from the Greenland ice sheet and the Antarctic ice sheet that’s linked to global warming and the ice melting into the oceans. But also there is a large amount of decline from, for example, Northeast Asia, some parts of Central America, southwestern United States. This seems to be from agriculture, and it got such intense agriculture there that is using up all the freshwater that you can see changes in the gravity of the Earth from that. That is some of the cutting-edge research that’s showing areas of real concern in the last couple of years.

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Professor of Geography, University College London
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