Why biodiversity is worth caring about

If you had to build a machine that made clean water, kept soil fertile, pollinated crops, buffered floods and pulled carbon out of the air, it would be the most expensive project in human history. We already have that machine. It is the living world, and it runs on its own, for free, as long as we do not break it.

Nature as infrastructure

It helps to think of ecosystems the way you think of roads and power lines: as infrastructure we all depend on but rarely notice. Insects and birds pollinate a large share of the food crops we eat, which means no bees quietly means no almonds, apples or many other foods. Healthy catchments filter rainwater through soil and roots so that it reaches our dams clean, which is cheaper than treating dirty water later.

• Pollination: bees, birds and other animals fertilise a large share of the crops we grow.
• Clean water: forested, healthy catchments filter rain before it reaches our dams.
• Living soil: fungi, worms and microbes turn dead matter into the soil that grows food.
• Flood buffering: wetlands and mangroves soak up storm surges and slow floodwater before it hits towns.
• Medicine: a huge number of our drugs began as compounds found in plants, fungi and animals.

It is worth slowing down on pollination, because it shows how quiet and total the dependence really is. A flowering crop like an apple or an almond cannot set fruit until pollen moves from one flower to another, and for most of these plants that job is done by an animal, usually an insect, that visits the flower for its own reasons and carries pollen from bloom to bloom by accident. No visit, no pollen, no fruit. Over millions of years the flower and the insect shaped each other so that the deal works without either one meaning to help the other, and take the insect away and the deal simply stops.

You can see what that costs when it fails. In parts of south west China, where heavy pesticide use and habitat loss wiped out the local bees, farmers now pollinate their pear and apple trees by hand, climbing into the branches with small brushes and pots of pollen to touch each flower one at a time. It works, barely, but it is slow, expensive human labour doing worse than the insect that used to do it for nothing. That is the price tag of the service made visible, and it is a warning against assuming the machine will always run.

This is not abstract in Australia. Our almond orchards, mostly along the Murray in Victoria, New South Wales and South Australia, depend so heavily on bees that every spring beekeepers truck hundreds of thousands of hives across the country to the trees for the few weeks they flower. It is the biggest planned pollination event in the country, a whole industry resting on the labour of an insect, and it only works because we still have healthy bees to move.

The web nobody fully mapped

The reason this matters so much is that species do not stand alone. They depend on each other in a web we have only partly mapped. A predator keeps a grazer in check, the grazer shapes the grass, the grass holds the soil, the soil feeds the trees, the trees shelter the birds that spread the seeds. Pull one thread and you often cannot predict what unravels, because we never fully knew how it was tied together.

This is why losing a species is not like losing one part off a shelf of spare parts. It is more like removing a rivet from a plane. Lose one and the plane still flies. Lose enough, quietly, one at a time, and at some point something important gives way, and by then it is very hard to put back.

A common misconception

A lot of people quietly assume that biodiversity is a nice to have, something for documentaries and national parks, sitting to one side of the serious business of food, water and money. The opposite is closer to the truth. The serious business runs on top of the living world, not beside it. The crop needs the pollinator, the city needs the catchment, the farm needs the soil that the worms and fungi make, so when the living systems weaken, the costs turn up in grocery prices, water bills and failed harvests long before anyone thinks to blame a missing insect. Nature is not the decoration around the economy. It is part of the foundation under it.

Where this shows up in your week

You meet this every day without noticing. The fruit in your lunch, the honey on your toast, the coffee or chocolate you treat yourself to, all of it exists because an animal moved pollen for a plant somewhere. The clean water from the tap was filtered through a catchment before it reached the dam. Even the calm you feel walking through a park or along a beach is a service the living world hands you for free. Once you start seeing ecosystems as infrastructure, the question stops being why should I care about a beetle and becomes what am I quietly relying on that I have never had to pay for.

The honest extra reason

Everything above is the useful case, and it is real. But there is an honest extra reason that has nothing to do with usefulness. A world with lyrebirds and reef fish and old growth trees in it is simply a better world to live in than one without them. Plenty of people work to protect nature not because it pays, but because a living planet is worth caring about for its own sake. You are allowed to hold both reasons at once.

That is the ground the rest of this topic stands on. The next lessons tell the honest story of what is being lost, on land and in the sea, and why Australia in particular has so much to lose, and the case study at the end follows one small marsupial from the edge of extinction back towards safety. All of it makes more sense once you see the living world as the shared infrastructure this lesson describes.