Biology · Rung 4 of 4

Biodiversity and our impact

Ecosystem services are work someone would have to pay for if it stopped being done free, and the ugly name is deliberate so that this is visible. Bees pollinate a third of what we eat, forests pull carbon out and hold the soil, wetlands filter water, soil bacteria return nitrogen and plankton makes around half the oxygen you breathe. Biodiversity matters for the same reason you do not put all your savings in one share: if three species pollinate a crop and one falls ill, two remain. And almost every impact has its cause and its effect far apart in space and time, which is what makes them hard to attribute and harder to charge for: whoever fells a hillside is not whoever loses the fishing downstream.

Where this sits

Comes after
Food webs

Exercises from this rung

Generated by the app, from easiest to hardest

  1. What do wetlands give us?

    • pull carbon from the air, hold the soil and regulate rainfall
    • a third of what we eat depends on someone carrying pollen
    • filter water and cushion floods
    • makes around half the oxygen you breathe

    Why Filter water and cushion floods. They are called ecosystem services, and the ugly name is deliberate: it makes visible that this is work someone would have to pay for if it stopped being done free. Pollinating an apple orchard by hand costs money, and in parts of China it is already done.

    easier

  2. Why does biodiversity matter, beyond being beautiful?

    • Because a system with more species survives a blow better
    • Because the number of species has to stay fixed
    • Because the more species, the more oxygen is produced
    • Because rare species tend to be the most useful

    Why For the same reason you do not put all your savings in one share. If three different species pollinate a crop and one falls ill, two remain; if only one does, none remain. Variety is not an aesthetic luxury, it is what makes a failure a scare rather than a disaster.

    in between

  3. A young tree removes about 20 kg of CO₂ a year. How much does it remove in 4 years?

    Answer 80

    Why 20 × 4 = 80 kg. For scale: a return flight from Stockholm to Madrid is some five hundred kilos per person, so it would take several trees over several years. Planting trees helps and is far slower than it looks; not felling the grown ones is considerably more effective.

    harder