The Food and Agriculture Organisation tells us that biodiversity is declining. This being defined as a bad thing and something that should be dealt with. The problem here is that we rather need to be careful with our definitions. In certain circumstances a decline in biodiversity locally is exactly what we do want, for that’s what allows a global increase in it. Definitions matter.

Over the last two decades, approximately 20% of the earth’s vegetated surface has become less productive, said the report, launched on Friday.

Less productive at what? Supporting biodiversity? That might be something we desire. In the report itself this enlightening line:

.. in many production systems, transition to intensive production of a reduced number of species..

We’ve a name for intensive production of a reduced number of species. Farming. That’s actually what we’re trying to do with the practice, increase the output of selected species as against that of all others from the same area of land. We are deliberately reducing the biodiversity of that field being farmed, that’s the point of the exercise.

That’s also entirely desirable of course. For, the more efficiently, productively, we use each field we do use then the fewer fields in total we need to use. Meaning that more can be - and will be - left for nature to be ever so biodiverse in.

This is the old micro and macro of organic and industrial farming again. Organic allows more species to thrive alongside our food crops. Which is why we need to use more land for our food crops, leaving less for nature than industrialised farming does. We have more micro-biodiversity at the cost of less macro-.

Our definitions here matter. Which sort of biodiversity is it that people think important? Only once we know that can we begin to think through the solutions.