What does overshoot mean?

The Ecological Footprint shows that people are using the capacity of 1.5 Earths – but how can this be when there is only one Earth?

It's very easy to withdraw more money from a bank account than the interest this money generates. In the same way, it's possible to use renewable resources faster than they are being generated.

For example:
© Volker Kess / WWF / Jürgen Freund / Andrew Kerr / WW
Human activities contributing to ecological overshoot
© Volker Kess / WWF / Jürgen Freund / Andrew Kerr / WW

More wood can be taken from a forest each year than re-grows

More fish can be harvested each year than are replenished

More greenhouse gases can be emitted each year than vegetation can absorb

This is only possible for a limited time

If we keep on taking more renewable resources than can be replenished, then eventually they will become depleted.  

This has already happened locally in some places, for example the collapse of cod stocks in Newfoundland in the 1980s.

At present, people are often able to shift their sourcing when this happens – we go to a new fishing ground or forest, clear new land for farming, or target a different population or a still-common species.

But at current consumption rates, these resources will eventually run out too. Some ecosystems will collapse even before the resource is completely gone.

The consequences of excess greenhouse gases in the atmosphere are also already being seen, like climate change and ocean acidification. These place additional stresses on biodiversity and ecosystems.
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