Scientists may only be able to answer the really interesting questions about biodiversity and human society - such as what fraction of grasslands need to be protected if we are to secure water supplies- if and when they can standardise the observation of changes in biodiversity on a global scale.

This will be similar to what the climate change community did to standardise the measuring and monitoring of climate change variables in order to inform global policy-making.

There are, for example, 50 Essential Climate Variables that are all technically and economically feasible for systematic observation, underpinning the work of the United Nations Framework Convention on Climate Change (UNFCCC) and the Intergovernmental Panel on Climate Change (IPCC), explains Dr Bob Scholes, systems ecologist at the CSIR.

In a paper published in Science today, Scholes and 30 international scientists, led by Prof Henrique Miguel Pereira from the Centre for Environmental Biology of the University of Lisbon in Portugal, argue for a global system of harmonised observations to monitor biodiversity changes.

This global biodiversity monitoring system should be based on a set of essential variables that everyone agrees upon, and which are technically and economically feasible to measure.

According to one of the co-authors and an ecosystem services specialist at the CSIR, Dr Belinda Reyers, these variables (Essential Biodiversity Variables or EBVs) will provide the building blocks that need to be put in place so that scientists can answer the really interesting questions about the relationship between biodiversity and economic and social development.

Some of the suggested Essential Biodiversity Variables are, for example, the genetic diversity of selected wild and domestic species; the population abundances for groups of species representative of some taxa (e.g. birds); the three-dimensional structure of habitats; and the nutrient retention rate in sensitive ecosystems. These variables can be modelled globally, combining satellite remote sensing observations with local observations obtained by citizen scientists, and local, national and regional organisations.

According to Scholes, South Africa has a far better biodiversity observation system than most countries and, as a result, we have quite a defensible approach to, for instance, making decisions on the location of protected areas.

But, in the long term, it could be better: “The EBV approach shows how to take it beyond just 'what species occur where' down to the genetic level, where we can ask questions such as ‘how many rhino is too few?’ The approach also allows us to up it to the next level and ask questions about whole ecosystems, such as ‘what fraction of the grasslands need to be protected if we are to secure water supplies?’”

According to a media realise issued by GEO BON, the development of these variables will be crucial for robust calculation of the indicators to assess progress towards the 2020 targets of the Convention on Biological Diversity. They can also be used to develop scenarios for the future of biodiversity under different development policies.