Planetary Boundaries

It's a stressful time on Planet Earth. Uncertain. Challenging. Threatening...

It is also, still, a very beautiful time in a wondrous place...

This week I went to see the BBC feature film, Earth, on the big screen. Incredible cinematography, I am so glad I had the chance to see it in a theatre. In a loose kind of way, the film interweaves three main mother and offspring stories - a polar bear and her twins waking up after the winter hibernation to melting summer ice-sheets; an African Elephant and her calf on their annual Kalahari march to the Okavango in the hope of the flood that may or may not come; and a Humpback Whale and her calf trekking 4000 miles to the southern Ocean where increasing acidity is diminishing the blooming plankton that the whales and many other sea creatures depend on.

In this film, Earth landscapes, waterscapes and creatures are so rich, so alive, and seemingly, so plentiful, that you get caught up in a visual celebration of Natural splendour and abundance that is at odds with the warning narrative.

It is a reminder of today's connundrum - we are well-aware that we live on One Planet with finite "resources" that humans can tap for their growth and development. But, how finite is Earth? How limited are those "resources"?

Interestingly, these quantifying questions have been avoided by scientists and environmentalists, by journalists and politicians until very recently, when Johan Rockström and his colleagues from The Stockholm Resilience Centre ventured to define 9 Planetary Boundaries, and to present actual thresholds for 7 of them. (We have already long over-stepped 3 of these boundaries - which is critical because every boundary, of course, impacts on all the others. So even the 6 boundaries not yet breached, are significantly threatened and weakened.)

The authors offer the 9 Planetary Boundaries because quantifiable limits may well help us to be faster and firmer about finding the ways to carry on the business of being human in a safer space. But, of course, it is going to take a lot to get everyone to agree to what the limits actually are, or should be.

One of Nature's great life-enhancing principles is that it optimises the power of limits. One of human beings' great life-depleting attitudes is that we seem to regard limits as some kind of challenge to overcome so we can carry on doing whatever we like. We'll have to change our minds in order to find our prosperity and well-being within Planetary Boundaries. It means we need to harvest within the carrying capacity of soils and seas; we have to maintain an energy balance - we cannot use more than we add; we must function within a specific and strict range of temperatures conducive to Life.

The 9 Planetary Boundaries are:

• climate change
• rate of biodiversity loss (terrestrial and marine)
• interference with the nitrogen and phosphorus cycles
• stratospheric ozone depletion
• ocean acidification
• global freshwater use
• change in land use
• chemical pollution
• and atmospheric aerosol loading

A debate we don't really have time for is just begining. Thoughtful consideration about Planetary Boundaries could shift us into an appreciation of the real power of limits - that is, using them as devices for focus.

http://www.nature.com/ has a great set of articles including the authors' exposition and expert comments, go to: http://www.nature.com/news/specials/planetaryboundaries/index.html