On the same day as the new updated Planetary Boundaries analysis was published, two further closely related new studies came out as well: one on the ‘Great Acceleration’, the other on the Anthropocene’. Planetary boundaries, the Great Acceleration, and the Anthropocene are all basically parts of the same picture.

The Great Acceleration paper has the same lead author, Will Steffen, as the Planetary Boundaries update. It was published in ‘The Anthropocene Review’ – a journal with the peculiarity that its publishers (Sage) don’t allow subscriptions, despite three issues have appeared so far, because they haven’t decided how much to charge!

The new paper revisits an analysis originally published in 2004, which surveyed 24 important world trends – 12 in human activity and 12 in earth systems – over the whole period from the start of the industrial revolution (using the date 1750) right up to the latest available data at that time, 2000. The new analysis takes the story up to 2010.

What stands out most clearly is that ‘the Great Acceleration’ has kept on going. After fairly gentle upward curves in the graphs running from 1750 to 1950, the Acceleration then took off. Population has risen rapidly, world GDP continues to growth (the 2008 crash having made only a small dent in the trend), climate change continues, and ecosystems carry on to deteriorating. The other indicators highlighted reinforce this same picture.

However there are other features of the new analysis which are probably more interesting, as the Great Acceleration itself is fairly obvious, even though it might not be common knowledge how rapid it has been, or how recently in historical terms it has taken off. The update shows some intriguing exceptions to the general trends.

The rate of increase in land cultivated for agriculture is slowing down, as the amount of remaining suitable land declines. The number of large dams is no longer growing so rapidly, as it is limited by the number of large rivers. There has been a fall in the volume of fish caught in the oceans (and a shift to aquaculture) because of a reduction in wild fish stocks.   The stratospheric ozone layer has stabilised, due to international agreement to phase out CFCs. Population growth is no longer exponential, and there is now a possibility that world population might stabilise later this century.

This is a mixed bag. Some trends are slowing simply because the amount of space or scope for them is becoming used up. Some are slowing because of deliberate human activity – ozone being the prime example, with the possibility that population might eventually follow.

The other notable feature of the new analysis is the way in which the authors link it to the debate about the proposition that the Earth has now, as a result of human activity, entered a new geological period, the Anthropocene, in which human activity has become a major force in shaping the planet. The various features of the Great Acceleration tend to confirm this idea, because human impacts on the biosphere and atmosphere have grown to now be on a completely unprecedented scale.

Within that argument, there is another argument going on, which is about the date of the start of the Anthropocene. Some have proposed the industrial revolution as the starting point for this fundamental change. But the graphs indicate that a much more dramatic change set in around 1950, the beginning of the Great Acceleration. The paper says: “… the evidence of large-scale shifts in Earth System functioning prior to 1950 is weak. Of all the candidates for a start date for the Anthropocene, the beginning of the Great Acceleration is by far the most convincing from an Earth System science perspective.”

The same conclusion is reached, though from a different perspective, principally a geological one, by a different set of authors (though again they include Will Steffen), in a review of evidence about different possible start dates. In the journal ‘Quaternary International’, Jan Zalasiewicz et al. have published ‘When did the Anthropocene begin? A mid-twentieth century boundary level is stratigraphically optimal.’

The idea that the world is in a new geological era has not been officially accepted by the world’s geologists, but it may well become adopted in 2016, and even if it isn’t, it has already achieved widespread informal use, appearing in book titles, journal titles, and numerous articles and talks.

The paper considers three possible times – thousands of years ago (perhaps four thousand), the beginning of the industrial revolution, and the 1950ish ‘Great Acceleration’. The last of these has two important advantages as the starting point. It is a worldwide phenomenon, and also because of globalisation, it has been taking place at the same time in different parts of the world. As well as this, the appearance of nuclear materials from the first nuclear bomb explosion in 1945 has created a long-lasting geological marker, dispersed around the world, including “both poles and on all continents”, at a specific precise time. The article also lists several other possible markers from around the same time, reinforcing the argument. The conclusion proposed is therefore for 1945 as the beginning of the Anthropocene.

These two new papers, together with the Planetary Boundaries update, help to consolidate this set of ideas as an important guide to where we are now, not only in historical terms, but also in the long-term evolutionary process. It is only at that scale that it becomes possible to appreciate the significance of what is happening now.

Victor Anderson


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