In recent years, an increasing number of researchers have argued that the changes made by human beings have been so great as to amount to a new geological epoch, the Anthropocene. By changing the composition of the atmosphere and the world’s land surfaces, as well as the flora and fauna of both land and sea - and by increasing our population sevenfold in 200 years - it is argued that our influence has been as great or greater than that of natural processes. An international working group has been set up to settle the question of how geology should understand the current period, and is due to report in 2016. As an article in Nature in March 2015 argued: ‘The formal establishment of an Anthropocene Epoch would mark a fundamental change in the relationship between humans and the Earth system.’

Undoubtedly, human beings have started to have a significant effect on the planet. Rising levels of carbon dioxide are widely regarded as being largely caused by humans burning fossil fuels. Some researchers point to other signs of human influence, like radioactive dust from atom-bomb tests. But does this effect really overwhelm natural forces? Others point out that temperatures today may be little different from earlier periods before humans existed. Wildlife and plants have appeared and disappeared at various stages of natural history. Two critics note that while the term ‘Anthropocene’ may have some use in wider culture, ‘we are taken aback by the claim that scientists currently have sufficient evidence to define a distinctive and lasting imprint of our existence in the geologic record’. Many of those with the greatest interest in declaring a new geological epoch also believe that the effect of human beings has been a negative one. They want to send out a warning that we need to minimise the human impact on the natural world. Yet we could also proclaim such a new epoch in more positive terms - humans are finally gaining some mastery over nature, with enormous benefits in terms of our health, prosperity and longevity.

Why is this debate happening now? Does it reflect an excessive gloominess about our influence, with human progress now routinely discussed as ‘impact’? Or is it a welcome corrective to a rapacious economic system that is taking a terrible toll on the world around us, and ultimately humanity itself?