There have been a few times in the history of mankind when we nearly died out as a species. Anthropologists call these events “bottlenecks”, times when the population of humans shrank – perhaps to as few as 2,000 people over 50,000 years ago. At those levels, we would be categorised as an endangered species on the IUCN Red List, existing in even fewer numbers than wild tigers do today. We survived, and in fact we’ve thrived, mainly because we adapted our environment to suit our needs. But to what degree has the survival and triumph of our species changed our planet? The best people to answer this could well be those who have the grandest perspective. Geologists can take a 4.5-billion-year step back and look at the human impact on our planet in the context of its long history – they can identify changes in the rock record within layers of deposited sediments that build up and are compressed over time.

At the Planet Under Pressure conference in London, Diana Liverman and Will Steffen present something of a contrasting couple.

The two professors have been working together on a State of the Planet report, which has involved trawling through numerous reports and scientific papers. At the end of it all, the message of one appears somewhat optimistic, the other fundamentally pessimistic. They agree that changes to the world since about 1950 have been startling - rapid spread of the human population, accelerating exploitation of forests and marine resources, surging economic growth in successive waves across the world, and so on. This radical reshaping of the natural world by a single species is certainly unprecedented in Earth history, which a few years back led to scientists Paul Crutzen and Eugene Stoermer coining a special name for our epoch - the Anthropocene.

    There is increasing demand for the continent's limited water resources, the report warns

Continued inefficient use of water could threaten Europe's economy, productivity and ecosystems, a report has warned.