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.

Predators have roamed the planet for 500 million years. The earliest is thought to be some type of simple marine organism, a flatworm maybe or type of crustacean, perhaps a giant shrimp that feasted on ancient trilobites. Much later came the famous predatory dinosaurs such as T. rex, and later still large toothed mammals such as sabre toothed cats or modern wolves. But one or two hundred thousand years ago, the world’s most powerful predator arrived. Us. We lacked big teeth or sharp claws, huge tentacles or venomous bites. But we had intelligence, and the guile to produce tools and artificial weapons. And as we became ever better hunters we started harvesting animals on a great scale. We wiped out the passenger pigeon, the dodo, the great herds of North American bison. Last century we decimated great whale populations. Today the world’s fishing fleets routinely take more fish than scientists say is sustainable, leading to crashes in cod numbers for example, while people kill more large mammals in North America than all other causes put together. But out of our mass consumption of the world’s fauna appears a curious conundrum.

India village in Rajasthan relocates to protect tigers