Human impact affects Earth's global energy flow: study

London: The impact humans have made on Earth in terms of how they produce and consume resources has formed a 'striking new pattern' in the planet's global energy flow, according to a new study.

The research suggests that the Earth is now characterised by a geologically unprecedented pattern of global energy flow that is pervasively influenced by humans - and which is necessary for maintaining the complexity of modern human societies.

While analysing the Anthropocene phenomenon - an epoch where humans dominate the Earth's surface geology - researchers identified that human patterns of production and consumption are a key factor characterising the epoch, and when measured against the billion-year old patterns of planet Earth, they form a striking new pattern.

"Very big changes in our planet's pattern of biological production and consumption do not happen very often. The appearance of photosynthesis was one, about two and a half billion years ago," said Jan Zalasiewicz from University of Leicester in the UK.

"Then, a little over half a billion years ago, animals like trilobites appeared, to add scavengers and predators into a food web of increasing complexity," said Zalasiewicz.

"Other major events have happened since, such as five major mass extinctions, but even measured against these events, human-driven changes to production and consumption are distinctly new," he added.

"It is without precedent to have a single species appropriating something like one quarter of the net primary biological production of the planet and to become effectively the top predator both on land and at sea," said Carys Bennett from University of Leicester.

By digging phosphorus out of the ground and by fixing nitrogen out of the air to make fertilisers; and by exploiting hundreds of millions of years-worth of stored carbon-based energy in a still-accelerating trend, humans are increasing productivity well above natural levels - and directing much of it towards animals that have been re-engineered to suit our purposes.

"This refashioning of the relationship between Earth's production and consumption is leaving signals in strata now forming, and this helps characterise the Anthropocene as a geological time unit," said Zalasiewicz.

"It also has wider and more fundamental importance in signalling a new biological stage in this planet's evolution," he said.

According to researchers, recent changes in the Earth's biosphere, caused in part by human activity, are starting to become evident in rock and soil strata.

Unprecedented stratigraphic signals are challenging disciplines like geology and archaeology to assess such changes and put them in temporal context, relative to other major transitions in Earth's history, they said.

The findings were published in the journal Earth's Future.