The damaging climate consequences of carbon emissions will grow and persist for millennia

Boston: The damaging climate consequences of carbon emissions will grow and persist for millennia without a dramatic new global energy strategy, a new study has warned. Rising global temperatures, ice field and glacial melting and rising sea levels are among the climatic changes that could ultimately lead to the submergence of coastal areas that are home to 1.3 billion people today, researchers said.

"What our analysis shows is that this era of global warming will be as big as the end of the Ice Age. And what we are seeing is a massive departure from the environmental stability civilisation has enjoyed during the last 10,000 years of its development," said Jeremy Shakun from Boston College in US.

For the study, an international team of researchers generated new scenarios for temperature rise, glacial melting, sea-level rise and coastal flooding based on state-of-the-art climate and ice sheet models. They used a projected global output of 1,280 billion tonnes of carbon across the next few centuries, far below estimated reserves of at least 9,500 billion tonnes.

The projected consequences at this level of carbon emissions include an increase in the global average temperature, which will exceed the recognised 'guardrail' of two degrees Celsius, and melting of glaciers and the massive ice sheets of Greenland and Antarctica which will combine for a rise in sea levels of 25 metres, researchers said.

The study also found that coastal submersion could displace as many as 1.3 billion people worldwide, a number that now accounts for approximately 19 per cent of the world's population. As many as 25 'megacities' around the world could see rising oceans force at least 50 per cent of their populations from their homes and businesses, researchers said.

The perspective on the future-looking projections comes from looking back at the last Ice Age, which ended approximately 10,000 years ago. Researchers developed a clearer portrait of that era of glacial melting and how the climate responded to and recovered from than era of significant climatic changes.

They reconstructed a record of natural carbon emission, temperature rise, glacial melting and sea-level rise stretching back 20,000 years to the peak of the Ice Age. That paleo-climatological portrait shows, for example, that the sea-level rise of 130 meters required roughly 10,000 years to retreat as a stabilised climate emerged in which human civilisation has flourished.

"This gives us the opportunity to provide the long view on global temperature and sea level rise, from the end of the Ice Age to today and then onward another 10,000 years into the future," said Shakun. The findings hold implications for policy makers because the projections reveal the intractability of a climate change across millennia, researchers said. The findings were published in the journal Nature Climate Change.