Sea-level rise ‘could last twice as long as human history’ | Environment | Damian Carrington, The Guardian

Research warns of the long timescale of climate change impacts unless urgent action is taken to cut emissions drastically Plastic waste near Dakar, Senegal. Around two-thirds of the national population lives in the Dakar coastal area, which is threatened by sea-level rise.

Huge sea-level rises caused by climate change will last far longer than the entire history of human civilisation to date, according to new research, unless the brief window of opportunity of the next few decades is used to cut carbon emissions drastically. Even if global warming is capped at governments’ target of 2C – which is already seen as difficult – 20% of the world’s population will eventually have to migrate away from coasts swamped by rising oceans. Cities including New York, London, Rio de Janeiro, Cairo, Calcutta, Jakarta and Shanghai would all be submerged. “Much of the carbon we are putting in the air from burning fossil fuels will stay there for thousands of years,” said Prof Peter Clark, at Oregon State University in the US and who led the new work. “People need to understand that the effects of climate change won’t go away, at least not for thousands of generations.” “The long-term view sends the chilling message of what the real risks and consequences are of the fossil fuel era,” said Prof Thomas Stocker, at the University of Bern, Switzerland and also part of the research team. “It will commit us to massive adaptation efforts so that for many, dislocation and migration becomes the only option.” The report, published in the journal Nature Climate Change, notes most research looks at the impacts of global warming by 2100 and so misses one of the biggest consequences for civilisation – the long-term melting of polar ice caps and sea-level rise. This is because the great ice sheets take thousand of years to react fully to higher temperatures. The researchers say this long-term view raises moral questions about the kind of environment being passed down to future generations. The research shows that even with climate change limited to 2C by tough emissions cuts, sea level would rise by 25 metres over the next 2,000 years or so and remain there for at least 10,000 years – twice as long as human history. If today’s burning of coal, oil and gas is not curbed, the sea would rise by 50m, completely changing the map of the world. “We can’t keep building seawalls that are 25m high,” said Clark. “Entire populations of cities will eventually have to move.” Advertisement By far the greatest contributor to the sea level rise – about 80% – would be the melting of the Antarctic ice sheet. Another new study in Nature Climate Change published on Monday reveals that some large Antarctic ice sheets are dangerously close to losing the sea ice shelves that hold back their flow into the ocean.

Read more: Sea-level rise ‘could last twice as long as human history’ | Environment | The Guardian

Author: Makere

A Maori/Scots New Zealander transplanted to Canada. Grandmother, academic, indigenous scholar, sometime singer, sometime activist, who cares passionately about our world.