Climate guru James Hansen warns of much worse than expected sea level rise | Environment | The Guardian

The current rate of global warming could raise sea levels by “several meters” over the coming century, rendering most of the world’s coastal cities uninhabitable and helping unleash devastating storms, according to a paper published by James Hansen, the former Nasa scientist who is considered the father of modern climate change awareness. The research, published in Atmospheric Chemistry and Physics, references past climatic conditions, recent observations and future models to warn the melting of the Antarctic and Greenland ice sheets will contribute to a far worse sea level increase than previously thought. Sea level rise is accelerating; how much it costs is up to us.

Without a sharp reduction in greenhouse gas emissions, the global sea level is likely to increase “several meters over a timescale of 50 to 150 years”, the paper states, warning that the Earth’s oceans were six to nine meters higher during the Eemian period – an interglacial phase about 120,000 years ago that was less than 1C warmer than it is today. Global warming of 2C above pre-industrial times – the world is already halfway to this mark – would be “dangerous” and risk submerging cities, the paper said. A separate study, released in February, warned that New York, London, Rio de Janeiro and Shanghai will be among the cities at risk from flooding by 2100. Hansen’s research, written with 18 international colleagues, warns that humanity would not be able to properly adapt to such changes, although the paper concedes its conclusions “differ fundamentally from existing climate change assessments”. The IPCC has predicted a sea level rise of up to one meter by 2100, if emissions are not constrained. Hansen, and other scientists, have argued the UN body’s assessment is too conservative as it doesn’t factor in the potential disintegration of the polar ice sheets. Hansen’s latest work has proved controversial because it was initially published in draft form last July without undergoing a peer review process. Some scientists have questioned the assumptions made by Hansen and the soaring rate of sea level rise envisioned by his research, which has now been peer-reviewed and published.

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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

World Is Locked into About 1.5°C Warming & Risks Are Rising, New Climate Report Finds

In the Andes of South America and across the mountains of Central Asia, the glaciers are receding. As temperatures continue to warm, their melting will bring more water to farms and cities earlier in the growing season, raising the risk of damaging floods. Within a few decades, however, the risk of flood in these areas will become risk of drought. Without action to stop the drivers of climate change, most of the Andean glaciers and two-thirds of Central Asia’s glaciers could be gone by the end of the century.These changes are already underway, with global temperatures 0.8 degrees Celsius above pre-industrial times, and the impact on food security, water supplies and livelihoods is just beginning.A new report explores the impact of climate change in Latin America and the Caribbean, the Middle East and North Africa, and Eastern Europe and Central Asia and finds that warming of close to 1.5°C above pre-industrial times is already locked into Earth’s atmospheric system by past and predicted greenhouse gas emissions. Without concerted action to reduce emissions, the planet is on pace for 2°C warming by mid-century and 4°C or more by the time today’s teenagers are in their 80s.The report warns that as temperatures rise, heat extremes on par with the heat waves in the United States in 2012 and Russia in 2010 will become more common. Melting permafrost will release methane, a powerful greenhouse gas that will drive more warming in a dangerous feedback loop. Forests, including the Amazon, are also at risk. A world even 1.5°C will mean more severe droughts and global sea level rise, increasing the risk of damage from storm surges and crop loss and raising the cost of adaptation for millions of people.

Source: World Is Locked into About 1.5°C Warming & Risks Are Rising, New Climate Report Finds