Tag: Sea Level Rise

New Study Shows West Antarctic Ice Sheet Might Be Safer from Collapse This Century

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Lemaire Canal in West Antarctic
Glacier breaking edge in the Lemaire Canal. The Lemaire Canal is a narrow ship passage. It separates the island of Booth from the Antarctic Peninsula. Credit: W. Bulach, CC BY-SA 4.0, via Wikimedia Commons, December 8, 2005.

Some Climate Threats May Be Less Urgent, But Action Is Still Needed to Protect Ice Sheets

A recent study led by researchers at Dartmouth College brings some good news about the West Antarctic Ice Sheet, particularly Thwaites Glacier. Scientists have found that this massive ice sheet might be less likely to collapse during the 21st century than we previously feared. This discovery could mean that the threat of rapidly rising sea levels is not as immediate as some had thought.

What Is MICI and Why Does It Matter?

MICI stands for Marine Ice Cliff Instability. It’s a big concern in the world of climate science. The idea is that if the floating ice shelves around Antarctica collapse, they could expose tall ice cliffs. These cliffs might break apart quickly, leading to more ice melting and causing sea levels to rise around the world. Previous studies suggested that MICI could cause the West Antarctic Ice Sheet to collapse, leading to significant sea level rise by the end of this century.

How This Study Was Done

Scientists from several universities used advanced computer models to simulate what might happen to Thwaites Glacier if its ice shelf collapses. They applied new methods to gain a clearer understanding of the ice sheet’s stability. These models are more detailed and realistic than the ones used in older studies.

The new methods took into account how the ice both bends and breaks. This made the models more realistic in showing how the ice sheet might behave if the ice shelves collapse and tall cliffs are exposed.

The study also used more advanced and detailed models. By using three different models (ISSM, STREAMICE, and Úa), the researchers made sure their results were not limited to just one type of model. This approach gave a clearer picture of how stable the West Antarctic Ice Sheet might be, especially concerning MICI.

Key Findings: Less Risk of Collapse

The study’s results are reassuring. Even in the worst-case scenarios, where the ice shelf collapses completely, the models show that the glacier would likely remain stable throughout the 21st century. The exposed ice cliffs wouldn’t be tall enough to cause the runaway collapse that was previously feared.

Two important factors help keep the glacier stable:

  1. Faster Ice Movement: If the ice shelf collapses, the ice behind it would begin moving faster, which surprisingly helps prevent the cliffs from breaking apart.

  2. Thinning Ice: The ice near the front would become thinner, making the cliffs less likely to reach dangerous heights.

Why This Matters for Sea Levels

This study suggests that the scenarios where sea levels rise quickly due to the collapse of the West Antarctic Ice Sheet might not happen as soon as we thought. However, the scientists warn that other processes could still cause the ice to melt over the long term. We shouldn’t assume everything is fine, but it’s a relief to know that we might have more time to address these challenges.

Call to Action

This study is a reminder that while some climate threats may be less urgent than we feared, we still need to take action. Ice sheets like the West Antarctic are still at risk in the long run.

Morlighem, M., Goldberg, D., Barnes, J. M., Bassis, J. N., Benn, D. I., Crawford, A. J., Gudmundsson, G. H., & Seroussi, H. (2024). The West Antarctic Ice Sheet may not be vulnerable to marine ice cliff instability during the 21st century. Science Advances, 10(eado7794).

Ocean warming study so distressing, some scientists didn’t even want to talk about it

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Ship in the ocean, Hamburg, Germany. Photo by Martin Damboldt from Pexels.
Ship in the ocean, Hamburg, Germany. Photo by Martin Damboldt from Pexels.

“This is one of those ‘sit up and read very carefully’ moments,” said one science journalist.

By Julia Conley, Common Dreams

Scientists are so alarmed by a new study on ocean warming that some declined to speak about it on the record, the BBC reported Tuesday.

“One spoke of being ‘extremely worried and completely stressed,'” the outlet reported regarding a scientist who was approached about research published in the journal Earth System Science Data on April 17, as the study warned that the ocean is heating up more rapidly than experts previously realized—posing a greater risk for sea-level rise, extreme weather, and the loss of marine ecosystems.

Scientists from institutions including Mercator Ocean International in France, Scripps Institution of Oceanography in the United States, and Royal Netherlands Institute for Sea Research collaborated to discover that as the planet has accumulated as much heat in the past 15 years as it did in the previous 45 years, the majority of the excess heat has been absorbed by the oceans.

In March, researchers examining the ocean off the east coast of North America found that the water’s surface was 13.8°C, or 24.8°F, hotter than the average temperature between 1981 and 2011.

The study notes that a rapid drop in shipping-related pollution could be behind some of the most recent warming, since fuel regulations introduced in 2020 by the International Maritime Organization reduced the heat-reflecting aerosol particles in the atmosphere and caused the ocean to absorb more energy.

But that doesn’t account for the average global ocean surface temperature rising by 0.9°C from preindustrial levels, with 0.6°C taking place in the last four decades.

The study represents “one of those ‘sit up and read very carefully’ moments,” said former BBC science editor David Shukman.

Lead study author Karina Von Schuckmann of Mercator Ocean International told the BBC that “it’s not yet well established, why such a rapid change, and such a huge change is happening.”

“We have doubled the heat in the climate system the last 15 years, I don’t want to say this is climate change, or natural variability or a mixture of both, we don’t know yet,” she said. “But we do see this change.”

Scientists have consistently warned that the continued burning of fossil fuels by humans is heating the planet, including the oceans. Hotter oceans could lead to further glacial melting—in turn weakening ocean currents that carry warm water across the globe and support the global food chain—as well as intensified hurricanes and tropical storms, ocean acidification, and rising sea levels due to thermal expansion.

A study published earlier this year also found that rising ocean temperatures combined with high levels of salinity lead to the “stratification” of the oceans, and in turn, a loss of oxygen in the water.

“Deoxygenation itself is a nightmare for not only marine life and ecosystems but also for humans and our terrestrial ecosystems,” researchers from the Chinese Academy of Sciences, the National Center for Atmospheric Research, and the National Oceanic and Atmospheric Administration said in January. “Reducing oceanic diversity and displacing important species can wreak havoc on fishing-dependent communities and their economies, and this can have a ripple effect on the way most people are able to interact with their environment.”

The unusual warming trend over recent years has been detected as a strong El Niño Southern Oscillation (ENSO) is expected to form in the coming months—a naturally occurring phenomenon that warms oceans and will reverse the cooling impact of La Niña, which has been in effect for the past three years.

“If a new El Niño comes on top of it, we will probably have additional global warming of 0.2-0.25°C,” Dr. Josef Ludescher of the Potsdam Institute for Climate Research told the BBC.

The world’s oceans are a crucial tool in moderating the climate, as they absorb heat trapped in the atmosphere by greenhouse gases.

Too much warming has led to concerns among scientists that “as more heat goes into the ocean, the waters may be less able to store excess energy,” the BBC reported.

The anxiety of climate experts regarding the new findings, said the global climate action movement Extinction Rebellion, drives home the point that “scientists are just people with lives and families who’ve learnt to understand the implications of data better.”

‘We must trigger social tipping points’

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Photo by William Bossen on Unsplash
Photo by William Bossen on Unsplash

The risk of dangerous, cascading tipping points in natural systems escalates above 1.5°C of global warming, states a recent study.

By Yasmin Dahnoun, Ecologist (Creative Commons 4.0).

Multiple climate tipping points could be triggered if global temperature rises beyond 1.5°C above pre-industrial levels, according to a major new analysis published in the journal Science.

Even at current levels of global heating, the world is already at risk of triggering five dangerous climate tipping points, and risks increase with each tenth of a degree of further warming.

An international research team synthesized evidence for tipping points, their temperature thresholds, timescales, and impacts from a comprehensive review of over 200 papers published since 2008 when climate tipping points were first rigorously defined. They have increased the list of potential tipping points from nine to sixteen.

Die-off

The research concludes that we are already in the danger zone for five climate tipping points: melting of the Greenland and West Antarctic ice sheets, widespread abrupt permafrost thaw, the collapse of convection in the Labrador Sea, and massive die-off of tropical coral reefs.

The paper was published ahead of a major conference, Tipping Points: from climate crisis to positive transformation, at the University of Exeter, which will take place next week.

Four of these move from “possible” to “likely” at 1.5°C global warming, with five more becoming possible around this level of heating.

David Armstrong McKay, from Stockholm Resilience Centre, University of Exeter, and the Earth Commission, was the lead author of the report. He said: “We can see signs of destabilization already in parts of the West Antarctic and Greenland ice sheets, in permafrost regions, the Amazon rainforest, and potentially the Atlantic overturning circulation as well.

“The world is already at risk of some tipping points. As global temperatures rise further, more tipping points become possible. The chance of crossing tipping points can be reduced by rapidly cutting greenhouse gas emissions, starting immediately.”

Safe

The Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), stated that risks of triggering climate tipping points become high by around 2°C above preindustrial temperatures and very high by 2.5-4°C.

The new analysis indicates that earth may have already left a “safe” climate state when temperatures exceeded approximately 1°C above preindustrial temperatures.

A conclusion of the research is therefore that even the United Nations’ Paris Agreement goal to avoid dangerous climate change by limiting warming to well below 2°C and preferably 1.5°C is not fully safe.

However, the study provides strong scientific support for the Paris Agreement and associated efforts to limit global warming to 1.5°C, as while some tipping points are possible or likely at this temperature level, the risk escalates beyond this point.

Liveable 

To have a 50 percent chance of achieving 1.5°C and thus limiting tipping point risks, global greenhouse gas emissions must be cut by half by 2030, reaching net zero by 2050.

Co-author Johan Rockström, the co-chair of the Earth Commission and director of the Potsdam Institute for Climate Impact Research, said: “The world is heading towards 2-3°C of global warming.

“This sets earth on course to cross multiple dangerous tipping points that will be disastrous for people across the world.

“To maintain liveable conditions on earth, protect people from rising extremes, and enable stable societies, we must do everything possible to prevent crossing tipping points. Every tenth of a degree counts.”

Decarbonising 

Tim Lenton, director of the Global Systems Institute at the University of Exeter and a member of the Earth Commission, was a co-author of the report. He said: “Since I first assessed climate tipping points in 2008, the list has grown and our assessment of the risk they pose has increased dramatically.

“Our new work provides compelling evidence that the world must radically accelerate decarbonizing the economy to limit the risk of crossing climate tipping points.

“To achieve that, we now need to trigger positive social tipping points that accelerate the transformation to a clean-energy future.

“We may also have to adapt to cope with climate tipping points that we fail to avoid, and support those who could suffer uninsurable losses and damages.”

Collapse

Scouring paleoclimate data, current observations, and the outputs from climate models, the international team concluded that 16 major biophysical systems involved in regulating the earth’s climate (so-called “tipping elements”) have the potential to cross tipping points where change becomes self-sustaining.

That means even if the temperature stops rising, once the ice sheet, ocean, or rainforest has passed a tipping point it will carry on changing to a new state.

How long the transition takes varies from decades to thousands of years depending on the system.

For example, ecosystems and atmospheric circulation patterns can change quickly, while ice sheet collapse is slower but leads to an unavoidable sea-level rise of several meters.

The researchers categorized the tipping elements into nine systems that affect the entire earth system, such as Antarctica and the Amazon rainforest, and a further seven systems that if tipped would have profound regional consequences.

Interlinked 

The latter include the West African monsoon and the death of most coral reefs around the equator.

Several new tipping elements such as Labrador Sea convection and East Antarctic subglacial basins have been added compared to the 2008 assessment, while Arctic summer sea ice and the El Niño Southern Oscillation (ENSO) have been removed for lack of evidence of tipping dynamics.

Co-author Ricarda Winkelmann, a researcher at the Potsdam Institute for Climate Impact Research and a member of the Earth Commission, said: “Importantly, many tipping elements in the earth system are interlinked, making cascading tipping points a serious additional concern.

“In fact, interactions can lower the critical temperature thresholds beyond which individual tipping elements begin destabilizing in the long run.”