‘We must trigger social tipping points’

September 11, 2022 / activist360

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.”

How marsh grass could help protect us from climate change

October 24, 2021 / activist360 / Leave a comment

*Marshland in Holden Beach, USA, likely to have prevented storms and surges from having a worse impact in North Carolina. Photo by Steve Adams on Unsplash*

By David L. Chandler, World Economic Forum (Public License).

Coastal marsh plants provide significant protection from surges and devastating storms.
Research in MIT’s Parson’s lab can help coastal planners to take important details into account when planning projects.
Countries must take advantage of this modeling in order to restore marshland with specific plants in certain areas.

Marsh plants, which are ubiquitous along the world’s shorelines, can play a major role in mitigating the damage to coastlines as sea levels rise and storm surges increase. Now, a new MIT study provides greater detail about how these protective benefits work under real-world conditions shaped by waves and currents.

The study combined laboratory experiments using simulated plants in a large wave tank along with mathematical modeling. It appears in the journal Physical Review — Fluids, in a paper by former MIT visiting doctoral student Xiaoxia Zhang, now a postdoc at Dalian University of Technology, and professor of civil and environmental engineering Heidi Nepf.

“After a few years, the marsh grasses start to trap and hold the sediment, and the elevation gets higher and higher, which might keep up with sea level rise.”
—Xiaoxia Zhang, now a postdoc at Dalian University of Technology, and professor of civil and environmental engineering Heidi Nepf

A new MIT study provides greater detail about how thes protective benefits of marsh plants work under real-world conditions shaped by waves and currents. The simulated plants used in lab experiments were designed based on Spartina alterniflora, which is a common coastal marsh plant. Credit: Xiaoxia Zhang.

It’s already clear that coastal marsh plants provide significant protection from surges and devastating storms. For example, it has been estimated that the damage caused by Hurricane Sandy was reduced by $625 million thanks to the damping of wave energy provided by extensive areas of marsh along the affected coasts. But the new MIT analysis incorporates details of plant morphology, such as the number and spacing of flexible leaves versus stiffer stems, and the complex interactions of currents and waves that may be coming from different directions.

This level of detail could enable coastal restoration planners to determine the area of marsh needed to mitigate expected amounts of storm surge or sea-level rise, and to decide which types of plants to introduce to maximize protection.

“When you go to a marsh, you often will see that the plants are arranged in zones,” says Nepf, who is the Donald and Martha Harleman Professor of Civil and Environmental Engineering. “Along the edge, you tend to have plants that are more flexible, because they are using their flexibility to reduce the wave forces they feel. In the next zone, the plants are a little more rigid and have a bit more leaves.”

As the zones progress, the plants become stiffer, leafier, and more effective at absorbing wave energy thanks to their greater leaf area. The new modeling done in this research, which incorporated work with simulated plants in the 24-meter-long wave tank at MIT’s Parsons Lab, can enable coastal planners to take these kinds of details into account when planning protection, mitigation, or restoration projects.

“If you put the stiffest plants at the edge, they might not survive, because they’re feeling very high wave forces. By describing why Mother Nature organizes plants in this way, we can hopefully design a more sustainable restoration,” Nepf says.

Once established, the marsh plants provide a positive feedback cycle that helps to not only stabilize but also build up these delicate coastal lands, Zhang says. “After a few years, the marsh grasses start to trap and hold the sediment, and the elevation gets higher and higher, which might keep up with sea level rise,” she says.

Awareness of the protective effects of marshland has been growing, Nepf says. For example, the Netherlands has been restoring lost marshland outside the dikes that surround much of the nation’s agricultural land, finding that the marsh can protect the dikes from erosion; the marsh and dikes work together much more effectively than the dikes alone at preventing flooding.

But most such efforts so far have been largely empirical, trial-and-error plans, Nepf says. Now, they could take advantage of this modeling to know just how much marshland with what types of plants would be needed to provide the desired level of protection.

It also provides a more quantitative way to estimate the value provided by marshes, she says. “It could allow you to more accurately say, ‘40 meters of marsh will reduce waves this much and therefore will reduce overtopping of your levee by this much.’ Someone could use that to say, ‘I’m going to save this much money over the next 10 years if I reduce flooding by maintaining this marsh.’ It might help generate some political motivation for restoration efforts.”

Nepf herself is already trying to get some of these findings included in coastal planning processes. She serves on a practitioner panel led by Chris Esposito of the Water Institute of the Gulf, which serves the storm-battered Louisiana coastline. “We’d like to get this work into the coatal simulations that are used for large-scale restoration and coastal planning,” she says.

*This photo shows examples of Spartina alterniflora in China. Credit: Xiaoxia Zhang.*

“Understanding the wave damping process in real vegetation wetlands is of critical value, as it is needed in the assessment of the coastal defense value of these wetlands,” says Zhan Hu, an associate professor of marine sciences at Sun Yat-Sen University, who was not associated with this work. “The challenge, however, lies in the quantitative representation of the wave damping process, in which many factors are at play, such as plant flexibility, morphology, and coexisting currents.”

The new study, Hu says, “neatly combines experimental findings and analytical modeling to reveal the impact of each factor in the wave damping process. … Overall, this work is a solid step forward toward a more accurate assessment of wave damping capacity of real coastal wetlands, which is needed for science-based design and management of nature-based coastal protection.”

The work was partly supported by the National Science Foundation and the China Scholarship Council.

Antarctica Reveals Greater Urgency to Act on Climate Change

March 13, 2021 / activist360 / Leave a comment

The more we learn about Antarctica, the greater the urgency to act on climate change.

By John Letzing, Digital Editor, Strategic Intelligence, World Economic Forum (Public License).

A number of troubling discoveries have been made related to Antarctica.

Reports point to record ice shelf melt contributing to sea level rise.

Curbing emissions could limit the impact of warming on the continent.

In the pitch-black depths beneath 900 metres of Antarctic ice shelf, scientists recently made a curious discovery: something’s living down there.

The detection of sponges and other “unidentifiable” animals that defy established science is just one in a steady stream of revelations about a forbidding region. Frequently, these insights help build a stronger case for doing more to combat climate change.

Antarctica may be remote and desolate, but it could affect us all relatively soon. Sea levels are now expected to rise more quickly than had been anticipated as recently as 2019, and melting Antarctic glaciers and ice sheets are a contributing factor. The continent has been losing an estimated 150 billion metric tons of ice every year since 2002.

According to results published last week of a study that strapped sensors to seals, rapidly melting Antarctic glaciers are changing nearby ocean water more than realized – with implications for the climate and future sea level rise. A study published not long before that suggested the second-biggest ice shelf on the Antarctic peninsula experienced record melting during the 2019-2020 summer season.

Last year, it was discovered that the ice shelves making up about three-quarters of Antarctica’s coastline, and helping to hold glaciers in place, are melting faster than they’re being replenished. Ultimately, the continent holds enough ice to raise sea levels by 60 metres. Since 1880, global mean sea level has risen by only about 24 centimetres.

As ice departs from Antarctica it can be lethal; a massive iceberg that broke off an ice shelf more than three years ago was bearing down on South Georgia Island and its population of penguins before recently breaking up. Experts say a changing climate is pushing more ice to Antarctica’s edges, where it can encounter warming water and snap off.

Cast Adrift: Tracked Antarctic icebergs at least 15 nautical miles (27.8 km) long as of 5 March, including a remnant of A68A - the iceberg that threatened South Georgia Island. — Cast Adrift: Tracked Antarctic icebergs at least 15 nautical miles (27.8 km) long as of 5 March, including a remnant of A68A – the iceberg that threatened South Georgia Island.
Image: World Economic Forum

Earlier this month, an iceberg bigger than New York City broke off the Brunt Ice Shelf in Antarctica. Scientists say this was part of a natural process and didn’t have direct ties to climate change – though such “calving” events have become increasingly frequent.

Antarctica recorded its hottest days on record slightly more than a year ago, but conditions remain far from ideal for human activity (they are, however, great for preserving a lost wallet for a half-century). Still, changes in the region can impact more populated parts of the world in ways that go beyond rising sea levels.

For example, the polar vortex over Antarctica, a wind pattern driven by the contrast between the frigid pole and the warmth at lower latitudes, can impact temperatures and rainfall patterns in Australia; a weakened polar vortex can induce hot and dry extremes there.

There are a number of things just about anyone can do to help blunt the effects of climate change on Antarctica and the rest of the world, ranging from flying less to eating less meat. If we manage to cut emissions and hold warming to 2°C above pre-industrial levels, sea level rise by the end of this century could be just half of what it would be otherwise.

Source: "Four decades of Antarctica Ice Sheet mass balance from 1979-2017" Proceedings of the National Academy of Sciences, Jan. 2019. Image: World Economic Forum — *Source: “Four decades of Antarctica Ice Sheet mass balance from 1979-2017” Proceedings of the National Academy of Sciences, Jan. 2019. Image: World Economic Forum.*

The notion of ice melt in Antarctica contributing to sea level rise isn’t merely theoretical. A study published in 2019 estimated that a six-fold increase in yearly ice mass loss in Antarctica caused global sea levels to rise by more than half an inch between roughly the time Margaret Thatcher became prime minister in the UK, and Emmanuel Macron became the president of France.

For more context, here are links to further reading from the World Economic Forum’s Strategic Intelligence platform:

Scientists turned to seals for that Antarctic glacial meltwater study because harsh winter conditions limit the use of ships or planes to make observations, according to this report. Seven southern elephant seals and seven Weddell seals were deployed. (Science Daily)

The discovery of life 900 metres beneath Antarctic ice was an accident, according to this report – researchers had drilled a borehole in search of sediment samples, and instead found 13 sponges and 22 unidentifiable “stalked organisms.” (Big Think)

Australia’s plans to build an airport with a 2.7-kilometre paved runway in eastern Antarctica is deemed controversial, according to this report – due to its potential environmental impact, and “major” geopolitical concerns. (The Diplomat)

A recent study found that the West Antarctic Ice Sheet has declined steadily, as expected, but the East Antarctic Ice Sheet is far more sensitive to spikes in the weather than thought – which could make modelling of sea level rise more accurate, according to this report. (Eos)

This piece argues that preventive measures have to be taken to limit the impacts of climate change, tourism, fishing, and research infrastructure on the western Antarctic Peninsula – before it’s too late. (Nature)

According to this report, the ability of waves to transport large microplastics faster than previously thought helps us understand why they’re now found throughout the ocean – including around Antarctica. (The Conversation)

Turns out we may have had it all wrong when it comes to melting icebergs. This study found that while current models assume they melt uniformly, they actually do so at different speeds based on shape – a discovery that could help better assess climate change. (Science Daily)

On the Strategic Intelligence platform, you can find feeds of expert analysis related to Antarctica, Climate Change and hundreds of additional topics. You’ll need to register to view.