Evidence is mounting that several Earth systems are on the verge of breaching their tipping points. Scientists warn that triggering them poses grave threats for our planet’s life-support systems. There is still a window of opportunity to prevent this breach but it’s closing faster than we realise.
Evidence is mounting that several Earth systems are on the verge of breaching their tipping points. Scientists warn that triggering them poses grave threats for our planet’s life-support systems. There is still a window of opportunity to prevent this breach but it’s closing faster than we realise.
Tap the + signs to read more about each tipping point.
They cover barely 0.2% of the seafloor, yet these underwater oases are home to more than a quarter of the world’s marine species. There has been relatively little bleaching of corals in South Africa. But as the planet continues to warm, there is concern that Africa’s southernmost coral reefs are also edging towards a tipping point.
By Tony Carnie
Sheltering and feeding a multitude of fish and other sea creatures that cluster around their countless nooks and crannies, coral reefs are a vibrant jungle of life and colour.
They cover barely 0.2% of the seafloor, yet these underwater oases are home to more than a quarter of the world’s marine species. They help to feed and support hundreds of millions of coastal folk around the world, contributing $375-million in ecosystem services and resources annually.
But their location along shorelines also exposes them to a wide variety of human pressures. Quite apart from the growing stream of sewage and chemical pollution or unsustainable fishing practices, there is a bigger but less visible threat to the very foundation of these underwater jungles.
Though they have evolved and adapted to live within a specific climatic range, corals are now especially vulnerable to the steady increase in global sea water temperature, as reported in a succession of expert scientific reports from the Intergovernmental Panel on Climate Change (IPCC).
Corals can tolerate temperature variations between the winter and summer months, but there comes a point when corals are overwhelmed by sustained periods of abnormal heating and begin to “bleach”.
Mass coral bleaching is caused by unusually high water temperatures that stress corals. Coral polyps will expel the symbiotic algae that live in their tissues, exposing the white skeleton underneath. Corals typically recover from mild bleaching, gradually recovering their colour by repopulating their algae. However, if the bleaching is severe or prolonged, individual polyps or whole colonies will die. (Source: National Oceanic and Atmospheric Administration/NOAA)
According to the IPCC, the ocean has absorbed more than 90% of the additional heat accumulated in the atmosphere by the greenhouse effect since the industrial revolution.
The expert panel concludes that marine heat waves have become more frequent over recent decades and they are projected to “become commonplace, and will likely push marine organisms and ecosystems to the limits of their resilience”.
Marine ecologist Dr Sean Porter likens coral reefs to canaries in a coal mine — a natural early-warning system that can alert scientists to the onset of wider-scale harm to the marine ecosystem.
These projections by the IPCC have also been borne out by a visible increase in the number of coral bleaching events in several parts of the world.
As far back as the late nineteen eighties, scientists began to study bleaching along the coast of California. But the issue really began to capture public attention after the first global-scale bleaching event was reported in 1998. This was followed by the 2014–2017 global coral-bleaching event, which killed corals and other reef organisms over thousands of square kilometres.
Two years ago, Kenyan marine biologist Dr David Obura and colleagues warned that — with up to 50% of the world’s coral reefs already degraded, and with 14% lost over the last decade — the weight of evidence suggests that there is now a “window of only several decades before (the) collapse of these flagship ecosystems”.
Closer to home, there has been relatively little bleaching of corals in South Africa, until recently. But now, as the planet continues to warm, there is concern that Africa’s southernmost coral reefs are also edging towards a tipping point.
Climate tipping points are critical thresholds in Earth systems which, if exceeded, can lead to significant and possibly irreversible changes. For example, a relatively small rise in global temperatures due to fossil fuel burning can flick a switch, triggering a rainforest into becoming a dry savannah. Crossing one harmful tipping point could trigger others, causing a domino effect of accelerating and unmanageable change to humanity’s life-support systems.
Marine ecologist Dr Sean Porter likens coral reefs to canaries in a coal mine — a natural early-warning system that can alert scientists to the onset of wider-scale harm to the marine ecosystem.
Because corals are very sensitive to changes in the marine environment — especially water temperature — coral reefs could become one of the first ecosystems to go extinct, suggests Porter, a senior scientist and reef ecologist at the Durban-based Oceanographic Research Institute (ORI).
Back in 1998, during the first documented global bleaching event, only negligible bleaching was recorded on the high-latitude coral reefs of Maputaland that form part of the iSimangaliso Wetland Park and World Heritage site.
While some reefs along the East African coast experienced up to 90% mortality due to bleaching in 1998, less than 1% of the hard corals around Sodwana Bay were visibly bleached.
Subsequently, in 2000, 2005 and 2016, approximately 10% of the coral cover at Sodwana Bay has shown signs of bleaching. The most recent bleaching event in 2016 coincided with an extended El Niño phase, and highlighted the vulnerability of iSimangaliso’s coral reefs to temperature-related stress. With 2023 the warmest year on record, widespread coral bleaching also happened in the northern hemisphere during the boreal summer.
Worryingly, recent research by Porter, Professor Michael Schleyer and Masters student Tanja Hanekom, suggests that the negative effects of global warming on local coral reefs in iSimangaliso are likely to be discernible as early as 2028, when the monthly average temperature in February is forecast to reach 28.8°C (based on the “intermediate” climate modelling scenario RCP 4.5).
This critical temperature threshold of 28.8°C is the point at which local corals begin to experience heat stress that induces bleaching, in a region where average water temperatures over the last 25 years have been just over 24°C.
Porter explains that if anomalously high temperatures are sustained over a period of weeks, corals will generally turn white and slowly die, whereas corals can still potentially recover if the temperature spikes are brief.
As part of the research project, scientists collected samples of hard and soft corals from Two-Mile Reef off Sodwana Bay, and then studied their responses to projected temperature changes in the ORI research aquarium in Durban.
They concluded that monthly average temperatures of 28.8°C or more within a particular year are predicted to be reached for three consecutive years by 2041, under the RCP 4.5 climate change scenario. This was “likely to have devastating consequences on several coral physiological parameters, and by virtue, coral reef communities at large”.
However, cautions Porter, there is still no certainty about how greenhouse gas levels will rise globally over the coming decades, while global climate model forecasts also have their limitations, and there is further uncertainty about the adaptive potential of corals to thermal anomalies induced by marine heat waves and global warming.
“We have been monitoring corals off Sodwana for 31 years, but it’s an extremely difficult question to answer with any certainty,” he says, in response to a Daily Maverick query about when South Africa’s coral reefs are likely to reach a tipping point.
Recent research has also detected high levels of organochlorine pesticides in soft corals from Maputaland, which could potentially reduce their resilience to global warming, further complicating forecasts on when local coral reefs are likely to be significantly impacted by climate change.
In a recent interview with The Guardian, Australian marine biologist and climate scientist Prof Ove Hoegh-Guldberg suggested that the coral reefs of the world are headed for “catastrophe” at the current level of unmitigated carbon emissions.
“It only has to be 1°C warmer than the summer maxima for about six weeks before you get a bleaching event… There are no good solutions at the moment, so it’s a fight that we are losing.”
Spanish marine biologist Prof Carlos M Duarte has taken a somewhat more optimistic view on whether it’s still possible to rescue corals — as well as other threatened vital marine ecosystems such as seagrasses.
Duarte says that seagrass meadows occupy only 0.1% of the global seafloor, yet remove nearly a third of all the carbon sequestered on the seafloor annually.
“One hectare of seagrass sequesters as much as 15ha of pristine Amazonian forest,” he says, highlighting their critical role in capturing and storing carbon emissions.
Four years ago, Duarte helped to establish the Coral Research & Development Accelerator Platform, a global initiative to develop and scale up technologies to save the world’s corals.
They include a project by Nicole Fogarty of the University of North Carolina to use cutting-edge genetic engineering technologies (such as whole-genome sequencing and CRISPR) to identify and insert specific genes into corals, in an effort to make them more tolerant of the rising ocean temperatures.
Researchers from the California Academy of Sciences hope to build a new coral rearing lab in Honduras, which will serve as a training centre for coral husbandry and assisted sexual reproduction.
A Columbian researcher will receive funding to develop a probiotic to boost the immune responses of corals to resist stony coral tissue loss disease, a highly lethal disease first reported off the coast of Florida in 2014 that has since spread rapidly throughout the Caribbean.
The urgency of finding a solution to the global crisis is further underlined by the fact that a tipping point for corals could cascade to affect other marine ecosystems — and humanity.
The University of Exeter Global Tipping Points report published in December notes that: “If reefs are forced by climate change into low-productivity states, and if these states in turn force fish communities across a tipping point into a less diverse and less productive state, many coastal human communities will be forced to modify their lifestyles in significant ways.”
Such changes could in turn lead to tipping points for human society, because fish and corals are central to the nutrition, income and social dynamics of numerous coastal communities, globally. DM
Climate change looms large over our planet with one of its most concerning threats being the predicted melt of the Greenland Ice Sheet, a massive expanse covering most of Greenland and the largest ice mass in the Northern Hemisphere.
By Kristin Engel
A view of Rimfaxe glacier on the King Frederick VI Coast in the Sermersooq municipality, taken from a commercial aircraft at 40,000ft, on September 24, 2023 over southeastern Greenland. The Rimfaxe glacier flows roughly southeastward between high peaks and has its terminus in the Sehested Fjord shortly after its confluence with the Guldfaxe Glacier that joins it from the west. (Image: Jim Dyson/Getty Images)
A view of Rimfaxe glacier on the King Frederick VI Coast in the Sermersooq municipality, taken from a commercial aircraft at 40,000ft, on September 24, 2023 over southeastern Greenland. The Rimfaxe glacier flows roughly southeastward between high peaks and has its terminus in the Sehested Fjord shortly after its confluence with the Guldfaxe Glacier that joins it from the west. (Image: Jim Dyson/Getty Images)
It harbours enough frozen water to raise sea levels by seven metres if it were to melt completely by 2100. And, according to the National Oceanic and Atmospheric Administration’s Arctic report card for 2023, it already has had a global impact on people and the environment through habitat loss, coastal erosion, saltwater intrusion, increased flooding and in some areas, permanent inundation.
The idea of such a collapse might have seemed far-fetched in the past, but increasing studies, research and lived experience point to a concerning reality that rising global temperatures and greenhouse gas emissions are endangering the stability of the Greenland ice sheet.
While historically durable, climate scientists warn that the ice sheet’s equilibrium is being jeopardised as feedback mechanisms that previously stabilised it have started to reverse. These include the loss of protective ice shelves, surface melting and glacier retreat.
In recent months research into this melt has pointed to an alarming trend. According to research published in the journal Nature, almost all Greenland’s glaciers have thinned or retreated over the past few decades, which has increased the rate of sea level rise (SLR), accelerated glacier thinning, and had an impact on climate change globally.
Another study published in February found that large tracts of the ice sheet that melted in Greenland were now supporting vegetation as the ecosystem has changed with vast tracts of ice replaced by ponds, bare rock and shrubbery.
Professor Pedro Monteiro, from the Stellenbosch University School for Climate Studies, told Daily Maverick there are two steps in the impact of the collapse of Greenland ice sheets and ice shelves on sea level rise. He said the collapse of the ice shelves can affect sea level rise by about 1.5m whereas the ice sheets can cause sea level rise of up to seven metres.
Monteiro warned that essentially all land less than 7m above sea level would be under threat should this tipping point be breached, but the actual impact would depend on the rate of collapse versus the rate and capacity of major adaptation.
“The collapse of the Greenland ice sheet goes beyond SLR to impact the large-scale ocean circulation (meridional overturning circulation, or MOC) by changing the density of surface water in the North Atlantic Ocean.
“This could shut the MOC that re-distributes heat towards the high latitudes, which could result in the enhanced warming of the Southern Ocean and the associated collapse of the Antarctic ice shelves—another tipping point. So one tipping point could initiate a series of global tipping points,” he said.
David McKay, a climate-biosphere scientist working as a Research Impact Fellow at the University of Exeter’s Global Systems Institute helping to lead the Global Tipping Points Report, explained that despite forming during colder “glacial” periods, the Greenland Ice Sheet remained stable during the warmer Holocene of the past few thousand years.
However, if temperatures get too high, he said the ice sheet feedback mechanisms could go into further reverse and destabilise the ice sheet instead – as melt increases the ice sheet loses mass and its height falls, dropping its surface into warmer air which further amplifies melting, while the ice sheet getting smaller exposes more bare ground around it that absorbs more heat and raises local temperatures too.
“Scientists think there’s a warming level beyond which the Greenland Ice Sheet would start to lose mass irreversibly until it reaches a small fraction of its current size, and that this threshold lies somewhere between around one and three degrees of global warming (with a best estimate of beyond 1.5C),” he said.
Economist Anton Cartwright, a researcher at the University of Cape Town’s African Centre Cities and author of the first series of studies on the impacts of sea level rise in Cape Town, told Daily Maverick that sea level rise was the supertanker of climate change.
“It is slow to start but will carry on long after atmospheric temps stop warming. The oceans will keep rising over the rest of this century… It’s already very hard to stop, and it’s going to carry on causing risks long after the atmosphere has stopped warming. That’s because of the energy transfer between the atmosphere and the ocean,” he said.
The difficulty was that the sea was never level, there were tides, winds, currents, and storms to consider as well. But around Cape Town, Cartwright said that about 12 to 14 centimetres of sea level rise had already happened over the past 50 to 100 years.
“That doesn’t sound like very much, but we are going to keep having more – even if we’re going to stop atmospheric warming tomorrow, we’ll [still lose] probably 40 centimetres by 2050 or so,” he said.
Losing 7m by 2100 is unthinkable, but Cartwright warned that should this materialise, the V&A Waterfront, Seapoint Promenade (and half of Sea Point), as well as the Durban harbour would be submerged. He indicated that in fact, the Cape Peninsula would become an island at about 16 metres.
“I don’t expect to see 7m in my lifetime as a 51-year-old but we should be planning for that in our long-term planning,” he said.
Monteiro warned that the Greenland Ice Sheet tipping point referred to the irreversibility of the destruction of the ice sheet regardless of the mitigation measures.
However, he cautioned that the timescale was uncertain. “It could take decades to centuries (called deep uncertainty). [But] effectively we are committing the planet’s coastal environments to seven-plus metres of SLR.”
Monteiro warned that arresting warming to less than 1.5 °C was the most important intervention to prevent catastrophic climate change across the board.
Cartwright agreed, saying it would be extremely difficult to tell when and whether we have already reached the Greenland ice sheet collapse tipping point… “by the time you know for sure it’s too late”.
“We’ve got to get to net zero by 2050. We’re not on track, but it’s not impossible… That then gives us a chance on all these tipping points. We don’t know if we have crossed the tipping point… but Net zero by 2050 gives us a chance.”
If a complete collapse of the Greenland Ice Sheet were ever realised, Cartwright said that more people, agriculture and coastal areas would be at risk. “We’re already seeing more permanent flooding sooner than expected,” he said.
According to McKay, places most affected would include small island states like the Maldives, Palau, and Kiribati which face considerable land loss this century and total loss in the long term.
Megacities like Bangkok, Ho Chi Minh City, Mumbai, Shanghai, London or New York would require expensive investment for protection and in the long-term possible relocation.
Coastal breadbasket regions like the Mississippi, Mekong, and Nile Deltas face yield decline from flooding, salt damage and eventual disappearance, and many coastal ecosystems like mangrove forests risk being lost as well.
McKay said that South Africa was not as exposed to sea level rise as some of these places, but regional factors are likely to amplify South Africa’s future sea level rise beyond the global average.
“As such, amplified SLR still poses a growing threat to its coastlines requiring coastal municipalities like Cape Town, Gqeberha, and Durban to escalate infrastructure investment and possible loss in the longer term,” he said.
Dr Melanie Lück-Vogel, a senior researcher with the coastal systems research group at the Council for Scientific and Industrial Research, said sea level rise would permanently flood low-lying coastal infrastructure, and as South Africa’s coast was relatively steep, permanent flooding would mainly affect estuaries and areas like Wilderness and the wider St Lucia area.
“Permanently elevated sea levels will lead to storm surges reaching further inland, thus potentially also affecting houses and infrastructure which are currently not affected by coastal storms,
“While residential infrastructure is one concern, traffic and service infrastructure will be affected as well, such as road and railways, power and sewage treatment infrastructure and ports, which will have a major economic impact if damaged and will require major adaptation actions, optimally relocation,” she said.
Beyond sea level rise impacts, McKay said extra meltwater from ice melt could also disrupt ocean circulation in the North Atlantic, which could shift weather patterns in Europe and tropical monsoon regions with substantial implications for global food security.
Experts and scientists warned that the main way to stop the Greenland Ice Sheet collapse remained halting the adding greenhouse gases to the atmosphere as soon as possible.
They said that holding global warming to 1.5°C or lower would give us the best chance to prevent tipping, which would require emissions to halve by 2030 and reach zero around 2050.
However, McKay warned that global warming had reached around 1.25°C already, and the remaining “carbon budget” for 1.5°C – how much more carbon dioxide could be emitted before 1.5°C was locked in – would be used up in only six years at current rates, with 1.5°C likely to be reached in the early 2030s.
“A silver lining though is that ice sheet tipping takes a long time to start, and so it may be possible to “overshoot” 1.5°C for a few decades and still prevent tipping if temperatures fall back below 1.5°C before the century’s end.
“We also don’t know exactly what the ice sheet’s tipping threshold is – it could be a little lower or higher, which may give some wriggle room if we’re lucky. This means that even if 1.5°C is breached we can still have a shot at preventing ice sheet collapse by stopping emissions as soon as possible,” McKay said. DM
It plays a crucial role in stabilising the global climate, and acts as a giant carbon sink, absorbing massive amounts of carbon dioxide from the atmosphere. But the vast, oxygen-producing rainforest could be running out of breath.
By Don Pinnock
Image: Tom Fisk/Pexels
Image: Tom Fisk/Pexels
The latticed steel tower vaulting up from the gloomy forest floor through the canopy high overhead was reminiscent of something, but the memory wouldn’t form. Halfway up the gantry it did: it was Enid Blyton’s fabulous children’s story, The Magic Faraway Tree.
That takes place in an enchanted wood in which a gigantic tree grows. It’s so tall that its topmost branches reach through the clouds and into strange lands that settle for a time overhead, then move on. Each time the children climb, what they find is something completely unexpected.
Slogging up past massive trunks, I had no idea what to expect. The “land” of the Amazon is all in the canopy, a zone of leaves about seven metres deep. Finally pushing through large drip-tip leaves and cloying humidity into sunlit sky, what lay all around to the horizon in every direction was beyond imagining. It was like endless, mist-laced broccoli in many shades of green, dotted with pink and yellow blooms of ipê trees, all entangled in colourful lianas and saturated with life.
Rainbow-coloured parrots and toucans squawked and chatted and below their glidepaths, the trees rippled with capuchin, squirrel, saki and spider monkeys. Heard but not seen were the eerie calls of howler monkeys, the loudest land animal on earth. In a single tree, scientists have discovered 950 species of beetle.
Before me was a crucible of earth’s biodiversity, a vast treasure trove of life, huge, beautiful and possibly dying. It was hard to take in. My eyes welled up at the immensity and glory of this mysterious rainforest and its fragility.
Back down on the gloom-shrouded ground felt like being underwater. The forest seemed both alien and like home. Something deep in my psyche knew this was the sort of place in which we became Homo sapiens.
I’d flown in to Puerto Maldonado the day before from Cusco in Peru, cresting the spiky Andes and diving down into the headwaters of the great Amazon River. From the airport we loaded our bags onto a narrow wooden canoe, powered by what seemed to be a lawnmower on a pole for the trip downriver, amid clouds of bright butterflies. Some of us were going to meet ayahuasca shamans who would take them on journeys of another sort; I was headed to a research camp for a few days of Amazon immersion. A love affair was being born.
The Amazon is a big, old forest which has been around for 65 million years. It is estimated to contain 390 billion trees made up of 16,000 species, which hold around 120 billion tonnes of carbon. Flitting among them are 2,500 butterfly, 806 bird and 293 mammal species, plus 22 different nationalities that all speak a different language.
The problem is that the rest of us humans are placing this amazing place under severe threat. This is not a good thing, because forests are the second biggest oxygen factory on the planet (phytoplankton are the biggest) and the Amazon holds enough carbon, if released, to cook the earth through global warming.
A paper, Critical Transitions in the Amazon, just published in the journal Nature by a team of researchers from Brazil, US, UK, Germany and the Netherlands warns that climate change, combined with deforestation and water stress, is pushing the Amazon to a tipping point. It’s moving towards a fragile situation where just a small disturbance could cause an abrupt shift in the state of the ecosystem, leading to partial collapse. By 2025, say the researchers, up to half of what’s termed “the lungs of the Earth” could be beyond repair.
The Amazon plays a crucial role in stabilising the global climate. It acts as a giant carbon sink, absorbing vast amounts of carbon dioxide from the atmosphere. But logging, mining, agriculture and oil extraction are leading to deforestation.
Reducing the forest cover diminishes its moisture feedback loop, leading to drier conditions and making the remaining forest more susceptible to fire and further deforestation.
When large swathes of rainforest are cleared, it disrupts the regional hydrological cycle. Trees in the Amazon release vast amounts of water into the atmosphere through transpiration. This not only supports forest sustainability, but feeds rainfall across South America and helps stabilise the Earth’s climate.
Climate change adds to the problem by increasing the frequency and intensity of droughts, which weaken the forest’s resilience, increasing the likelihood of its transition to a savannah-like state.
The research published in Nature estimates that by 2050, between 10% and 47% of Amazonian forests will be exposed to disturbances that could trigger “unexpected ecosystem transitions”.
Source: Amazonia for Life
“The Amazon biome has already lost 13% of its original forest area due to deforestation (or 15% if we consider young secondary forests). Among the remaining old-growth forests, at least 38% have been degraded by land use disturbances and repeated extreme droughts.”
Satellite observations confirm that the rainforest is also steadily warming and, in the dry season, is more than 20C higher than 40 years ago. According to the study, aircraft measurements show that southeast Amazon forests are now emitting more carbon than they absorb, probably because of deforestation and fire.
A big problem is that road networks are being carved into the forest. These facilitate illegal activities, promoting more deforestation, logging, agricultural activities and fire spreading throughout the core of the Amazon.
The extent of the fires hit home in 2019 when winds brought smoke from forest fires into São Paulo. It was so thick that afternoon skies were darkened and streetlights had to be switched on.
Another study, published in Science Advances, notes that though tipping points are hard to predict over an area as large as the Amazon, there are early signs that such points are approaching. The study likens it to the wobble of a spinning top before it falls over.
One indicator of the wobble is that the dry season now lasts 15 days longer than it used to. In Bolivia, destruction through mainly oil extraction is close to tipping point, with 24% of the country’s Amazon devastated. A report by Amazonia For Life estimates that oil fields in the rainforest now cover 80 million hectares.
Rising CO2 levels are good for trees, which need it to grow. Today’s vast coal deposits are the result of massive forests that covered the earth when carbon levels were much higher than today. The Amazon is benefiting from our production of CO2, but the gains are unfortunately probably more than offset by logging and fires.
The map above shows parts of the Amazon forest that have been destroyed by deforestation, fires and other causes. (Source: Amazon at risk ~Amazonia For Life Project)
The map above shows parts of the Amazon forest that have been destroyed by deforestation, fires and other causes. (Source: Amazon at risk ~Amazonia For Life Project)
The good news, however, is that forest loss in the Brazilian Amazon (nine countries make up the Amazonian basin) fell by about 60% from July 2023, after the new administration led by Luiz Inácio Lula da Silva took power in Brazil with a pledge to protect the forest.
In 2021 the 60 member states of the International Union for Conservation of Nature signed off on a commitment to protect 80% of the Amazon by 2025. It’s a target unlikely to be reached, but it focussed attention on the fact that what happens in the Amazon is not a local but global issue.
The forest’s best guardians, according to the Nature report, are indigenous peoples and local communities who are key to maintaining the ecosystem’s resilience to global change.
“Humans have been present in the Amazon for at least 12,000 years and extensively managing landscapes for 6,000 years. By creating new cultural niches, humans partly modified the Amazonian flora, increasing their food security, even during times of past climate change, without the need for large-scale deforestation.”
Their diverse ecological knowledge about plants, animals and landscapes, says the study, allows them to quickly identify and respond to environmental changes and defend their territories against illegal deforestation and land use disturbances.
“They hold the deepest secrets of how to keep the Amazon forests standing. More than half of the Amazon should be under [their] territorial management, so that the entire region can be preserved”.
However, frequent murders linked to logging, farming and oil corporations of indigenous leaders fighting to preserve pristine forest areas are a worrying trend. “The figures are alarming,” said Ángela Kaxuyana, an indigenous leader of the Coordination of Indigenous Organizations of the Brazilian Amazon, in an interview with Mongabay.com
“There is a significant increase in deforestation and, related to this deforestation, is the killing of indigenous leaders defending their territory. We are on the brink of a serious collapse that would impact not only indigenous people, but all of humanity.”
The Amazon rainforest now stands at a critical juncture. Its fate hangs in the balance, threatened by human activities and climate change. The potential tipping point is a stark reminder of the interconnectedness of Earth’s systems and the far-reaching consequences of their destabilisation.
A mineral exploration mine near Sao Felix do Xingu, Para state, Brazil, on Monday, Oct. 4, 2021. Destruction of the Brazilian Amazon accelerated this year to levels unseen since 2006, with more than 5,019 square miles of forest lost between August 2020 and July 2021. (Image: Jonne Roriz/Bloomberg via Getty Images)
A mineral exploration mine near Sao Felix do Xingu, Para state, Brazil, on Monday, Oct. 4, 2021. Destruction of the Brazilian Amazon accelerated this year to levels unseen since 2006, with more than 5,019 square miles of forest lost between August 2020 and July 2021. (Image: Jonne Roriz/Bloomberg via Getty Images)
As I stepped into the wobbly, narrow canoe for a ride back to Puerto Maldonado, my problem with a tipping point had more to do with flesh-eating piranha and lurking caiman in the slow-moving murky water.
On the way upriver, we stopped to pick up the ayahuasca travellers who’d been communing with the spirits of the forest. Their gazing about in wide-eyed wonder at what the chemical gods of the Amazon had shown them was infectious. I hoped those gods had workable plans for its preservation. It’s a truly magical place. It may be far away from most of us, but its gift is inside us with every breath we take. DM
It’s like a giant conveyor belt of water that transports heat from the tropics to the northern latitudes, influencing the climate of Europe, North America and Africa, and if humanity doesn’t stop pumping planet-heating gases into the air, it will collapse, with potentially catastrophic consequences.
By Ethan van Diemen
Ocean currents (Image: Francisco Kenneny/ Unsplash)
Ocean currents (Image: Francisco Kenneny/ Unsplash)
It’s called the Atlantic Meridional Overturning Circulation (AMOC) and a recent study suggests that it could collapse sooner than anticipated – and this becomes ever more likely as we continue emitting greenhouse gases at the current rate.
Responding to questions from Daily Maverick, Dr David Armstrong McKay, a climate-biosphere scientist and Research Impact Fellow at the University of Exeter’s Global Systems Institute, broke down the science.
The AMOC, Mckay explained, is “a set of ocean currents that move warm water along the Atlantic’s surface towards the Arctic, where it gets cold and salty enough to sink (as it gets denser, causing a process oceanographers call ‘convection’) and flows back down the Atlantic along the ocean floor. This helps to mix the ocean, pulling carbon down into the deep ocean, and keeps eastern North America and northern Europe much warmer than they would be otherwise.”
According to the National Oceanic and Atmospheric Administration (NOAA), “the entire circulation cycle of the AMOC, and the global conveyor belt, is quite slow. It takes an estimated 1,000 years for a parcel (any given cubic metre) of water to complete its journey along the belt. Even though the whole process is slow on its own, there is some evidence that the AMOC is slowing down further.”
Most alarmingly for South Africans, the NOAA notes that “research shows [AMOC] is weakening over the past century” but “whether or not it will continue to slow or stop circulating completely remains uncertain” and “if the AMOC does continue to slow down, however, it could have far-reaching climate impacts. For example, if the planet continues to warm, freshwater from melting ice at the poles would shift the rain belt in South Africa, causing droughts for millions of people.”
The slowing down, or collapse, of the AMOC is therefore considered to be one of the climate tipping points.
To understand this further, Dr Laura Pereira, an associate professor of sustainability transformations and futures at the University of the Witwatersrand, pointed Daily Maverick in the direction of a report she presented at COP28 in Dubai which dealt with these tipping points.
In remarks attributed to her, she explained that: “A tipping point occurs when a small change sparks an often rapid and irreversible transformation, and the effects can be positive or negative” and that “based on an assessment of 26 negative Earth system tipping points, business as usual is no longer possible – with rapid changes to nature and societies already happening, and more coming.”
The report, titled the “Global Tipping Points Report”, defines a tipping point as “occurring when change in part of a system becomes self-perpetuating beyond a threshold, leading to substantial, widespread, frequently abrupt and often irreversible impact”.
As it relates to the collapse of the AMOC, the report lays out a key message: “There is evidence for tipping points in the overturning circulations in the Atlantic and the Southern ocean, as well as for the west African monsoon.”
It continues that “the warming of oceans, modified wind patterns and increasing freshwater influx from melting ice hold the potential to disrupt established circulation patterns. We find evidence for tipping points in the Atlantic Meridional Overturning Circulation (AMOC), the North Atlantic Subpolar Gyre (SPG), and the Antarctic Overturning Circulation, which may collapse under warmer and ‘fresher’ (i.e. less salty) conditions.
“A slowdown or collapse of these oceanic circulations would have far-reaching consequences for the rest of the climate system, such as shifts in the monsoons. There is evidence that this has happened in the past, having led to vastly different states of the Sahara following abrupt changes in the west African monsoon, which we also classify as a tipping system.”
The report lists some of the main biophysical impacts associated with a collapse or slowdown of the AMOC.
These include:
The Tipping Points report builds on previous scholarship on the AMOC. In an article in the journal Nature Communications published in July 2023, the authors noted that they “estimate a collapse of the AMOC to occur around mid-century under the current scenario of future emissions”, adding that “we show that a transition of the AMOC is most likely to occur around 2025-2095 (95% confidence interval)”.
Professor Penny Holliday, head of marine physics and ocean circulation at the National Oceanography Centre, and principal investigator for OSNAP, an international programme researching AMOC processes, variability and impacts, in response to the study outlined some of the likely impacts of the AMOC collapsing.
“The AMOC carries huge amounts of heat northwards through the whole Atlantic Ocean, setting climate conditions for all the Earth’s continents. If it switched off, the result after a few decades would be much lower surface temperatures and stronger winds across the whole northern hemisphere (land and ocean).
“Heat would pool in the Southern Ocean and South Atlantic, but over the southern continents temperatures would also decrease. Major rainfall zones would shift, leading to far less rainfall over Europe, North and Central America, north and central Africa and Asia, and more over the Amazon, Australia and southern Africa.”
Holliday continued that “sea ice would extend southwards from the Arctic into the subpolar North Atlantic, and the Antarctic sea ice would extend northwards. For people and governments this would lead to dramatic change in every nation’s ability to provide enough food and water for its population.
“Energy supply and demand would change rapidly with new climate conditions and infrastructures would need heavy investment to adapt and cope. The patterns of vector-borne disease and health (including mental health) would be profoundly affected. Worldwide, many land and marine ecosystems would be unable to cope and adapt to such fast-changing climate conditions and biodiversity would be severely impacted.”
Most recently, the AMOC made headlines after a new study published in the journal Science Advance in February 2024 noted in its abstract that the results of the study “indicate that the present-day AMOC is on route to tipping”.
The authors of the study expound on the impacts, writing that “the AMOC collapse dramatically changes the redistribution of heat (and salt) and results in a cooling of the northern hemisphere, while the southern hemisphere slightly warms… in comparison with the present-day global mean surface temperature trend (due to climate change) of about 0.2°C per decade, no realistic adaptation measures can deal with such rapid temperature changes under an AMOC collapse.”
But it’s not all doom and gloom. Yet.
McKay told Daily Maverick that “the main way to stop AMOC collapse is to stop adding greenhouse gases to the atmosphere as soon as possible. We recently assessed AMOC collapse as being likely beyond 4C of global warming but possible from as low as 1.4C (although with only low confidence). Holding global warming to 1.5C or lower then would give us the best chance to minimise the likelihood of tipping, which would require emissions to halve by 2030 and reach zero around 2050.
“However, global warming has reached around 1.25C already, and the remaining ‘carbon budget’ for 1.5C – how much more carbon dioxide can be emitted before 1.5C is locked in – will be used up in only six years at current rates, with 1.5C likely to be reached in the early 2030s.
“A silver lining though is that we don’t know exactly what the AMOC’s tipping threshold is – it could be a little lower or higher, and may depend on some other factors, which may give some wriggle room if we’re lucky. This means even if 1.5C is breached we can still have a shot at preventing AMOC collapse by stopping emissions as soon as possible.” DM
In 2023, scientists were dumbstruck by ice lows that ‘fell off the cliff’, an international gathering of south polar experts have heard. The latest discoveries into the deep past also reveal how Antarctic ‘tipping points’ could reshape backyard coastlines across the globe.
By Tiara Walters
East Antarctic ice as seen from the SA Agulhas I in December 2009. (Image: Tiara Walters)
If the science profession is one that demands caution, it might be said that Antarctic researchers – drawn to a remote world that enforces hardiness and introspection – have a brand of reserve all their own.
Yet, at an international gathering of Antarctic experts in Hobart, Tasmania, prominent scientists such as Professor Matt King expressed astonishment at how warming seems to be rewriting the southern frontier.
Like Cape Town and others, Hobart is one of the southern hemisphere’s five Antarctic “gateway” cities. This city perches on the edge of the Earth, but it is also known to host the world’s highest density of south polar specialists.
What polar scientists talk about here, in the laid-back Tasmanian capital, often gives a strong forecast of Antarctica’s role as a global thermostat, regulating interactions among ice, wind and ocean currents.
To describe 2023’s truly alarming observations, King, a geophysicist, used emotive words to address his peers and a smattering of public attendees at the February event.
“In 2023 we saw something quite remarkable. Our leading sea ice scientists were genuinely agog. Gobsmacked. The adjectives ran out throughout the year,” said King, director at the Australian Centre for Excellence in Antarctic Science (ACEAS).
This event marked the first Australian visit of Germany’s flagship icebreaker, Polarstern, which next headed south to probe Antarctica’s trillion-dollar question: What on Earth does the eastern part of the icy continent plan to do in a hotter world?
“Almost every day of 2023 was a record-breaking low. It wasn’t just a blip, where it shrunk back and then grew again,” King mused.
Observations, added the geophysicist, suggested the stable extent of sea ice was no longer stable – both 2016 and 2022 “fell off a cliff”.
Professor Matt King, director at the Australian Centre for Excellence in Antarctic Science. (Photo: Supplied)
Professor Matt King, director at the Australian Centre for Excellence in Antarctic Science. (Photo: Supplied)
“The mechanisms behind that are very poorly understood,” he observed. “I find that very sobering, as a scientist, to think that we may be sitting here in a position where we are passing tipping points. What might be committing us to decades and centuries of change – and not knowing about it.”
At the end of February, the US National Snow and Ice Data Center said Antarctic sea ice this season had dropped below 1.99 million square kilometres, hitting “a third low in a row”. Beaten by 2023, it still tied for the second-lowest annual amount of sea ice in the 1979-to-2024 satellite record.
A tipping point is a “code red” threshold we do not want to cross.
When already vulnerable systems, such as West Antarctica, go beyond a point of balance, they tip into a self-perpetuating mode, potentially contributing metres of sea level. This may be impossible to reverse over decades and centuries.
The sleeping Antarctic behemoth – forged from the bottom parts of the eastern and western hemispheres – holds 60m of sea-level rise.
1. Over 40% of Antarctica’s ice shelves reduced in volume over 25 years. Almost all the ice shelves in western #Antarctica lost ice from 1997 to 2021. In contrast, most on the eastern side stayed the same or increased in volume.
— Australian Antarctic Program Partnership (@Ant_Partnership) October 13, 2023
Animation: Planetary Visions/@ESA pic.twitter.com/6Wu5EuUkFD
1. Over 40% of Antarctica’s ice shelves reduced in volume over 25 years. Almost all the ice shelves in western #Antarctica lost ice from 1997 to 2021. In contrast, most on the eastern side stayed the same or increased in volume.
— Australian Antarctic Program Partnership (@Ant_Partnership) October 13, 2023
Animation: Planetary Visions/@ESA pic.twitter.com/6Wu5EuUkFD
South polar researchers know more about West Antarctica. The less-understood east – once thought quite stable – is now showing signs of waking up on the wrong side of the planet, ACEAS also revealed in February.
Sea ice is already in the ocean, so if you think it is going to raise sea levels you could be accused of smoking lichen. Or perhaps just drop a block of ice in a glass of water to see what happens: The surface displaces, but does not rise.
However, sea ice matters a lot for life in Antarctica.
During 2022’s record ice lows, nearly 10,000 emperor penguin chicks drowned in the Bellingshausen Sea before they could learn to swim and do other penguin things, according to the British Antarctic Survey. Tragic breeding failures like these, disruptions to algae growth and shifting phytoplankton blooms have cascading effects through the food web.
Krill is a crustacean that forms the base of the Antarctic food web. “If they don’t find good ice, they have a problem,” said Dr Klaus Meiners, a climate programme lead for the Australian government’s Antarctic division – currently weathering “catastrophic” budget cuts of about AUD$25-million.
Retaining sea ice as a reflective, protective shield is also critical because the more this type of ice melts, the more the surrounding waters absorb heat.
(The same sort of reinforcing feedback applies to the continental ice sheets, thus the land ice. When ice sheets melt and flow into the ocean, they warm the ocean, which melts the base of those sheets right back, and so it goes.)
An ice-covered sea also girdles the gargantuan shelves that plug and stabilise the slow-moving hinterland sheets.
Abyssal ocean warming driven by Antarctic overturning slowdown. (Source: Matthew England and Qian Li)
Abyssal ocean warming driven by Antarctic overturning slowdown. (Source: Matthew England and Qian Li)
And when too much sheet and shelf ice enters the Southern Ocean, which swirls right around the frozen continent, it contributes to sea level rise and makes the water less salty.
In March 2023, Australian scientists including the ACEAS warned that a transformation of currents, driven by these freshwater ice flows, would probably slow Antarctic “overturning” circulation by more than 40% by 2050. This would stagnate the bottom of the world oceans, with significant, long-lasting effects on fisheries and economies.
They called this the Southern Ocean’s “Day after Tomorrow” moment.
Weeks later, in May, their updated data showed this circulation may already have slowed by 30%.
King, therefore, was hardly exaggerating.
3/5 'New abnormal': first evidence is emerging of a regime shift underway in the Southern Ocean, with a new study in @Nature's @CommsEarth by @saef_arc & @Ant_Partnership ➡️ https://t.co/BC9hEfN10b
— Australian Antarctic Program Partnership (@Ant_Partnership) September 13, 2023
📷 Kym Newbery @AusAntarctic pic.twitter.com/i8KHUcd1HN
3/5 'New abnormal': first evidence is emerging of a regime shift underway in the Southern Ocean, with a new study in @Nature's @CommsEarth by @saef_arc & @Ant_Partnership ➡️ https://t.co/BC9hEfN10b
— Australian Antarctic Program Partnership (@Ant_Partnership) September 13, 2023
📷 Kym Newbery @AusAntarctic pic.twitter.com/i8KHUcd1HN
Published in the journal Nature Geoscience, the British Antarctic Survey also announced in February “the first direct evidence that the West Antarctic Ice Sheet shrank suddenly and dramatically at the end of the last Ice Age, around 8,000 years ago”.
“It could happen again if parts of this ice sheet become unstable,” said lead author Professor Eric Wolff of Cambridge University’s Department of Earth Sciences.
The study also found that the ice sheet thinned equal to the height of the Empire State Building – in just under 200 years.
To understand what Antarctica might do in Africa, we could travel back to the Pliocene – an older proxy for a world in which big carbon can revise global temperatures and expanding oceans can swallow liveable land.
Back then, several million years ago, the atmosphere’s carbon dioxide needle hovered around 400 parts per million (ppm).
That is a little less than today’s roughly 420 ppm – yet these conditions churned up sea levels for South Africa’s Cape region many metres higher than modern oceans, a 2020 paper by the American Geophysical Union suggests.
Several storeys of water submerged the South African coastline then.
The windswept town of Hondeklip Bay in the Northern Cape revealed a 33m-high fossil shoreline, said study lead Professor Paul Hearty, a sea level specialist at the Jackson School of Geosciences at the University of Texas at Austin.
A long-time collaborator of the climatologist James Hansen – who put rising temperatures on the map by testifying before US Congress in 1988 – Hearty told Daily Maverick that “you have to melt about 25% to 30% of Antarctica” to explain primordial oceans that once pushed into the South African interior.
(And, he added, melt “all” of Greenland.)
Only 100 years have ticked by since the atmosphere enjoyed the geological equivalent of piña coladas and a mild beach holiday – at pre-industrial levels of 280ppm.
We are now heading towards the mid-420s and, in one of several papers Hearty wrote with Hansen, they warned that the Paris Agreement’s upper target of 2°C warming “above the pre-industrial level is highly dangerous”. Global sea levels could rise up to 3m per century, reinforcing the need to stay below 1.5°C.
Patella and Fissurella limpet shells attached to a large boulder indicate an ancient shoreline near Saldanha, Western Cape coast. (Image: Paul Hearty)
Patella and Fissurella limpet shells attached to a large boulder indicate an ancient shoreline near Saldanha, Western Cape coast. (Image: Paul Hearty)
Volcanos, weathered rock and buried organic stuff spewing out a collective CO2 motherload into the atmosphere explained why the mercury ran amok.
Temperatures were about 2°C to 3°C warmer, co-author and paleoclimate authority Professor Maureen Raymo told Daily Maverick.
“That is a natural process happening on time scales of millions of years,” cautioned Raymo, recent director of Columbia University’s Lamont-Doherty Earth Observatory, which popularised the term “global warming”. Raymo now works as the G Unger Vetlesen Professor of Earth and Climate Science there.
Current humans were also geological agents, she remarked, but we were adding CO2 to the atmosphere at 10 times the natural rate.
Antarctic ice sheets would continue to lose mass over decades and centuries, the Hobart experts said – and a naturally cooler period would only re-emerge after about 100 to 400 centuries.
Admittedly, tipping points may “elevate the risk to humanity to a scale that is unbearable”, triggering “conflict, economic burden, death and diseases”, said Antje Boetius, director of Germany’s Alfred Wegener Institute, which operates the Polarstern.
Antarctic continental ice drilled by Australian and German scientists in the Bunger Hills area near Denman Glacier, East Antarctica, January 2024. (Image: Alfred Wegener Institute / Marcus Gutjahr, GEOMAR)
They also show that Antarctica, far from being a remote place of seemingly little relevance, is of profound concern to how we do life here on Planet Earth.
As the IPCC’s special cryosphere report reminds, about 700 million people live in low-lying coastal zones.
There was a more practical, hopeful even, way to look at tipping points, said Boetius.
“And so for the sense of hope,” she offered, like rebounding whale numbers, “if economy, regulations, human action, planning and hope come together, there is no such thing yet as a tipping point we have crossed.”
King quipped that much of the East Antarctic sea floor was so poorly understood that it was like a place “where dragons live”. More financial investment was overdue.
“We are having sort of guesses at what’s there,” said King, “and no doubt we smooth over some of the deep trenches that could be really important.” DM
Watch the full recording of the Hobart-hosted tipping points talk, organised by the German embassy to Australia with the Alfred Wegener Institute.
While the thawing of permafrost is a natural part of the earth’s cycle, anthropogenic climate change (caused by human activity) is accelerating the rate of this thaw — causing it to warm and thaw at a rate that it shouldn’t be, and wouldn’t be if humans weren’t around.
By Julia Evans
In this aerial view partially collapsed Fluchthorn mountain stands above a swath of rock and gravel deposited by its rockslide into the valley below on June 22, 2023 near Galtur, Austria. On June 12 approximately one million cubic meters of rock fell from the mountain, shortening the mountain by 19 meters, from 3,399 meters to 3,380 meters, and bringing down the cross on its peak. Scientists blame melting permafrost, which is undoing the natural bonding effect of ice within high alpine rock. (Image: Sean Gallup/Getty Images)
In the frigid realms of the Arctic and high mountains of Kilimanjaro, a problem is unfolding beneath our feet: the thawing of permafrost. This frozen layer of ground can hold ancient life, and thawing it can lead to the release of an unknown crisis, the collapse of foundations and accelerate climate change.
Permafrost acts like nature’s deep freezer; it refers to the thermal state of the ground that can include ice, rock, soil and organic matter. To be considered permafrost, the ground temperature needs to remain frozen (0°C or below) for at least two consecutive years, explained Dr Christel Hansen, senior geospatial science lecturer at the University of Pretoria.
This frozen blanket, sprawling across more than a quarter of the Northern Hemisphere, plays a fascinating role as a preservation chamber for ancient plant and animal remains, capturing them in a frozen state before the natural decomposition process could take its course.
While the majority of permafrost occurs in the Northern Hemisphere, in Arctic regions such as Alaska, Greenland, Russia and China, Hansen, whose research interests include cold-climate geomorphology, Antarctic landscapes and permafrost dynamics, explained that permafrost can occur elsewhere on the planet, from the ocean floor to high mountains (the Himalayas, the Andes, sporadically on Kilimanjaro), and in the Antarctic, as long as the local climate ensures the ground remains frozen for at least two years in a row.
But permafrost doesn’t hold its chill forever; it thaws when temperatures breach freezing point.
Physical Geography Professor Stefan Grab, from Wits University’s School of Geography, Archaeology & Environmental Studies, told Daily Maverick that a warming climate was the main reason behind this thaw, driven by factors such as burning fossil fuels — but other reasons such as geothermal heating, volcanic eruptions, natural or human erosion of the ‘active’ layer (active protective layer to permafrost) contributed to the thaw.
Millions of people live in permafrost zones, and have houses and structures built on what was once rock-solid ground. So when this thaws they face the frontline impacts.
“The permafrost acts like concrete, keeping the foundations firm and secure,” explained Grab, “but when this thaws (or ice melts), it is like breaking up that ‘concrete’ foundation, and so as the ground becomes more mobile… so the foundations begin to crack and themselves start moving. This can cause collapse of buildings, pipelines, roads and other infrastructure.”
This can also create sinkholes, cause unstable slopes and lead to slopes collapsing with rockfalls, landslides and some quite spectacular coastal erosion when large chunks of the coast break off because of a weakening of the ground brought on by thaw.
It’s already begun — large parts of Russia have experienced collapsing structures. Sinkholes and mountainous areas around the world undergo rockfalls due to permafrost thaw.
Permafrost thaw, caused by a warming climate, is natural — it would occur even if humans didn’t exist.
“In Earth’s history, as the climate changes over the hundreds of thousands and millions of years, permafrost would have receded (thawed), it would have grown and receded again and grown, in the cycles as the climate changes,” said Hansen.
But what’s important to understand is that the rate at which it’s happening and its knock-on effects now are thanks to human-induced climate change.
Human activity (like burning fossil fuels), has increased air temperatures, leading to more severe and accelerated consequences and knock-on effects.
Professor David Hedding from the Department of Geography at Unisa, whose research interests include geomorphology, climate change and Antarctic science, explained that geographic distribution of permafrost had changed naturally over time (from 10- to 100,000-year timescales).
“But the rate at which permafrost is thawing can be linked to anthropogenically induced climate change over decades to centuries (much shorter time frames),” said Hedding. “It’s this rapid thawing that is releasing stored carbon into the atmosphere, further exacerbating climate change.”
As permafrost thaws, it doesn’t just set free ancient plants and animal remains; it also releases vast amounts of methane and carbon dioxide — potent greenhouse gases.
The European Space Agency highlights that the Arctic permafrost stores almost 1,700 billion tonnes of carbon dioxide.
Dr Gwynneth Matcher, Instrument scientist at the South African Institute for Aquatic Biodiversity (SAIAB) and Research Associate with Rhodes University’s Department of Biochemistry and Microbiology explained to Daily Maverick how this works; as permafrost warms, the ice melts and water becomes available.
As all organisms need water to live, once water becomes available, the microbes in the permafrost wake up (come out of hibernation) and eat the organic matter in the plants, animals and bacteria that were frozen with them.
“When they start to degrade (or eat) this organic matter, Carbon dioxide and methane are released as a byproduct — just like a car burns/eats petrol and then exhaust fumes from the exhaust pipe of the car is expelled,” said Matcher.
But it’s not just the release of greenhouse gases that have scientists concerned — with this thaw comes the potential to release bacteria, unknown viruses and even nuclear waste and radiation.
Matcher explained that many bacterial and viral species present in organisms and soil and water, can survive being frozen for a long time (ie are dormant) and as soon as the permafrost thaws, these bacteria and viral species “wake up” and become active again.
This means that bacteria and viruses from thousands of years ago can become active again when permafrost begins to thaw.
“When the body comes in contact with a bacteria or virus it has never seen before, there is a delay because the immune system does not immediately recognise and react to the bacteria/virus,” said Matcher.
“Viruses and bacteria in the permafrost have not been seen/experienced by modern man which means that we are vulnerable to these pathogens,” she said, explaining that our immune systems have not been trained to recognise the pathogens.
Permafrost acts like nature’s deep freezer; it refers to the thermal state of the ground that can include ice, rock, soil and organic matter. To be considered permafrost, the ground temperature needs to remain frozen (0°C or below) for at least two consecutive years, explained Dr Christel Hansen, senior geospatial science lecturer at the University of Pretoria.
This frozen blanket, sprawling across more than a quarter of the Northern Hemisphere, plays a fascinating role as a preservation chamber for ancient plant and animal remains, capturing them in a frozen state before the natural decomposition process could take its course.
While the majority of permafrost occurs in the Northern Hemisphere, in Arctic regions such as Alaska, Greenland, Russia and China, Hansen, whose research interests include cold-climate geomorphology, Antarctic landscapes and permafrost dynamics, explained that permafrost can occur elsewhere on the planet, from the ocean floor to high mountains (the Himalayas, the Andes, sporadically on Kilimanjaro), and in the Antarctic, as long as the local climate ensures the ground remains frozen for at least two years in a row.
But permafrost doesn’t hold its chill forever; it thaws when temperatures breach freezing point.
Physical Geography Professor Stefan Grab, from Wits University’s School of Geography, Archaeology & Environmental Studies, told Daily Maverick that a warming climate was the main reason behind this thaw, driven by factors such as burning fossil fuels — but other reasons such as geothermal heating, volcanic eruptions, natural or human erosion of the ‘active’ layer (active protective layer to permafrost) contributed to the thaw.
Millions of people live in permafrost zones, and have houses and structures built on what was once rock-solid ground. So when this thaws they face the frontline impacts.
“The permafrost acts like concrete, keeping the foundations firm and secure,” explained Grab, “but when this thaws (or ice melts), it is like breaking up that ‘concrete’ foundation, and so as the ground becomes more mobile… so the foundations begin to crack and themselves start moving. This can cause collapse of buildings, pipelines, roads and other infrastructure.”
This can also create sinkholes, cause unstable slopes and lead to slopes collapsing with rockfalls, landslides and some quite spectacular coastal erosion when large chunks of the coast break off because of a weakening of the ground brought on by thaw.
It’s already begun — large parts of Russia have experienced collapsing structures. Sinkholes and mountainous areas around the world undergo rockfalls due to permafrost thaw.
“Although permafrost covers most of Russia and Canada, the thawing of permafrost in these regions will release immense amounts of carbon which will have impacts on global climate including the climate of southern Africa,” said Hansen.
It’s well proven that greenhouse gases accelerate global warming. The scientific community has discovered global warming will increase the frequency and intensity of [naturally occurring] climate events, like heatwaves, droughts, extreme rainfall and flooding.
“An important tenet in environmental science is that environmental problems are never confined by political boundaries,” said Loubser, “There tend to be global problems with global consequences that require global solutions.”
So while permafrost zones like Siberia will have direct impacts that we won’t deal with here, we will definitely feel the knock-on effects of the release of greenhouse gases.
“Because, anything that affects the climate, or things like the global circulatory system, will have a global effect — it has to.”
Grab’s answer is a sobering “not much”. Slowing down global warming by cutting greenhouse gas emissions remains our best bet.
Professor Hedding suggests reducing fossil fuel use and heeding recommendations from IPCC reports.
“Actually trying to erase [the impact of thawing] would be extremely difficult,” said Loubser. “I think it makes more sense to try to plan for what is going to happen.”
Hansen explained that with permafrost, the tipping point isn’t about whether we can return to that thermal state, but rather the irreversible outcomes of what is released from this permafrost thaw.
“If the temperature reduces sufficiently to bring back that frozen environment, yes, the ground can become permafrost, again,” said Hansen, “but you cannot reverse the effect of having a thaw in the beginning already (like releasing greenhouse gases for several decades to come and organic material).”
Hansen said that it might trigger a feedback loop –“the thawing permafrost worsens climate change because the thawing of permafrost releases carbon stored in permafrost which will further accelerate climate change causing more permafrost thawing,” said Hedding.
While Grab doesn’t believe that permafrost-related greenhouse gas emissions alone would create a “tipping point”, he agreed that the impacts from permafrost thaw, combined with the increase of global burning of vegetation, increased outputs from direct anthropogenic activities and the destruction of carbon sinks (like deforestation), would.
“In combination, these factors can lead to specific types of tipping points or situations of ‘no return’,” said Grab. DM
This collapse of Arctic sea ice threatens the delicate balance of our entire planet and scientists say it is increasingly likely in the not-too-distant future.
By Ethan van Diemen
The Arctic, a vast expanse of ice and snow at the top of our planet, has long been a sentinel of climate change. Its frozen seas, once considered impervious to human influence, now reveal a chilling truth: we stand on the precipice of an irreversible tipping point. Sooner than we think, we may have a seasonally ice-free Arctic.
This melt of Arctic sea ice threatens the delicate balance of our entire planet and scientists say it is increasingly likely in the not-too-distant future.
For South Africans, the icy expanse of the Arctic might seem a world away, yet a dramatic shift unfolding there – the potential collapse of sea ice – holds the power to disrupt weather patterns, ocean currents, and marine ecosystems, with consequences that could reach our shores.
This is the chilling reality of climate tipping points, where a change pushes the Earth’s system past a critical threshold, triggering drastic and irreversible consequences.
The Global Tipping Points Report defines “sea ice” as being “frozen sea water that floats on the sea surface. It forms in the polar oceans whenever the temperature of the seawater drops below its freezing point of around -1.8°C.”
This frozen layer acts as Earth’s giant reflective blanket, bouncing sunlight back into space and keeping the planet cool. As our planet warms, in large part due to anthropogenic greenhouse gas emissions, this vital shield is shrinking.
Surpassing this critical threshold – at a yet uncertain point – could trigger a self-reinforcing, positive feedback loop. Less ice means less reflection, leading to more warming of the ocean surface, which melts even more ice. This vicious cycle could lead to a seasonally ice-free Arctic, with far-reaching and not fully understood consequences.
Dr Marcello Vichi, a lecturer in the Department of Oceanography at the University of Cape Town (UCT) and Director of the Marine and Antarctic Research for Innovation and Sustainability (Maris) shared more details with Daily Maverick.
Speaking over the phone, Vichi explained that a tipping point is “considered to be an unrecoverable threshold. After that, things are not going to get back to normal.”
“So what the Arctic ice, and actually all polar regions do on the functioning of the Earth, is that they are the cooling system of the planet. So they very much cool the atmosphere, they contribute to the maintenance of the overall temperature of the Earth and of course, they contribute to the seasonal variation. So you have colder conditions during winter time and warmer conditions during summer time.
“If we’re talking about an Arctic sea ice collapse, it means that we will very likely, according to the conditions and the situation we’re going through at the moment, and also considering future projections…the Arctic will be sea ice free in summer very soon,” Vichi explained.
The exact time frame is not assured “Given the many variables and many uncertainties that are there, but very soon means in the next 20 years,” the professor explained.
Vichi explained what some of the potential impacts of this collapse of seasonal sea ice may be.
“Sea ice is a seasonal element of the Earth, just like the greening of the big forests in the North. It’s likely to continue to happen, but what will be a major tipping point is that there won’t be any presence of sea ice during summertime.
This is best described by the concept of albedo. “The albedo is the reflectivity of a surface. Sea ice is much more reflective, just like a white car and a black car. When you have a white car, you’re usually going to feel the heat a lot less than on a black car out in the sun. That is due to the albedo of the surface.”
“White surfaces have a much larger albedo, so they reflect more sunlight than the black one. So when you remove sea ice from the surface of the ocean, you expose more open ocean that is darker, it absorbs more radiation from the sun, more sunlight, and it warms up. By warming up, it melts more ice. So that is what we call a positive feedback loop. And because our Earth is now becoming so warm, this albedo feedback has gone beyond the tipping point and the sea ice is going to be melted entirely,” Vichi explained.
But what happens if there is no Arctic sea ice during the summer months?
“The impacts are actually quite dramatic,” Vichi explained, saying we would likely have “shorter winter conditions” and that “the food web which has adjusted to this cycle, won’t be able to cope with that.”
“So we will have a mismatch between the moment in which a predator will find their prey and before they adjust, it’s going to take longer with major consequences on the food web and the animals that are living in the Arctic.”
While most of the direct impacts of this will be felt in the northern hemisphere, we live in an interconnected world and economic environment and the loss of sea ice could set off or exacerbate larger socioeconomic and geopolitical issues. Among these are the changes in global shipping, fishing and other maritime activities.
The Tipping Points report outlines some of the other potential impacts. Among them, a “possible contribution to increase in extreme weather events” and “changes in pollutant and microplastic transport in the ice-free Arctic.”
But the larger concern lay in the unanticipated or unknown impacts.
“How much all the change in the Arctic would impact the rest of the environment is what is called ‘teleconnections’. “Something happening in one place through a cascade of relationships that is already existing in the system, but we are now modifying, could have unexpected consequences far away,” the professor explained.
“What’s been happening in the last three to four years is raising a major alarm. Both poles were pretty much aligning and now responding to what we call the ‘polar amplification’, which is driven by this ice-albedo feedback.
The tipping points report explains that polar amplification alludes to the fact “that the Arctic is warming more rapidly than the rest of the planet, partly driven by sea ice loss. This reduces the equator-pole temperature contrast” and that “this can result in circulation features which accelerate regional extreme weather occurrence trends.”
“So this is in a way saying the scientists were right, but it’s not good news for our planet, unfortunately. So we do have to act as quickly as possible,” Vichi said.
“So one can understand, once all the ice has been removed, it’s unlikely to get warmer than that because the feedback doesn’t exist anymore and then it’s more similar to any other ocean. But we actually don’t know that ocean. We don’t know what’s going on besides what our models are doing but there may be processes that we have never experienced and we are not able to include in our models.”
So what is to be done? Beyond drastically reducing our greenhouse gas emissions to mitigate the worst impacts, “we can’t arrest the tipping points, unfortunately,” said Vichi.
Historical emissions have already done a lot of damage, the professor explained.
“So that means that basically, this tipping point is unavoidable. So we have to adapt to these conditions and make sure that we are prepared and we have people that are properly educated to understand the complexity of this one.” DM
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