Researchers see signs of destabilisation 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.
Photo: Katrin Lindbäck/azotelibrary.com
14. The Meaning of Life
You are the end-point of your own genes' evolution. You are the descendant of survivors, each of whom bred successfully and never once failed – for 3.5 billion years! Think about that for a moment. In a world in which, for very many individuals, an early death and failure to breed were by far the most likely outcome, not one single one of your ancestors failed to produce at least one offspring. If they had failed, your gene-line would have ended there and then. You are the product of billions of passes through the sieve of selection and at every pass your gene-line passed the fitness test. Your genes are good at surviving; and you are unique in the history of the cosmos. The likelihood of you being alive at all is almost vanishingly small and yet here you are. Never before has anyone with your combination of genes, your collection of atoms and your history existed.
And you never will again.
Almost all your genes have spent much longer being something else than they have being human. Your ancestors were there when Europe and Africa split off from the Americas. They were there as small mammal-like reptiles when dinosaurs ruled the earth. They saw pterodactyls flying overhead. They survived the mass-extinction which ended the dinosaurs’ reign and they saw the birds and the bats grow wings and take to the air.
Your ancestors swam in the Cambrian seas and crawled out onto the land as early air-gulping fish destined to become four–legged animals with lungs. Your ancestors lived through the Carboniferous era when dense forests of tree ferns grew in steaming jungles where dragonflies with meter-wide wings flew. They saw the trees fall and form the piles of vegetation destined to be coal as the climate changed and the Carboniferous forests collapsed. They saw the first flowering plants as plants and insects formed their mutual-benefit society.
Your ancestors lived through the first great toxic waste disaster when the cyanobacteria produced oxygen and triggered a mass extinction; and they learned to turn it to their advantage by evolving aerobic respiration.
Your ancestors were bacteria; maybe they were archaea; they may have been the strange Ediacarans which were the earliest known multi-cellular organisms. In almost every one of your cells, in your genes, you carry a record of your evolution, of the entire human evolution story, and of a great deal of the evolution story of every other living thing.
Your journey through space and time has been an adventure of disasters, adaptation, survival and recovery, many, many times you will have been on the brink of extinction - the fate of 99% of all known ancient species - yet your ancestors survived and because they were good at surviving you are here and now.
You will live for a mere flash in the time-scale of the Universe but in the vast darkness of the cosmos there can surely be few flashes as bright as your bright spark of consciousness.
Be proud. Be very proud. But at the same time be humbled by the enormity of the events which produced you and the fragility of it all.
Stars died and because they died, you live. You are made by stars out of stardust and in a very real sense; because you are made of the same stuff the Universe is made of and are a part of it, there is something even more wonderful about you. Through you, though not just through you, and maybe not just here on this small planet, the Universe has gained self–awareness and can begin to understand itself.
Through you it can stand on the surface of this beautiful little jewel in the cosmos, can look up in awe at itself and think "Wow!"
You are special. You are unique and you were nearly 14 billion years in the making.
That is your story. Enjoy it while it lasts.
Please bear in mind also that every other human being; every mammal; every bird, insect, spider, fish, or worm; every plant; indeed, every other living thing, has made the same journey you have made. Each is unique and the descendant of survivors. Each has an unbroken gene-line going back to the first replicator. They are your relatives. Like you they are part of the whole web of interdependent things we call life on earth.
To end their life will end their gene-line for the first and only time in the history of the Universe. Something which has taken nearly 14 billion years to produce, and 3.5 billion years to perfect, will have been extinguished forever.
Each of them is worthy of respect and each of them deserves the one opportunity to experience life that chance has given them.
Life is too rare, precious and wonderful a thing to take lightly.
And the meaning of life?
The meaning of life is whatever meaning you want to give your life. It is your life. Do with it whatever you want with it, but try not to waste it.
The above is what I wrote back in June, 2017, when we were already becoming aware that something bad was happening to the climate. That change has accelerated in recent years culminating in this year’s record drought and high temperatures in the UK and the rest of Europe, catastrophic floods in various places and wildfires in America.
Nothing is now more important than saving our home in the cosmos - our beautiful jewel of a planet, the little "spaceship Earth", that is our only available life-support system. If we fail, we not only waste the 3.5 billion years of progress and adaptation that produced us, but the gene line of every other species which shares this planet with us. We will have failed. We will have done the most disastrous thing that has ever been done to Earth, far worse than the meteor strike that wiped out the dinosaurs, or the toxic waste disaster when oxygen poisoned nearly everything. Humans will have done that; nothing and no-one else, and no-one else can stop it happening.
To spell out the danger we are in, an international team of researchers, including scientists from the Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden, the Global Systems Institute, University of Exeter, Exeter, UK, and the Potsdam Institute for Climate Impact Research, Potsdam, Germany, have concluded that we may already be at 5 major climate tipping points, and have identified a further 11 tipping points which could be triggered with as little as a further 0.1oC rise in global mean temperature. They have publised their findings in Nature.
The news release from the Stockholm Resilience Centre which accompanies the publication states in in unequivocal terms:
Human emissions have already pushed Earth into the danger zone. Five of sixteen identified tipping point may be triggered at today’s temperaturesThe team give more technical details in the structured abstract to their paper on Science:Story highlightsFROM NINE TO SIXTEEN: 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.
- The world is already at risk of passing five dangerous climate tipping points
- Four of these move from possible events to likely at 1.5°C global warming, with five more becoming possible around this level of heating
- Risks increase with each tenth of a degree of further warming
Even at current levels of global heating the world is already at risk of passing five dangerous climate tipping points, and risks increase with each tenth of a degree of further warming.
An international research team synthesised 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.
The research concludes human emissions have already pushed Earth into the tipping points danger zone.
Five of the sixteen may be triggered at today’s temperatures:Four of these move from possible events to likely at 1.5°C global warming, with five more becoming possible around this level of heating.
- The Greenland ice sheets
- West Antarctic ice sheets
- Widespread abrupt permafrost thaw
- Collapse of convection in the Labrador Sea
- Massive die-off of tropical coral
Already left safe climateThe world is already at risk of some tipping points. As global temperatures rise further, more tipping points become possible.
David I. Armstrong McKay, lead author
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.
This new analysis indicates that Earth may have already left a ‘safe’ climate state when temperatures exceeded approximately 1°C warming. A conclusion of the research is therefore that even the United Nations’ Paris Agreement goal to limit warming to well-below 2°C and preferably 1.5°C is not enough to fully avoid dangerous climate change.
According to the assessment, tipping point likelihood increases markedly in the ‘Paris range’ of 1.5-2°C warming, with even higher risks beyond 2°C.
The study provides strong scientific support for the Paris Agreement and associated efforts to limit global warming to 1.5°C, because it shows that the risk of tipping points escalates beyond this level.
To have a 50% 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, co-chair of the Earth Commission and director of the Potsdam Institute for Climate Impact Research reflects on the current trajectory of climate change.
New tipping elements
The researchers categorised 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. 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.
The location of climate tipping elements in the cryosphere (blue), biosphere (green) and ocean/atmosphere (orange), and global warming levels their tipping points will likely be triggered at.
Summary Map by Earth Commission/Globaïa.
Updating global risks
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 destabilising in the long-run.
Ricarda Winkelmann, co-author
Potsdam Institute for Climate Impact Research
Member of the Earth CommissionWe have made a first step towards updating the world on tipping point risks. There is an urgent need for a deeper international analysis, especially on tipping element interactions, towards which the Earth Commission is starting a Tipping Points Model Intercomparison Project (“TIPMIP”).
David I. Armstrong McKay, lead author
Stockholm Resilience Centre
Stockholm University, Stockholm, Sweden.
Read Exceeding 1.5°C global warming could trigger multiple climate tipping points
Structured AbstractThe solution to this impending disaster is in our hands and our hands alone. We must reduce our CO2 emissions and that means using more and more renewable energy sources such as wind and tidal power, and possibly nuclear power, and we have to find ways to pull CO2 out of the atmosphere and lock it up out of harm's way. The recession caused by the COVID-19 pandemic cannot be used as an excuse to abandon emission targets and explore new sources of fossil fuels.
INTRODUCTION
Climate tipping points (CTPs) are a source of growing scientific, policy, and public concern. They occur when change in large parts of the climate system—known as tipping elements—become self-perpetuating beyond a warming threshold. Triggering CTPs leads to significant, policy-relevant impacts, including substantial sea level rise from collapsing ice sheets, dieback of biodiverse biomes such as the Amazon rainforest or warm-water corals, and carbon release from thawing permafrost. Nine policy-relevant tipping elements and their CTPs were originally identified by Lenton et al. (2008). We carry out the first comprehensive reassessment of all suggested tipping elements, their CTPs, and the timescales and impacts of tipping. We also highlight steps to further improve understanding of CTPs, including an expert elicitation, a model intercomparison project, and early warning systems leveraging deep learning and remotely sensed data.
RATIONALE
Since the original identification of tipping elements there have been substantial advances in scientific understanding from paleoclimate, observational, and model-based studies. Additional tipping elements have been proposed (e.g., parts of the East Antarctic ice sheet) and the status of others (e.g., Arctic summer sea ice) has been questioned. Observations have revealed that parts of the West Antarctic ice sheet may have already passed a tipping point. Potential early warning signals of the Greenland ice sheet, Atlantic Meridional Overturning Circulation, and Amazon rainforest destabilization have been detected. Multiple abrupt shifts have been found in climate models. Recent work has suggested that up to 15 tipping elements are now active (Lenton et al., 2019). Hence it is timely to synthesize this new knowledge to provide a revised shortlist of potential tipping elements and their CTP thresholds.
RESULTS
We identify nine global “core” tipping elements which contribute substantially to Earth system functioning and seven regional “impact” tipping elements which contribute substantially to human welfare or have great value as unique features of the Earth system (see figure). Their estimated CTP thresholds have significant implications for climate policy: Current global warming of ~1.1°C above pre-industrial already lies within the lower end of five CTP uncertainty ranges. Six CTPs become likely (with a further four possible) within the Paris Agreement range of 1.5 to <2°C warming, including collapse of the Greenland and West Antarctic ice sheets, die-off of low-latitude coral reefs, and widespread abrupt permafrost thaw. An additional CTP becomes likely and another three possible at the ~2.6°C of warming expected under current policies.
CONCLUSION
Our assessment provides strong scientific evidence for urgent action to mitigate climate change. We show that even the Paris Agreement goal of limiting warming to well below 2°C and preferably 1.5°C is not safe as 1.5°C and above risks crossing multiple tipping points. Crossing these CTPs can generate positive feedbacks that increase the likelihood of crossing other CTPs. Currently the world is heading toward ~2 to 3°C of global warming; at best, if all net-zero pledges and nationally determined contributions are implemented it could reach just below 2°C. This would lower tipping point risks somewhat but would still be dangerous as it could trigger multiple climate tipping points.
Abstract
Climate tipping points occur when change in a part of the climate system becomes self-perpetuating beyond a warming threshold, leading to substantial Earth system impacts. Synthesizing paleoclimate, observational, and model-based studies, we provide a revised shortlist of global “core” tipping elements and regional “impact” tipping elements and their temperature thresholds. Current global warming of ~1.1°C above preindustrial temperatures already lies within the lower end of some tipping point uncertainty ranges. Several tipping points may be triggered in the Paris Agreement range of 1.5 to <2°C global warming, with many more likely at the 2 to 3°C of warming expected on current policy trajectories. This strengthens the evidence base for urgent action to mitigate climate change and to develop improved tipping point risk assessment, early warning capability, and adaptation strategies.
Armstrong McKay, David I.; Staal, Arie; Abrams, Jesse F.; Winkelmann, Ricarda; Sakschewski, Boris; Loriani, Sina; Fetzer, Ingo; Cornell, Sarah E.; Rockström, Johan; Lenton, Timothy M.
Exceeding 1.5°C global warming could trigger multiple climate tipping points
Science (2022) 377(6611), eabn7950; doi: 10.1126/science.abn7950
Copyright © 2022 The Authors.
Published by American Association for the Advancement of Science
Reprinted with kind permission under licence #5386550519911
And we cannot afford to elect more climate denying political leaders.
Our lives depend on it.
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