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Climate tipping point looms: irreversible impacts and a positive 'tipping point'

2022-09-23 08:35:37Chinese Industry Information Station

过去二十年来,Timothy Timothy, Director of the Global Systems Institute at the University of Exeter, UK·莱顿(Timothy Lenton)Professor has been eyeing how global climate change is triggering tipping points for Earth's natural systems.若发生这种情况,will bring major challenges to human society.

2008年,他在《美国国家科学院院刊》(PANS)Posted a concern“Critical Elements in Earth's Climate System”的论文.This article, which was later cited by many scientists, greatly advanced research in the field of tipping points.当时,He presented in his thesis9个临界点,and ranked according to their likelihood of occurring.

十多年来,The concept of a climate tipping point is attracting increasing attention.今年9月,Professor Leiden's team is here《科学》(Science)A new study published in the journal,Re-evaluated since2008published by the scientific community over the years200Data from multiple papers on tipping points.他们发现,Major global climate tipping points may now have increased to16个,withering of the Amazon rainforest、Arctic sea ice extent is decreasing、Mass death of coral reefs around the world and more.

Leiden's latest study points out,自工业革命以来,Human-caused global warming has reached1.1摄氏度,全球有5A critical point is already in the danger zone.Suppose global warming is reached1.5摄氏度,其中4A critical point is likely to be triggered or even crossed,同时另外5A critical point will enter the danger zone;If global warming is reached2摄氏度以上,will trigger last6个临界点.

after the study was published,Professor Leiden gave a seminar at the University of Exeter,Scientists from all over the world、Economists and civil society representatives come together,Not only bring their latest research findings and views,Also discuss how to deal with global warming“临界点”的前景.

at the opening ceremony of the seminar,Professor Leighton said:“We are convening this meeting because we feel strongly that human activity is pushing the Earth system to a destructive tipping point.我认为,Our best way to avoid these bad tipping points、It may also be the last hope by discovering and triggering some ‘Positive tipping point ’,The tipping point will change our society,Changing our relationship with the rest of the Earth system.”

Just as this seminar was held,第77The United Nations General Assembly is also on9月13Day kicked off in New York, the United States on the other side of the ocean.在开幕式上,UN Secretary-General Guterres renews call for global attention to climate crisis.

就在两周前,by the World Meteorological Organization ( WMO ) Coordinate a publication issued by various United Nations agencies“United Science”报告显示,Despite warnings about climate change in recent years more and more,But governments and businesses are not changing fast enough,The consequences are already being felt in increasingly extreme weather around the world,Some climate tipping points may have been breached.

As Leiden accepted the surging news( during the interview,“Extreme weather around the world in recent years has sent more and more disturbing signals——If the world reaches a climate tipping point,We will face irreversible changes in the climate system.”

不过,瑞典皇家科学院院士、A professor of physical meteorology at the University of Gothenburg in Sweden has a different view,“Individual climate tipping point impacts are regional,A single tipping point triggered does not equate to a major change in global average temperature.”他认为,Due to data and model issues,There are still large uncertainties in the relevant conclusions,Scientists have to accumulate more research.

2021年1月,Cracks discovered by British Antarctic Survey during flyover of Brent Ice Shelf.

What is the climate tipping point?

In the plenary session of the opening ceremony of the workshop,Professor Leiden used an animated diagram to visualize the concept of tipping points in the Earth system.

“like many complex systems,There are two stable states here.(左半边)The figure of the ball starts moving from a basin,The depth of the basin represents how stable this state is.System pressure causes left basin to become unstable,The ball is pushed around in the basin for a short period of time——Similar to extreme weather events in the climate system.最终,The ball is pushed through the increasingly unstable left basin,suddenly fell into another basin.在那里,It is a new steady state,It is not easy to return from it.”Leighton explained.

Schematic diagram of the climate tipping point concept

事实上,20年前,联合国政府间气候变化专门委员会(IPCC)就提出了 “气候临界点” 的概念,and gives its definition in its official glossary :“As far as the climate system is concerned, 临界点(Tipping point)Refers to the critical threshold at which the global or regional climate changes from one stable state to another.”

fake use2018William Nobel Laureate in Economics·Nordhaus in his writings《气候赌场》to further understand the concept of climate tipping points,Then imagine a canoe floating on the water,When the canoe is tipped into the water,Balance can be maintained at first,But once the hull tilts to a certain extent,The canoe would capsize in an instant——The angle of inclination that instantly capsizes the canoe is the critical point.

更通俗地说,The critical point is the key point where quantitative change causes qualitative change,是压死骆驼的最后一根稻草.

Leighton told The Paper,The key to tipping point changes is that,在一个“become so powerful that it can propel itself”的系统中,存在着一种“正反馈机制”(postive feedback).Leighton gives another example to illustrate this feature.“If a person hears a fire alarm,Run to the exit,will cause the other two to escape,The four escaped after that,Eight people fled,Then we have a tipping point and ‘自我推进’的  ‘Escape feedback’情况.”

Wu Yixiu, project director of Shanghai Pudong Yike Circulation Technology Promotion Center, who has been concerned about climate change for a long time, told The Paper,Why the tipping point is important,It is because in addition to the breakthrough of each critical point, it will have a great impact on the ecological environment.,Also because it has two characteristics that cannot be ignored.

The first feature is irreversibility.The cumulative time to reach the tipping point can be very long,during this cumulative time period,Efforts to avoid triggering tipping points make sense,And once the tipping point is triggered,The whole system can suffer bad results very quickly——after the critical point,The system will enter a new equilibrium,But it won't be the same again.

The second characteristic is unpredictability,And that's where it's most dangerous:Although people know the danger is coming,It is impossible to predict exactly when the tipping point will come..When we realize the tipping point is coming,The tipping point has actually been triggered.

Layton is worried,有“Sufficient scientific evidence”表明,The world is already close to potentially producing significant、长期、Risk of tipping point of irreversible impact,Even some point may have been triggered.

早在2020年,Layton's team is here《自然》杂志发文指出,More than half of the world's identified climate tipping points are already active,Several of these tipping points are very near.

此次发表的《科学》The study goes further,The world is heating up now1.1Celsius has pushed several tipping points into“may have crossed”范围——These include the collapse of the Greenland and West Antarctic ice sheets、Mass mortality of tropical coral reefs worldwide and thawing of permafrost in the northern hemisphere.

“We give a fairly large range of uncertainty,但(some tipping points)Definitely in the danger zone .We may be in the process of a larger trigger and even crossing a tipping point,We hope it hasn't crossed yet,But it's becoming more and more likely.”Leighton told The Paper.

Leighton further added,The summer weather conditions in recent years have been so extreme that it is difficult to make them part of the current state.“maybe it hints at the existence of another weather condition,This is my worry.”莱顿说.

瑞典皇家科学院院士、Chen Deliang, a professor of physical meteorology at the University of Gothenburg in Sweden, did not participate in the above research,But as an international climate expert, he told The Paper,The significance of the Leiden team's research is to summarize scientists' understanding of the tipping point so far.,Then put it together and make a judgment,得出一个结论:Roughly at what temperature would a significant change occur,Critical point will be triggered and even crossed.

“不过要指出的是,All individual climate tipping point impacts are regional,A single tipping point triggered does not equate to a major change in global average temperature,And because of data and model issues,There are still large uncertainties in the relevant conclusions,We need to accumulate more research.”Chen Deliang said.

尽管如此,Most climate experts agree,This study outlines the most significant climate change challenges we will face in the future.

The world according to the latest research from Leiden16个临界点

Impact of climate tipping points

近年来,Awareness of the huge impacts of climate tipping points has increased across society,This is thanks in large part to the work of scientists like Leiden.

Leighton told The Paper,当他在2008When publishing papers on tipping points in,Some aspects of the forecast are still theoretical.但从那时起,As the rate of damage from climate catastrophic events increases and scientists improve their ability to observe climate change,Tipping point evidence strengthened.在最新发表的研究中,His team was determined in total16个临界点,If these critical points are triggered,将产生“profound regional impact”.

2008Nine major tipping points are listed in the Leiden paper,Most of them are in2018Intergovernmental Panel on Climate Change(IPCC)发布的《全球升温1.5摄氏度特别报告》里也有提到.

These tipping points include:(1)Withering of the Amazon rainforest;(2)Arctic sea ice extent is decreasing;(3)Atlantic Meridional Overturning Circulation(AMOC)的减弱;(4)北美的Boreal forest fires and pests;(5)Mass death of coral reefs around the world;(6)Greenland ice sheet melts faster; (7)永久冻土层解冻;(8)West Antarctic ice sheet melts faster;(9)East Antarctica's ice sheet melts faster.

2008Nine major climate tipping points identified in

事实上,Some of these tipping points may have been triggered.Leighton told The Paper,Research over the past decade shows that,Glacier melt in West Antarctica's Amundsen Sea may have breached tipping point ——The evolution of each model is displayed,在这片区域,海洋、Land and bedrock meet “交界线” Continuing to retreat.If all the glaciers in West Antarctica melt,could cause global sea levels to rise by about3米.

The same thing is happening on the ice sheet of Greenland in the northern hemisphere.Correlation model studies show that,Greenland ice sheet melting tipping point is heating up1.5℃may be triggered.If the Greenland Ice Sheet were to melt,It will raise global sea levels by approx.7米.

Layton agrees,The researchers also need more observational data and time to determine whether the relevant ice sheets have reached a tipping point,但可以肯定的是,Antarctica and Greenland's ice sheet is on the earth“最脆弱”one of the critical points,The current distance has triggered the massive melting of the ice caps in the two places “非常接近”.

If the west Antarctic ice and the Greenland ice sheet melting point is triggered,will eventually lead to a ten-meter rise in global sea levels,纽约、洛杉矶、圣彼得堡、新奥尔良、上海、Edinburgh and other major coastal cities around the world,It will be submerged by the sea and cease to exist.

Another tipping point with a huge threat is the thawing of the permafrost.There is about twice the amount of carbon sequestered in the current global atmosphere..IPCC 报告写到:If according to the current heating rate,全球约70%Melting permafrost will by the end of the century,Once the carbon slumbering in the permafrost is unsealed,Will continue to release for a long time and it's hard to stop,This will further strengthen the vicious circle of the greenhouse effect.

Amazon Rainforest is the largest tropical rainforest in the world,Habitat for one tenth of the world's known species,It is also the largest carbon storage in the world、Carbon sequestering forests.At the university of Essex, seminar,Niklas, Professor of Earth System Modeling at the Technical University of Munich, Germany·Bulls(Niklas Boers)表示,自2003年以来,due to deforestation and climate change,Three-quarters of the Amazon rainforest has been lost“恢复力”.这“The Amazon may have been pushed to the tipping point of rainforest withering”,Monsoon knock-on effect in South America,减少30%至40%的降水量.

Wu Yixiu told The Paper,As a powerful helper in mitigating climate change,The long-term storage of carbon in the Amazon rainforest is roughly equivalent to the total emissions of all human beings in ten years.Once this critical point is breached,Such a high amount of carbon released into the atmosphere,will increase the global carbon dioxide concentration10%.

on the ocean side,Atlantic Meridional Overturning Circulation(AMOC)is a major current system in the Atlantic,And it may already be at its weakest point in thousands of years.

Stephen Professor of Marine Physics at the University of Potsdam, Germany·Ramstorff(Stefan Rahmstorf)The professor further stated at the meeting,“几周前,Some unpublished data I've seen suggests,AMOCmay be in the past1170The weakest period in ten thousand years.”

AMOCFurther weakening could bring huge influence in Europe,cause more storms、Colder winters and an increase in extreme heat, heatwaves and droughts across Europe.

也有专家表示,Tipping point for mass death of coral reefs globally is biggest concern,因为这“Directly affects the livelihoods of hundreds of millions of people”,especially inhabitants of poorer tropical regions,They depend directly on reef-related fisheries for their livelihoods.

Most experts agree,观测证据表明,Some major Earth system tipping points are losing stability.Johann, Director of the Potsdam Institute for Climate Impact Research, Germany · Rockstrom(Johan Rockstrom)compare it to lighting a fuse on a bomb,“The fuse will burn,until the big bang.”

Chen Deliang told The Paper,“If we have a good understanding of how the Earth system works,Then the prediction will be more accurate.过去发生的(Climate event data)can help us improve our understanding,But models are not a substitute for the future.Many of the climate events happening right now have never happened in the past,This is a huge challenge for predicting the future.”

What worries scientists more in recent years is that,Global tipping points are interconnected,A tipping point was breached,May increase the risk of other tipping points being breached.Once the climate change dominoes are toppled,the global cascading effect(Global Cascade) will become inevitable.If this chain reaction occurs,Global average temperatures will rise to more than the past120any time in a thousand years,Earth will become“Greenhouse Earth”,Ultimately form a threat to human existence and civilization.

“大约十年前,We believe this is only a theoretical possibility,Now we have more direct evidence of cause and effect.”Leighton told The Paper.

Leighton explained in detail:Like the melting of the Greenland ice sheet,would inject a lot of fresh water into the North Atlantic,Further weakening of the Atlantic Meridional Overturning Circulation,This reduces heat transfer from the southern hemisphere to the northern hemisphere,The ocean of the heat in the southern hemisphere,Further heating up the melting of the Antarctic ice sheet.

White ice and snow covering the poles could have reflected sunlight,But if the snow melts,Bare brown earth and oceans will absorb more solar thermal radiation,Adding to the melting of the permafrost layer,Let more snow melt,形成恶性循环.

对此,Chen Deliang also agreed,不过他指出,How exactly different tipping points around the world interact with each other,How big is the impact still needs further scientific research.

2021年9月11日,Located approximately south of Nuuk, Greenland80Selma m glaciers are melting.


How to deal with looming climate tipping points?at the University of Exeter conference,Participants launched a project called“Positive turning point”(Positive Tipping Point)的倡议 ,Expect to trigger rapid transformation in global society ,In order to timely respond to the climate crisis.

Leiden explained to The Paper as an example,一个“Positive turning point”It could be the accelerated decline in renewable energy prices and the huge political support for deploying these technologies.

“我们相信,An important way to change entrenched behaviors is to find social and political ‘Positive tipping point’.We must find and trigger these positive tipping points in socioeconomic systems,Fundamentally accelerate the decarbonization of the global economy,To limit the risks from a very damaging tipping point in the climate system.”

Scientists at University of Exeter meeting highlight,Now turn funding and attention to rapidly scaling up zero-carbon renewable energy,Many catastrophic tipping points can still be prevented.Right now in many places,Renewables are already as cheap as fossil fuels.Most major car and truck makers are now planning to stop producing fossil fuel vehicles.

Martin College, Oxford University, UK(Oxford Martin School)Duo Yin, Director of the Complexity Economics Program·法默(Doyne Farmer)在会上表示,The cost of renewable energy is expected to drop significantly over the next few decades,that any other energy source will soon become uncompetitive.

Leighton cites the UK as an example:“A decade ago coal accounts for the country's electricity40% ,Now the UK is planning to arrive2024Stop using coal to generate electricity,This is a positive turning point.”

And the change is caused by three things in common:Investment in wind power、Introducing carbon pricing and EU carbon trading in the power generation sector.“Once investing in coal becomes unprofitable,Companies will start dismantling coal-fired power stations.”莱顿说.

另一方面,Public awareness and participation still needs to be improved.According to research firm Ipsos last year G20a national opinion poll,While awareness of the climate and biodiversity crisis has grown,But they still know very little about the scale of behavior change needed.

83%的受访者表示,I want to do more to protect and restore nature.然而,When asked what action will be taken,Top priorities indicated by the majority include increasing waste recycling and avoiding overpackaging,And change eating habits、Behavioral changes that have a bigger impact on climate, such as reducing the use of fuel vehicles and flying, are rarely mentioned.

尽管挑战巨大,Leiden, who has been studying climate tipping points for years, isn't sinking into pessimism.“My personal philosophy is,See yourself as part of the entire earth's biological systems.The climate crisis tells us it's a learning to work with nature,rather than a process of confrontation.”莱顿说.

他补充道,“I think another reason is for our children,They make me worry about the future,But it also gave me the best hope.”

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