27/08/2020

(AU) Gas Is Not Transition Energy We Were Promised, New Research Suggests

Sydney Morning Herald - Nick O'Malley

The good news about natural gas is that when it is burnt it creates between 40 and 50 per cent less carbon dioxide than coal would to create the same amount of energy.

This is why it has been embraced by some climate activists and governments as a useful energy source to replace coal and oil while renewable energy technologies catch up with global energy demand.

Gas appears to be no cleaner an energy source than coal, new research suggests. Credit: Glenn Hunt

But the good news ends there, and there is a lot more to the story.

Before it is burnt natural gas is mostly made up of methane, and methane is estimated to be about 28 times more potent a greenhouse gas than carbon dioxide over a 100-year period.

Over a 20-year period - about the time scientists believe we have to try to prevent the worst impacts of global warming - it is up to 80 times more potent at warming the planet than carbon dioxide.

The United States’ Environmental Protection Agency estimates that for every cubic metre of methane extracted by the US oil and gas industry, 1.4 per cent escapes into the atmosphere as so-called fugitive emissions.

But more recent research suggests this estimate is drastically low, and that, in fact, the industry in the US is leaking 13 million metric tonnes of methane a year, or 2.3 per cent.

It is not yet clear how much fugitive methane is released by the Australian gas industry, but new technologies now allow scientists to accurately measure it and the data is expected to be published in the coming months.

The US Environmental Defence Fund estimated that, in America, if just 3 per cent of methane escapes, gas is no cleaner an energy source than coal.

Either way, as gas begins to displace coal - or in Japan, nuclear power - as an energy source, its significance as a warming agent via both the carbon dioxide it produces when burnt and via fugitive methane emissions is growing rapidly.

According to research published last month by the CSIRO's Global Carbon Project, at the end of 2019, methane concentration in the atmosphere reached 1,875 parts per billion – more than 2½ times higher than pre-industrial levels. This was a level consistent with the climate warming by a catastrophic 3-4 degrees Celsius by 2100.

Between 2008 and 2017, 60 per cent of methane emissions were man-made, created by agriculture and waste, followed by oil and gas production and then the burning of biofuels.

The most recent research suggests that agriculture and the use of fossil fuels - mainly gas - are equal contributors to the rise of methane in the atmosphere over the past decade, says Dr Pep Canadell, a senior scientist with the CSIRO and director of the Global Carbon Project.

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(AU) Chief Scientist Alan Finkel Fires Back On Gas Criticism From Colleagues

Sydney Morning Herald - Nick O'Malley

Australia's Chief Scientist, Dr Alan Finkel, has defended his position on the use of natural gas after being criticised by some of the nation's leading climate change scientists, saying it would remain one of the nation's key energy sources.

"There will be times when supply from renewable electricity generators will be inadequate to meet demand and occasionally such periods will last many days and affect adjacent jurisdictions," Dr Finkel wrote.

Dr Alan Finkel has defended his position on the use of natural gas following criticism from a group of Australian climate scientists. Credit: Jessica Hromas

On Monday The Sydney Morning Herald and The Age reported that a group of 25 leading Australian scientists had written to Dr Finkel, voicing their concern that his support for the use of gas was not supported by scientific evidence about the need for the rapid abandonment of fossil fuels to tackle climate change.

They were particularly concerned about elements of Dr Finkel's address to the National Press Club earlier this year, which preceded the government's adoption of an economic stimulus policy backed by an expansion of the gas industry.

Dr Finkel wrote that as he said in his press club address, "the adoption of more renewable electricity will be faster, more economical and more reliable if natural gas fired electricity generation continues to be available in the near- to medium-term."

"Natural gas fired electricity can pick up where batteries and pumped hydroelectricity run short. Furthermore, natural gas fired electricity has an important firming role to play as, and when, existing coal-fired stations close due to age or competition," he wrote.



He wrote that greenhouse gas emissions caused by burning coal gas to generate electricity were lower than that created by burning coal, "even when upstream fugitive emissions of methane are included in the analysis". He also wrote that because gas-fired power stations could ramp up faster than coal-fired power stations they did not need to operate for as long to meet shortfalls in renewable power in the grid.

"The combination of lower emissions per megawatt-hour and a smaller number of operating hours means that natural gas fired electricity can make a valuable contribution to reliability during our transition to a low emissions electricity system."

Dr Finkel wrote that he has not commented on an expanded role of gas for industry, rather his focus has been on the use of gas-fired electricity generation alongside renewable energy.

One of the signatories to the letter, Professor Will Steffen, said Dr Finkel had not addressed its key points.

"He is addressing engineering problems. He is not speaking about the fact that using gas as a transition fuel is not compatible with meeting Paris Agreement climate targets to which Australia is a signatory," he said.

Former chief scientist Penny Sackett, who did not sign the letter, said that there was no time for a decades' long switch from coal to gas.

"'Fuel switching' from coal to gas is policy based on factors that were at play around the turn of the century or before, not in today's world and beyond," she said. "The last thing we need is to increase fossil fuel production at a time when coal, gas and oil must all decline starting now in order to stay well below 2°C of global heating."

Asked in Parliament by Greens leader Adam Bandt if he shared the concerns of the scientists, Prime Minister Scott Morrison reiterated the government's view that gas would not only help sustain Australian jobs and industry, but also supported a transition to a low carbon economy.

"That is why we want to see more of it and get more out of the ground, Mr Speaker, so we can fuel the jobs that this country needs as we come out of the COVID-19 recession."

He noted that government members were "united in that view of gas".

"We all support it, Mr Speaker. We are all behind it. I believe the Australian people will also."

He noted that the Labor Party appeared to be divided over the issue. Labor energy spokesman, Mark Butler, declined to comment.

The independent MP Zali Steggall said she was "very concerned about Dr Finkel's statements on gas as a transition fuel for "decades to come".

"The Government relies on Dr Finkel's views to justify a focus on gas, and yet his advice is at odds with scientists across the country who say a gas-led recovery is not in line with tackling the emissions reduction challenge we must do under the Paris Agreement," she said.

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(AU) 4 Reasons Why A Gas-Led Economic Recovery Is A Terrible, Naïve Idea

The Conversation - 

Shutterstock

Author
 is Director of the Centre for Energy and Natural Resources Law, Deakin Law School, Deakin University.     
Australia’s leading scientists have sent an open letter to Chief Scientist Alan Finkel, speaking out against his support for natural gas. Finkel has said natural gas plays a critical role in Australia’s transition to clean energy. But, as the scientists write:
that approach is not consistent with a safe climate nor, more specifically, with the Paris Agreement. There is no role for an expansion of the gas industry.
And yet, momentum in the support for gas investment is building. Leaked draft recommendations from the government’s top business advisers support a gas-led economic recovery from the COVID-19 pandemic. They call for a A$6 billion investment in gas development in Australia.

This is a terrible idea. Spending billions on gas infrastructure and development under the guise of a COVID-19 economic recovery strategy — with no attempt to address pricing or anti-competitive behaviour — is ill-considered and injudicious.

It will not herald Australia’s economic recovery. Rather, it’s likely to hinder it.

The proposals ignore obvious concerns

The draft recommendations — from the National COVID-19 Coordination Commission — include lifting the moratorium on fracking and coal seam gas in New South Wales and remaining restrictions in Victoria, and reducing red and “green tape”.

In a speech in February to the National Press Club, Alan Finkel said gas was vital in Australia’s transition to clean energy. AAP Image/Mick Tsikas

It also recommends providing low-cost capital to existing small and medium market participants, underwriting costs at priority supply hubs, and investing in strategic pipeline development.But the proposals have failed to address a range of fundamental concerns.
  1. gas is an emissions-intensive fuel
  2. demand for fossil fuels are in terminal decline across the world and investing in new infrastructure today is likely to generate stranded assets in the not-too-distant future
  3. renewable technology and storage capacity have rapidly accelerated, so gas is no longer a necessary transition resource, contrary to Finkel’s claims
  4. domestic gas pricing in the east coast market is unregulated.
Let’s explore each point.

The effect on climate change

Accelerating gas production will increase greenhouse gas emissions. Approximately half of Australian gas reserves need to remain in the ground if global warming is to stay under 2℃ by 2030.

Natural gas primarily consists of methane, and the role of methane in global warming cannot be overstated. It’s estimated that over 20 years, methane traps 86 times as much heat in the atmosphere as carbon dioxide.

And fast-tracking controversial projects, such as the Narrabri Gas Project in northern NSW, will add an estimated 500 million tonnes of additional greenhouse gases into the atmosphere.

Accelerating such unconventional gas projects also threatens to exacerbate damage to forests, wildlife habitat, water quality and water levels because of land clearing, chemical contamination and fracking.

A protest in 2017 against Santos’ plans for a major coal seam gas field near Narrabri. This gas project will pump enormous amounts of greenhouse gases into the atmosphere. AAP Image/Paul Miller

These potential threats are enormous concerns for our agricultural sector. Insurance Australia Group, one of the largest insurance companies in Australia, has indicated it will no longer provide public liability insurance for farmers if coal seam gas equipment is on their land.Fossil fuels in decline

Investing in gas makes absolutely no sense when renewable energy and storage solutions are expanding at such a rapid pace.

It will only result in stranded assets. Stranded assets are investments that don’t generate a viable economic return. The financial risks associated with stranded fossil fuel assets are prompting many large institutions to join the growing divestment movement.

Solar, wind and hydropower are rolling out at unprecedented speed. Globally, renewable power capacity is set to expand by 50% between 2019 and 2024, led by solar PV.

Solar PV alone accounts for almost 60% of the expected growth, with onshore wind representing one-quarter. This is followed by offshore wind capacity, which is forecast to triple by 2024.

Solar PV accounts for almost 60% of the growth in renewables. AAP Image/Lukas Coch

Domestic pricing is far too expensive

Domestic gas in Australia’s east coast market is ridiculously expensive. The east coast gas market in Australia is like a cartel, and consumers and industry have experienced enormous price hikes over the last decade. This means there is not even a cost incentive for investing in gas.

Indeed, the price shock from rising gas prices has forced major manufacturing and chemical plants to close.

The domestic price of gas has trebled over the last decade, even though the international price of gas has plummeted by up to 40% during the pandemic.

As Australian Competition and Consumer Commission chair Rod Simms declared in the interim gas report released last week, these price issues are “extremely concerning” and raise “serious questions about the level of competition among producers”.

To date, the federal government has done very little in response, despite the implementation of the Australian Domestic Gas Security Mechanism in 2017.

This mechanism gives the minister the power to restrict LNG exports when there’s insufficient domestic supply. The idea is that shoring up supply would stabilise domestic pricing.

Former chief executive of Fortescue Metals Nev Power heads the government’s COVID-19 commission. AAP Image/Joel Carrett

But the minister has never exercised the power. The draft proposals put forward by the National COVID-19 Coordination Commission do not address these concerns.

A gas-led disaster

There is no doubt gas producers are suffering. COVID-19 has resulted in US$11 billion of Chevron gas and LNG assets being put up for sale.

And the reduction in energy demand caused by COVID-19 has produced record low oil prices. Low oil prices can stifle investment in new sources of supply, reducing the ability and incentive of producers to explore for and develop gas.

It’s clear the National COVID-19 Coordination Commission’s recommendations are oriented towards helping gas producers. But investing in gas production and development won’t help Australia as a whole recover from the pandemic.

The age of peak fossil fuel is over. Accelerating renewable energy production, which coheres with climate targets and a decarbonising global economy, is the only way forward.

A COVID-19 economic strategy that fails to appreciate this not only naïve, it’s contrary to the interests of broader Australia.

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26/08/2020

(AU) Australia's Chief Scientist Is Wrong On Gas, Say Leading Experts

Sydney Morning Herald - Nick O'Malley

A group of leading Australian scientists has taken the unusual step of writing to the Chief Scientist, Dr Alan Finkel, saying his support for gas as an energy source "is not consistent with a safe climate".

"We are making a definite and profound statement that the advice the Chief Scientist is giving is in opposition to the evidence the Australian scientific community has gathered about the climatic system and the way it is changing," Professor Will Steffen, the founding director of the Australian National University's Climate Change Institute, said of the decision to write the letter.

Scientists have taken the rare step of speaking out about Chief Scientist Dr Alan Finkel's support for the use of gas as a transition fuel to a cleaner energy system. Credit: Attila Csaszar

The letter's signatories include many world-leading Australian experts and lead authors with the Intergovernmental Panel on Climate Change. They include professors John Church, Matthew England and Steven Sherwood from the University of NSW's Climate Change Research Centre, Professor Mark Howden of the Australian National University and Professor Graeme Pearman of the University of Melbourne.

"We are writing to you as Chief Scientist with our concerns about your strategy for dealing with climate change, and to offer any scientific advice that you might find useful on climate change issues," begins the letter, which is signed by 25 scientists.

Professor Steffen said the scientists' decision to take the unusual step of speaking out about the Chief Scientist was prompted in part by elements of Dr Finkel's address to the National Press Club in February, as well as other public comments he has made about gas.

Professor Steffen said more would have signed the letter but could not as they were employed by government agencies such as the CSIRO and the Bureau of Meteorology.

In the speech Dr Finkel outlined how Australia needed to electrify its energy system to meet Paris climate goals.

He said that as renewable energy generation, storage and transmission technologies are scaled up to decarbonise the economy, gas would play a "critical role", and that the transition could take decades.

The speech, made shortly before the government embraced a gas-led economic recovery from the economic crisis caused by COVID-19, caused concern among elements of the scientific community who see gas as an increasingly destructive global warming agent.

"He seems to be speaking in ignorance of or [to be] ignoring the overwhelming amount of evidence gathered by his own scientific community about the impact of the gas industry on the climate," said Professor Steffen.

Professor Steffen said that Australia's Paris climate targets were weak, set politically and had no scientific basis; that even if they were to be met Australia would still not be doing its fair share to mitigate global warming under the agreement, and that the use of gas as a transition energy source was quickly making the situation worse.

In the letter the scientists applaud Dr Finkel's support for a transition to renewable energy, but take issue with his support for the government's advocacy for an ongoing role for gas.



"Our concern ... relates to the scale and speed of the decarbonisation challenge required to meet the Paris Agreement, and, in particular, your support for the use of gas as a transition fuel over ‘many decades'," they write.

"Unfortunately, that approach is not consistent with a safe climate nor, more specifically, with the Paris Agreement. There is no role for an expansion of the gas industry."

"The combustion of natural gas is now the fastest growing source of carbon dioxide to the atmosphere, the most important greenhouse gas driving climate change.

"On a decadal time frame, methane is a far more potent greenhouse gas than carbon dioxide.

"In Australia, the rapid rise in methane emissions is due to the expansion of the natural gas industry. The rate of methane leakage from the full gas economy, from exploration through to end use, has far exceeded earlier estimates."

Energy and Emissions Reduction Minister Angus Taylor as well as the National COVID-19 Coordination Commission support gas as an energy source that is less carbon intensive than coal and that can quickly be ramped up or down to support renewable energy sources in the grid.

A spokeswoman for the Office of the Chief Scientist said Dr Finkel was considering his response and would comment in due course.

A spokesman for Mr Taylor said that the International Energy Agency has estimated that coal-to-gas switching has avoided more than half a billion tonnes of emissions between 2010 and 2018.

"A separate CSIRO assessment of Queensland LNG production found that gas alone can reduce emissions from electricity production by up to 50 per cent. When gas backs up solar and wind, the emissions savings are even greater.

"Australia's gas exports are reducing emissions in importing countries overseas where they displace more emissions-intensive alternatives or backup renewables.

Dr Pep Canadell, executive director of the Global Carbon Project and a chief research scientist at the CSIRO said greenhouse gas emissions from the gas industry in Australia were "skyrocketing".

"They are not taking Australia in the direction it needs to go."

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AU) Corporate Climate Risk Disclosures Must Show More: IGCC

Financial Standard - Annabelle Dickson



Investors using companies' climate change risk disclosures to manage investment decisions and portfolio risk want more changes to understand how the risk information translates into action.

The latest report by the Investor Group on Climate Change (IGCC), Full Disclosure: Improving corporate reporting on climate risk, found that improvements are needed in climate risk disclosure to make it more useful for risk assessment and portfolio management.

Since the Task Force on Climate-related Financial Disclosure released its recommendations in 2017, there has been increased reporting on climate-related risks however gaps remain between the information provided and that required by investors.

IGCC surveyed 50 investors from 22 organisations in Australia and New Zealand with more than $1.1 trillion in collective funds under management.

The investors are calling for companies to discuss how climate change risk informs strategy and planning, evidence the board understands climate-related risks and assessment of the impact of actions taken to manage these risks.

Furthermore, investors want companies to provide data evidence for claims they make about climate-related risks such as evidence of relevant expertise in executives and board, discussion of input and assumptions made in scenario analysis and disclosure of the assumptions underpinning a business model.

Australian Ethical head of ethics research Stuart Palmer said: "Improved disclosure is needed for investors to manage climate change risk in their portfolios and make accurate assessments of the performance and prospects of companies."

"Critically, investors want companies to show not just that climate risk is being assessed but how this is informing and changing their strategies and decision-making from board governance to capital expenditure to future business opportunities."

Just over half the respondents represented asset/fund managers and a third represented institutional investors.

The majority consider climate change a financial risk in investment analysis and around 40% use climate disclosures on a daily or weekly basis.

Nearly all investors (84%) use disclosures as a basis for engagement with companies, followed by using them as a part of environmental, social and governance integration (76%).

IGCC chief executive Emma Herd said: "Around the world different jurisdictions are working out how to ensure consistent, clear and investable climate risk disclosure that translates to action in capital markets."

"Some markets are using voluntary guidance developed by regulators. Others, like New Zealand and Canada, are moving to mandatory disclosure regimes, something which should now be considered in Australia given the systemic risks climate change poses to our economy."

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(AU) Consumers Push Corporate Agriculture To Move Quickly On Zero Emissions, Leaving National Farmers Federation Target Behind

ABC Rural - David Claughton

Livestock are responsible for 70 per cent of greenhouse emissions from agriculture but changes to feed, management and genetics is helping to reduce the impact. (Supplied: Jon Wright, Blue-E)

The National Farmers Federation (NFF) has announced its support for zero carbon emissions from agriculture by 2050, but is it too little, too late?

Corporate agriculture is acting with greater urgency, while the red meat industry has adopted a much more ambitious deadline of 2030.

There have been a series of big announcements on emissions from large agricultural corporations in recent weeks, driven by changing consumer demand around the world.

US retailers are reporting a doubling in demand for plant-based food during the pandemic and that trend is being replicated in Australia.

Brazilian giant JBS has established a plant-based range of food products to go alongside its massive abattoir business to improve its credentials and respond to growing demand for alternatives.

Woolworths, along with billionaire pastoralist Andrew Forrest, is backing a $15-million CSIRO project to put seaweed into cattle feed which can reportedly reduce emissions by more than 80 per cent.

Despite that, farm lobby groups like the New South Wales Farmers Association have announced only conditional support for the NFF target of net zero emissions by 2050.

They want clarity on how farmers will be expected to do it, and a guarantee it will not cost them more to comply.

Queensland lobby group Agforce abstained over its concerns about the lack of work underpinning the NFF target.

Meat industry facing the biggest challenge

Agriculture is responsible for 14 per cent of Australia's emissions and cattle make up the 70 per cent of those.

When cows burp and fart, they convert grass into methane which is a potent greenhouse gas.

The most effective way to bring those emissions down is to change what the animal eats and to improve the animal's ability to convert feed to protein through breeding and genetics.

Cattle breeder Jon Wright has cut methane emissions from his cattle by 30 per cent through genetics and management systems. (ABC News: Tim Fookes)

NSW grazier Jon Wright has been breeding "low-emission" cattle for decades but he is sceptical about the industry's ability to achieve that goal.
"To actually set some goals is a huge, huge challenge and if you want me to put money on when will we get there, I'm probably not going to," he said.
Mr Wright said the problem for the industry is that most of Australia's meat supply comes out of rangelands in Queensland and the Northern Territory and he does not think it will be easy for those graziers to change their practices or access low emissions food and genetics.

He said retailers may need to reconsider sourcing beef from those areas.

"Now that's pretty horrible to say and pretty hard to think about, but people up in those areas have to prove how they can produce a lower emissions product if they're going to stay in business," Mr Wright said.

Changes to nutrition could help significantly reduce emissions from cattle in feedlots but it may be much harder on the rangelands of inland Australia. (ABC Rural: Matt Brann)

Nuffield scholar Ellen Litchfield, from Wilpoorinna Station in South Australia, travelled the world looking at ways to reduce emissions in the rangelands grazing areas.

She believed they were actually much better placed to reduce emissions and care for the planet generally than livestock in feedlots or other production systems.

"We're still in the process of doing a carbon footprint for the station and I think there needs to be some research into the carbon footprint of extensive grass fed systems, but the emissions from these cattle are so much lower and we're not using grain that could be used for something else," she said.

Changing cattle feed a big part of the solution

Global animal nutrition company Alltech signed up to the United Nations Sustainable Development Goals and started its own initiative to reduce emissions, called the Planet of Plenty.

It set benchmarks to monitor its progress on lowering greenhouse gas emissions and reducing energy and water consumption.

Alltech produce and distribute animal feed to 120 countries, including Australia, so they are in a position to make a difference with low emissions feed.

Global animal feed company Alltech have conducted more than 9,000 farm assessments and found that environmentally efficient farms are often the most profitable as well. (Supplied: Alltech)

They are focussing on rumen modifiers that can directly reduce methane emissions by altering the biochemistry of the rumen to inhibit methane-producing microbes in the rumen.

Vice president Matthew Smith said livestock emissions are going down globally, even though beef and dairy production is going up and that is because animal production is becoming more efficient.

"If a cow produces more milk or if a beef animal is heavier, has higher daily live weight gain, there are more kilos to divide that methane across," he said.

Genetics could drive emissions in cattle down

Jon Wright thinks it is possible to reduce emission by about 30 per cent, using genetics and cattle management systems.

He has been breeding cattle that need less feed to gain weight and his focus is on early weaning his calves.

That gives his cows time to put on weight before they get pregnant again and then his focus is on halving their usual rations in order to halve their emissions.
"They will eat 15kg day if you let them, [but] they will maintain weight and maintain their condition in pregnancy on half that."
Are Australian targets ambitious enough?

Alltech vice president Matthew Smith says Australia is on track to meet the Paris Accord target for agriculture, other countries have more ambitious targets. (Supplied: Alltech)
Australia is on track to meet the Paris Accorde to reduce emission from agriculture to 26 to 28 per cent of 2005 levels, according to Matthew Smith from Alltech

"In 2020 Australia is on track to do that, levels have dropped 5-6 per cent," he said.

While some countries were not so successful, Mr Smith still believed a much more ambitious goal was achievable for Australia.
"New Zealand isn't far away from you, they have a bold target, and there are many countries in Europe looking at 40 and 50 per cent reductions," he said.
But Mr Smith said measurement systems still varied and that was a problem.

"Unless there is one clear system in place to do that measurement it becomes really difficult to say 'what system do I use?'" he said.

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25/08/2020

We Pieced Together The Most Precise Records Of Major Climate Events From Thousands Of Years Ago. Here’s What We Found

The Conversation - Ellen Corrick | John Hellstrom | Russell Drysdale

Markus Rex/Alfred Wegener Institute via AP

Authors


Between 115,000 and 11,700 years ago, the Earth would have been almost unrecognisable. 

 Massive ice-sheets covered northern Europe and northern Asia, and about half of North America, and global sea-levels were as much as 130 meters lower than today.

In this period, known as the “last glacial period”, the climate was much cooler and drier than today. It was punctuated by some of the largest and most rapid climate change events in Earth’s recent geological history.

For a long time, scientists have pondered how closely timed these abrupt climate change events were between Greenland and other regions of the world — far beyond the Arctic.

In our research, published today in Science, we’ve shown abrupt climate changes across the Northern Hemisphere and into the southern mid-latitudes occurred simultaneously, within decades of each other, throughout the last glacial period. We’ve also determined exactly when the abrupt changes occurred, much more precisely than before.

This can help us predict how abrupt climate changes might play out in the future.

A series of abrupt climate changes

Scientists can peer into Earth’s climate history through long ice cylinders, called “ice cores”, drilled from the Greenland ice sheet. Changes in the chemical composition of these ice cores reveal that the surrounding atmospheric temperature repeatedly warmed by 8-16℃, and each time within just a few decades.

An ice core. Ancient ice can reveal what the surrounding climate was once like. AAP Image/ACECRC

Each warming event was followed by a more gradual period of cooling. These abrupt warming and cooling events happened more than 25 times throughout the last glacial period, and are known as Dansgaard-Oeschger events.

They reflect changes in circulation patterns of the Atlantic Ocean.While we have records of climate changes from many regions, the relative timing of these changes between Greenland and across the northern hemisphere into the southern sub-tropics is not well understood.

This has been difficult to resolve because we need very precisely dated records to make exact comparisons in timing. Ice cores provide a wealth of information about Dansgaard-Oeschger events. But while they faithfully reproduce the patterns of past climate, they are difficult to date very precisely.

Crystal time capsules beneath our feet

For our study, we turned to more precisely datable climate records: those from cave stalagmites.

Stalagmites are cave mineral deposits, which build up layer-by-layer on the cave floor. Their growth is fed by water dripping from the cave ceiling, which carries with it a chemical signal of temperature and rainfall conditions above the cave at that time. This signal is trapped in the crystal structure of the growing stalagmite.

Stalagmites can be dated very precisely, by measuring the decay of minute amounts of uranium trapped in them. This key feature enables us to compare the timing of climate events from place to place.

Stalagmites hold chemical signals that reveal what the climate above the cave was like thousands of years ago. Shutterstock

However, long, high-quality stalagmite records are rare. Scientists from around the world have been working for more than 20 years to produce these records. Only now that enough records are available, we are able to make precise comparisons of the timing of Dansgaard-Oeschger events between different regions.

We collated and compared 63 published stalagmite records from caves in Asia, Europe and South America, and we determined the timings of abrupt climate changes in each.

What we found

Our results show that during each Dansgaard-Oeschger event, climate changes felt in Asia, South America and Europe occurred within decades of one another. Being able to determine this level of synchrony is remarkable, given we are looking at events that occurred many tens of thousands of years ago.

This means that as large temperature increases were occurring in Greenland, abrupt changes were also occurring in air temperature and rainfall in Europe, and in the monsoon systems in Asia and South America.

So why is this important? First of all, finding that climate change events occurred in lots of different parts of the world within decades provides clues as to how they started in the first place.

It tells us the changes were likely propagated from the North Atlantic region to these locations through the re-organisation of patterns in atmospheric circulation. And knowing this can help scientists narrow down the underlying triggers, which are still not conclusive.

And our findings mean the precise ages from the stalagmites can be used to better date ice cores, enhancing one of the most important records we have of the last glacial climate.

In the last glacial period, vast ice sheets covered much of the world. Shutterstock

Implications for the future

The abrupt climate changes we studied occurred under very different conditions compared to the climate of today.

While our ancestors lived through the last glacial period, humans are unlikely to experience Dansgaard-Oeschger events for many thousands of years, until the earth has again cooled to glacial temperatures.

However, piecing together the puzzle of how abrupt climate changes took place in the past will help us to understand how abrupt climate changes might occur in the future. For example, our findings will help validate climate models used to predict climate changes.

Showing that profound changes in climate can occur simultaneously across large regions of the Earth highlights just how unstable and interconnected our climate system can be.

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