08/05/2020

(AU) 6,000 Years Of Climate History: An Ancient Lake In The Murray-Darling Has Yielded Its Secrets

The Conversation - Hannah Power | Anna Helfensdorfer | Tom Hubble

Tom Hubble

Authors
For millions of years, the Murray River has flowed from the Australian Alps across the inland plains, winding through South Australia before emptying into the ocean. But the final leg of its journey once looked vastly different.

Our research released today conclusively shows what has long been suspected: 6,000 years ago, water levels in the Lower Murray River were so high that much of the system in South Australia comprised a huge lake.

We also uncovered an invaluable long-term record of floods and droughts in the Murray Darling Basin, by drilling deep into layers of silt and clay built up over 12,000 years.

Our findings point to how Australia’s most important river system might be altered by future sea level rise. What’s more, a better record of past floods and drought will help manage water use in Australia’s most important river system.

The Lower Murray River today and a computer-generated image of what Lake Mannum may have looked like between 5,000 and 8,500 years ago when sea levels were 2 metres higher than they are today. Original photo: Tom Hubble. Modified image: Kathirine Sentas.

 Probing the past

Our climate is changing and sea levels are rising. Scientists are working hard to forecast what environments such as rivers and estuaries will look like under higher sea levels and, in Australia, more intense droughts and floods.

One way to do this is to look back to a period 5,000-8,000 years ago, to a point in the sea level cycle known as the Holocene highstand. The Holocene refers to the past 11,700 years or so of Earth’s history. The highstand is the point at which sea levels were highest.

Today, the Murray River crosses into South Australia and flows within a narrow valley, then gradually widens towards Lake Alexandrina where it empties into the sea.

But it wasn’t always this way. After the peak of the last glacial period 18,000 years ago, melting ice caused sea levels to rise from about 120 metres below today’s level. About 6,000 years ago, sea level peaked at two metres above today’s level.

Researchers have previously hypothesised that over several thousand years, the high sea level at the mouth of the Murray acted like a dam, causing water to back up in the river, creating a saltwater lake known as Lake Mannum.

Our research confirms that the lake existed, and that it was enormous - stretching from the mouth of the Murray to about 200 kilometres upstream near Swan Reach.

We used high resolution two- and three-dimensional modelling modelling of water levels and flows to confirm the presence of the lake, and how it formed.

Layers of history

The naturally still waters of Lake Mannum acted as a enormous trap for clay and silt discharged upstream. Under various conditions, such as floods, the sediment travelled downstream and settled to the lake’s floor.

Today, the climate history for the Murray-Darling Basin is written in these sediment layers.

We collected a 30 metre-long sediment core from the present day floodplain of the Lower Murray River.

The core contains an 11-metre section of sediment deposited on the floor of Lake Mannum between 8,500 and 5,000 years ago. Each metre took roughly 315 years to accumulate - about three millimetres a year.

We believe each layer in the core probably represents an episode of increased or decreased river flow.

Most layers were probably produced when snow melt from the Australian Alps in spring and summer transported mud along the river system. Some layers will represent large floods that came down the Murray River, while others will represent floods that flowed down the Darling.

Longer-term variations in the thickness of the layers may correspond to extended periods of wetter and drier weather.

The next phase of our research will involve a close analysis of the sediment layers to obtain a reliable, detailed, high resolution record of flood and drought in the Murray Darling Basin.

What can we learn?

As sea level dropped to modern levels over the last 5,000 years, the lake slowly drained and turned back into a river.

These days, the lower Murray River is intensively managed. Five barrages, or barriers, have been erected near the river mouth to keep the water fresh by preventing seawater from creeping in, and to maintain water levels. Significant volumes of water have been extracted for irrigation and domestic use.

Some people argue the barrages should be removed to restore the natural tidal estuary and allow sea water to influence lake levels. Their removal is unlikely in the near future. But our research gives insight into what could happen if the barrages were removed, and sea levels rise under climate change.

The Lower Murray River near Mannum confined within the Lower Murray Gorge. Photo: Tom Hubble

We expect the next step in our research, analysing the sediment cores, to provide valuable data on long-term river flows and indicate whether intense droughts, such as the Millenium drought, are more or less frequent than the once-in-a-century figure often suggested.

In future, water managers deciding on water allocations may benefit from knowing how much water has historically come down the system, and how often.

Links
at No comments:

Climate Change And Coronavirus: Five Charts About The Biggest Carbon Crash

BBC Science & Environment - Matt McGrath

Traffic has almost disappeared in many cities around the world, such as LA. Getty Images

We're living through the biggest carbon crash ever recorded.

No war, no recession, no previous pandemic has had such a dramatic impact on emissions of CO2 over the past century as Covid-19 has in a few short months.

Multiple sources indicate we are now living through an unrivalled drop in carbon output.

But even though we will see a massive fall this year, the concentrations of CO2 that are in the atmosphere and warming our planet won't stabilise until the world reaches net-zero.

As our chart shows, since the Spanish flu killed millions over 100 years ago, the global expansion of emissions of CO2, from the use of oil, gas and coal has risen massively.



While these energy sources have transformed the world, the carbon seeping into our atmosphere has driven up global temperatures by just over 1C since the mid-1850s.

They could rise by 3-4C by the end of this century if CO2 levels aren't savagely reduced.

Over the past 100 years, as indicated on the graphic, a number of events have shown that dramatic falls in carbon are possible.

Much is made of the financial crash in 2008-2009, but in reality, carbon emissions only fell by around 450 million tonnes between 2008 and 2009.

This is much smaller than the fall in CO2 in the aftermath of World War II, which saw a drop of around 800 million tonnes.


Coronavirus and climate change a "double crisis", say activists

It is also smaller than the global recession in the early 1980s that followed the oil crisis of the late 1970s.

During this period, CO2 went down by around one billion tonnes.

But the coronavirus pandemic of 2020 dwarves all of these previous shocks by some distance.

In a few months, demand for energy globally has fallen off a cliff.

The International Energy Agency (IEA) says that the world will use 6% less this year - equivalent to losing the entire energy demand of India.

This will feed through to large falls in CO2.

Getty Images

 A number of different analyses, including this one from Carbon Brief, show that emissions this year will fall by 4-8%, somewhere between 2 and 3 billion tonnes of the warming gas.

That's between six and ten times larger than during the last global recession.

We're travelling less

By air and on roads, the world has cut back heavily on travel.

Full lockdowns have also pushed global electricity demand down by 20% or more, says the IEA.

Across the full year, the need for electricity will fall by 5% - the biggest drop since the Great Depression of the 1930s.



"This is an historic shock to the entire energy world," says Dr Fatih Birol, IEA executive director.

The changes in energy demand will have a knock-on effect on global coal demand, which is set to fall 8% this year.

With China the first country to stall its economy in response to the virus, coal use dropped sharply at first, though it is now rebounding and the expectation among energy analysts is that production this year will be down by just over 1%.

Researchers say the biggest thing hitting CO2 emissions right now is the reduction in road transport.

Air travel has fallen by half in the US. Getty Images

According to the IEA global average road transport activity fell to 50% of the 2019 level by the end of March 2020.

As can be seen in our chart, almost every country has seen a huge drop in road use. This has resulted in a massive fall in the use of oil.

"Back in the 2009 recession, average oil demand dropped by 1.3 million barrels per day versus 2008. And now 2020 is set to average 10 million barrels per day less than 2019." said Erik Holm Reiso, from Rystad Energy, an independent research firm.

"It's a much more severe cycle."

Similarly, air travel has dropped hugely, but by different amounts in different regions.



In Europe, the number of flights is down around 90%, whereas in the US it has been more resilient with around half the number of planes taking off compared to last year.

Globally, though, the demand for jet fuel is down 65% year-on-year to April.

"What we're seeing is that the largest relative reduction is in air traffic," said Robbie Andrew, a senior researcher at the Centre for International Climate and Environmental Research (Cicero).

"But air emissions are only about 3% of global total. So while the relative reductions in land transport are lower than air transport, the absolute reductions there are much more significant."

It's not the same everywhere

While the lockdown might feel rather uniform across the world, there have been huge variations in emissions reductions from different cities.

If we take Paris and New York as examples, the contrast, as shown on our chart, is huge.

Paris saw a CO2 drop of 72% (+/-15%) in the month of March compared to normal.

New York in the same period, saw a CO2 fall of around 10%.

Paris has seen a dramatic fall in CO2 since the lockdown began. Getty Images

So why the big difference?

"In the Paris area, there are no large fossil fuel power plants, or industrial sites," said Philippe Ciais, from the Institut Pierre Simon Laplace in Paris.

"Another difference is whether buildings are heated with fuels or with electricity. In France, around 70% of electricity comes from nuclear."

Much of New York's CO2 comes from emissions related to the heating of buildings. But significant emissions come from fossil fuel plants based within the city limits. Cars make up a much smaller proportion of overall energy use.



"I guess something to think about is that we shut down the entire city and got a reduction of 10% in the CO2 emissions," said Prof Róisín Commane from Columbia University in New York.

"We are still emitting more than 80% of our previous CO2 emissions. That is a massive number. So personal behaviour really isn't going to fix the carbon emission problem. We need a systematic change in how energy is generated and transmitted."


Our Planet Matters: Climate change explained

Have CO2 emissions already peaked?

Back in 2008, the European electricity industry was hit badly by the global financial recession and demand for power fell sharply.

But when that demand picked up again, it was solar and wind that were by then large enough to supply all the growth.

Europe's use of fossil fuels to produce electricity never returned to the level it had been at before the crash.

Experts now believe something similar could happen with the coronavirus pandemic.

"In about half of the world, we've already seen peak demand for fossil fuels," said Kingsmill Bond, from independent financial think tank Carbon Tracker.

Air pollution has cleared in some parts of Nepal due to restrictions there. Getty Images

"In Europe it was 2005, in the USA 2007."

This means that the trend in demand has been downhill ever since.

He added: "There has been a global coal demand peak in 2013. If you look at car demand, it is increasingly accepted that you saw peak conventional car demand in 2017."

So will the pandemic's big hit on carbon mean that last year, 2019, becomes the year the world reached a turning point?

Not so fast.

The carbon emissions drop that followed the recession in 2009 was followed by a sharp rise of almost 6% in 2010.

Something similar could happen over the next couple of years.

"At this point, we do not see any clear signs that the pandemic and our societal response to it will lead to significant and permanent changes in the path of future global emissions," said Robbie Andrew from Cicero.

"Right at the moment what we're seeing are immediate emissions responses, and following most previous crises, global emissions have returned to their pre-crisis trajectory."

The oil industry has ground to a halt as demand has slumped. Getty Images

What if CO2 was cut like this each year?

To keep the world on track to stay under 1.5C this century, the world needs similar cuts for the foreseeable future to keep this target in view.

"If Covid-19 leads to a drop in emissions of around 5% in 2020, then that is the sort of reduction we need every year until net-zero emissions are reached around 2050," said Glen Peters, also from Cicero.

"Such emissions reductions will not happen via lockdowns and restrictions, but by climate policies that lead to the deployment of clean technologies and reductions in demand for energy."

Energy experts believe there will be a bounce back next year, but that, long term, the world will move to greener fuels.



But it may not be enough to keep temperatures down to safer levels.

"That downward slope will accelerate over time beyond peak fossil energy," said Erik Holm Reiso, from Rystad Energy.

"That doesn't chime with 1.5C, but maybe 1.8-1.9C degrees could be within reach and this situation right now could help achieve that, I think."

Lessons learnt?

Many climate researchers are optimistic that this deadly pandemic has taught governments some critical lessons that they can apply to the problem of rising temperatures.

The big challenge is to ensure the recovery has a green focus.

According to Prof Gail Whiteman from Lancaster University, UK, it was almost impossible to believe that governments around the world, when faced with a health emergency, would put humanity ahead of the economy. But they did.

"We can recover from an existential, complex threat and emerge much stronger and more resilient," she says.

"Which strengthens the idea that we can do things differently on climate, that we can tackle this one.

"I think it gives us huge energy."

Links
at No comments:

(AU) It’s Time Coalition Listened To Experts On Climate And Energy, And Plotted A Green New Deal

RenewEconomy - Giles Parkinson

AAP Image/Lukas Coch

 is founder and editor of Renew Economy, and is also the founder of One Step Off The Grid and founder/editor of The Driven. 
Giles has been a journalist for 35 years and is a former business and deputy editor of the Australian Financial Review.
Here’s a story you may have missed: Morrison and Co have announced the creation of new platform for investment in renewable energy power plants, with a particular focus on large-scale wind, solar PV and storage.

True story. It was announced here, just a few weeks ago.

It didn’t get a mention in Australian media because – sadly and predictably – it’s not the Australian prime minister, Scott Morrison, and his cohort in charge of the Australian government making such a move, it’s the New Zealand investment firm by the same name, albeit with an ampersand – Morrison & Co. And it’s about Europe rather than Australia.

But it does invite a question. As Australia emerges from its economic “hibernation” imposed by the Covid-19 pandemic, and the government looks to re-boot economic and investment activity, and deliver both short- and long-term benefits, what are the chances that the federal Coalition government will listen as closely and respectfully to climate scientists and energy experts as it has to its health professionals?

These are some of the topics we will be investigating in this week’s Stimulus Summit, an online webinar jointly hosted by RenewEconomy and the Smart Energy Council that will feature Queensland premier Annastacia Palaszczuk , four state energy ministers (both Liberal and Labor), and a cast of energy experts and analysts including Ross Garnaut, Anna Skarbek, Oliver Yates, Maria Atkinson and Simon Holmes à Court.

The prime minister, Scott Morrison, has often said that he is yet to see the evidence that lowering emissions at the pace needed to avert a climate crisis can be achieved in a way that doesn’t create an economic crisis too. He must either be blind, or cocooned by an advisory group made up of many former coal lobbyists. Or a bit of both.

The evidence has been in abundance, and available for years. It can be found in the works of the International Energy Agency, the UN, from the CSIRO, the networks lobby, the Australian Energy Market Operator, the big utilities and any number of private and public think tanks and universities, both here and overseas.

And this past week has delivered more evidence that directly addresses the two most critical questions asked about the clean energy transition. Do renewables really offer an avenue for a cheaper energy supply? And can the grid, and therefore the economy, cope with a supply of electricity that comes predominantly, if not entirely, from wind and solar?

The answer was unequivocal to both questions. Yes, they do, and yes, it can.

Bloomberg NEF got the ball rolling with its latest update pointing to the plunging cost of wind and solar, which is now the cheapest option for new generation for 85 per cent of the world’s power supply, and most obviously in Australia.



The global average cost of wind has plunged another 9 per cent in the last six months alone, and solar by 5 per cent (and 90 per cent in less than a decade). Battery storage costs are falling even faster.

“In Australia, renewables are by far the cheapest new source of bulk generation,” says the Sydney-based BNEF analyst Lara Panjkov.

The Australian Energy Market Operator then delivered the news that there is no technical reason why the grid can’t have a very high level of renewables in the main grid. It has already outlined, in its Integrated System Plan, a pathway to 90 per cent renewables by 2040, and last week it looked at what is needed to ensure that up to 75 per cent of the grid can be powered by wind and solar at any one time, by 2025.

“Australia already has the technical capability to safely operate a power system where three-quarters of our energy at times comes from wind and solar energy generation,” says AEMO chief executive Audrey Zibelman, whose responsibility it is to keep the lights on.

Zibelman agrees that wind and solar are clearly the lowest-cost way of providing electricity, but to harness that power source to its potential requires a change in market design and regulatory requirements.



This graph above shows the levels of wind and solar that can be easily accommodated now, and how much can be accommodated if the market rules and regulations are adjusted for the new technology. The “step change” scenario has a 100 per cent wind and solar on occasions by 2025. Just think, a decade ago many were arguing that 10 per cent wind and solar penetration was the limit.

Some experts now argue that Australian can go a lot quicker. And gain even more benefits. Ross Garnaut thinks 100 per cent renewables is achievable in the early 2030s, ClimateWorks’ Anna Skarbek says a rapid uptake of renewables 75 per cent annualised, not just instant by 2030) is key to also lower emissions in buildings and transport. Many major utilities think AEMO is too conservative on some of its technology costs.

But the biggest failure of Australia’s energy market in the last six years has been the glacial pace of market and regulatory reform, and infrastructure investment. And you can blame that on the lack of federal government leadership.

Morrison and Co, the Australian political mob, like to boast that Australia has installed more wind and solar than any other country on a per capita basis over the last couple of years. The bitter irony is that they have spent much of the last six years trying to stop that very thing from happening, and now there is no short, medium, or long-term vision, to focus the minds of the regulatory bodies who have been so slow to move.

The situation has so enraged and frustrated state ministers that they have gone their own way. Victoria and NSW have announced they are by-passing the federal regulatory framework because it is too slow to keep pace with their renewable energy targets.

Nearly every state has emissions and renewable energy targets far more ambitious than the federal government, and the two states with the most ambition – Tasmania (200 per cent renewables by 2040) and South Australia (net 100 per cent renewables by 2030) – are both conservative governments.

Which shows that this is not simply an ideological issue, unless there is the coal lobby involved. And it is no coincidence that these two states, along with the ACT (already at 100 per cent equivalent renewable supply in 2020) are three jurisdictions that have no coal industry.

Alas, there is no indication – yet – that the Morrison government is about to change its tune. In fact, all the signs are pointing the other way. “I like to think of the other side of Covid-19 as being a gas-fired recovery,” energy minister Angus Taylor, a determined anti-wind campaigner before and after he came into parliament, told the Murdoch media’s Daily Telegraph last week.

Resources minister Keith Pitt says that coal and gas are the key to Australia’s economic recovery, and Neville Power, the so-called Post Covid business co-ordination Tsar appointed by Morrison, is on the same page, saying he sees natural gas as the solution for a clean and cheap energy future for Australia.

Surprise, surprise, Power is also a director of aspiring gas company Strike Energy. The committee Power heads is full of gas and coal industry people. 

And Taylor couldn’t help himself last week when he leapt on the AEMO report to highlight what he suggested were the overwhelming complexities of having more wind and solar, a prospect he has been fighting since before he entered parliament and has continued well into his tenure as the country’s energy minister.

The answer, he seemed to suggest, was more gas. And to try and deflect attention from the obvious solutions at hand – wind, solar, storage, and new market designs and regulatory changes – Taylor has been pushing a “technology roadmap”, pretending that the solutions for reducing emissions are not readily available.

New technologies may be needed for complicated areas such as agriculture and manufacturing (steel, for example), but in the main grid, the solutions are already here.

New data last week pointed to the fact that wind and solar had helped slash Australia’s electricity emissions by 20 per cent over the last few years. AEMO says a near 90 per cent reduction in emissions is possible by 2040. Analysts Reputex say not only that, but it will deliver lower prices and a reliable grid

The Morrison government appears to be convinced that the world will continue to want an expanded menu of fossil fuels – coal and gas. But the signs indicate otherwise, particularly after Covid-19. The conservative International Energy Agency notes that renewables have been the most resilient energy sector player as prices and investment in gas and coal crash. Even Shell says it could accelerate the transition to clean energy.

“Demand for fossil fuels is falling across the board for coal, oil and natural gas. At the same time, we’re seeing a major shift towards low-carbon sources of electricity including wind, solar PV, hydropower and nuclear,” the IEA said.

“Low-carbon technologies are now set to extend their lead as the largest source of global electricity generation, reaching 40% of the power mix in 2020.”

On Monday, Taylor made one important step forward by announcing the creation of a new $300 million fund to be managed by the Clean Energy Finance Corporation to pursue renewable hydrogen, one of the valid technologies that needs support, and which has the potential of replacing Australia’s fossil fuel experts.

But the Morrison government can still barely bring itself to mention the words “wind” and “solar”, or even electric vehicles. Perhaps out of fear of being shouted down by the ultra-conservative commentators on talkback radio and in the Murdoch media.

Imagine, though, if they had the same attitude to the Covid-19 pandemic, and held the same disregard for the health experts. The outcome would be appalling. The US and Brazil show us just how bad.

Links

at No comments: