Inequalities Fuel Human Impacts On Climate

Climate News Network - Tim Radford*

Scientists seek precision research tools to measure how human impacts and inequalities will feed back into future climate change.

Refugees forced from their homes by serious floods in Bihar state, northeast India. Image: Balazs Gardi via Flickr

For the second time this year, a group of climate scientists has called for a new approach to climate change research to produce a better and more precise idea of how the world will change as global average temperatures rise.
The call comes only weeks after a distinguished international team reminded researchers that some details of the planetary climate machine are still unresolved – such as what happens to all the carbon released by fossil fuel combustion, and how rainfall patterns will change in the decades to follow.
Neither group is challenging the general climate models, which broadly predict that, unless action is taken, global average temperatures could rise by 4°C and global sea levels by a metre or so. What each wants is more detailed answers.
The latest call comes from a team of US and Japanese scientists, who argue in their report in National Science Review journal that the human dimension is missing. What people do over the next decades will feed back into the mechanics of climate change.

Missing dimensions
The missing dimensions of the human impacts and contribution, they say, are threefold: the economic inequalities that stoke conflict and drive migration; the levels and patterns of consumption of resources that fuel these inequalities; and the numbers of people consuming these resources and demanding energy to improve their lives over the next two generations.
For instance, the scientists say, human choices make a difference. The rate of atmospheric concentrations of the greenhouse gases carbon dioxide, methane and nitrous oxide increased 700-fold, 1,000-fold and 300-fold respectively after the “green revolution” of the 1960s, compared with pre-industrial levels.
Population growth was a factor. So was economic growth. And this corresponded to a doubling of human impacts every 17 years.
“The doubling of this impact is shockingly rapid,” says the study leader, Safa Motesharri, a systems scientist at the University of Maryland’s National Socio-Environmental Synthesis Centre.

“These human impacts can only truly
be understood within the context
of economic inequality”

His co-author, Jorge Rivas, a researcher in environmental sustainability and political economy at the Institute for Global Environment and Society in Maryland, says: “These human impacts can only truly be understood within the context of economic inequality.
“The average per capita resource use in wealthy countries is five to 10 times higher than in developing countries, and the developed countries are responsible for over three-quarters of cumulative greenhouse gas emissions from 1850 to 2000.”
A third Maryland colleague, geographer Klaus Hubacek, says: “The disparity is even greater when inequality within countries is included. For example, about 50% of the world’s people live on less than $3 per day, 75% on less than $8.50, and 90% on less than $23.

Matter of urgency
“One effect of this inequality is that the top 10% produce almost as much total carbon emissions as the bottom 90% combined.”
So the researchers argue that, as a matter of urgency, climate modellers must try to make sense of the future by coupling their understanding of the Earth system – aspects such as temperature, evaporation, rainfall, forests, deserts, icecaps – with the human systems of agriculture, urban growth, investment, traffic, aid and trade.
“We cannot separate the issues of population growth, resource consumption, the burning of fossil fuels, and climate risk,” says Michael Mann, director of  the Earth System Science Centre at Penn State University, but who was not an author of the study.
“They are part of a coupled dynamical system, and, as the authors show, this has dire potential consequences for societal collapse. The implications couldn’t be more profound.” – Climate News Network

*Tim Radford, a founding editor of Climate News Network, worked for The Guardian for 32 years, for most of that time as science editor. He has been covering climate change since 1988.

Links

• It's More than Just Climate Change
• Call to unravel basic climate change
• Modeling sustainability: population, inequality, consumption, and bidirectional coupling of the Earth and Human Systems
• China trumps US on climate change
• Battery power boost to renewables
• Solar energy powers sustainable solutions

As Global Food Demand Rises, Climate Change Is Hitting Our Staple Crops

The Conversation - Andrew Borrell

Farmers face falling crop yields and growing food demand. Shutterstock

While increases in population and wealth will lift global demand for food by up to 70% by 2050, agriculture is already feeling the effects of climate change. This is expected to continue in coming decades.
Scientists and farmers will need to act on multiple fronts to counter falling crop yields and feed more people. As with previous agricultural revolutions, we need a new set of plant characteristics to meet the challenge.
When it comes to the staple crops – wheat, rice, maize, soybean, barley and sorghum – research has found changes in rainfall and temperature explain about 30% of the yearly variation in agricultural yields. All six crops responded negatively to increasing temperatures – most likely associated with increases in crop development rates and water stress. In particular, wheat, maize and barley show a negative response to increased temperatures. But, overall, rainfall trends had only minor effects on crop yields in these studies.
Since 1950, average global temperatures have risen by roughly 0.13°C per decade. An even faster rate of roughly 0.2°C of warming per decade is expected over the next few decades.
As temperatures rise, rainfall patterns change. Increased heat also leads to greater evaporation and surface drying, which further intensifies and prolongs droughts.
A warmer atmosphere can also hold more water – about 7% more water vapour for every 1°C increase in temperature. This ultimately results in storms with more intense rainfall. A review of rainfall patterns shows changes in the amount of rainfall everywhere.

Maize yields are predicted to decline with climate change. Shutterstock

Falling yields
Crop yields around Australia have been hard hit by recent weather. Last year, for instance, the outlook for mungbeans was excellent. But the hot, dry weather has hurt growers. The extreme conditions have reduced average yields from an expected 1-1.5 tonnes per hectare to just 0.1-0.5 tonnes per hectare.
Sorghum and cotton crops fared little better, due to depleted soil water, lack of in-crop rainfall, and extreme heat. Fruit and vegetables, from strawberries to lettuce, were also hit hard.
But the story is larger than this. Globally, production of maize and wheat between 1980 and 2008 was 3.8% and 5.5% below what we would have expected without temperature increases. One model, which combines historical crop production and weather data, projects significant reductions in production of several key African crops. For maize, the predicted decline is as much as 22% by 2050.
Feeding more people in these changing conditions is the challenge before us. It will require crops that are highly adapted to dry and hot environments. The so-called "Green Revolution" of the 1960s and 1970s created plants with short stature and enhanced responsiveness to nitrogen fertilizer.
Now, a new set of plant characteristics is needed to further increase crop yield, by making plants resilient to the challenges of a water-scarce planet.

Dr Niaba Teme, a sorghum breeder, examines the panicle of a drought-adapted genotype in Mali, Africa. Author provided

Developing resilient crops for a highly variable climate
Resilient crops will require significant research and action on multiple fronts – to create adaptation to drought and waterlogging, and tolerance to cold, heat and salinity. Whatever we do, we also need to factor in that agriculture contributes significantly to greenhouse gas emissions (GHGs).
Scientists are meeting this challenge by creating a framework for adapting to climate change. We are identifying favourable combinations of crop varieties (genotypes) and management practices (agronomy) to work together in a complex system.
We can mitigate the effects of some climate variations with good management practices. For example, to tackle drought, we can alter planting dates, fertilizer, irrigation, row spacing, population and cropping systems.
Genotypic solutions can bolster this approach. The challenge is to identify favourable combinations of genotypes (G) and management (M) practices in a variable environment (E). Understanding the interaction between genotypes, management and the environment (GxMxE) is critical to improving grain yield under hot and dry conditions.
Genetic and management solutions can be used to develop climate-resilient crops for highly variable environments in Australia and globally. Sorghum is a great example. It is the dietary staple for over 500 million people in more than 30 countries, making it the world's fifth-most-important crop for human consumption after rice, wheat, maize and potatoes.

Sorghum with (left) and without (right) stay-green under terminal drought in India. Author provided

 'Stay-green' in sorghum is an example of a genetic solution to drought that has been deployed in Australia, India and sub-Saharan Africa. Crops with stay-green maintain greener stems and leaves during drought, resulting in increased stem strength, grain size and yield. This genetic solution can be combined with a management solution (e.g. reduced plant population) to optimise production and food security in highly variable and water-limited environments.
Other projects in India have found that alternate wetting and drying (AWD) irrigation in rice, compared with normal flooded production, can reduce water use by about 32%. And, by maintaining an aerobic environment in the soil, it reduces methane emissions five-fold.
Climate change, water, agriculture and food security form a critical nexus for the 21st century. We need to create and implement practices that will increase yields, while overcoming changing conditions and limiting the emissions from the agricultural sector. There is no room for complacency here.

Links

• El Niño is over, but has left its mark across the world
• Charcoal rot: a threat to staple food crops in South Africa
• 'CO₂ is food for plants!' What will higher emissions mean for crop productivity?

'Disastrous': Australia's Carbon Emissions Jump As Coal-Fired Power Ramps Up

Fairfax - Peter Hannam

Australia's greenhouse gas pollution jumped in 2015-16 as coal use continued to rise after the scrapping of the carbon price, making it harder to meet its emissions targets.
Overall emissions are up 3.4 per cent compared with 2014-15 and up 7.5 per cent since the Abbott government eliminated the carbon price in June 2014, the Australian Conservation Foundation said, citing new data released under the National Greenhouse & Energy Reporting Scheme.

La Trobe Valley's Loy Yang coal-fired power station is among the big polluters. Photo: Paul Harris

The data suggests that Australia's emissions are set to be higher at the end of the decade than they were in 2000, although credits earned in interim years will enable the country to meet its 2020 goals. The 2030 goal of cutting pollution at least 26 per cent on 2005-levels will be harder to meet the longer annual emissions keep rising.
Hugh Saddler, an honorary associate professor at the Australian National University, said total grid-connected generation – which excludes power plants at mines or other standalone sites – rose 3.3 per cent during 2015-16, and emissions gained 1.7 per cent.
"Although there was a modest improvement in emissions intensity – undoubtedly because of more wind generation driven by the large-scale Renewable Energy Target – it was not enough to offset the relatively larger increase in demand, as consequently total emissions went up," Dr Saddler said.
So-called scope 1 and scope 2 emissions from Australia's electricity sector rose by 2.6 per cent on 2014-15 levels and are up 5 per cent since the carbon tax ended, the conservation foundation said.
"This latest data provides more evidence Turnbull government policies that are supposedly designed to cut Australia's climate pollution are simply not doing the job," Kelly O'Shanassy, ACF's chief executive, said.
"Instead of acknowledging global warming as a national crisis that demands immediate, serious action, the federal government is considering giving Adani a $1 billion loan for a coal-carting railway line [in Queenland] and wants the Clean Energy Finance Corporation to fund new coal-fired power stations," she said.

APRA's blunt climate change warning
The Australian Prudential Regulation Authority's very blunt warning of the obvious physical risks and transition risks of moving to a low-carbon economy. Michael Pascoe comments.

In NSW, emissions from the state's five coal-fired power stations rose 7 per cent in the year, or 3 million tonnes, to 49 million.
"The NSW government last November committed to zero carbon emissions by 2050, but they don't have a plan to get us there," Brad Smith, the NSW Nature Conservation Council's senior energy and climate campaigner, said. "This is a disastrous result caused by the failure of leadership from state and federal governments."
Josh Frydenberg, the federal environment and energy minister, said Australia is on target to beat the 2020 goals by 224 million tonnes, and that more than half of the increased emissions in the past year came from the expansion of LNG production, while agriculture-related emissions fell 3.4 per cent.
"Significant progress has also been made in reaching our 2030 target under the Paris Agreement with an improvement of more than 50 per cent since the last projections," he said. "In fact, Australia's emissions per capita and emissions per unit of GDP are now at their lowest level in 27 years."
However, Mark Butler, Labor's climate spokesman, said the data showed the government's "energy crisis is failing on all three metrics: price, reliability and pollution".
Adam Bandt, the Greens' climate spokesman, said Prime Minister Turnbull was fast becoming a "king of pollution" by "pandering to the climate change-denying Trumps of his party".

Links

• Coral bleaching returns to the Great Barrier Reef
• Green bank receives $1.2 billion coal power plant funding request
• Ross Garnaut’s bright idea
• Australia's emissions rise by 2.2 per cent

Antarctic Sea Ice 'Obliterates' Previous Minimum Record, In Remarkable Reverse

Fairfax - Peter Hannam

There is about 10 per cent less sea ice in Antarctica this year than the previous record minimum - a stunning reversal after new highs were set in 2014.
The sea ice extent around the southern continent dropped to 2.135 million square kilometres on Sunday, and expanded 25,000 square kilometres the following day, indicating the freezing season has likely begun, said Jan Lieser, a sea ice scientist at the Hobart-based Antarctic Climate and Ecosystems Co-operative Research Centre.

Antarctic sea ice swings from record large extent to record lows in just two and a half years. Photo: Ross Norton

The area covered by sea ice had been tracking below the previous record low of 2.32 million square kilometres set in February 2011 for the previous 19 days, and ended up 10 per cent lower. (See chart compiled by Japan Aerospace Exploration Agency for ice coverage.)

Australasian Antarctic Expedition - Sir Douglas Mawson
Australian geologist Sir Douglas Mawson led the Australasian Antarctic Expedition (AAE); an Australasian scientific team that explored part of Antarctica between 1911 and 1914. Video courtesy of Mawson Huts Foundation.

"One would probably say that the old record was obliterated," Dr Lieser said.
The switch from a sea-ice maximum around Antarctica to its annual low is "one of the biggest natural cycles we see in the world", with as much as 90 per cent of the ice only a year old at the most, he said.
Reliable satellite records only go back to 1979, and it's harder to access ice thickness compared with the North Pole, with Arctic ice mostly accessible from above or via submarine below.
In the southern winter of 2014, sea ice around Antarctica reached a record large extent. At the time, climate change sceptics were keen to highlight the increase in the south as a counterpoint to the more steadily decreasing Arctic ice.

Last winter, though, ice around Antarctica began thawing about a month earlier than normal. Minimum air temperatures have been breaking records daily since about early November in a region of the planet where global warming has been amongst the most rapid, Dr Lieser said.

'Along came 2016'
"[Sea-ice] variability was typical of what we'd seen for the whole period [since 1979], but then along came 2016," said Ian Simmonds, from the  School of Earth Sciences at the University of Melbourne. "It's remarkable."

Adult humpback whale breaching in the Gerlache Strait, Antarctica: More room to move than in any previous year on record. Photo: Michael Nolan

The average ice coverage over last year shrank 1.2 million square kilometres – or about the size of NSW, Tasmania and Victoria – compared with 2015, he said.
(See chart below from the US National Snow and Ice Data Center, showing how rapidly ice coverage anomalies shifted.)

Arctic too
Sea ice is now at record lows at both ends of the planet, exposing more of the dark seas to solar radiation, rather it being reflected back to space.
The lack of ice will likely add to the build-up in heat in the oceans that could hinder ice recovery in the south and accelerate the melt in the north as seasons shift towards winter and summer, respectively.

Arctic Sea Ice Extent/Concentration

The Ross Sea is virtually ice free and half the Weddell Sea ice has gone, Dr Lieser said.
While the loss of floating ice doesn't affect sea levels, its absence leaves shore-based ice shelves exposed to faster melting and accelerated glacier movement. "It opens up the vulnerability of the ice shelves around there," Dr Lieser said.
Professor Simmonds said several factors were at play in the Antarctic, such as the strengthening of westerly winds that tend to push sea-ice northwards.
Countering that, though, was the long-anticipated thermodynamic effect that warming ocean temperatures - with the Southern Ocean a major heat sink globally - would limit sea ice growth by melting the bergs from below.
While it's too early to tell whether the second effect is becoming a dominant factor during the current ice retreat, long-term climate models suggest that it will play the major role at some point, Professor Simmonds said..
Antarctic temperatures - along with those in the high Arctic - have been among the fastest rising anywhere, as rising greenhouse gases drive climate change.
Gwen Fenton, chief scientist of the Australian Antarctic Division, told Senate estimates on Monday that air over the Antarctic Peninsula had warmed about 2.8 degrees over the past 50 years alone.

Links

• Coral bleaching returns to the Great Barrier Reef
• Sea ice spread around Antarctica hit a record low
• The eight weather events this year that shook world
• Coral bleaching returns to the Great Barrier Reef

New Mercury Threat To Oceans From Climate Change

BBC - Matt McGrath

There have been concerns over the levels of mercury in fish for many years. Getty Images

Rising temperatures could boost mercury levels in fish by up to seven times the current rates, say Swedish researchers.

They've discovered a new way in which warming increases levels of the toxin in sea creatures.
In experiments, they found that extra rainfall drives up the amount of organic material flowing into the seas.
This alters the food chain, adding another layer of complex organisms which boosts the concentrations of mercury up the line.
The study has been published in the journal, Science Advances.

Toxic form
Mercury is one of the world's most toxic metals, and according to the World Health Organization, is one of the top ten threats to public health. The substance at high levels has been linked to damage to the nervous system, paralysis and mental impairment in children.

Mercury is used in many parts of the world especially in gold mining. Getty Images

The most common form of exposure to mercury is by eating fish containing methylmercury, an organic form of the chemical which forms when bacteria react with mercury in water, soil or plants.
Levels of mercury in the world's ecosystems have increased by between 200 and 500%, since the industrial revolution say experts, driven up by the use of fossil fuels such as coal.
In recent years there are have been concentrated efforts to limit the amount of mercury entering the environment, with an international treaty, called the Minamata Convention, signed by 136 countries in place since 2013.

Researcher Erik Bjorn injects mercury into sediment samples. Sofi Jonsson

But this new study suggests that climate change could be driving up levels of methylmercury in a manner not previously recognised.
In a large laboratory, Swedish researchers recreated the conditions found in the Bothnian sea estuary. They discovered that as temperatures increase, there is an increased run-off of organic matter into the world's oceans and lakes. This encourages the growth of bacteria at the expense of phytoplankton.
"When bacteria become abundant in the water there is also a growth of a new type of predators that feed on bacteria," lead author Dr Erik Bjorn from Umea University in Sweden told BBC News.
"You basically get one extra step in the food chain and methylmercury is enriched by about a factor of ten in each such step in the food web."
Under the warmest climate scenario suggested by the Intergovernmental Panel on Climate Change, there would be an increase in organic matter run-off of 15-20% by the end of this century. This in turn would see levels of methylmercury in zooplankton, the bottom link in the food chain, grow by between two and seven fold.

Sediment cores were recovered from Swedish coastal waters for use in the mercury experiments. Erik Lundberg

Different parts of the world will suffer different impacts say the researchers, with lakes and coastal waters in the northern hemisphere being the most likely to have significant increases in methylmercury levels in fish, while the Mediterranean, the central US and Southern Africa will likely see reductions.
Researchers hope that the Minamata treaty will be successful and countries reduce the amount of mercury that is being produced. Otherwise this discovery of a previously unknown source could have impacts for human health.
"If we reduce mercury emissions, then we need to know how fast will ecosystems recover," said Dr Bjorn.
"If we don't do anything and mercury doesn't decrease, and we add this on top then the implications would be severe."
Other researchers in the field say that the new study highlights important issues that have previously been little known.
"This work experimentally proves that climate change will have a significant effect of methylmercury budgets in coastal waters and its concentrations in fish," said Milena Horvat from the Jozef Stefan Institute in Slovenia.
"This work will also have an important impact on future scenario simulations on the presence of mercury in fish in response to global mercury reductions from emission sources (primarily industrial)."

Links

• UN: Climate change efforts 'unstoppable'
• Attack on experts 'undermines science'
• Plane flies along giant Antarctic crack
• World v Trump on global climate deal?

Half Of The World's Species Could Become Extinct, Biologists Say

Mashable - Maria Gallucci

The Dodo bird is about to gain a lot of extinct friends. Image: Peter Macdiarmid/Getty Images

Here's the sobering truth: Around half the species on Earth today could disappear by middle of the century, unless we humans can tackle climate change and slow our population growth.
That's a view shared by leading biologists and ecologists, many of whom are gathering in the Vatican this week for a wonky but optimistic-sounding conference: "How To Save the Natural World on Which We Depend."
Scientists estimate that by mid-century, as many as 30 to 50 percent of all species could face extinction.
"The living fabric of the world ... is slipping through our fingers without our showing much sign of caring," the Pontifical Academy of Sciences, which organized the conference, said on its website.
The Catholic Church has made ecological issues a top concern under Pope Francis.

Pope Francis addresses a U.N. food summit in Rome, Nov. 20, 2014. Image: FAO via Getty Images

The pontiff's 2015 encyclical, called Laudato Si, urges the world's 1.2 billion Roman Catholics — and everyone else — to protect the environment and spare communities from climate change, water and food scarcity, and toxic pollution.
In a section on biodiversity, Pope Francis writes, "Because all creatures are connected, each must be cherished with love and respect, for all of us as living creatures are dependent on one another."
Starting Monday, scientists, scholars and Catholic leaders will focus on the threats to not only well-known species like polar bears and elephants, but other, less famous varieties of animal and plant life as well. Humans need biological diversity to ensure we still have abundant food supplies, disease-curing medicines, breathable air and drinkable water, among other vital benefits.
The conference will focus on the so-called "sixth extinction," which our planet is likely experiencing right now.

During Earth's 4.5-billion-year history, five major extinction events have wiped out nearly all the species on the planet, the geological record shows. The last die-off happened around 65 million years ago, when dinosaurs disappeared. Asteroid strikes, volcanic eruptions and natural climate shifts were likely to blame for those past events.
The planet may now be heading for a sixth mass die-off, this time because of humans.
Before today, about one to five species a year would become extinct due to natural causes. Scientists estimate we're now lowering species at 1,000 to 10,000 times the normal rate, Harvard Medical School researchers found in a 2008 report.
Burning fossil fuels for energy, clear-cutting forests for agriculture, filling in wetlands to build cities, dumping pollution in the ocean — all these activities are making Earth less hospitable to microscopic organisms and majestic beasts alike.


via GIPHY

Our soaring population, set to reach 11.2 billion people by 2100, only adds more planetary stress.
Estimates for extinction rates this century are far from certain and vary, though most are still troubling.
A 2015 study by University of Connecticut professor Mark Urban suggested up to one in six species — or 16 percent — could become extinct in 2100.
"The extinctions we face pose and even greater threat to civilization than climate change, for the simple reason they are irreversible," Peter Raven, a biologist at the Missouri Botanical Garden, told the Observer ahead of the Vatican conference.

Links

• The Extinction Crisis
• Biological Extinction
• Regions at Greatest Risk for Species Extinction the Least Studied
• Africa's elusive forest elephants are disappearing

ANU: Wind, Solar And Hydro Grid Cheapest Option For Australia

Renew Economy - Giles Parkinson

A new study by energy experts from the Australian National University suggests that a 100 per cent renewable energy electricity grid – with 90 per cent of power coming from wind and solar – will be significantly cheaper future option than a coal or gas-fired network in Australia.
The study, led by Andrew Blakers, Bin Lu and Matthew Stocks, suggests that with most of Australia's current fleet of coal generators due to retire before 2030, a mix of solar PV and wind energy, backed up by pumped hydro, will be the cheapest option for Australia, and this includes integration costs.
The report says that wind is currently about $64/MWh and solar $78/MWh, but the costs of both technologies are falling fast, with both expected to cost around $50/MWh when much of the needed capacity is built. With the cost of balancing, this results in a levellised cost of energy (LCOE) of around $75/MWh.
By contrast, the LCOE of coal is $80/MWh, and some estimates – such as those by Bloomberg New Energy Finance which adds in factors such as the cost of finance risk – put it much higher.
Blakers says his team did not need to dial that higher price of coal into the equation: "We don't include a risk premium or carbon pricing or fuel price escalation or threat of premature closure because renewables doesn't need any of this to compete," he says.
Nor do his estimates include any carbon price, which will further tip the balance in favour of renewables. Nor do they include future cost reductions in wind and solar. "There is no end in sight to cost reductions," Blakers says.
"Much of Australia's coal power stations will reach the end of their economic life over the next 15 years. It will be cheaper to replace these with renewable energy." The two key outcomes of this modelling is that the additional cost of balancing renewable energy supply with demand on an hourly basis throughout the year is relatively small: $A25-$A30/MWh (US$19-23/MWh), and that means that the overall cost of a wind and solar dominated grid is much lower than previous estimates.
Indeed, the ANU team suggest that less storage is needed than thought. The optimum amount of pumped hydro is 15-25 GW of power capacity with 15-30 hours of energy storage.
This is based on more wind than solar. If Hwind and PV annual energy generation is constrained to be similar then higher power (25 GW) and lower energy storage (12-21hours) is optimum.
Total storage of 450 GWh +/- 30% is optimum for all the scenarios. This is equivalent to the average electricity consumed in the NEM in 19 hours.
At this stage it should be pointed out that Blakers is a long time proponent of pumped hydro, and this modelling appears designed to support that technology.
For instance, the modelling avoids any "heroic" assumptions about technologies that have not been deployed at scale – meaning battery storage and solar thermal and storage are not included, and neither is geothermal or ocean energy.
Nor does the modelling – which looks at every hour of the year based on data from 2006-2010 – assume other opportunities such as demand management, when consumers agree and sometimes get paid for reducing their load at critical moments on the grid.
The modelling shows that a large fraction of the balancing costs relates to "periods of several successive days of overcast and windless weather that occur once every few years."
Substantial reductions in balancing costs are possible through contractual load shedding (as occurred in Tomago aluminium smelter and BHP's Olympic Dam recently), and the occasional use of legacy coal and gas generators to charge pumped hydro reservoirs if needed.
Another option is managing the charging times of batteries in electric cars.
"Although we have not modelled dynamical stability on a time scale of sub-seconds to minutes we note that pumped hydro) can provide excellent inertial energy, spinning reserve, rapid start, black start capability, voltage regulation and frequency control," the authors write.
Pumped hydro has become a focus of attention in recent weeks, advocated by the Coalition government and others, seemingly in the absence of any consideration about the falling costs of battery storage.
EnergyAustralia last week announced a study into a large 100MW pumped hydro facility on South Australia's Yorke Peninsular. This work includes contributions from the ANU team.
So, how much does all this cost? The ANU team estimates $184 billion, or $152 billion at future prices of wind and solar. But before the Coalition and others start to hyperventilate about the billions to be spent, the ANU team also point out that this means no fuel costs in the future.
That's why the key number is $75/MWh, which is around one third of the price that Queenslanders have been paying so far this year for their coal and gas power, making the investment in a 116MW solar farm by zinc producer Sun Metals, which is looking to expand its facility, as a good idea.
Some other interesting points from the study:

• A sensitivity analysis has been performed on the baseline scenario by varying the following cost- components by +/- 25%: PV, wind, PHES, HVDC/HVAC, system lifetimes and discount rate. The effect on LCOE is less than +/- $2/MWh except for system lifetimes, for which the effect is +/- $5/MWh, and wind capital cost and discount rate, for both of which the effect is +/- $10/MWh (about 10%).
• Large scale deployment of electric vehicles and heat pumps would increase electricity demand by up to 40%. Importantly these devices have large scale storage in the form of batteries in vehicles and heat/cool in water stores and the building fabric. This storage may substantially reduce LCOB in the future.
• The LCOB (levellised cost of balancing) calculated in this work is an upper bound. A large fraction of LCOB relates to periods of several days of overcast and windless weather that occur once every few years. Substantial reductions in LCOB are possible through reduced capital and maintenance costs, contractual load shedding, the occasional.
• In most scenarios the modelling meets the NEM reliability standard of no more than 0.002% of unmet load (4 GWh per year) without demand management." However, in other scenarios we assume that demand management is employed during critical periods, which are typically cold wet windless weeks in winter that occur once every few years.

"During these periods the PHES reservoirs run down to zero over a few days because there is insufficient wind and PV generation to recharge them, leading to a shortfall in supply. The amount of PV, wind and PHES storage could be increased to cover this shortfall. However, this substantial extra investment would be utilised only for a few days every few years."
One suggestion is to relax the reliability standards: "A portion of the savings in investment in PV, wind and PHES would be available to compensate certain consumers for partial loss of supply for a few days every few years. For example, reducing the overall cost of electricity supply by $2/MWh by allowing an unmet load of 336 GWh per 5 years would save $2 billion per 5 years, which is equivalent to $6,000 per unmet MWh.
Hmmm, but just imagine the headlines.

Links

• Global battery storage industry to fight Australia home bans
• CSIRO says Australia can get to 100 per cent renewable energy
• Blackouts: How market operator BoM-ed out on weather forecasts
• ZEN Energy reveals "Big Battery" plans for South Australia