James Ha, Grattan InstitutePolitical momentum is growing in Australia to cut greenhouse gas emissions to net-zero by 2050. On Friday, Treasurer Josh Frydenberg was the latest member of the federal government to throw his weight behind the goal, and over the weekend, Prime Minister Scott Morrison acknowledged “the world is transitioning to a new energy economy”.
But for Australia to achieve net-zero across the economy, emissions from agriculture must fall dramatically. Agriculture contributed about 15% to Australia’s greenhouse gas emissions in 2019 – most of it from cattle and sheep. If herd numbers recover from the recent drought, the sector’s emissions are projected to rise.
Cutting agriculture emissions will not be easy. The difficulties have reportedly triggered concern in the Nationals’ about the cost of the transition for farmers, including calls for agriculture to be carved out of any net-zero target.
But as our new Grattan Institute report today makes clear, agriculture must not be granted this exemption. Instead, the federal government should do more to encourage farmers to adopt low-emissions technologies and practices – some of which can be deployed now.
Many farmers want to be part of the climate solution – and must be – for three main reasons.
First, the agriculture sector is uniquely vulnerable to a changing climate. Already, changes in rainfall have cut profits across the sector by 23% compared to what could have been achieved in pre-2000 conditions. The effect is even worse for cropping farmers.
Livestock farmers face risks, too. If global warming reaches 3℃, livestock in northern Australia are expected to suffer heat stress almost daily.
Second, parts of the sector are highly exposed to international markets – for example, about three-quarters of Australia’s red meat is exported.
There are fears Australian producers may face a border tax in some markets if they don’t cut emissions.
The European Union, for instance, plans to introduce tariffs as early as 2023 on some products from countries without effective carbon pricing, though agriculture will not be included initially.
Third, the industry recognises action on climate change can often boost farm productivity, or help farmers secure resilient revenue streams. For example, trees provide shade for animals, while good soil management can preserve the land’s fertility. Both activities can store carbon and may generate carbon credits.
Carbon credits can be used to offset farm emissions, or sold to other emitters. In a net-zero future, farmers can maximise their carbon credit revenue by minimising their own emissions, leaving them more carbon credits to sell.
The agriculture sector itself is increasingly embracing the net-zero goal. The National Farmers Federation supports an economy-wide aspiration to be net-zero by 2050, with some conditions. The red meat and pork industries have gone further, committing to be carbon neutral by 2030 and 2025 respectively.
The sector’s non-animal emissions largely came from burning diesel, the use of fertiliser, and the breakdown of leftover plant material from cropping.
Unlike in, say, the electricity sector, it’s not possible to completely eliminate agricultural emissions, and deep emissions cuts look difficult in the near term. That’s because methane produced in the stomachs of cattle and sheep represents more than 60% of agricultural emissions; these cannot be captured, or eliminated through renewable energy technology.
Supplements added to stock feed – which reduce the amount of methane the animal produces – are the most promising options to reduce agricultural emissions. These supplements include red algae and the chemical 3-nitrooxypropanol, both of which may cut methane by up to 90% if used consistently at the right dose.
But it’s difficult to distribute these feed supplements to Australian grazing cattle and sheep every day. At any given time, only about 4% of Australia’s cattle are in feedlots where their diet can be easily controlled.
Diesel use can be reduced by electrifying farm machinery, but electric models are not yet widely available or affordable for all purposes.
These challenges slow the realistic rate at which the sector can cut emissions. Yet there are things that can be done today.
Many manure emissions can be avoided through smarter management. For example, on intensive livestock farms, manure is often stored in ponds where it releases methane. This methane can be captured and burnt, emitting the weaker greenhouse gas, carbon dioxide, instead.
And better targeted fertiliser use is a clear win-win – it would save farmers money and reduce emissions of nitrous oxide, a potent greenhouse gas.
Governments must walk and chew gum
An economy-wide carbon price would be the best way for Australia to reduce emissions in an economically efficient manner. But the political reality is that carbon pricing is out of reach, at least for now. So Australia should pursue sector-specific policies – including in agriculture.
Governments must walk and chew gum. That means introducing policies to support emissions-reducing actions that farmers can take today, while investing alongside the industry in potential high-impact solutions for the longer term.
Accelerating near-term action will require improving the federal government’s Emissions Reduction Fund, to help more farmers generate Australian carbon credit units. It will also require more investment in outreach programs to give farmers the knowledge they need to reduce emissions.
Improving the long-term emissions outlook for the agriculture sector requires investment in high-impact research, development and deployment. Bringing down the cost of new technologies is possible with deployment at scale: all governments should consider what combination of subsidies, penalties and regulations will best drive this.
Agriculture must not become the missing piece in Australia’s net-zero puzzle. Without action today, the sector may become Australia’s largest source of emissions in coming decades. This would require hugely expensive carbon offsetting – paid for by taxpayers, consumers and farmers themselves.
The potential impacts of climate change on employment and the livability of the regions have not been adequately considered. Even if emissions are curtailed, Australia likely faces billions of dollars of adaptation costs for rural communities.
As the IPCC’s Sixth Assessment Report (published last month) makes clear, the climate will change regardless of any mitigation actions taken now.
Even under its modest conservative projections, worldwide temperatures will rise by 1.5℃. That may not sound like much, but it will double the frequency of droughts — from once every 10 years to once every five.
Worse still, a 2℃ temperature rise — also a likely outcome without substantial emission reductions — will make droughts 2.5 times more frequent.
Climate change is already hurting Australian farmers. Compared with historical averages, agricultural profits have fallen 23% over the 20 years to 2020. This trend will continue.
The Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES) predicts a likely scenario is that overall farm profit will fall by 13% by 2050. There will be significant differences between regions. Cropping profits in Western Australia, for example, are predicted to drop 32%.
Effect of 2001-2020 seasonal conditions on farm profit
With higher emissions, the reductions will be worse. Estimates of the fall in farm profits range from 11% to 50%.
These changes go beyond the cycles of weather with which Australian farmers have always had to cope. Inconsistent water supplies, increased natural disasters and greater production risks will render agricultural production in many areas uneconomic.
Due to these climatic changes agricultural assets, both land and infrastructure, could become virtually worthless – so-called stranded assets.
No future without water
Vibrant regional communities aren’t just about farms. They are interdependent networks of businesses, towns, public infrastructure and people.
The effect of falls in farm income will ripple throughout these communities. Lower output will mean fewer jobs. If farms close, so will other regional businesses, leading to more stranded assets. Those affected could face displacement along with an inability to sell their homes and businesses.
And of course these communities can’t survive without water.
So far development planning in Australia has not adequately considered the potential impacts of the climate on livability, especially in rural communities.
This failure to account for climate change exacerbates the potential for stranded assets.
For example, the NSW Auditor General reported in September 2020 that the state government had “not effectively supported or overseen town water infrastructure planning in regional NSW since at least 2014”. This contributed during the intense drought of 2019 to at least ten regional NSW cities or towns coming close to “zero” water.
In some areas these water problems are being compounded by population growth.
Consider, for instance, the NSW townships surrounding Canberra. In January 2020 the town of Braidwood (about halfway between Canberra and Batemans Bay) had to start trucking in water when its own water source, the Shoalhaven river, stopped flowing. Yet nearby Bungedore (about 50 km away) is building a new high school due to population growth.
This “tree-change” trend, with people leaving cities in search of a better lifestyle and more affordable housing, is widespread. It appears to have been amplified by the COVID-19 pandemic, with figures showing net internal migration of people out of Sydney and Melbourne.
More investment in adaptation needed
There is an urgent need for a comprehensive assessment by all levels of government of risks to livelihoods in agriculture and regional communities, and of the default risk on stranded assets.
Budget projections need to account for climate-change adaptation and economic structural change.
In last year’s budget the federal government committed to investing A$20 billion “to ensure Australia is leading the way in the adoption of new low-emissions technologies while supporting jobs and strengthening our economy”.
As important as this is, we must start planning and spending on adaptation.
The A$1.2 billion over five years the federal budget allocated for natural disasters is just the beginning. In some regions changed farming practices, subsidised insurance and investment in water infrastructure may be enough. But proper infrastructure takes many years to plan, and to build.
Some areas are going to become unviable. We will need deal with the loss of entire communities, and internal climate refugees.
It is time to start budgeting for the costs of living with climate change, not just the costs of cutting emissions.
But while the pain of drought is fading from view for some, the challenge of a changing climate continues to loom large.
Farmers have endured a poor run of conditions over the last 20 years, including a reduction in average rainfall (particularly in southern Australia during the winter cropping season) and general increases in temperature.
While these trends relate to climate change, uncertainty remains over how they will develop, particularly over how much rain or drought farmers will face.
Research published today by the Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES) examines the effects of past and potential future changes in climate, and sets out how productivity gains to date have been helping farmers adapt to the drier and hotter conditions.
Conditions have been tough
The research examines the effect on farms of climate conditions over the past 20 years, compared to the preceding 50 years.
Holding other factors constant (including commodity prices and technology) ABARES estimates the post-2000 shift in conditions reduced farm profits by an average of 23%, or around A$29,000 per farm per year.
As with past research, these effects have been strongest among cropping farmers in south-eastern and southern-western Australia, with impacts of over 50% observed in some of the most severely affected areas.
Effect of 2001 to 2020 climate conditions on average farm profit
Farmers have been adapting
While these changes in conditions have been dramatic, farmers’ adaptation has been equally impressive.
After controlling for climate, farm productivity (the output from a given amount of land and other inputs) has climbed around 28% since 1989, with a much larger 68% gain in the cropping sector.
These gains have offset the adverse climate conditions and along with increases in commodity prices have allowed farmers to maintain and even increase average production and profit levels over the last decade.
While productivity growth in agriculture is nothing new, the recent gains have been especially focused on adapting to drier and hotter conditions.
Within the cropping sector, for example, a range of new technologies and practices have emerged to better utilise soil moisture to cope with lower rainfall.
While climate models generally project a hotter and drier future, a wide range of outcomes are possible, particularly for rainfall.
Climate projections suggest that nationally farmers could experience reductions in average winter season rainfall of 3% to 30% by 2050 (compared to 1950-2000).
The study simulates the effect of future climate change scenarios with current farm technology and no further productivity gains.
As such, these scenarios are not a prediction, but an indication of which regions and sectors might be under the greatest pressure to adapt.
For example, under most scenarios cropping farmers in Western Australia will face more pressure than those in eastern Australia.
Livestock farms will also face more pressure under high emissions scenarios as they are especially impacted by higher temperatures.
Generally, inland low-rainfall farming areas are expected to face greater challenges than regions closer to the coast.
Simulated change in farm profits relative to historical (1950 to 2000) climate
There is more work ahead
Recent experience shows that productivity growth can help offset the impact of a changing climate.
However, there remains uncertainty over how far technology can push farm efficiency beyond current levels.
Further, even if technology can offset climate impacts, other exporting nations could still become more competitive relative to Australia, if they are less affected by climate change or can adapt faster.
Here, investment in research and development remains crucial, including efforts to improve the productivity and reduce the carbon footprint of existing crop and livestock systems, along with research into more transformational responses to help diversify farm incomes.
This could include for example, carbon and biodiversity farming, plantation forestry and the use of land to produce renewable energy.
Carbon and biodiversity farming schemes are the subject of ongoing research and policy trials, and already we have seen farmers generate significant revenue from carbon farming.
Uncertainty over the future climate, especially rainfall, remains a key constraint on adaptation. Efforts to refine and better communicate climate information through initiatives such as Climate Services for Agriculture could help farmers and governments make more informed decisions.
While the future is still highly uncertain, the challenge of adapting to climate change is here and now.
Significant resources have been committed in this area, including the Australian government’s Future Drought Fund.
We need to make the most of these investments to prepare for whatever the future holds.
Farmers can encourage and accelerate this process through methods that increase plant production, such as improving nutrient management or sowing permanent pastures. For each unit of atmospheric carbon they remove in this way, farmers can earn “carbon credits” to be sold in emissions trading markets.
But not all carbon credits are created equal. In one high-profile deal in January, an Australian farm sold soil carbon credits to Microsoft under a scheme based in the United States. We analysed the methodology behind the trade, and found some increases in soil carbon claimed under the scheme were far too optimistic.
It’s just one of several problems raised by the sale of carbon credits offshore. If not addressed, the credibility of carbon trading will be undermined. Ultimately the climate – and the planet – will be the loser.
What is soil carbon trading?
Plants naturally remove carbon dioxide (CO₂) from the air through photosynthesis. As plants decompose, carbon-laden organic matter is added to the soil. If more organic matter is added than is lost, soil carbon levels increase.
Carbon trading schemes require the increase in soil carbon levels to be measured. The measurement methods are well-established, but can be costly and complex because they involve collecting and analysing large numbers of soil samples. And different carbon credit schemes measure the change in different ways – some more robust than others.
The Australian government’s Emissions Reduction Fund has a rigorous approach to soil sampling, laboratory analysis and calculation of credits. This ensures only genuine removals of atmospheric carbon are rewarded, in the form of “Australian Carbon Credit Units”.
Farmers can choose other schemes under which to earn carbon credits, such as the US-based carbon offset platform Regen Network.
Regen Network’s method for estimating soil carbon largely involves collecting data via satellite imagery. The extent of physical on-the-ground soil sampling is limited.
Regen Network issues “CarbonPlus credits” to farmers deemed to have increased soil carbon stores. Farmers then sell these credits on the Regen Network trading platform.
‘A number of concerns’
It was Regen Network which sold Microsoft the soil carbon credits generated by an Australian farm, Wilmot Station. Wilmot is owned by the Macdoch Group, and other Macdoch properties have also claimed carbon credits under the Regen Scheme.
Regen Network should be applauded for making its methods and calculations available online. And we appreciate Regen’s open, collaborative approach to developing its methods.
However, we have reviewed their documents and have a number of concerns:
the dry weight of soil in a known volume, also known as “bulk density”, is a key factor in calculating soil carbon stocks. Rather than bulk density being measured from field samples, it was calculated using an equation. We examined this method and determined it was far less reliable than field sampling
Estimates of soil carbon were not adjusted for gravel content. Because gravel contains no carbon, carbon stock may have been overestimated
The remote sensing used by Regen Network involved assessment of vegetation cover via satellite imagery, from which soil carbon levels were estimated. However, vegetation cover obscures soil, and research has found predictions of soil carbon using this method are highly uncertain.
Wilmot increased soil carbon, or “sequestration”, through changes to grazing and pasture management. The resulting rates of carbon storage calculated by Regen Network were extremely high – 7,660 tonnes of carbon over 1,094 hectares. This amounts to 7 tonnes of carbon per hectare from 2018 to 2019.
These results are not consistent with our experience of what is possible through pasture management. For example, the CSIRO has documented soil carbon increases of 0.1 to 0.3 tonnes of carbon per hectare per year in Australia from a range of methods to increase pasture production.
We believe inaccurate methods have led to the carbon increase being overestimated. Thus, it appears excess carbon credits may have been awarded.
Many carbon trading schemes apply rules to ensure integrity is maintained. These include:
an “additionality test” to ensure the extra carbon storage in the soil would not have happened anyway. It would prevent, for example, farmers claiming credits for practices they adopted in the past
ensuring sequestered carbon is maintained over time
disallowing double-counting of credits – for example, by preventing a country claiming credits that have been sold offshore.
The Emissions Reduction Fund and other well-recognised international schemes, such as Verra and Gold Standard, apply these rules stringently. Regen Network’s safeguards are less rigorous.
Responses to these claims from Regen Network and Macdoch Group can be found at the end of this article. A full response from Regen can also be found here.
Not in the national interest?
Putting aside the problems noted above, the offshore sale of soil carbon credits generated by Australian farmers raises other concerns.
First, selling credits offshore means Australia loses out, by not being able to claim the abatement towards our own government and industry targets.
Second, soil carbon does not have unlimited emissions reduction potential. The quantum of carbon that can be stored in each hectare of soil is constrained, and limited by factors such as land availability and climate change. So measures to increase soil carbon should not detract from society’s efforts to reduce emissions from fossil fuel use.
And third, ensuring carbon remains in soil long after it’s deposited is a challenge because soil microbes break down organic matter. Carbon credit schemes commonly manage this by requiring a “buffer” of unsold credits. If stored carbon is lost, farmers must relinquish credits from the buffer.
If the loss is greater than the buffer, credits must be purchased to make up the difference. This exposes farmers to financial risk, especially if carbon prices rise.
Soil carbon is a promising way for Australia to substantially reduce its emissions. But methods used to measure gains in soil carbon must be accurate.
Carbon markets must be regulated to ensure credit is awarded for genuine abatement, and risks to farmers are limited. And the extent to which offshore carbon markets prevent Australia from meeting its own obligations to reduce emissions should be clarified and managed.
Improving the integrity of soil carbon trading will have benefits beyond emissions reduction. It will also improve soil health and farm productivity, helping agriculture become more resilient under climate change.
Regen Network response
Regen Network provided The Conversation with a response to concerns raised in this article. The full nine-page statement provided by Regen Network is available here.
The following is a brief summary of Regen Network’s statement:
– Limited on-ground soil sampling: Regen Network said its usual minimum number of soil samples was not reached in the case of Wilmot Station, because historical soil samples – taken before the project began – were used. To compensate for this, relevant sample data from a different farm was combined with data from Wilmot.
“We understand the use of ancillary data does not follow best practice and our team is working hard to ensure future projects are run using a sufficient number of samples,” Regen Network said.
– Bulk density: Regen Network said the historical sample data from Wilmot did not include “bulk density” measurements needed to estimate carbon stocks, which required “deviations” from its usual methodology. However the company was taking steps to ensure such estimates in future projects “can be provided with higher degrees of accuracy”.
– Gravel content: Regen Network said lab reports for soil samples included only the weight, not volume, of gravel present. “Best sampling practice should include the gravel volume as an essential parameter for accurate bulk density measurements. We will make sure to address this in our next round of upgrades and appreciate the observation!” the statement said.
– Remote sensing of vegetation: Regen Network said it did not use vegetation assessment at Wilmot station. It tested a vegetation assessment index at another property and found it ineffective at estimating soil carbon. At Wilmot station Regen used so-called individual “spectral bands” to estimate soil carbon at locations where on-ground sampling was not undertaken.
– Sequestration rates at Wilmot: Regen Network said while it was difficult to directly compare local sequestration rates across climatic and geologic zones, the sequestration rates for the projects in question “fall within the relatively wide range of sequestration rates” reported in key scientific studies.
Regen Network said its methodology “provides a conservative estimate on the final number of credits issued”. Its statement outlines the steps taken to ensure soil carbon levels are not overestimated.
– Integrity safeguards: Regen Network said it employs standards “based both on existing standards of reputable programs […] and inputs from project developers, in order to come up with a standard that not only is rigorous but also practical”. Regen Network takes steps to ensure additionality and permanence of carbon stores, as well as avoid double counting of carbon credits generated through their platform.
A more detailed response from Regen Network can be found here.
Wilmot Station response
Wilmot Station provided the following response from Alasdair Macleod, chairman of Macdoch Group. It has been edited for brevity:
We entered into the deals with Regen Network/Microsoft because we wanted to give a hint of the huge potential that we believe exists for farmers in Australia and globally to sequester soil carbon which can be sold through offset markets or via other methods of value creation.
Whilst we recognise that the soil carbon credits generated on the Macdoch Group properties in the Regen Network/Microsoft deal will not be included in Australia’s national carbon accounts, it is our hope that over time the regulated market will move towards including appropriately rigorous transactions such as these in some form.
At the same time we have also been working closely with the Australian government, industry organisations, academia and other interested parties on Macdoch Group properties to develop appropriate soil carbon methodologies under the government’s Climate Solutions Fund.
This is because carbon measurement methodologies are an evolving science. We have always acknowledged and will welcome improvements that will be made over the coming years to the methodologies utilised by both the voluntary and regulated markets.
In any event it has become clear that there is huge demand from the private sector for offset deals of this nature and we will continue to work towards ensuring that other farmers can take advantage of the opportunities that will become available to those that are farming in a carbon-friendly fashion.
The National Farmer’s Federation says Australia needs a tougher policy on climate, today calling on the Morrison government to commit to an economy wide target of net-zero greenhouse gas emission by 2050.
It’s quite reasonable for the farming sector to call for stronger action on climate change. Agriculture is particularly vulnerable to a changing climate, and the sector is on its way to having the technologies to become “carbon neutral”, while maintaining profitability.
A climate-ready and carbon neutral food production sector is vital to the future of Australia’s food security and economy.
Paris Agreement is driving change
Under the 2015 Paris Agreement, 196 countries pledged to reduce their emissions, with the goal of net-zero emissions by 2050. Some 119 of these national commitments include cutting emissions from agriculture, and 61 specifically mentioned livestock emissions.
Emissions from agriculture largely comprise methane (from livestock production), nitrous oxide (from nitrogen in soils) and to a lesser extent, carbon dioxide (from machinery burning fossil fuel, and the use of lime and urea on soils).
In Australia, emissions from the sector have fallen by 10.8% since 1990, partly as a result of drought and an increasingly variable climate affecting agricultural production (for example, wheat production).
But the National Farmers’ Federation wants the sector to grow to more than A$100 billion in farm gate output by 2030 – far higher than the current trajectory of $84 billion. This implies future growth in emissions if mitigation strategies are not deployed.
Runs on the board
Players in Australia’s agriculture sector are already showing how net-zero emissions can be achieved.
Our research has shown two livestock properties in Australia – Talaheni and Jigsaw farms – have also achieved carbon neutral production. In both cases, this was mainly achieved through regeneration of soil and tree carbon on their properties, which effectively draws down an equivalent amount of carbon dioxide from the atmosphere to balance with their farm emissions.
Most of these examples are based on offsetting farm emissions – through buying carbon credits or regenerating soil and tree carbon – rather than direct reductions in emissions such as methane and nitrous oxide.
But significant options are available, or emerging, to reduce emissions of “enteric” methane – the result of fermentation in the foregut of ruminants such as cattle, sheep and goats.
For example, livestock can be fed dietary supplements high in oils and tannins that restrict the microbes that generate methane in the animal’s stomach. Oil and tannins are also a byproduct of agricultural waste products such as grape marc (the solid waste left after grapes are pressed) and have been found to reduce methane emissions by around 20%.
Other promising technologies are about to enter the market. These include 3-NOP and Asparagopsis, which actively inhibit key enzymes in methane generation. Both technologies may reduce methane by up to 80%.
There are also active research programs exploring ways to breed animals that produce less methane, and raise animals that produce negligible methane later in life.
On farms, nitrous oxide is mainly lost through a process called “denitrification”. This is where bacteria convert soil nitrates into nitrogen gases, which then escape from the soil into the atmosphere. Options to significantly reduce these losses are emerging, including efficient nitrogen fertilisers, and balancing the diets of animals.
There is also significant interest in off-grid renewable energy in the agricultural sector. This is due to the falling price of renewable technology, increased retail prices for electricity and the rising cost to farms of getting connected to the grid.
What’s more, the first hydrogen-powered tractors are now available – meaning the days of diesel and petrol consumption on farms could end.
More work is needed
In this race towards addressing climate change, we must ensure the integrity of carbon neutral claims. This is where standards or protocols are required.
Australian researchers have recently developed a standard for the red meat sector’s carbon neutral target, captured in simple calculators aligned with the Australian national greenhouse gas inventory. This allow farmers to audit their progress towards carbon neutral production.
Technology has moved a long way from the days when changing the diet of livestock was the only option to reduce farm emissions. However significant research is still required to achieve a 100% carbon neutral agriculture sector – and this requires the Australian government to co-invest with agriculture industries.
And in the long term, we must ensure measures to reduce emissions from farming also meet targets for productivity, biodiversity and climate resilience.
Fossil fuels and agriculture are driving a dangerous acceleration in methane emissions, at a rate consistent with a 3-4℃ rise in global temperatures this century.
Our twopapers published today provide a troubling report card on the global methane budget, and explore what it means for achieving the Paris Agreement target of limiting warming to well below 2℃.
Methane concentration in the atmosphere reached 1,875 parts per billion at the end of 2019 – more than two and a half times higher than pre-industrial levels.
Once emitted, methane stays in the atmosphere for about nine years – a far shorter period than carbon dioxide. However its global warming potential is 86 times higher than carbon dioxide when averaged over 20 years and 28 times higher over 100 years.
In Australia, methane emissions from fossil fuels are rising due to expansion of the natural gas industry, while agriculture emissions are falling.
Balancing the global methane budget
We produced a methane “budget” in which we tracked both methane sources and sinks. Methane sources include human activities such as agriculture and burning fossil fuels, as well as natural sources such as wetlands. Sinks refer to the destruction of methane in the atmosphere and soils.
Our data show methane emissions grew almost 10% from the decade of 2000-2006 to the most recent year of the study, 2017.
Atmospheric methane is increasing by around 12 parts per billion each year – a rate consistent with a scenario modelled by the Intergovernmental Panel on Climate Change under which Earth warms by 3-4℃ by 2100.
From 2008-2017, 60% of methane emissions were man-made. These include, in order of contribution:
agriculture and waste, particularly emissions from ruminant animals (livestock), manure, landfills, and rice farming
the production and use of fossil fuels, mainly from the oil and gas industry, followed by coal mining
biomass burning, from wood burning for heating, bushfires and burning biofuels.
The remaining emissions (40%) come from natural sources. In order of contribution, these include:
wetlands, mostly in tropical regions and cold parts of the planet such as Siberia and Canada
lakes and rivers
natural geological sources on land and oceans such as gas–oil seeps and mud volcanoes
smaller sources such as tiny termites in the savannas of Africa and Australia.
So what about the sinks? Some 90% of methane is ultimately destroyed, or oxidised, in the lower atmosphere when it reacts with hydroxyl radicals. The rest is destroyed in the higher atmosphere and in soils.
Increasing methane concentrations in the atmosphere could, in part, be due to a decreasing rate of methane destruction as well as rising emissions. However, our findings don’t suggest this is the case.
Measurements show that methane is accumulating in the atmosphere because human activity is producing it at a much faster rate than it’s being destroyed.
Source of the problem
The biggest contributors to the methane increase were regions at tropical latitudes, such as Brazil, South Asia and Southeast Asia, followed by those at the northern-mid latitude such as the US, Europe and China.
In Australia, agriculture is the biggest source of methane. Livestock are the predominant cause of emissions in this sector, which have declined slowly over time.
The fossil fuel industry is the next biggest contributor in Australia. Over the past six years, methane emissions from this sector have increased due to expansion of the natural gas industry, and associated “fugitive” emissions – those that escape or are released during gas production and transport.
Tropical emissions were dominated by increases in the agriculture and waste sector, whereas northern-mid latitude emissions came mostly from burning fossil fuels. When comparing global emissions in 2000-2006 to those in 2017, both agriculture and fossil fuels use contributed equally to the emissions growth.
Since 2000, coal mining has contributed most to rising methane emissions from the fossil fuel sector. But the natural gas industry’s rapid growth means its contribution is growing.
Some scientists fear global warming will cause carbon-rich permafrost (ground in the Arctic that is frozen year-round) to thaw, releasing large amounts of methane.
But in the northern high latitudes, we found no increase in methane emissions between the last two decades. There are several possible explanations for this. Improved ground, aerial and satellite surveys are needed to ensure emissions in this vast region are not being missed.
Fixing our methane leaks
Around the world, considerable research and development efforts are seeking ways to reduce methane emissions. Methods to remove methane from the atmosphere are also being explored.
Europe shows what’s possible. There, our research shows methane emissions have declined over the past two decades – largely due to agriculture and waste policies which led to better managing of livestock, manure and landfill.
The extraction, processing and transport of fossil fuels contributes to substantial methane emissions. But “super-emitters” – oil and gas sites that release a large volume of methane – contribute disproportionately to the problem.
This skewed distribution presents opportunities. Technology is available that would enable super-emitters to significantly reduce emissions in a very cost effective way.
Clearly, current upward trends in methane emissions are incompatible with meeting the goals of the Paris climate agreement. But methane’s short lifetime in the atmosphere means any action taken today would bring results in just nine years. That provides a huge opportunity for rapid climate change mitigation.
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I would like to know how much difference we could make to our commitment under the Paris Agreement and our total greenhouse gas emissions if we removed all cows and sheep from the country and grew plants in their place (hemp, wheat, oats etc). Surely we could easily become carbon neutral if we removed all livestock? How much more oxygen would be produced from plants growing instead? How would this offset our emissions? And what if we returned the land the animals were on to native forests or even pine plantations?
This is an interesting question and gives me the opportunity for some nice – albeit partly unrealistic – model calculations. Before I start, just two comments regarding the question itself.
Oxygen concentrations have been relatively stable at around 21% of the air we breathe for millions of years. This will not change markedly even if carbon dioxide emissions increase for years to come. Carbon dioxide concentrations, even in the most pessimistic emissions scenarios, will only get to around 0.1% of the atmosphere, hardly affecting the air’s oxygen content.
Secondly, grazing animals like cows and sheep emit methane — and that’s what harms the climate, not the grassland itself. Hemp or wheat plantations would have a similar capacity to take up carbon dioxide as grassland. But growing trees is what makes the difference.
New Zealand has about 10 million hectares of grassland. Let us assume that mature native bush or mature pine forests store the equivalent of roughly 1,000 tonnes of carbon dioxide per hectare.
If it takes 250 years to grow mature native forests on all former agricultural land, this would lock away 10 billion tonnes of carbon dioxide within that time span, offsetting our carbon dioxide emissions (energy, waste and other smaller sources) during the 250 years of regrowth. Because pine forest grows faster, we would overcompensate for our emissions until the forest matures (allow 50 years for this), creating a net carbon sink.
Note these calculations are based on extremely crude assumptions, such as linear growth, absence of fire and other disturbances, constant emissions (our population will increase, and so will emissions), ignorance of soil processes, and many more.
If agricultural land was used to grow crops, we would save the 40 megatonnes of carbon dioxide equivalent emitted by livestock in the form of methane, but we would not store a substantial amount of carbon per hectare.
How should we interpret this rough estimate? First, we must acknowledge even with our best intentions, we still need to eat, and converting all agricultural land to forest would leave us importing food from overseas — certainly not great for the global carbon budget.
Second, it shows if livestock numbers were at least reduced, and we all turned to a more plant-based diet, we could reduce our emissions substantially. The effect would be similar to reforesting large parts of the country.
Third, this example also shows that eventually, be it after 250 years in the case of growing native forests, or after about 50 years in the case of pine forests, our net carbon emissions would be positive again. As the forests mature, carbon stores are gradually replenished and our emissions would no longer be compensated. Mature forests eventually become carbon neutral.
Even though the above calculations are coarse, this shows that a realistic (and quick) way to a carbon-neutral New Zealand will likely involve three steps: reduction of emissions (both in the agricultural and energy sectors), reforestation (both native bush and fast growing exotics), and a move to a more plant-based diet.
Last week we learned woody vegetation in New South Wales is being cleared at more than double the rate of the previous decade – and agriculture was responsible for more than half the destruction.
Farming now covers 58% of Australia, or 385 million hectares, and accounts for 59% of water extracted.
It’s painfully clear nature is buckling under the weight of farming’s demands. In the past decade, the federal government has listed ten ecological communities as endangered, or critically endangered, as a result of farming development and practices.
So how can we accommodate the needs of both farming and nature? Research shows us how – but it means accepting land as a finite resource, and operating within its limits. In doing so, farmers will also reap benefits.
Healthy grazing landscapes
In the 1990s, I worked as a research ecologist in the cattle country of sub-tropical Queensland. The prevailing culture valued agricultural development over conservation. Yet many of these producers lived on viable farms that supported a wealth of native plants and animals.
They made a living from the native grassy eucalypt woodlands, an ecosystem that extends from Cape York to Tasmania. In these healthy landscapes, vigorous pastures of tall perennial grasses protected the soil, enriched it with carbon and fed the cattle.
By 2006, 4.5 million hectares of box-gum grassy woodland – or 90% – in temperate Australia had been destroyed.
A template for sustainability
Back in Queensland in the 1990s, my colleagues and I devised a template for sustainable land use. Funded by the livestock industry and a now-defunct federal corporation, we worked with producers and government agencies to find the right balance between farm production and conserving natural resources.
Our research concluded that for farming to be sustainable, intensive land uses must be limited. Such intensive uses include crops and non-native pastures. They are “high input”, typically requiring fertilisers, herbicides and pesticides, and some form of cultivation. They return greater yields but kill native plants, and are prone to soil and nutrient runoff into waterways.
But our template was not adopted as conventional farming practice. In the past 20 years, Australia’s cropping area has increased by 18,200 square kilometres.
By 2019, 38,000 square kilometres of poplar box grassy woodland in Australia had been cleared – more than half the size of Tasmania. The ecosystem was listed as endangered in 2019. Until that point, it had been considered invasive native scrub in NSW – exempting it from clearing regulations – and was systematically cleared for agriculture in Queensland.
Regenerating the land
Hearteningly, our research was recently revived in a multidisciplinary study of regenerative grazing on the grassy woodlands of NSW. The template was used to assess the ecological condition of participating farms.
The study examined differences in profitability between graziers who had adopted regenerative techniques such as low-input pasture management, and all other sheep, sheep-beef and mixed cropping-grazing farmers in their region.
It found regenerative grazing was often more profitable than other types of farming, especially in dry years. Regenerative farmers also experienced significantly higher than average well-being compared with other NSW farmers.
So what does our template involve? First, it identifies four types of land use relevant to farmed grassy woodland regions.
Second, it specifies the proportion of land that should be allocated to each use, in order to achieve landscape health (see pie chart below). The proportions can be applied to single farm, or entire districts or regions.
Intensive land use involves activities that replace nearly all native species. If these activities occupy more than 30% of the landscape, there’s insufficient habitat to maintain many native species, especially plants.
At least 10% of land must be devoted to nature conservation. The remaining 60% of the land should involve low-intensity activity such as grazed native pasture and timber production. If managed well, these land uses can support human livelihoods and a diversity of native species.
Within that split of land use, total native woodland should be no less than 30%. This guarantees connected habitats for native plants and animals, enabling movement and breeding opportunities.
Respect the land’s limits
Australians ask a lot of our land. It must make space for our houses, businesses, and roads. It should support all species to prevent extinctions. And it must produce our food and fibre.
Global population growth demands a rapid rise in food production. But relying on intensive agriculture to achieve this is unsustainable. Aside from damaging the land, it increases greenhouse gas emissions though mechanisation, fertilisation, chemical use and tree clearing.
To meet the challenges of the future we must ensure farmed landscapes retain their ecological functions. In particular, maintaining biodiversity is key to climate adaptation. And as many of Australia’s plants and animals march towards extinction, the need to reverse biodiversity loss has never been greater.
Farmers can be profitable while maintaining and improving the ecological health of their land. It’s time to look harder at farming models that respect the limits of nature, and recognise that less can be more.
This month, federal authorities finally announced an upcoming ban on mercury-containing pesticide in Australia. We are one of the last countries in the world to do so, despite overwhelming evidence over more than 60 years that mercury use as fungicide in agriculture is dangerous.
Mercury is a toxic element that damages human health and the environment, even in low concentrations. In humans, mercury exposure is associated with problems such as kidney damage, neurological impairment and delayed cognitive development in children.
But Australia is yet to ratify an international treaty to reduce mercury emissions from other sources, such as the dental industry and coal-fired power stations. This is our next challenge.
A mercury disaster
Mercury became a popular pesticide ingredient for agriculture in the early 1900s, and a number of poisoning events ensued throughout the world.
They include the Iraq grain disaster in 1971-72, when grain seed treated with mercury was imported from Mexico and the United States. The seed was not meant for human consumption, but rural communities used it to make bread, and 459 people died.
In the decades since, most countries have banned the production and/or use of mercury-based pesticides on crops. In 1995 Australia discontinued their use in most applications, such as turf farming.
Despite this, authorities exempted a fungicide containing mercury known as Shirtan. They restricted its use to sugar cane farming in Queensland, New South Wales, Western Australia and the Northern Territory.
According to the sugar cane industry, about 80% of growers use Shirtan to treat pineapple sett rot disease.
But this month, the Australian Pesticides and Veterinary Medicines Authority cancelled the approval of the mercury-containing active ingredient in Shirtan, methoxyethylmercuric chloride. The decision was made at the request of the ingredient’s manufacturer, Alpha Chemicals.
Shirtan’s registration was cancelled last week. It will no longer be produced in Australia, but existing supplies can be sold to, and used by, sugar cane farmers for the next year until it is fully banned.
Workers and nature at risk
Over the past 25 years, Australia’s continued use of Shirtan allowed about 50,000 kilograms of mercury into the environment. The effect on river and reef ecosystems is largely unknown.
What is known is that mercury can be toxic even at very low concentrations, and research is needed to understand its ecological impacts.
The use of mercury-based pesticide has also created a high risk of exposure for sugar cane workers. At most risk are those not familiar with safety procedures for handling toxic materials, and who may have been poorly supervised. This risk has been exacerbated by the use itinerant workers, particularly those from a non-English speaking background.
Further, in the hot and humid conditions of Northern Australia, it has been reported that workers may have removed protective gloves to avoid sweating. Again, research is needed to determine the implication of these practices for human health.
To this end, Mercury Australia, a multi-disciplinary network of researchers, has formed to address the environmental, health and other issues surrounding mercury use, both contemporary and historical.
Australia is yet to ratify
The Minamata Convention on Mercury is a global treaty to control mercury use and release into the environment. Australia signed onto the convention in 2013 but is yet to ratify it.
If Australia ratified the Minamata Convention, it would provide impetus for a timely review and, if necessary, update of mercury regulations across Australia.
Emissions from coal-fired power stations in Australia are regulated by the states through pollution control licences. Some states would likely have to amend these licences if Australia ratified the convention. For example, Victorian licences for coal-fired power stations currently do not include limits on mercury emissions.
Climate change is already affecting the amount of food that farmers can produce. Several recent extreme weather events, which are only likely to become more frequent as the world continues heating up, provide stark illustrations of what this impact can look like. Climate change is already affecting the amount of food that farmers can produce. For example, crop sowing in the UK was delayed in autumn 2019 and some emerging crops were damaged because of wet weather. Meanwhile in Australia, considerable drought has been immensely damaging.
But climate change can also have a knock-on impact on farming by affecting the quality of seeds, making it harder to establish seedlings that then grow into mature, food-producing plants. My research group has recently published a study showing that even brief periods of high temperature or drought can reduce seed quality in rice, depending on exactly when they occur in the seed’s development.
Nonetheless, it is possible to breed improved varieties to help crops adapt to the changing climate. And the resources needed to do this are being collected and conserved in “genebanks”, libraries of seeds conserving crop plant diversity for future use.
In much of the developing world in particular, the supply of affordable, good-quality seed limits farmers’ ability to establish crops. Seeds need to be stored between harvest and later sowing and poor-quality seeds don’t survive very long in storage. Once planted, low-quality seeds are less likely to emerge as seedlings and more likely to fail later on, producing a lower plant density in the field and a lower crop yield as a result.
For this reason, investigating seed quality is an important way of assessing such effects of climate on cereal crop production. We already know that climate change can reduce the quality of cereal seeds used for food, food ingredients and for planting future crops.
The main factor that affects seed quality in this way tends to be temperature, but the amount and timing of rainfall is also important. This impact can come from changes in average weather patterns, but short periods of extreme temperature or rainfall are just as important when they coincide with sensitive stages in crop development. For example, research in the 1990s revealed that brief high temperature periods during and immediately before a crop flowers reduces the number of seeds produced and therefore the resulting grain yield in many cereal crops.
Our research has now confirmed that seed quality in rice is damaged most when brief hot spells coincide with early seed development. It also revealed that drought during the early development of the seeds also reduces their quality at maturity. And, unsurprisingly, the damage is even greater when both these things happen together.
In contrast, warmer temperatures later in the maturation process can benefit rice seed quality as the seeds dry out. But flooding that submerges the seed can also cause damage, which gets worse the later it occurs during maturation. This shows why we have to include the effects of changing rainfall as well as temperature and the precise timing of extreme weather when looking at how seed quality is affected.
Our research has also shown that different seed varieties have different levels of resilience to these environmental stresses. This means that farming in the future will depend on selecting and breeding the right varieties to respond to the changing climate.
The world now has a global network of genebanks storing seeds from a wide variety of plants, which helps safeguard their genetic diversity. For example, the International Rice Genebank maintains more than 130,000 samples of cultivated species of rice, its wild relatives and closely-related species, while the AfricaRice genebank maintains 20,000 samples.
Our finding mean that, when scientists breed new crop varieties using genebank samples as “parents”, they should include the ability to produce high-quality seed in stressful environments in the variety’s selected traits. In this way, we should be able to produce new varieties of seeds that can withstand the increasingly extreme pressures of climate change.
This article was amended to make clear that climate change increases the likely frequency of extreme weather events rather than being demonstrably responsible for individual examples.