Turning methane into carbon dioxide could help us fight climate change



It’s not cows’ fault they fart, but the methane they produce is warming the planet.
Robert Bye/Unsplash

Pep Canadell, CSIRO and Rob Jackson, Stanford University

Discussions on how to address climate change have focused, very appropriately, on reducing greenhouse gas emissions, particularly those of carbon dioxide, the major contributor to climate change and a long-lived greenhouse gas. Reducing emissions should remain the paramount climate goal.

However, greenhouse gas emissions have been increasing now for two centuries. Damage to the atmosphere is already profound enough that reducing emissions alone won’t be enough to avoid effects like extreme weather and changing weather patterns.

In a paper published today in Nature Sustainability, we propose a new technique to clean the atmosphere of the second most powerful greenhouse gas people produce: methane. The technique could restore the concentration of methane to levels found before the Industrial Revolution, and in doing so, reduce global warming by one-sixth.

Our new technique sounds paradoxical at first: turning methane into carbon dioxide. It’s a concept at this stage, and won’t be cheap, but it would add to the tool kit needed to tackle climate change.

The methane menace

After carbon dioxide, methane is the second most important greenhouse gas leading to human-induced climate change. Methane packs a climate punch: it is 84 times more powerful than carbon dioxide in warming the planet over the first 20 years of its molecular life.




Read more:
Methane is a potent pollutant – let’s keep it out of the atmosphere


Methane emissions from human activities are now larger than all natural sources combined. Agriculture and energy production generate most of them, including emissions from cattle, rice paddies and oil and gas wells.

The result is methane concentrations in the atmosphere have increased by 150% from pre-industrial times, and continue to grow. Finding ways to reduce or remove methane will therefore have an outsize and fast-acting effect in the fight against climate change.


Global Carbon Atlas

What we propose

The single biggest challenge for removing methane from the atmosphere is its low concentration, only about 2 parts per million. In contrast, carbon dioxide is now at 415 parts per million, roughly 200 times higher. Both gases are much more diluted in air than when found in the exhaust of a car or in a cow’s burp, and both would be better served by keeping them out of the atmosphere to start with.

Nonetheless, emissions continue. What if we could capture the methane after its release and convert it into something less damaging to climate?




Read more:
What is a pre-industrial climate and why does it matter?


That is why our paper proposes removing all methane in the atmosphere produced by human activities – by oxidising it to carbon dioxide. Such an approach has not been proposed before: previously, all removal techniques have only been applied to carbon dioxide.

This is the equivalent of turning 3.2 billion tonnes of methane into 8.2 billion tonnes of carbon dioxide (equivalent to several months of global emissions). The surprising aspect to this trade is that it would reduce global warming by 15%, because methane is so much more warming than carbon dioxide.

Proposed industrial array to oxidise methane to carbon dioxide.
Jackson et al. 2019 Nature Sustainability

This reaction yields energy rather than requires it. It does require a catalyst, though, such as a metal, that converts methane from the air and turns it into carbon dioxide.

One fit-for-purpose family of catalysts are zeolites. They are crystalline materials that consist of aluminum, silicon and oxygen, with a very porous molecular structure that can act as a sponge to soak up methane.

They are well known to industrial researchers trying to oxidise methane to methanol, a valuable chemical feedstock.

We envision arrays of electric fans powered by renewable energy to force large volumes of air into chambers, where the catalyst is exposed to air. The catalyst is then heated in oxygen to form and release CO₂. Such arrays of fans could be placed anywhere where renewable energy – and enough space – is available.

We calculate that with removal costs per tonne of CO₂ rising quickly from US$50 to US$500 or more this century, consistent with mitigation scenarios that keep global warming below 2℃, this technique could be economically feasible and even profitable.

We won’t know for sure, though, until future research highlights the precise chemistry and industrial infrastructure needed.

Beyond the clean-up we propose here, methane removal and atmospheric restoration could be an extra tool in humanity’s belt as we aim for stringent climate targets, while providing new economic opportunities.




Read more:
Why methane should be treated differently compared to long-lived greenhouse gases


Future research and development will determine the technical and economic feasibility of methane removal. Even if successful, methane- and other carbon-removal technologies are no substitute for strong and rapid emissions reductions if we are to avoid the worst impacts of global warming.The Conversation

Pep Canadell, Chief research scientist, CSIRO Oceans and Atmosphere; and Executive Director, Global Carbon Project, CSIRO and Rob Jackson, Chair, Department of Earth System Science, and Chair of the Global Carbon Project, globalcarbonproject.org, Stanford University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

NZ introduces groundbreaking zero carbon bill, including targets for agricultural methane



Agriculture – including methane from cows and sheep – currently contributes almost half of New Zealand’s greenhouse emissions.
from http://www.shutterstock.com, CC BY-ND

Robert McLachlan, Massey University

New Zealand’s long-awaited zero carbon bill will create sweeping changes to the management of emissions, setting a global benchmark with ambitious reduction targets for all major greenhouse gases.

The bill includes two separate targets – one for the long-lived greenhouse gases carbon dioxide and nitrous oxide, and another target specifically for biogenic methane, produced by livestock and landfill waste.

Launching the bill, Prime Minister Jacinda Ardern said:

Carbon dioxide is the most important thing we need to tackle – that’s why we’ve taken a net zero carbon approach. Agriculture is incredibly important to New Zealand, but it also needs to be part of the solution. That is why we have listened to the science and also heard the industry and created a specific target for biogenic methane.

The Climate Change Response (Zero Carbon) Amendment Bill will:

  • Create a target of reducing all greenhouse gases, except biogenic methane, to net zero by 2050
  • Create a separate target to reduce emissions of biogenic methane by 10% by 2030, and 24-47% by 2050 (relative to 2017 levels)
  • Establish a new, independent climate commission to provide emissions budgets, expert advice, and monitoring to help keep successive governments on track
  • Require government to implement policies for climate change risk assessment, a national adaptation plan, and progress reporting on implementation of the plan.



Read more:
Climate change is hitting hard across New Zealand, official report finds


Bringing in agriculture

Preparing the bill has been a lengthy process. The government was committed to working with its coalition partners and also with the opposition National Party, to ensure the bill’s long-term viability. A consultation process in 2018 yielded 15,000 submissions, more than 90% of which asked for an advisory, independent climate commission, provision for adapting to the effects of climate change and a target of net zero by 2050 for all gasses.

Throughout this period there has been discussion of the role and responsibility of agriculture, which contributes 48% of New Zealand’s total greenhouse gas emissions. This is an important issue not just for New Zealand and all agricultural nations, but for world food supply.


Ministry for the Environment, CC BY-ND

Another critical question involved forestry. Pathways to net zero involve planting a lot of trees, but this is a short-term solution with only partly understood consequences. Recently, the Parliamentary Commissioner for the Environment suggested an approach in which forestry could offset only agricultural, non-fossil emissions.

Now we know how the government has threaded its way between these difficult choices.




Read more:
NZ’s environmental watchdog challenges climate policy on farm emissions and forestry offsets


Separate targets for different gases

In signing the Paris Agreement, New Zealand agreed to hold the increase in the global average temperature to well below 2°C and to make efforts to limit it to 1.5°C. The bill is guided by the latest Intergovernmental Panel on Climate Change (IPCC) report, which details three pathways to limit warming to 1.5°C. All of them involve significant reductions in agricultural methane (by 23%-69% by 2050).

Farmers will be pleased with the “two baskets” approach, in which biogenic methane is treated differently from other gasses. But the bill does require total biogenic emissions to fall. They cannot be offset by planting trees. The climate commission, once established, and the minister will have to come up with policies that actually reduce emissions.

In the short term, that will likely involve decisions about livestock stocking rates: retiring the least profitable sheep and beef farms, and improving efficiency in the dairy industry with fewer animals but increased productivity on the remaining land. Longer term options include methane inhibitors, selective breeding, and a possible methane vaccine.

Ambitious net zero target

Net zero by 2050 on all other gasses, including offsetting by forestry, is still an ambitious target. New Zealand’s emissions rose sharply in 2017 and effective mechanisms to phase out fossil fuels are not yet in place. It is likely that with protests in Auckland over a local 10 cents a litre fuel tax – albeit brought in to fund public transport and not as a carbon tax per se – the government may be feeling they have to tread delicately here.

But the bill requires real action. The first carbon budget will cover 2022-2025. Work to strengthen New Zealand’s Emissions Trading Scheme is already underway and will likely involve a falling cap on emissions that will raise the carbon price, currently capped at NZ$25.




Read more:
Why NZ’s emissions trading scheme should have an auction reserve price


In initial reaction to the bill, the National Party welcomed all aspects of it except the 24-47% reduction target for methane, which they believe should have been left to the climate commission. Coalition partner New Zealand First is talking up their contribution and how they had the agriculture sector’s interests at heart.

While climate activist groups welcomed the bill, Greenpeace criticised the bill for not being legally enforceable and described the 10% cut in methane as “miserly”. The youth action group Generation Zero, one of the first to call for zero carbon legislation, is understandably delighted. Even so, they say the law does not match the urgency of the crisis. And it’s true that since the bill was first mooted, we have seen a stronger sense of urgency, from the Extinction Rebellion to Greta Thunberg to the UK parliament’s declaration of a climate emergency.




Read more:
UK becomes first country to declare a ‘climate emergency’


New Zealand’s bill is a pioneering effort to respond in detail to the 1.5ºC target and to base a national plan around the science reported by the IPCC.

Many other countries are in the process of setting and strengthening targets. Ireland’s Parliamentary Joint Committee on Climate recently recommended adopting a target of net zero for all gasses by 2050. Scotland will strengthen its target to net zero carbon dioxide and methane by 2040 and net zero all gasses by 2045. Less than a week after this announcement, the Scottish government dropped plans to cut air departure fees (currently £13 for short and £78 for long flights, and double for business class).

One country that has set a specific goals for agricultural methane is Uruguay, with a target of reducing emissions per kilogram of beef by 33%-46% by 2030. In the countries mentioned above, not so different from New Zealand, agriculture produces 35%, 23%, and 55% of emissions, respectively.

New Zealand has learned from processes that have worked elsewhere, notably the UK’s Climate Change Commission, which attempts to balance science, public involvement and the sovereignty of parliament. Perhaps our present experience in balancing the demands of different interest groups and economic sectors, with diverse mitigation opportunities and costs, can now help others.The Conversation

Robert McLachlan, Professor in Applied Mathematics, Massey University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

New Zealand’s zero carbon bill: much ado about methane



File 20180712 27039 1d1g807.jpg?ixlib=rb 1.1
New Zealand is considering whether or not agricultural greenhouse gases should be considered as part of the country’s transition to a low-emission economy.
from http://www.shutterstock.com, CC BY-SA

Robert McLachlan, Massey University

New Zealand could become the first country in the world to put a price on greenhouse gas emissions from agriculture.

Leading up to the 2017 election, the now Prime Minister Jacinda Ardern famously described climate change as “my generation’s nuclear-free moment”. The promised zero carbon bill is now underway, but in an unusual move, many provisions been thrown open to the public in a consultation exercise led by Minister for Climate Change James Shaw.

More than 4,000 submissions have already been made, with a week still to go, and the crunch point is whether or not agriculture should be part of the country’s transition to a low-emission economy.




Read more:
New Zealand’s productivity commission charts course to low-emission future


Zero carbon options

Many of the 16 questions in the consultation document concern the proposed climate change commission and how far its powers should extend. But the most contentious question refers to the definition of what “zero carbon” actually means.

The government has set a net zero carbon target for 2050, but in the consultation it is asking people to pick one of three options:

  1. net zero carbon dioxide – reducing net carbon dioxide emissions to zero by 2050

  2. net zero long-lived gases and stabilised short-lived gases – carbon dioxide and nitrous oxide to net zero by 2050, while stabilising methane

  3. net zero emissions – net zero emissions across all greenhouse gases by 2050

The three main gases of concern are carbon dioxide (long-lived, and mostly produced by burning fossil fuels), nitrous oxide (also long-lived, and mostly produced by synthetic fertilisers and animal manures) and methane (short-lived, and mostly produced by burping cows and sheep). New Zealand’s emissions of these gases in 2016 were 34 million tonnes (Mt), 9Mt, and 34Mt of carbon dioxide equivalent (CO₂e), respectively.

All three options refer to “net” emissions, which means that emissions can be offset by land use changes, primarily carbon stored in trees. In option 1, only carbon dioxide is offset. In option 2, carbon dioxide and nitrous oxide are offset and methane is stabilised. In option 3, all greenhouses gases are offset.

Gathering support

Opposition leader Simon Bridges has declared his support for the establishment of a climate change commission. DairyNZ, an industry body, has appointed 15 dairy farmers as “climate change ambassadors” and has been running a nationwide series of workshops on the role of agricultural emissions.

Earlier this month, Ardern and the Farming Leaders Group (representing most large farming bodies) published a joint statement that the farming sector and the government are committed to working together to achieve net zero emissions from agri-food production by 2050. Not long after, the Climate Leaders Coalition, representing 60 large corporations, announced their support for strong action to reduce emissions and for the zero carbon bill.

However, the devil is in the detail. While option 2 involves stabilising methane emissions, for example, it does not specify at what level or how this would be determined. Former Green Party co-leader Jeanette Fitzsimons has argued that methane emissions need to be cut hard and fast, whereas farming groups would prefer to stabilise emissions at their present levels.




Read more:
Why methane should be treated differently compared to long-lived greenhouse gases


This would be a much less ambitious 2050 target than option 3, potentially leaving the full 34Mt of present methane emissions untouched. Under current international rules, this would amount to an overall reduction in emissions of about 50% on New Zealand’s 1990 levels and would likely be judged insufficient in terms of the Paris climate agreement. This may not be what people thought they were voting for in 2017.

Why we can’t ignore methane

To keep warming below 2℃ above pre-industrial global temperatures, CO₂ emissions will need to fall below zero (that is, into net removals) by the 2050s to 2070s, along with deep reductions of all other greenhouse gases. To stay close to 1.5℃, the more ambitious of the twin Paris goals, CO₂ emissions would need to reach net zero by the 2040s. If net removals cannot be achieved, global CO₂ emissions will need to reach zero sooner.

Therefore, global pressure to reduce agricultural emissions, especially from ruminants, is likely to increase. A recent study found that agriculture is responsible for 26% of human-caused greenhouse emissions, and that meat and dairy provide 18% of calories and 37% of protein, while producing 60% of agriculture’s greenhouse gases.

A new report by Massey University’s Ralph Sims for the UN Global Environment Facility concludes that currently, the global food supply system is not sustainable, and that present policies will not cut agricultural emissions sufficiently to limit global warming to 1.5℃ above pre-industrial levels.

Finding a way forward

Reducing agricultural emissions without reducing stock numbers significantly is difficult. Many options are being explored, from breeding low-emission animals and selecting low-emission feeds to housing animals off-pasture and methane inhibitors and vaccines.

But any of these will face a cost and it is unclear who should pay. Non-agricultural industries, including the fossil fuel sector, are already in New Zealand’s Emissions Trading Scheme (ETS) and would like agriculture to pay for emissions created on the farm. Agricultural industries argue that they should not pay until cost-effective mitigation options are available and their international competitors face a similar cost.

The government has come up with a compromise. Its coalition agreement states that if agriculture were to be included in the ETS, only 5% would enter into the scheme, initially. The amount of money involved here is small – NZ$40 million a year – in an industry with annual export earnings of NZ$20 billion. It would add about 0.17% to the price of whole milk powder and 0.5% to the wholesale price of beef.

The ConversationHowever, it would set an important precedent. New Zealand would become the first country in the world to put a price agricultural emissions. Many people hope that the zero carbon bill will represent a turning point. It may even inspire other countries to follow suit.

Robert McLachlan, Professor in Applied Mathematics, Massey University

This article was originally published on The Conversation. Read the original article.

Why methane should be treated differently compared to long-lived greenhouse gases



File 20180607 137295 b7km0d.jpg?ixlib=rb 1.1
Livestock is a significant source of methane, a potent but short-lived greenhouse gas.
from http://www.shutterstock.com, CC BY-SA

Dave Frame, Victoria University of Wellington; Adrian Henry Macey, Victoria University of Wellington, and Myles Allen, University of Oxford

New research provides a way out of a longstanding quandary in climate policy: how best to account for the warming effects of greenhouse gases that have different atmospheric lifetimes.

Carbon dioxide is a long-lived greenhouse gas, whereas methane is comparatively short-lived. Long-lived “stock pollutants” remain in the atmosphere for centuries, increasing in concentration as long as their emissions continue and causing more and more warming. Short-lived “flow pollutants” disappear much more rapidly. As long as their emissions remain constant, their concentration and warming effect remain roughly constant as well.

Our research demonstrates a better way to reflect how different greenhouse gases affect global temperatures over time.

Cost of pollution

The difference between stock and flow pollutants is shown in the figure below. Flow pollutant emissions, for example of methane, do not persist. Emissions in period one, and the same emissions in period two, lead to a constant (or roughly constant) amount of the pollutant in the atmosphere (or river, lake, or sea).

With stock pollutants, such as carbon dioxide, concentrations of the pollutant accumulate as emissions continue.

Flow and stock pollutants over time. In the first period, one unit of each pollutant is emitted, leading to one unit of concentration. After each period, the flow pollutant decays, while the stock pollutant remains in the environment.
provided by author, CC BY

The economic theory of pollution suggests different approaches to greenhouse gases with long or short lifetimes in the atmosphere. The social cost (the cost society ought to pay) of flow pollution is constant over time, because the next unit of pollution is just replacing the last, recently decayed unit. This justifies a constant price on flow pollutants.

In the case of stock pollutants, the social cost increases with constant emissions as concentrations of the pollutant rise, and as damages rise, too. This justifies a rising price on stock pollutants.




Read more:
Cows exude lots of methane, but taxing beef won’t cut emissions


A brief history of greenhouse gas “equivalence”

In climate policy, we routinely encounter the idea of “CO₂-equivalence” between different sorts of gases, and many people treat it as accepted and unproblematic. Yet researchers have debated for decades about the adequacy of this approach. To summarise a long train of scientific papers and opinion pieces, there is no perfect or universal way to compare the effects of greenhouse gases with very different lifetimes.

This point was made in the first major climate report produced by the Intergovernmental Panel on Climate Change (IPCC) way back in 1990. Those early discussions were loaded with caveats: global warming potentials (GWP), which underpin the traditional practice of CO₂-equivalence, were introduced as “a simple approach … to illustrate the difficulties inherent in the concept”.

The problem with developing a concept is that people might use it. Worse, they might use it and ignore all the caveats that attended its development. This is, more or less, what happened with GWPs as used to create CO₂-equivalence.

The science caveats were there, and suggestions for alternatives or improvements have continued to appear in the literature. But policymakers needed something (or thought they did), and the international climate negotiations community grasped the first option that became available, although this has not been without challenges from some countries.

Better ways to compare stocks and flows

An explanation of the scientific issues, and how we address them, is contained in this article by Michelle Cain. The approach in our new paper shows that modifying the use of GWP to better account for the differences between short- and long-lived gases can better link emissions to warming.

Under current policies, stock and flow pollutants are treated as being equivalent and therefore interchangeable. This is a mistake, because if people make trade-offs between emissions reductions such that they allow stock pollutants to grow while reducing flow pollutants, they will ultimately leave a warmer world behind in the long term. Instead, we should develop policies that address methane and other flow pollutants in line with their effects.

Then the true impact of an emission on warming can be easily assessed. For countries with high methane emissions, for example from agriculture, this can make a huge difference to how their emissions are judged.

For a lot of countries, this issue is of secondary importance. But for some countries, particularly poor ones, it matters a lot. Countries with a relatively high share of methane in their emissions portfolios tend to be either middle-income countries with large agriculture sectors and high levels of renewables in their electricity mix (such as much of Latin America), or less developed countries where agricultural emissions dominate because their energy sector is small.

This is why we think the new research has some promise. We think we have a better way to conceive of multi-gas climate targets. This chimes with new possibilities in climate policy, because under the Paris Agreement countries are free to innovate in how they approach climate policy.

Improving the environmental integrity of climate policy

This could take several forms. For some countries, it may be that the new approach provides a better way of comparing different gases within a single-basket approach to greenhouse gases, as in an emissions trading scheme or taxation system. For others, it could be used to set separate but coherent emissions targets for long- and short-lived gases within a two-basket approach to climate policy. Either way, the new approach means countries can signal the centrality of carbon dioxide reductions in their policy mix, while limiting the warming effect of shorter-lived gases.

The new way of using global warming potentials demonstrably outperforms the traditional method in a range of emission scenarios, providing a much more accurate indication of how stock and flow pollutants affect global temperatures. This is especially so under climate mitigation scenarios.

Well designed policies would assist sectoral fairness within countries, too. Policies that reflect the different roles of stock and flow pollutants would give farmers and rice growers a more reasonable way to control their emissions and reduce their impact on the environment, while still acknowledging the primacy of carbon dioxide emissions in the climate change problem.

The ConversationAn ideal approach would be a policy that aimed for zero emissions of stock pollutants such as carbon dioxide and low but stable (or gently declining) emissions of flow pollutants such as methane. Achieving both goals would mean that a farm, or potentially a country, can do a better, clearer job of stopping its contribution to warming.

Dave Frame, Professor of Climate Change, Victoria University of Wellington; Adrian Henry Macey, Senior Associate, Institute for Governance and Policy Studies; Adjunct Professor, New Zealand Climate Change Research Institute. , Victoria University of Wellington, and Myles Allen, Professor of Geosystem Science, Leader of ECI Climate Research Programme, University of Oxford

This article was originally published on The Conversation. Read the original article.

Antarctic ice reveals that fossil fuel extraction leaks more methane than thought



File 20170823 13299 1u60k1n
The analysis of large amounts of ice from Antarctica’s Taylor Valley has helped scientists to tease apart the natural and human-made sources of the potent greenhouse gas methane.
Hinrich Schaefer, CC BY-ND

Hinrich Schaefer, National Institute of Water and Atmospheric

The fossil fuel industry is a larger contributor to atmospheric methane levels than previously thought, according to our research which shows that natural seepage of this potent greenhouse gas from oil and gas reservoirs is more modest than had been assumed.

In our research, published in Nature today, our international team studied Antarctic ice dating back to the last time the planet warmed rapidly, roughly 11,000 years ago.

Katja Riedel and Hinrich Schaefer discuss NIWA’s ice coring work at Taylor Glacier in Antarctica.

We found that natural seepage of methane from oil and gas fields is much lower than anticipated, implying that leakage caused by fossil fuel extraction has a larger role in today’s emissions of this greenhouse gas.

However, we also found that vast stores of methane in permafrost and undersea gas hydrates did not release large amounts of their contents during the rapid warming at the end of the most recent ice age, relieving fears of a catastrophic methane release in response to the current warming.

The ice is processed in a large melter before samples are shipped back to New Zealand.
Hinrich Schaefer, CC BY-ND

A greenhouse gas history

Methane levels started to increase with the industrial revolution and are now 2.5 times higher than they ever were naturally. They have caused one-third of the observed increase in global average temperatures relative to pre-industrial times.

If we are to reduce methane emissions, we need to understand where it comes from. Quantifying different sources is notoriously tricky, but it is especially hard when natural and human-driven emissions happen at the same time, through similar processes.


Read more: Detecting methane leaks with infrared cameras: they’re fast, but are they effective


The most important of these cases is natural methane seepage from oil and gas fields, also known as geologic emissions, which often occurs alongside leakage from production wells and pipelines.

The total is reasonably well known, but where is the split between natural and industrial?

To make matters worse, human-caused climate change could destabilise permafrost or ice-like sediments called gas hydrates (or clathrates), both of which have the potential to release more methane than any human activity and reinforce climate change. This scenario has been hypothesised for past warming events (the “clathrate gun”) and for future runaway climate change (the so-called “Arctic methane bomb”). But how likely are these events?

Antarctic ice traps tiny bubbles of air, which represents a sample of ancient atmospheres.
Hinrich Schaefer, CC BY-ND

The time capsule

To find answers, we needed a time capsule. This is provided by tiny air bubbles enclosed in polar ice, which preserve ancient atmospheres. By using radiocarbon (14C) dating to determine the age of methane from the end of the last ice age, we can work out how much methane comes from contemporary processes, like wetland production, and how much is from previously stored methane. During the time the methane is stored in permafrost, sediments or gas fields, the 14C decays away so that these sources emit methane that is radiocarbon-free.

In the absence of strong environmental change and industrial fossil fuel production, all radiocarbon-free methane in samples from, say, 12,000 years ago will be from geologic emissions. From that baseline, we can then see if additional radiocarbon-free methane is released from permafrost or hydrates during rapid warming, which occurred around 11,500 years ago while methane levels shot up.

Tracking methane in ice

The problem is that there is not much air in an ice sample, very little methane in that air, and a tiny fraction of that methane contains a radiocarbon (14C) atom. There is no hope of doing the measurements on traditional ice cores.

Our team therefore went to Taylor Glacier, in the Dry Valleys of Antarctica. Here, topography, glacier flow and wind force ancient ice layers to the surface. This provides virtually unlimited sample material that spans the end of the last ice age.

A tonne of ice yielded only a drop of methane.
Hinrich Schaefer, CC BY-ND

For a single measurement, we drilled a tonne of ice (equivalent to a cube with one-metre sides) and melted it in the field to liberate the enclosed air. From the gas-tight melter, the air was transferred to vacuum flasks and shipped to New Zealand. In the laboratory, we extracted the pure methane out of these 100-litre air samples, to obtain a volume the size of a water drop.

Only every trillionth of the methane molecules contains a 14C atom. Our collaborators in Australia were able to measure exactly how big that minute fraction is in each sample and if it changed during the studied period.

Low seepage, no gun, no bomb

Because radiocarbon decays at a known rate, the amount of 14C gives a radiocarbon age. In all our samples the radiocarbon date was consistent with the sample age.

Radiocarbon-free methane emissions did not increase the radiocarbon age. They must have been very low in pre-industrial times, even during a rapid warming event. The latter indicates that there was no clathrate gun or Arctic methane bomb going off.

So, while today’s conditions differ from the ice-covered world 12,000 years ago, our findings implicate that permafrost and gas hydrates are not too likely to release large amounts of methane in future warming. That is good news.

Wetlands must have been responsible for the increase in methane at the end of the ice age. They have a lesser capacity for emissions than the immense permafrost and clathrate stores.

Geologic emissions are likely to be lower today than in the ice age, partly because we have since drained shallow gas fields that are most prone to natural seepage. Yet, our highest estimates are only about half of the lower margin estimated for today. The total assessment (natural plus industrial) for fossil-fuel methane emissions has recently been increased.

In addition, we now find that a larger part of that must come from industrial activities, raising the latter to one third of all methane sources globally. For comparison, the last IPCC report put them at 17%.

The ConversationMeasurements in modern air suggest that the rise in methane levels over the last years is dominated by agricultural emissions, which must therefore be mitigated. Our new research shows that the impact of fossil fuel use on the historic methane rise is larger than assumed. In order to mitigate climate change, methane emissions from oil, gas and coal production must be cut sharply.

Hinrich Schaefer, Research Scientist Trace Gases, National Institute of Water and Atmospheric

This article was originally published on The Conversation. Read the original article.

Capturing the true wealth of Australia’s waste



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Methane is produced in landfill when organic waste decomposes.
Shutterstock

William Clarke, The University of Queensland and Bernadette McCabe, University of Southern Queensland

One of the byproducts of landfill is “landfill gas”, a mixture of mostly methane and carbon dioxide generated by decomposing organic material. Methane is a particularly potent greenhouse gas, but it can be captured from landfill and used to generate clean electricity.

Methane capture is a valuable source of power but, more importantly, it can significantly reduce Australia’s methane emissions. However the opportunity to produce energy from waste is largely being squandered, as up to 80% of the potential methane in waste is not used.

If more councils were prepared to invest in better facilities, Australians would benefit from less waste in landfill and more energy in our grids. Even the by-product from using state-of-art processing methods can be used as a bio-fertiliser.


Read more: Explainer: how much landfill does Australia have?


And while these facilities are initially more expensive, Australians are generally very willing to recycle, compost and take advantage of community schemes to reduce waste. It’s reasonable to assume that a considerable percentage of our population would support updating landfill plants to reduce methane emissions.

Recycling in Australia

Australia may have a bad rap when it comes to waste recycling, but there are plenty of positives.

Australians produce approximately 600 kilograms of domestic waste per person, per year – no more than most northern European countries, which set the benchmark in sustainable waste management.

Looking at kerbside bins we, on average, recycle 30-35% of that waste, saving much of our paper, glass, aluminium and steel from landfill (which also saves and reduces emissions).

Although the household recycling rate in Australia is less than the best-performing EU recycling rates of 40-45%, this is primarily due to a lack of access to (or awareness of) schemes to recycle e-waste and metals. Data therefore suggests that at the community level, there is a willingness to minimise and recycle waste.


Read more:

Australia is still miles behind in recycling electronic products

Campaigns urging us to ‘care more’ about food waste miss the point


Between 55% and 60% of kerbside waste sent to landfill in Australia is organic material. Over 65% of this organic fraction is food waste, similar to the make-up of the EU organic waste stream, comprised of 68% of food waste.

Despite this large fraction, approximately half of the household organic we produce – mostly garden waste – is separately collected and disposed, again demonstrating high participation by the community in recycling when collection and disposal options are available.

Turning waste into energy

Energy recovery from waste is the conversion of non-recyclable material into useable heat, electricity, or fuel. Solid inorganic waste can be converted to energy by combustion, but organic waste like kitchen and and garden refuse has too much moisture to be treated this way.


Read more: Explainer: why we should be turning waste into fuel


Instead, when organic waste is sent to landfill it is broken down naturally by microorganisms. This process releases methane, a greenhouse gas 25 times more potent than carbon dioxide.

Around 130 landfills in Australia are capturing methane and using it to generate electricity. Based on installed power generation capacity and the amount of waste received, Australia’s largest landfills use 20-30% of the potential methane in waste for electricity generation.

Ravenhall in Melbourne processes 1.4 million tonnes of waste per year, and proposes to generate 8.8 megawatts (MW) of electricity by 2020. Roughly 461,000 tonnes of waste goes to Woodlawn in NSW, and in 2011 it generated 4MW of electrical power. Swanbank in Queensland receives 500,000 tonnes a year and generates 1.1MW.

The remainder of the methane is flared due to poor gas quality or insufficient transmission infrastructure, is oxidised as it migrates towards the surface of the landfill, or simply escapes. The methane generating capacity of waste is also diminished because organics begin composting as soon as they reach landfill.

But there are more efficient ways to capture methane using specialised anaerobic digestion tanks. The process is simple: an anaerobic (oxygen free) tank is filled with organic waste, which is broken down by bacteria to produce biogas. This is similar to the natural process that occurs in landfill, but is much more controlled and efficient in a tank.


Read more: Biogas: smells like a solution to our energy and waste problems


The biogas can be combusted to produce electricity and heat, or can be converted to pure biomethane to be used either in the mains gas grid, or as a renewable transport fuel. In contrast to landfills, 60-80% of the methane potential of waste is used to generate electricity in anaerobic digesters, with most of the remainder used to power waste handling and the digestion process.

The nutrient-rich sludge that remains after anaerobic digestion, called digestate, is also a valuable biofertiliser. It can support food production, and further reduce greenhouse gases by decreasing our reliance on energy-intensive manufactured fertilisers.

The use of food waste as a feedstock for anaerobic digestion is largely untapped in Australia but has huge potential. A site in Sydney’s geographic centre (Earth Power Technologies) and Richgro’s Jandakot facility near Perth are part of a handful that are converting food waste to energy using this technology.

The future of organic recycling

Local council recycling and waste infrastructure is typically not a priority election issue, except for those close to existing or proposed landfills.


Read more: Australian recycling plants have no incentive to improve


Ratepayers are generally not informed of the possibility of separately collecting food waste, either for industrial-scale composting or methane capture. We have the right to this information, with costs and benefits presented in the context of the costs we already pay for waste management, and relative to the environmental performance of landfill.

As an example, landfill operators often promote the number of homes they power by electricity generated from methane as a key measure of sustainability. But how does this compare to the electricity and heat that might be obtained from an anaerobic digester that processes the same waste?

The ConversationGiven the choice, the Australian community may have an appetite to extend organic recycling beyond well-established garden waste composting. They only have to be asked.

William Clarke, Professor of waste management, The University of Queensland and Bernadette McCabe, Associate Professor and Principal Scientist, University of Southern Queensland

This article was originally published on The Conversation. Read the original article.

Methane from food production might be the next wildcard in climate change


Pep Canadell, CSIRO; Ben Poulter, NASA; Marielle Saunois, Institut Pierre-Simon Laplace; Paul Krummel, CSIRO; Philippe Bousquet, Université de Versailles Saint-Quentin en Yvelines – Université Paris-Saclay , and Rob Jackson, Stanford University

Methane concentrations in the atmosphere are growing faster than any time in the past 20 years. The increase is largely driven by the growth in food production, according to the Global Methane Budget released today. Methane is contributing less to global warming than carbon dioxide (CO₂), but it is a very powerful greenhouse gas.

Since 2014, methane concentrations in the atmosphere have begun to track the most carbon-intensive pathways developed for the 21st century by the Intergovernmental Panel on Climate Change (IPCC).

The growth of methane emissions from human activities comes at a time when CO₂ emissions from burning fossil fuels have stalled over the past three years.

If these trends continue, methane growth could become a dangerous climate wildcard, overwhelming efforts to reduce CO₂ in the short term.

Methane concentration pathways from IPCC and observations from the NOAA measuring network (Saunois et al 2016, Environmental Research Letters). The projected global warming range by the year 2100, relative to 1850-1900, is shown for each pathway.

In two papers published today (see here and here), we bring together the most comprehensive ensemble of data and models to build a complete picture of methane and where it is going – the global methane budget. This includes all major natural and human sources of methane, and the places where it ends up in methane “sinks” such as the atmosphere and the land.

This work is a companion effort to the global CO₂ budget published annually, both by international scientists under the Global Carbon Project.

Where does all the methane go?

Methane is emitted from multiple sources, mostly from land, and accumulates in the atmosphere. In our greenhouse gas budgets, we look at two important numbers.

First, we look at emissions (which activities are producing greenhouse gases).

Second, we look at where this gas ends up. The important quantity here is the accumulation (concentration) of methane in the atmosphere, which leads to global warming. The accumulation results from the difference between total emissions and the destruction of methane in the atmosphere and uptake by soil bacteria.

CO₂ emissions take centre stage in most discussions to limit climate change. The focus is well justified, given that CO₂ is responsible for more than 80% of global warming due to greenhouse gases. The concentration of CO₂ in the atmosphere (now around 400 parts per million) has risen by 44% since the Industrial Revolution (around the year 1750).

While CO₂ in the atmosphere has increased steadily, methane concentrations grew relatively slowly throughout the 2000s, but since 2007 have grown ten times faster. Methane increased faster still in 2014 and 2015.

Remarkably, this growth is occurring on top of methane concentrations that are already 150% higher than at the start of the Industrial Revolution (now around 1,834 parts per billion).

The global methane budget is important for other reasons too: it is less well understood than the CO₂ budget and is influenced to a much greater extent by a wide variety of human activities. About 60% of all methane emissions come from human actions.

These include living sources – such as livestock, rice paddies and landfills – and fossil fuel sources, such as emissions during the extraction and use of coal, oil and natural gas.

We know less about natural sources of methane, such as those from wetlands, permafrost, termites and geological seeps.

Biomass and biofuel burning originates from both human and natural fires.

Global methane budget 2003-2012 based on Saunois et al. 2016, Earth System Science Data. See the Global Carbon Atlas at http://www.globalcarbonatlas.org.

Given the rapid increase in methane concentrations in the atmosphere, what factors are responsible for its increase?

Uncovering the causes

Scientists are still uncovering the reasons for the rise. Possibilities include: increased emissions from agriculture, particularly from rice and cattle production; emissions from tropical and northern wetlands; and greater losses during the extraction and use of fossil fuels, such as from fracking in the United States. Changes in how much methane is destroyed in the atmosphere might also be a contributor.

Our approach shows an emerging and consistent picture, with a suggested dominant source along with other contributing secondary sources.

First, carbon isotopes suggest a stronger contribution from living sources than from fossil fuels. These isotopes reflect the weights of carbon atoms in methane from different sources. Methane from fossil fuel use also increased, but evidently not by as much as from living sources.

Second, our analysis suggests that the tropics were a dominant contributor to the atmospheric growth. This is consistent with the vast agricultural development and wetland areas found there (and consistent with increased emissions from living sources).

This also excludes a dominant role for fossil fuels, which we would expect to be concentrated in temperate regions such as the US and China. Those emissions have increased, but not by as much as from tropical and living sources.

Third, state-of-the-art global wetland models show little evidence for any significant increase in wetland emissions over the study period.

The overall chain of evidence suggests that agriculture, including livestock, is likely to be a dominant cause of the rapid increase in methane concentrations. This is consistent with increased emissions reported by the Food and Agriculture Organisation and does not exclude the role of other sources.

Remarkably, there is still a gap between what we know about methane emissions and methane concentrations in the atmosphere. If we add all the methane emissions estimated with data inventories and models, we get a number bigger than the one consistent with the growth in methane concentrations. This highlights the need for better accounting and reporting of methane emissions.

We also don’t know enough about emissions from wetlands, thawing permafrost and the destruction of methane in the atmosphere.

The way forward

At a time when global CO₂ emissions from fossil fuels and industry have stalled for three consecutive years, the upward methane trend we highlight in our new papers is unwelcome news. Food production will continue to grow strongly to meet the demands of a growing global population and to feed a growing global middle class keen on diets richer in meat.

However, unlike CO₂, which remains in the atmosphere for centuries, a molecule of methane lasts only about 10 years.

This, combined with methane’s super global warming potency, means we have a massive opportunity. If we cut methane emissions now, this will have a rapid impact on methane concentrations in the atmosphere, and therefore on global warming.

There are large global and domestic efforts to support more climate-friendly food production with many successes, ample opportunities for improvement, and potential game-changers.

However, current efforts are insufficient if we are to follow pathways consistent with keeping global warming to below 2℃. Reducing methane emissions needs to become a prevalent feature in the global pursuit of the sustainable future outlined in the Paris Agreement.

The Conversation

Pep Canadell, CSIRO Scientist, and Executive Director of the Global Carbon Project, CSIRO; Ben Poulter, Research scientist, NASA; Marielle Saunois, Enseignant chercheur à l’Université de Versailles Saint Quentin; chercheur au Laboratoire des Sciences du Climat et de l’Environnement, Institut Pierre-Simon Laplace; Paul Krummel, Research Group Leader, CSIRO; Philippe Bousquet, Professeur à l’université de Versailles Saint-Quentin en Yvelines, chercheur au Laboratoire des sciences du climat et de l’environnement (LSCE), membre de l’Institut de France, auteur contributif d’un chapitre des deux derniers rapports du GIEC, Université de Versailles Saint-Quentin en Yvelines – Université Paris-Saclay , and Rob Jackson, Professor, Earth System Science and Chair of the Global Carbon Project, Stanford University

This article was originally published on The Conversation. Read the original article.