Rising seas allow coastal wetlands to store more carbon



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Carbon storage in Australian mangroves can help mitigate climate change.
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Kerrylee Rogers, University of Wollongong; Jeffrey Kelleway, Macquarie University, and Neil Saintilan, Macquarie University

Coastal wetlands don’t cover much global area but they punch well above their carbon weight by sequestering the most atmospheric carbon dioxide of all natural ecosystems.

Termed “blue carbon ecosystems” by virtue of their connection to the sea, the salty, oxygen-depleted soils in which wetlands grow are ideal for burying and storing organic carbon.

In our research, published today in Nature, we found that carbon storage by coastal wetlands is linked to sea-level rise. Our findings suggest as sea levels rise, these wetlands can help mitigate climate change.

Sea-level rise benefits coastal wetlands

We looked at how changing sea levels over the past few millennia has affected coastal wetlands (mostly mangroves and saltmarshes). We found they adapt to rising sea levels by increasing the height of their soil layers, capturing mineral sediment and accumulating dense root material. Much of this is carbon-rich material, which means rising sea levels prompt the wetlands to store even more carbon.

We investigated how saltmarshes have responded to variations in “relative sea level” over the past few millennia. (Relative sea level is the position of the water’s edge in relation to the land rather than the total volume of water within the ocean, which is called the eustatic sea level.)




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What does past sea-level rise tell us?

Global variation in the rate of sea-level rise over the past 6,000 years is largely related to the proximity of coastlines to ice sheets that extended over high northern latitudes during the last glacial period, some 26,000 years ago.

As ice sheets melted, northern continents slowly adjusted elevation in relation to the ocean due to flexure of the Earth’s mantle.

Karaaf Wetlands in Victoria, Australia.
Boobook48/flickr, CC BY-NC-SA

For much of North America and Europe, this has resulted in a gradual rise in relative sea level over the past few thousand years. By contrast, the southern continents of Australia, South America and Africa were less affected by glacial ice sheets, and sea-level history on these coastlines more closely reflects ocean surface “eustatic” trends, which stabilised over this period.

Our analysis of carbon stored in more than 300 saltmarshes across six continents showed that coastlines subject to consistent relative sea-level rise over the past 6,000 years had, on average, two to four times more carbon in the upper 20cm of sediment, and five to nine times more carbon in the lower 50-100cm of sediment, compared with saltmarshes on coastlines where sea level was more stable over the same period.

In other words, on coastlines where sea level is rising, organic carbon is more efficiently buried as the wetland grows and carbon is stored safely below the surface.

Give wetlands more space

We propose that the difference in saltmarsh carbon storage in wetlands of the southern hemisphere and the North Atlantic is related to “accommodation space”: the space available for a wetland to store mineral and organic sediments.

Coastal wetlands live within the upper portion of the intertidal zone, roughly between mean sea level and the upper limit of high tide.

These tidal boundaries define where coastal wetlands can store mineral and organic material. As mineral and organic material accumulates within this zone it creates layers, raising the ground of the wetlands.

The coastal wetlands of Broome, Western Australia.
Shutterstock

New accommodation space for storage of carbon is therefore created when the sea is rising, as has happened on many shorelines of the North Atlantic Ocean over the past 6,000 years.

To confirm this theory we analysed changes in carbon storage within a unique wetland that has experienced rapid relative sea-level rise over the past 30 years.




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When underground mine supports were removed from a coal mine under Lake Macquarie in southeastern Australia in the 1980s, the shoreline subsided a metre in a matter of months, causing a relative rise in sea level.

Following this the rate of mineral accumulation doubled, and the rate of organic accumulation increased fourfold, with much of the organic material being carbon. The result suggests that sea-level rise over the coming decades might transform our relatively low-carbon southern hemisphere marshes into carbon sequestration hot-spots.

How to help coastal wetlands

The coastlines of Africa, Australia, China and South America, where stable sea levels over the past few millennia have constrained accommodation space, contain about half of the world’s saltmarshes.

Saltmarsh on the shores of Westernport Bay in Victoria.
Author provided

A doubling of carbon sequestration in these wetlands, we’ve estimated, could remove an extra 5 million tonnes of CO₂ from the atmosphere per year. However, this potential benefit is compromised by the ongoing clearance and reclamation of these wetlands.

Preserving coastal wetlands is critical. Some coastal areas around the world have been cut off from tides to lessen floods, but restoring this connection will promote coastal wetlands – which also reduce the effects of floods – and carbon capture, as well as increase biodiversity and fisheries production.




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In some cases, planning for future wetland expansion will mean restricting coastal developments, however these decisions will provide returns in terms of avoided nuisance flooding as the sea rises.

Finally, the increased carbon storage will help mitigate climate change. Wetlands store flood water, buffer the coast from storms, cycle nutrients through the ecosystem and provided vital sea and land habitat. They are precious, and worth protecting.


The authors would like to acknowledge the contribution of their colleagues, Janine Adams, Lisa Schile-Beers and Colin Woodroffe.The Conversation

Kerrylee Rogers, Associate Professor, University of Wollongong; Jeffrey Kelleway, Postdoctoral Research Fellow in Environmental Sciences, Macquarie University, and Neil Saintilan, Head, Department of Environmental Science, Macquarie University

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

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Eighteen countries showing the way to carbon zero


Pep Canadell, CSIRO; Corinne Le Quéré, University of East Anglia; Glen Peters, Center for International Climate and Environment Research – Oslo; Jan Ivar Korsbakken, Center for International Climate and Environment Research – Oslo, and Robbie Andrew, Center for International Climate and Environment Research – Oslo

Eighteen countries from developed economies have had declining carbon dioxide emissions from fossil fuels for at least a decade. While every nation is unique, they share some common themes that can show Australia, and the world, a viable path to reducing emissions.

Global CO₂ emissions from fossil fuels continue to increase, with record high emissions in 2018 and further growth anticipated for 2019. This trend is linked to global economic growth, which is largely still powered by the burning of fossil fuels.




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Significant reductions in the energy and carbon intensities of the global economy have not been sufficient to trigger decreases in global emissions.

But 18 countries have been doing something different. A new analysis sheds light on how they have changed their emission trajectories. There is no “silver bullet”, and every country has unique characteristics, but three elements emerge from the group: a high penetration of renewable energy in the electricity sector, a decline in energy use, and a high number of energy and climate policies in place. Something is working for these countries.

Australia was not part of the study, as its CO₂ emissions from the burning of fossil fuels remained largely stable over the study period 2005-2015 while the country’s economy grew. However, emissions of all greenhouse gases across all sectors of the economy (including land use change) declined over most of the same period, a trend that reversed in 2014 since when emissions have increased.

Why did emissions decline?

The 18 countries shown below all peaked their fossil fuel emissions no later than 2005 and had significant declines thereafter to 2015, the period covered by our study.

Changes in CO2 emissions from fossil fuel combustion for 18 countries with declining emissions during 2005-2015. Countries are ordered by how soon their emissions peaked and began to decline.
Le Quéré et al. Nature Climate Change (2019) based on data from the International Energy Agency @IEA/OECD

Uniformly, the largest contribution to emissions reductions – about 47% – was due to decreases in the fossil share of energy production, while reductions in overall energy use contributed 36%.

However, there are large differences in the relative importance of the factors that drove emissions reductions in the various countries. For instance, reduced energy use dominated emissions reductions in many countries of the European Union, whereas a more balanced spread of factors dominated in the United States, with the single largest contributor being the switch from coal to gas. Emissions reductions in Austria, Finland and Sweden were due to an increased share of non-fossil and renewable energy.

Interestingly, our analyses suggest that there is a correlation between the number of policies to promote the uptake of renewable energy and the decline in the 18 countries.

The declining emissions were not caused by the consumption of products produced elsewhere during the period examined. Earlier in the 2000s, this practice of outsourcing emissions to other countries (for example by moving manufacturing offshore) was a significant driver of emissions decline in many developed countries. But that effect has diminished.

The lasting consequences of the 2008 global financial crisis on the global economy however did have an impact, and partially explained the reduced energy use in many countries.

How significant are these emissions declines?

Emissions declined by 2.4% per year during 2005-15 across the 18 countries.

One could argue this decline is not particularly meaningful because global fossil fuel emissions continued to grow at 2.2% per year during the same period. However, this group of countries is responsible for 28% of the global CO₂ emissions from fossil fuels. That is a sizeable fraction, and if the decline continues and further intensifies it can have a significant impact.

The 18 peak-and-decline countries also played a part in the stalling of global emissions between 2014 and 2016 while the global economy continued to grow, a combination that showed, briefly and for the first time, what accelerated decarbonisation would look like. While China did not have 10 years of continuous declining emissions (and hence it was not part of the group of 18 countries), it was the biggest contributor during this stalling.

There is no guarantee that the declining trends will continue over the coming decades. In fact, our global 2018 carbon budget report showed that some of the more recent country trends are fragile and require further policy and actions to strengthen the decreases and support long-term robust decarbonisation trends.




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If a journey of a thousand miles begins with a single step, it seems some countries have already begun walking that road. Now we all need to start running decisively.The Conversation

Pep Canadell, CSIRO Oceans and Atmosphere; Executive Director, Global Carbon Project, CSIRO; Corinne Le Quéré, Professor, Tyndall Centre for Climate Change Research, University of East Anglia; Glen Peters, Research Director, Center for International Climate and Environment Research – Oslo; Jan Ivar Korsbakken, Senior Researcher, Center for International Climate and Environment Research – Oslo, and Robbie Andrew, Senior Researcher, Center for International Climate and Environment Research – Oslo

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

Businesses think they’re on top of carbon risk, but tourism destinations have barely a clue



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Tourism accounts for 8% of global emissions, much of it from planes.
Shutterstock

Susanne Becken, Griffith University

The directors of most Australian companies are well aware of the impact of carbon emissions, not only on the environment but also on their own firms as emissions-intensive industries get lumbered with taxes and regulations designed to change their behaviour.

Many are getting out of emissions-intensive activities ahead of time.

But, with honourable exceptions, Australia’s tourism industry (and the Australian authorities that support it) is rolling on as if it’s business as usual.

This could be because tourism isn’t a single industry – it is a composite, made up of many industries that together create an experience, none of which take responsibility for the whole thing.

But tourism is a huge contributor to emissions, accounting for 8% of emissions worldwide and climbing as tourism grows faster than the economies it contributes to.




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Tourism operators are aiming for even faster growth, most of them apparently oblivious to clear evidence about what their industry is doing and the risks it is buying more heavily into.

If tourism destinations were companies…

If Australian tourist destinations were companies they would be likely to discuss the risks to their operating models from higher taxes, higher oil prices, extra regulation, and changes in consumer preferences.

Aviation is one of the biggest tourism-related emitters, with the regions that depend on air travel heavily exposed.

But at present the destination-specific carbon footprints from aviation are not recorded, making it difficult for destinations to assess the risks.

A recent paper published in Tourism Management has attempted to fill the gap, publishing nine indicators for every airport in the world.

The biggest emitter in terms of departing passengers is Los Angeles International Airport, producing 765 kilo-tonnes of CO₂ in just one month; January 2017.

When taking into account passenger volumes, one of the airports with the highest emissions per traveller is Buenos Aires. The average person departing that airport emits 391 kilograms of CO₂ and travels a distance of 5,651 km.

The analysis used Brisbane as one of four case studies.

Most of the journeys to Brisbane are long.

Brisbane’s share of itineraries under 400 km is very low at 0.7% (compared with destinations such as Copenhagen which has 9.1%). That indicates a relatively low potential to survive carbon risk by pivoting to public transport or electric planes, as Norway is planning to.

The average distance travelled from Brisbane is 2,852 km, a span exceeded by Auckland (4,561 km) but few other places.

As it happens, Brisbane Airport is working hard to minimise its on-the-ground environmental impact, but that’s not where its greatest threats come from.




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The indicators suggest that the destinations at most risk are islands, and those “off the beaten track” – the kind of destinations that tourism operators are increasingly keen to develop.

Queensland’s Outback Tourism Infrastructure Fund was established to do exactly that. It would be well advised to shift its focus to products that will survive even under scenarios of extreme decarbonisation.

They could include low-carbon transport systems and infrastructure, and a switch to domestic rather than international tourists.

Experience-based travel, slow travel and staycations are likely to become the future of tourism as holidaymakers continue to enjoy the things that tourism has always delivered, but without travelling as much and without burning as much carbon to do it.

An industry concerned about its future would start transforming now.




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The Conversation


Susanne Becken, Professor of Sustainable Tourism and Director, Griffith Institute for Tourism, Griffith University

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

What’s your beef? How ‘carbon labels’ can steer us towards environmentally friendly food choices



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Delicious, nutritious… and emissions-intensive.
Shutterstock.com

Adrian R. Camilleri, University of Technology Sydney; Dalia Patino-Echeverri, Duke University, and Rick Larrick, Duke University

What did you have for dinner last night? Might you have made a different choice if you had a simple way to compare the environmental impacts of different foods?

Most people do not recognise the environmental impact of their food choices. Our research, published in Nature Climate Change, shows that even when consumers do stop to think about the greenhouse gas emissions associated with their food, they tend to underestimate it.

Fortunately, our study also points to a potential solution. We found that a simple “carbon label” can nudge consumers in the right direction, just as nutrition information helps to highlight healthier options.




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Most food production is highly industrialised, and has environmental impacts that most people do not consider. In many parts of the world, conversion of land for beef and agricultural production is a major cause of deforestation. Natural gas is a key input in the manufacture of fertiliser. Refrigeration and transportation also depend heavily on fossil fuels.

Overall, food production contributes 19-29% of global greenhouse emissions. The biggest contributor is meat, particularly red meat. Cattle raised for beef and dairy products are major sources of methane, a potent greenhouse gas.

Meat production is inherently inefficient: fertiliser is used to grow feedstock, but only a small portion of this feed becomes animal protein. It takes about 38 kilograms of plant-based protein to produce 1kg of beef – an efficiency of just 3%. For comparison, pork has 9% efficiency and poultry has 13%.

We could therefore cut greenhouse emissions from food significantly by opting for more vegetarian or vegan meals.

Food for thought

To find out whether consumers appreciate the environmental impact of their food choices, we asked 512 US volunteers to estimate the greenhouse emissions of 19 common foods and 18 typical household appliances.

We told the respondents that a 100-watt incandescent light bulb turned on for 1 hour produces 100 “greenhouse gas emission units”, and asked them to make estimates about the other items using this reference unit. In these terms, a serving of beef produces 2,481 emission units.

As shown below, participants underestimated the true greenhouse gas emissions of foods and appliances in almost every case. For example, the average estimate for a serving of beef was around 130 emission units – more than an order of magnitude less than the true amount. Crucially, foods were much more underestimated than appliances.

Consumers consistently underestimate the greenhouse emissions of food.
Camilleri et al. Nature Climate Change 2018

Improving consumers’ knowledge

People often overestimate their understanding of common everyday objects and processes. You might think you have a pretty solid idea of how a toilet works, until you are asked to describe it in exact detail.

Food is a similarly familiar but complex phenomenon. We eat it every day, but its production and distribution processes are largely hidden. Unlike appliances, which have energy labels, are plugged into an electrical outlet, emit heat, and generally have clear indications of when they are using electricity, the release of greenhouse gases in the production and transportation of food is invisible.

One way to influence food choice is through labelling. We designed a new carbon label to communicate information about the total amount of greenhouse emissions involved in the production and transport of food.

Drawing on knowledge from the design of existing labels for nutrition, fuel economy and energy efficiency, we came up with the label shown below. It has two key features.

First, it translates greenhouse emissions into a concrete, familiar unit: equivalent number of light bulb minutes. A serving of beef and vegetable soup, for example, is roughly equivalent to a light bulb turned on for 2,127 minutes – or almost 36 hours.

Second, it displays the food’s relative environmental impact compared with other food, on an 11-point scale from green (low impact) to red (high impact). Our serving of beef and vegetable soup rates at 10 on the scale – deep into the red zone – because beef production is so emissions-intensive.

In the can – a carbon label for beef and vegetable soup reveals its high environmental impact.

To test the label, we asked 120 US volunteers to buy cans of soup from a selection of six. Half of the soups contained beef and the other half were vegetarian. Everyone was presented with price and standard nutritional information. Half of the group was also presented with our new carbon labels.

Volunteers who were shown the carbon labels chose significantly fewer beef soup options. Importantly, they also had more accurate perceptions of the relative carbon footprints of the different soups on offer.




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Figuring out the carbon footprint of every food item is difficult, expensive, and fraught with uncertainty. But we believe a simplified carbon label – perhaps using a traffic light system or showing relative scores for different foods – can help inform and empower consumers to reduce the environmental impact of their food choices.The Conversation

Adrian R. Camilleri, Senior Lecturer in Marketing, University of Technology Sydney; Dalia Patino-Echeverri, Associate professor, Duke University, and Rick Larrick, Professor of Management and Organizations, Duke University

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

Fresh thinking: the carbon tax that would leave households better off



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The UNSW climate dividend proposal will be launched on Wednesday by the Member for Wentworth Kerryn Phelps.
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Richard Holden, UNSW and Rosalind Dixon, UNSW

Today, as part of the UNSW Grand Challenge on Inequality, we release a study entitled A Climate Dividend for Australians that offers a practical solution to the twin problems of climate change and energy affordability.

It’s a serious, market-based approach to address climate change through a carbon tax, but it would also leave around three-quarters of Australians financially better off.

It is based on a carbon dividend plan formulated by the Washington-based Climate Leadership Council, which includes luminaries such as Larry Summers, George Schultz and James Baker. It is similar to a plan proposed by the US (and Australian) Citizens’ Climate Lobby.

How it would work

Carbon emissions would be taxed at A$50 per ton, with the proceeds returned to ordinary Australians as carbon dividends.

The dividends would be significant — a tax-free payment of about A$1,300 per adult.

The average household would be A$585 a year better off after taking account of price increases that would flow through from producers.




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If those households also cut their energy consumption as a result of the tax they would be even better off.

And the payment would be progressive, meaning the lowest-earning households would get the most. The lowest earning quarter would be A$1,305 a year better off.

Untaxed exports, fewer regulations

For energy and other producers making things to sell to Australians, the tax would do what all so-called Pigouvian taxes do — make them pay for the damage they do to others.

But Australian exporters to countries without such schemes would have their payments rebated.

Imports from countries without such schemes would be charged “fees” based on carbon content.




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This means Australian companies subjected to the tax wouldn’t be disadvantaged by imports from countries without it, and nor would importers from countries with such a tax.

The plan would permit the rollback of other restrictions on carbon emissions and expensive subsidies.

Our estimates suggest the rollbacks have the potential to save the Commonwealth A$2.5 billion per year.

It’s working overseas

Our plan is novel in the Australian context, but similar to one in the Canadian province of British Columbia which has a carbon tax that escalates until it reaches C$50 per ton, with proceeds returned to citizens via a dividends.




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Alaska also pays long-term dividends from common-property resources. The proceeds from its oil reserves have been distributed to citizens since 1982, totalling up to US$2,000 per person.

It could be phased in

We would be open to a gradual approach. One option we canvass in the report is beginning with a A$20 per metric ton tax and increasing it by A$5 a year until it reaches A$50 after six years.

The dividends would grow with the tax rate, but the bulk of households would immediately be better off in net terms and much better off over time.

And it would be simple

Our plan doesn’t create loopholes or incentives to get handouts from the government, as have previous plans that directed proceeds to polluters.

It will not satisfy climate-change deniers, but then no plan for action on climate change would do that — other than perhaps the governmment’s direct action policy, which provides a costly taxpayer-funded boondoggle to selected winners.




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But for those who understand that climate change is real, our plan balances the important benefits we gain from economic development and associated carbon emissions against the social cost of those emissions.

It does it in a way that provides compensation to all Australians, but on an equal basis, making the lowest-income Australians substantially better off.

It is the sort of policy that politicians who believe in both the realities of climate change as well as the power and benefits of markets ought to support.The Conversation

Richard Holden, Professor of Economics and PLuS Alliance Fellow, UNSW and Rosalind Dixon, Professor of Law, UNSW

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

We need more carbon in our soil to help Australian farmers through the drought


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Healthy soils can hold water even during droughts.
Evie Shaffer/Unsplash

Nanthi Bolan, University of Newcastle

Australia has never been a stranger to droughts, but climate change is now super-charging them.

Besides taking a toll on human health, droughts also bake the earth. This means the ground holds less water, creating a vicious cycle of dryness.

Our research has investigated ways to improve the health and structure of soil so it can hold more water, even during droughts. It’s vital to help farmers safeguard their soil as we adapt to an increasingly drought-prone climate.




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Soil moisture is key

The immediate effect of drought is complete loss of soil water. Low moisture reduces soil health and productivity, and increases the loss of fertile top soil through wind and water erosion.

To describe how we can improve soil health, we first need to explain some technical aspects of soil moisture.

Soil with good structure tends to hold moisture, protecting soil health and agricultural productivity.
Author provided

Soil moisture is dictated by three factors: the ability of the soil to absorb water; its capacity to store that water; and the speed at which the water is lost through evaporation and runoff, or used by growing plants.

These three factors are primarily determined by the proportions of sand, silt and clay; together these create the “soil structure”. The right mixture means there are plenty of “pores” – small open spaces in the soil.




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Soils dominated by very small “micropores” (30-75 micrometres), such as clay soil, tend to store more water than those dominated by macropores (more than 75 micrometers), such as sandy soil.

If the balance is skewed, soil can actually repel water, increasing runoff. This is a major concern in Australia, especially in some areas of Western Australia and South Australia.

Improving soil structure

Good soil structure essentially means it can hold more water for longer (other factors include compaction and surface crust).

Farmers can improve soil structure by using minimum tillage, crop rotation and return of crop residues after harvest.

Another important part of the puzzle is the amount of organic matter in the soil –it breaks down into carbon and nutrients, which is essential for absorbing and storing water.

There are three basic ways to increase the amount of organic matter a given area:

  • grow more plants in that spot, and leave the crop and root residue after harvest

  • slow down decomposition by tilling less and generally not disturbing the soil more than absolutely necessary

  • apply external organic matter through compost, mulch, biochar and biosolids (treated sewage sludge).

Typically, biosolids are used to give nutrients to the soil, but we researched its impact on carbon storage as well. When we visited a young farmer in Orange, NSW, he showed us two sites: one with biosolids, and one without. The site with biosolids grew a bumper crop of maize the farmer could use as fodder for his cattle; the field without it was stunted.

The farmer told us the extra carbon had captured more moisture, which meant strong seedling growth and a useful crop.




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This illustrates the value of biowastes including compost, manure, crop residues and biosolids in capturing and retaining moisture for crop growth, reducing the impact of drought on soil health and productivity.

Improving soil health cannot happen overnight, and it’s difficult to achieve while in midst of a drought. But how farmers manage their soil in the good times can help prepare them for managing the impacts of the next drought when it invariably comes.


The author would like to thank Dr Michael Crawford, CEO of Soil CRC, for his substantial contribution to this article.The Conversation

Nanthi Bolan, Professor of Enviornmental Science, University of Newcastle

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

You’ve heard of a carbon footprint – now it’s time to take steps to cut your nitrogen footprint



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Transport and livestock are both significant contributors to nitrogen pollution.
Annalucia/Shutterstock.com

Ee Ling Ng, University of Melbourne; Deli Chen, University of Melbourne, and Xia Liang, University of Melbourne

Nitrogen pollution has significant environmental and human health costs. Yet it is often conflated with other environmental problems, such as climate change, which is exacerbated by nitrous oxide (N₂O) and nitrogen oxides (NOₓ), or particulate smog, to which ammonia (NH₃) also contributes.

One way to understand our nitrogen use is to look at our nitrogen footprint. This is the amount of reactive nitrogen, which is all forms of nitrogen other than inert nitrogen gas, released into the environment from our daily activities that consume resources including food and energy.




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Our earlier research showed that Australia has a large nitrogen footprint. At up to 47kg of nitrogen per person each year, Australia is far ahead of the US (28kg per person), the second on the leaderboard of per capita reactive nitrogen emissions. Australians’ large nitrogen footprints are created largely by a diet rich in animal protein and high levels of coal use for energy.

The nitrogen footprint

Our new research, published in the Journal of Cleaner Production, takes this concept further by measuring the nitrogen footprint of an entire institution, in this case the University of Melbourne.

The institutional nitrogen footprint is the sum of individual activities at the workplace and institutional activities, such as powering laboratories and lecture theatres in the case of a university.

We calculated that the university’s annual nitrogen footprint is 139 tonnes of nitrogen. It is mainly attributable to three factors: food (37%), energy use (32%) and transport (28%).

The University of Melbourne’s nitrogen footprint in 2015 and projections for 2020.

At the university, food plays a dominant role through the meat and dairy consumed. Nitrogen emissions from food occur mainly during its production, whereas emissions from energy use come mainly from coal-powered electricity use and from fuel used during business travel.

Cutting nitrogen

We also modelled the steps that the university could take to reduce its nitrogen footprint. We found that it could be reduced by 60% by taking action to cut emissions from the three main contributing factors: food, energy use, and travel.

The good news is if the university implements all the changes to energy use detailed in its Sustainability Plan – which includes strategies such as adopting clean energy (solar and wind), optimising energy use and buying carbon credits – this would also reduce nitrogen pollution by as much as 29%.

Changing habits of air travel and food choices would be a challenge, as this requires altering the behaviour of people from a culture that places tremendous value on travelling and a love for coffee and meat.

Generally, Australians fly a lot compared to the rest of the world, at significant cost to the environment. We could offset the travel, and we do take that possibility into account, but as others have written before us, we should not make the mistake of assuming that emissions offsets make air travel “sustainable”.

The question that perhaps need to be asked, for work travel, is “to travel or not to travel?” Let’s face it, why are so many academic conferences set in idyllic locations, if not to entice us to attend?

Animal products are major contributors to nitrogen emissions, given the inefficiency of conversion from the feed to milk or meat. Would people be willing to change their latte, flat white or cappuccino to a long black, espresso or macchiato? Or a soy latte?




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As 96% of the nitrogen emissions occur outside the university’s boundaries, their detrimental effects are invisible to the person on the ground, while the burden of the pollution is often borne far away, both in time and space.

The ConversationBut, as our study shows for the first time, large institutions with lots of staff are well placed to take steps to cut their large nitrogen footprint.

Ee Ling Ng, Research fellow, University of Melbourne; Deli Chen, Professor, University of Melbourne, and Xia Liang, PhD candidate, University of Melbourne

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