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Our food system depends on nitrogen fertilisers. Nitrogen image from www.shutterstock.com

While carbon pollution gets all the headlines for its role in climate change, nitrogen pollution is arguably a more challenging problem. Somehow we need to grow more food to feed an expanding population while minimising the problems associated with nitrogen fertiliser use.

In Europe alone, the environmental and human health costs of nitrogen pollution are estimated to be €70-320 billion per year.

Nitrogen emissions such as ammonia, nitrogen oxide and nitrous oxides contribute to particulate matter and acid rain. These cause respiratory problems and cancers for people and damage to forests and buildings.

Nitrogenous gases also play an important role in global climate change. Nitrous oxide is a particularly potent greenhouse gas as it is over 300 times more effective at trapping heat in the atmosphere than carbon dioxide.

Nitrogen from fertiliser, effluent from livestock and human sewage boost the growth of algae and cause water pollution. The estimated A$8.2 billion damage bill to the Great Barrier Reef is a reminder that our choices on land have big impacts on land, water and the air downstream.

Lost nitrogen harms farmers too, as it represents reduced potential crop growth or wasted fertiliser. This impact is most acute for smallholder farmers in developing countries, for whom nitrogen fertiliser is often the biggest cost of farming. The reduced production from the lost nitrogen can represent as much as 25% of the household income.

The solution to the nitrogen challenge will need to come from a combination of technological innovation, policy and consumer action.

The essential ingredient

Nitrogen is an essential building block for amino acids, proteins and DNA. Plant growth depends on it; animals and people get it from eating plants or other animals.

Nitrogen gas (N₂) makes up 78% of the air, but it cannot be used by plants. Fertilisers are usually made from ammonia, a form of nitrogen that the plants prefer.

A century after the development of the Haber-Bosch process gave us a way to manufacture nitrogen fertiliser, our demand for it has yet to level off.

The use of nitrogen fertiliser has risen from 11 million tonnes in 1961 to 108 million tonnes in 2014. As carbon dioxide levels continue to rise in the atmosphere, some plants such as grains will also likely demand more nitrogen.

Wheat with and without nitrogen fertiliser. Deli Chen/ The University of Melbourne

In fact, nitrogen from fertiliser now accounts for more than half the protein in the human diet. Yet some 50% of applied nitrogen is lost to the environment in water run-off from fields, animal waste and gas emissions from soil microbe metabolism.

These losses have been increasing over the decades as nitrogen fertiliser use increases. Reactive nitrogen causes wide-ranging damage, and will cause more damage if nitrogen losses are not reined in.

Faced with a growing population and changing climate, we need more than ever to optimise the use of nitrogen and minimise the losses.

From farm to fork

One way to understand our nitrogen use is to look at our nitrogen footprint – the amount of nitrogen pollution released to the environment from food, housing, transportation and goods and services.

Research by University of Melbourne PhD candidate Emma Liang shows Australia has a large nitrogen footprint. At 47kg of nitrogen per person each year, Australia is far ahead of the US, which came in with 28kg of nitrogen per person.

A high-animal-protein diet appears to be driving Australia’s big nitrogen footprint. The consumption of animal products accounts for 82% of the Australian food nitrogen footprint.

Animal products carry high nitrogen costs compared to vegetable products. Both products start with the same cost in nitrogen as a result of growing a crop, but significant further losses occur as the animal consumes food throughout its life cycle.

The N-Footprint project aims to help individuals and institutions calculate their nitrogen footprints. It shows how we can each have an impact on nitrogen pollution through our everyday choices.

We can choose to eat lower nitrogen footprint protein diets, such as vegetables, chicken and seafood instead of beef and lamb. We can choose to reduce food waste by buying smaller quantities (and more frequently if necessary) and composting food waste. The good news is, if we reduce our nitrogen footprint, we also reduce our carbon footprint.

Back to the farm

In the meantime, efforts to use nitrogen more efficiently on farms must continue. We are getting better at understanding nitrogen losses from soil through micrometerological techniques.

From sitting in the sun with plastic bucket chambers, glass vials and syringes, scientists now use tall towers and lasers to detect small changes in gas concentrations over large areas and send the results directly to our computers.

Eddy covariance tower. Mei Bai/ The University of Melbourne

We now know nitrification (when ammonia is converted to nitrate) is an important contributor to nitrogen losses and therefore climate change and damage to ecosystems. It is a process researchers – and farmers – are targeting to reduce nitrogen losses.

Nitrification inhibitors are now used commercially to keep nitrogen in the ammonium form, which plants prefer, and to prevent the accumulation of nitrate, which is more easily lost to the environment.

As this technology advances, we are starting to answer the question of how these inhibitors affect the microbial communities that maintain the health of our soil and form the foundation of ecosystems.

For example, our research shows that 3,4-dimethylpyrazole phosphate (better known as DMPP) inhibits nitrification without affecting soil microbial community diversity.

There have also been exciting observations that the root systems of some tropical grasses inhibit nitrification. This opens up a management option to slow nitrification rates in the environment using genetic approaches.

Solving the challenge of nitrogen use will require research into more efficient ways for primary producers to use nitrogen, but it will also need government leadership and consumer choices to waste less or eat more plant protein. These tools will make the case for change clearer, and the task of feeding the world greener.

On December 4-8, leading international researchers are meeting in Melbourne for the 7th International Nitrogen Initiative Conference to discuss the best new solutions to problems in nitrogen use. For a more in-depth look at these issues, visit the INI2016 website or join a range of food and production experts at the Good Food for 9 Billion: Community Forum.

Ee Ling Ng works for The University of Melbourne. She receives funding from the Commonwealth Government.

Deli Chen receives funding from Australia Research Council, Meat Livestock Australia, Australian Centre for international Agricultural Research

Robert Edis receives funding from The Australian Centre for International Agricultural Research (ACIAR). He is affiliated with and employed by ACIAR.

Emma Liang receives funding from Meat and Livestock Australia​ and the ​Australia-China Joint Research Centre at the University of Melbourne.

In response to Dr Robin Shipp’s letter about the unfair requirements for charging electric cars (3 December), I’d like to point out one more: that you can’t pay cash for a charge. Whether you pay with a smartphone (that tracks you whenever it is operating), or with a proposed swipecard (that would track you whenever you use it), it does you wrong by tracking your movements. You can fill your car with gasoline anonymously, paying cash; electric cars should offer the same.

Related: Business secretary says electric vehicles at heart of industrial strategy

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Guardian Australia has partnered with NDEVR Environmental to produce a quarterly report calculating progress towards keeping global warming below 2C

Australia is blowing its carbon budget, projections reveal

by Nick Evershed and Michael Slezak

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Exclusive: In less than four years the country has ‘spent’ almost 20% of its greenhouse gas allowance to 2050, analysis shows

• Climate countdown: is Australia on track to avoid catastrophe?

Australia’s greenhouse gas emissions are rising despite global reduction efforts, according to detailed projections made by the consultants NDEVR Environmental.

Australia’s emissions jumped by 2.56m tonnes in the three months to September, putting them 1.55m tonnes off-track compared with commitments made in Paris, and 4.06m tonnes over levels demanded by scientifically based targets set by the government’s Climate Change Authority. Emissions for the year to September are above those for the year to September 2015.

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The distribution of surplus food in Ireland is being transformed by FoodCloud. Killian Fox meets the duo behind the venture

“Within one community, there can be a business that’s throwing away perfectly good food and just around the corner there’s a charity that’s struggling to feed people in need,” says Iseult Ward of FoodCloud, a remarkable social enterprise which she co-founded with Aoibheann O’Brien in 2012. “We wanted to connect the two.”

Ward, who is 26, was studying business and economics at Trinity College, Dublin, where O’Brien, 31, was completing a masters in environmental science. Neither were particularly tech-savvy – they bonded over “a love for food and a distaste for waste” – but that didn’t deter them from using technology to address the problem. “We developed an app that would help businesses notify charities when they had surplus food available,” says Ward.

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The official start of winter was heralded by days of sharp sunshine. Country Life’s editor at large celebrates the season’s natural beauty

Windscreens frozen, ground like iron, a vichyssoise of fog in the valleys – we’ve had the first intimations of a proper winter, and my friend’s blood is coursing. “Isn’t it the most exciting time of year?” he mumbled, from the depths of many layers of warm clothing. “I love the sharpness of the air, the crunch of frost underfoot.”

I’m with him. A lucky chum who has a house in the Caribbean told me about the temperature variance on Nevis; it will be 30C at Christmas, just as it was 30C in July. A superficially seductive prospect, I admit, but who wouldn’t rather have the drama of the changing year? Icicles hanging from the eaves, mulled wine simmering on the stove. As the 18th-century nature poet James Thomson put it, “Welcome kindred glooms!”

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Social researcher and author Rebecca Huntley uses the recipe for this very popular and accessible dish to highlight the varied threats to our future food supply from global climate change.

Social researcher and author Rebecca Huntley uses the recipe for this very popular and accessible dish to highlight the varied threats to our future food supply from global climate change.

A Republican-led panel promoted a misleading tabloid story alleging earth may not be warming, relying on data that leaves out important points of context

Climate scientists have denounced the House committee on science, space and technology after the Republican-held panel promoted a misleading story expressing skepticism that the earth is dangerously warming.

On Thursday afternoon, the committee tweeted a Breitbart article alleging: “Global Temperatures Plunge. Icy Silence from Climate Alarmists”. The story linked to a British tabloid, the Daily Mail, which claimed that global land temperatures were plummeting, and that humans were not responsible for years of steadily increasing heat.

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Air pollution is a serious problem in many Chinese cites and throughout the countryside. Now the government is taking action with new environmental laws and a crackdown on the most polluting factories. In Beijing coal fired power stations are being replaced by gas.

London’s Natural History Museum is preparing for a major display on whales which is scheduled to open in June 2017.

Stressed and dying coral release varying amounts of gas which influence the formation of clouds. Scientists are investigating the prospects for Queensland’s weather as parts of the Great Barrier Reef die following bleaching by hot ocean waters.

Dressed like an abalone diver in a rainforest ravine, the search for Tasmanian sapphire involves a lolly-scoop, a crow bar and physical endurance beyond the norm. This is a repeat episode from the Off Track archives.

Safety issues force many reactors offline prompting warnings of power cuts across France, higher energy prices and a rise in emissions

The company building the UK’s first new nuclear power station for decades is facing questions over the health of its fleet of French nuclear plants after an investigation which has left the country with the lowest level of nuclear power for 10 years and the prospect of power cuts during a cold snap.

Thirteen of Électricité de France’s (EDF) 58 atomic plants are offline, some due to planned maintenance, but most for safety checks ordered by the regulator over anomalies discovered in reactor parts.

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Abandoned working dogs and puppies find new homes; solar power runs composting machines; and Matt Wilson is living the dream, opening his own micro brewery in Albany in WA.

A huge alligator snapping turtle got stuck in a blocked drain pipe in Houston, Texas.

As a relatively new owner of a Nissan Leaf, I support entirely the need for adequate provision of charge points (Letters, 29 November). The ecotricity charging points at motorway services are great, even if they are now not free. But you can now only pay using a mobile phone app – not much use for my wife whose phone is too old to run the app, and not much use for anyone if their phone is lost or broken. What is wrong with a swipe card, as offered by Charge your Car at other charging points? But the biggest absurdity, as employed by all charging points, is that you pay by charging session, not by the amount of electricity you use. In a petrol or diesel car in an area with few fuel stations, you will top up whenever you have the opportunity even if it means putting in only, say, a quarter of a tank. Electric car users may need to follow that routine, but will have to pay the same however much electricity they need.
Dr Robin Shipp
Bristol

• Join the debate – email guardian.letters@theguardian.com

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The week’s top environment news stories and green events. If you are not already receiving this roundup, sign up here to get the briefing delivered to your inbox

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Hunter Mitchell raised thousands of dollars to save Osita the rhino.

Foreign secretary, who backs ban on ivory trade, breaks off London speech to make plea for ‘magnificent’ vulnerable animal

Boris Johnson has interrupted a sweeping speech on the UK’s geopolitical future to make a passionate plea to save the African elephant, saying they are on the brink of extinction as they “get turned into umbrella stands and billiard balls”.

In the midst of a speech at Chatham House to ambassadors and foreign policy advisers, the UK foreign secretary said he was “obsessed with the tragic fate of the African elephant”.

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