How do magpies detect worms and other food sources underground? I often see them look or listen, then rapidly hop across the ground and start digging with their beak and extract a worm or bug from the earth – Catherine, age 10, Perth.
You have posed a very good question.
Foraging for food can involve sight, hearing and even smell. In almost all cases learning is involved. Magpies are ground foragers, setting one foot before the other looking for food while walking, called walk-foraging. It looks like this:
Finding food on the ground, such as beetles and other insects, is not as easy as it may sound. The ground can be uneven and covered with leaves, grasses and rocks. Insects may be hiding, camouflaged, or staying so still it is hard for a magpie to notice them.
Detecting a small object on the ground requires keen vision and experience, to discriminate between the parts that are important and those that are not.
Magpie eyes, as for most birds, are on the side of the head (humans and other birds of prey, by contrast, have eyes that face forward).
To see a small area in front of them, close to the ground, birds use both eyes together (scientists call this binocular vision). But birds mostly see via the eyes looking out to the side (which is called monocular vision).
This picture gives you an idea of what a magpie can see with its left eye, what it can see with its right eye and what area it can see with both eyes working together (binocular vision).
You asked about underground foraging. Some of that foraging can also be done by sight. Worms, for instance, may leave a small mound (called a cast) on the surface and, to the experienced bird, this indicates that a worm is just below.
Magpies can also go a huge step further. They can identify big scarab larvae underground without any visual help at all.
Scarab larvae look like grubs. They munch on grassroots and can kill entire grazing fields. Once they transform into beetles (commonly called Christmas beetles) they can do even more damage by eating all the leaves off eucalyptus trees.
Here is the secret: magpies have such good hearing, they can hear the very faint sound of grass roots being chewed.
We know this from experiments using small speakers under the soil playing back recorded sounds of scarab beetle larvae. Magpies located the speaker every time and dug it up.
So how do they do it? Several movements are involved.
To make certain that a jab with its beak will hit the exact spot where the juicy grub is, the magpie first walks slowly and scans the ground. It then stops and looks closely at the ground – seemingly with both eyes working together.
Then, holding absolutely still, the magpie turns its head so the left side of the head and ear is close to the ground for a final confirming listen.
Finally, the bird straightens up, then executes a powerful jab into the ground before retrieving the grub.
That is very clever of the magpies. Very few animals can extract food they can’t see. Only great apes and humans were thought to have this ability. Clever magpies indeed. And farmers love them for keeping a major pest under control.
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According to the United Nations, food shortages are a threat due to climate change. Are food shortages a major threat to New Zealand due to climate change?
Climate change is altering conditions that sustain food production, with cascading consequences for food security and global economies. Recent research evaluated the simultaneous impacts of climate change on agriculture and marine fisheries globally.
Modelling of those impacts under a business-as-usual carbon emission scenario suggested about 90% of the world’s population – most of whom live in the least developed countries – will experience reductions in food production this century.
New Zealanders are fortunate to live in a part of the world blessed with relatively fertile soils, adequate water supplies and mild temperatures. This gives us a comparative advantage for agriculture and horticulture over many other countries, including our main trading partner, Australia.
New Zealand produces more than enough food for its population. Exports exceed local consumption, and climate-change induced food shortages should not be an imminent risk for New Zealand. But behind every general statement like this lies some rather more troubling detail.
As residents of a developed country, we are accustomed to accessing the world’s resources through supermarkets. New Zealanders take for granted that most foods (even those we do not produce, like rice or bananas) will be available all year round.
Asparagus, new potatoes and strawberries are examples of foods New Zealanders may expect to see only at particular times of the year, but if apples or kiwifruit are out of stock, people usually complain. Our expectations are based on imports of products when they are out of season in New Zealand. The availability of those imports may be seriously compromised by climate change.
A recent Ministry for the Environment report describes climate impacts, including detailed projections of the average temperature increase and changes in rainfall patterns across New Zealand. The consistent trends are towards wetter conditions in the west, drier in the east and the largest average temperature rises in the north.
Implications for agriculture are manifold. For example, many temperate crops require cool autumn or winter temperatures to initiate flowering or fruit ripening. Orchards may need to be relocated further south, or novel low-chill varieties may need to be bred, as is already happening around the world.
Insect pests and diseases are normally controlled by our low winter temperatures, but they may become more of a problem in the future. Introduced pests and diseases include fruit flies that have a major impact in Australia and other more tropical countries, but struggle to establish breeding colonies in New Zealand. Strong biosecurity controls are our best bet for reducing this risk.
What matters more than the gradual increase in temperature predicted by climate change models, is the greater frequency of extreme weather events. These include droughts, floods and hail, which can lead to total crop losses in particular regions. One obvious mitigation strategy is to expand the provision of irrigation in our drier eastern regions, but concerns over water quality in our rivers mean this is not a popular option with the public – for example on the Heretaunga Plains or in Canterbury.
Risks to imported products
New Zealand is a net exporter of dairy, beef, lamb and many fruit and vegetables, but for some products, we depend heavily on imports. Figures from the US Department of Agriculture are not perfect, but they highlight trade imbalances for major commodities.
New Zealand imports all rice and most of its wheat. It is a net importer of pork products. Horticultural data released annually in Fresh Facts show New Zealand’s major horticultural imports are (in order of value) wine, nuts, processed vegetables, coffee, bananas and table grapes. These imported products come primarily from Australia, China, the US and Ecuador – all countries that may be less resilient to climate change than New Zealand.
As a recent report by the UN Food and Agriculture Organisation (FAO) explains, rising temperatures, rising seas and the increasing frequency of adverse weather events will interact to reduce agricultural and horticultural productivity in many regions around the world. While New Zealand is unlikely to experience food shortages in the near future as a direct result of climate change, the price and availability of imported products may increase significantly.
Unfortunately, there is another important consideration. Some New Zealanders already experience food insecurity. The 2008/9 Adult Nutrition Survey found 14% of New Zealand households reported running out of food often or sometimes due to lack of money.
Perhaps rather than worrying about the future impact of climate change on the price or availability of imported rice or bananas, we should be paying more attention to this social inequity.
As a wealthy agricultural nation and a net exporter of food, it does not seem right that one sector of our society is already regularly experiencing food shortages.
Our diets can have a big environmental impact. The greenhouse gas emissions involved in producing and transporting various foods has been well researched, but have you ever thought about the water-scarcity impacts of producing your favourite foods? The answers may surprise you.
In research recently published in the journal Nutrients, we looked at the water scarcity footprints of the diets of 9,341 adult Australians, involving more than 5,000 foods. We measured both the amount of water used to produce a food, and whether water was scarce or abundant at the location it was drawn from.
The food system accounts for around 70% of global freshwater use. This means a concerted effort to minimise the water used to produce our food – while ensuring our diets remained healthy – would have a big impact in Australia, the driest inhabited continent on Earth.
Biscuits, beer or beef: which takes the most water to produce?
We found the average Australian’s diet had a water-scarcity footprint of 362 litres per day. It was slightly lower for women and lower for adults over 71 years of age.
A water-scarcity footprint consists of two elements: the litres of water used, multiplied by a weighting depending on whether water scarcity at the source is higher or lower than the global average.
Foods with some of the highest water-scarcity footprints were almonds (3,448 litres/kg), dried apricots (3,363 litres/kg) and breakfast cereal made from puffed rice (1,464 litres/kg).
In contrast, foods with some of the smallest water-scarcity footprint included wholemeal bread (11.3 litres/kg), oats (23.4 litres/kg), and soaked chickpeas (5.9 litres/kg).
It may surprise you that of the 9,000 diets studied, 25% of the water scarcity footprint came from discretionary foods and beverages such as cakes, biscuits, sugar-sweetened drinks and alcohol. They included a glass of wine (41 litres), a single serve of potato crisps (23 litres), and a small bar of milk chocolate (21 litres).
These foods don’t only add to our waistlines, but also our water-scarcity footprint. Previous studies have also shown these foods contribute around 30% of dietary greenhouse gas emissions in Australia.
The second highest food group in terms of contributing to water-scarcity was fruit, at 19%. This includes whole fruit and fresh (not sugar-sweetened) juices. It should be remembered that fruit is an essential part of a healthy diet, and generally Australians need to consume more fruit to meet recommendations.
Dairy products and alternatives (including non-dairy beverages made from soy, rice and nuts) came in third and bread and cereals ranked fourth.
The consumption of red meat – beef and lamb – contributed only 3.7% of the total dietary water-scarcity footprint. These results suggest that eating fresh meat is less important to water scarcity than most other food
groups, even cereals.
How to reduce water use in your diet
Not surprisingly, cutting out discretionary foods would be number one priority if you wanted to lower the water footprint of the food you eat, as well as the greenhouse gas emissions of production.
Over-consumption of discretionary foods is also closely linked to weight gain and obesity. Eating a variety of healthy foods, according to energy needs, is a helpful motto.
Aside from this, it is difficult to give recommendations that are relevant to consumers. We found that the variation in water-scarcity footprint of different foods within a food group was very high compared to the variation between food groups.
For example, a medium sized apple was found to contribute a water-scarcity footprint of three litres compared with more than 100 litres for a 250 ml glass of fresh orange juice. This reflects the relative use of irrigation water and the local water scarcity where these crops are grown. It also takes more fruit to produce juice than when fruit is consumed whole.
Two slices of wholegrain bread had a much lower water-scarcity footprint than a
cup of cooked rice (0.9 litres compared with 124 litres). Of the main protein sources, lamb had the lowest water-scarcity footprint per serve (5.5 litres). Lambs are rarely raised on irrigated pastures and when crops are used for feeding, these are similarly rarely irrigated.
Consumers generally lack the information they would need to choose core foods with a lower water-scarcity footprint. Added to this, diversity is an important principle of good nutrition and dissuading consumption of particular core foods could have adverse consequences for health.
Perhaps the best opportunities to reduce water scarcity impacts in the Australian food system lie in food production. There is often very large variation between producers in water scarcity footprint of the same farm commodity.
For example, a study of the water scarcity footprint of tomatoes grown for the Sydney market reported results ranging from 5.0 to 52.8 litres per kg. Variation in the water-scarcity footprint of milk produced in Victoria was reported to range from 0.7 to 262 litres. This mainly reflects differences in farming methods, with variation in the use of irrigation and also the local water scarcity level.
Water-scarcity footprint reductions could best be achieved through technological change, product reformulation and procurement strategies in agriculture and food industries.
Not all water is equal
This is the first study of its kind to report the water-scarcity footprint for a large number of individual self-selected diets.
This was no small task, given that 5,645 individual foods were identified. Many were processed foods which needed to be separated into their component ingredients.
It’s hard to say how these results compare to other countries as the same analysis has not been done elsewhere. The study did show a large variation in water-scarcity footprints within Australian diets, reflecting the diversity of our eating habits.
Water scarcity is just one important environmental aspects of food production and consumption. While we don’t suggest that dietary guidelines be amended based on water scarcity footprints, we hope this research will support more sustainable production and consumption of food.
The author originally disclosed that he undertakes research for Meat and Livestock Australia. His disclosure has been updated to specify that the above research is among the projects to which the MLA has contributed funding.
Reducing emissions from deforestation and farming is an urgent global priority if we want to control climate change. However, like many climate change problems, the solution is complicated. Cutting down forests to plant edible crops feeds some of the world’s hungriest people.
But villagers in the Himalayas are turning to a traditional practice that can slow land clearing and feed people: growing and collecting food from the forests.
Food in the forest
My research in the Himalayan region, where high population density means farmland is very scarce, investigated how people used their forests as a food source.
An “edible forest” is one in which people have planted trees and crops that can produce food in the forest, as well as harvesting what naturally grows. In fact, this is a traditional practice in the Himalayan region. A farmer I interviewed in Siding village, at the base of Mardi Himal – one of the peaks in Annapurna Himalayan range – told me:
I go to [the] forest when food is scarce at home. I collect vegetables, fruits, nuts, medicinal herbs, spices, roots and tubers. Sometimes I also collect wild honey, bamboo shoots and mushroom, which is consumed at home and also sold in the market. Occasionally, we also get wild meat.
Traditionally, these villagers see forest and farms as an extension of each other rather than distinct categories, and manage them so they support each other.
Generally, people plant trees useful for households – for their wood, for example, or fruit – in the forest close to the villages, and preserve those grown naturally.
The community itself protects the forest, in the past even pooling grains and cash to hire a guard if needed.
This forest food is supplementary, becoming more important in scarce times and as a buffer during famine. Taking wood for fuel or timber is strictly regulated, but there are no restrictions on gathering food, to the great benefit of the poorest.
Collecting food is mainly the work of women, who gather a few things whenever they go into the forest for firewood or animal fodder. They have a great deal of knowledge about edible plants. Men take part by hunting for honey and wild animals. Children, too, go to the forest in their free time to gather berries and tubers.
Sometimes villagers collect these foods to sell in nearby markets as a seasonal source of cash.
The centralised forest management and curtailment of traditional rights of the communities that came with modern forest bureaucracy in the Himalayan region distanced people from the forest. This also led to rapid deforestation between the mid-1960s to 1980s.
This trend was reversed in the early 1990s, when community rights came to the forefront and communally managed forestry gained a strong foothold. This helped reduce poverty. Yet it is still hard for locals to grow food in the forests as they once did. One farmer told me,
We do not destroy forest when collecting these things, but conservation regulation is making this collection difficult.
We need power to move from centralised governments to local stewardship and local knowledge. Government oversight would still be required to protect the local interests, but any new mechanism needs to be developed in consultation with local communities. Research institutions could play a role in finding better ways to meet the interest of local communities when they manage their forest.
If reforestation schemes can be expanded to take into account planting that doesn’t compromise tree coverage, we can encourage rapid growth of edible forests and speed up our response to climate change. It will help meet goals like food security, mitigation and adaptation to climate change, and reducing desertification and land degradation that the United Nations’ Intergovernmental Panel on Climate Change has recommended for sustainable land management in the light of climate change.
Wages sent home by those who move away is a huge part of food security and reducing poverty for many people. In 2018 about US$530 billion was transferred to low- and middle-income countries between family members, compared with US$162 billion in development aid.
This flow of money means families with marginal land – like farmland on hill slopes in Nepal’s case – can afford to slowly convert it to plantations or forests. Migration and remittances – which contribute some 28% of Nepal’s gross domestic product – helps increase forest coverage, especially in marginal lands vulnerable to erosion and landslides.
There is an opportunity to increase planting in these lands, which have been abandoned for farming. If official reforestation policies can acknowledge and support edible forests, we could see the Himalayan region lead the pack on a new way of thinking about forests and food.
Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.
If you have a question you’d like an expert to answer, please send it to firstname.lastname@example.org
I would like to know to what extent regenerative agriculture practices could play a role in reducing carbon emissions and producing food, including meat, in the future. From what I have read it seems to offer much, but I am curious about how much difference it would make if all of our farmers moved to this kind of land management practice. Or even most of them. – a question from Virginia
To identify and quantify the potential of regenerative agriculture to reduce greenhouse gas emissions, we first have to define what it means. If regenerative practices maintain or improve production, and reduce wasteful losses on the farm, then the answer tends to be yes. But to what degree is it better, and can we verify this yet?
Let’s first define how regenerative farming differs from other ways of farming. For example, North Americans listening to environmentally conscious media would be likely to define most of New Zealand pastoral agriculture systems as regenerative, when compared to the tilled fields of crops they see across most of their continent.
If milk and meat-producing animals are not farmed on pasture, farmers have to grow grains to feed them and transport the fodder to the animals, often over long distances. It’s hard to miss that the transport is inefficient, but easier to miss that nutrients excreted by the animals as manure or urine can’t go back to the land that fed them.
Returning nutrients to the land really matters because these build up soil, and grow more plants. We can’t sequester carbon in soil without returning nutrients to the soil.
New Zealand’s style of pastoral agricultural does this well, and we’re still improving as we focus on reducing nutrient losses to water.
First, the animals that efficiently digest tough plants – including cows, sheep, and goats – all belch the greenhouse gas methane. This is a direct result of their special stomachs, and chewing their cud. Therefore, farms will continue to have high greenhouse gas emissions per unit of meat and milk they produce. The recent Intergovernmental Panel on Climate Change (IPCC) report emphasised this, noting that changing diets can reduce emissions.
The second problem is worst in dairying. When a cow lifts its tail to urinate, litres of urine saturate a small area. The nitrogen content in this patch exceeds what plants and soil can retain, and the excess is lost to water as nitrate and to the air, partly as the powerful, long-lived greenhouse gas nitrous oxide.
Regenerative agriculture lacks a clear definition, but there is an opportunity for innovation around its core concept, which is a more circular economy. This means taking steps to reduce or recover losses, including those of nutrients and greenhouse gases.
The price premium and regulation linked to certification can limit the redesign of the organic agricultural systems to incremental improvements, limiting the inclusion of regenerative concepts. It also means that emission studies of organic agriculture may not reveal the potential benefits of regenerative agriculture.
Instead, the potential for a redesign of New Zealand’s style of pastoral dairy farming around regenerative principles provides a useful example of how progress might work. Pastures could shift from ryegrass and clover to a more diverse, more deeply rooted mix of alternate species such as chicory, plantains, lupins and other grasses. This system change would have three main benefits.
The first big win in farming is always enhanced production, and this is possible by better matching the ideal diet for cows. High performance ryegrass-clover pastures contain too little energy and too much protein. Diverse pastures fix this, allowing potential increases in production.
A second benefit will result when protein content of pasture doesn’t exceed what cows need to produce milk, reducing or diluting the nitrogen concentrated in the urine patches that are a main source of nitrous oxide emissions and impacts on water.
A third set of gains can result if the new, more diverse pastures are better at capturing and storing nutrients in soil, usually through deeper and more vigorous root growth. These three gains interrelate and create options for redesign of the farm system. This is best done by farmers, although models may help put the three pieces together into a win-win-win.
Whether you’re interested in local beef in Virginia, or the future of New Zealand’s dairy industry, the principles that define regenerative agriculture look promising for redesigning farming to reduce emissions. They may prove simpler than agriculture’s wider search for new ways of reducing greenhouse gas emissions, including genetically engineering ryegrass.
In wealthy societies we’ve become increasingly picky about what we eat. The “wrong” fruits and vegetables, the “wrong” animal parts, and the “wrong” animals inspire varying degrees of “yuck”.
Our repugnance at fruit and vegetables that fail to meet unblemished ideals means up to half of all produce is thrown away. Our distaste at anything other than certain choice cuts from certain animals means the same thing with cows and other livestock slaughtered for food. As for eating things like insects – perfectly good in some cultures – forget about it.
We set out to answer this by getting a better grip on how disgust works, focusing on disgust in everyday food choices, rather than aversions to the unknown or unfamiliar.
Our research suggests some disgust responses, once set early in childhood, are hard to shift.
But responses involving culturally conditioned ideas of what is “natural” may be modified over time.
Don’t eat that!
Disgust likely began as a powerful “basic” emotional reaction that evolved to steer us away from (and literally eject) potential contaminants – food that smelled and tasted bad. You can think of it as originally being a “don’t eat that” emotion.
The disgust system tends to be “conservative” – rejecting valid sources of possible nutrition that have characteristics implying they might be risky, and guiding us towards food choices that are ostensibly safer. Research by University of British Columbia psychologist Mark Schaller and colleagues suggests people who live in areas with historically high rates of disease not only have stricter food preparation rules but more “conservative” cultural traditions generally.
Is is unclear exactly how or when individual templates for what is disgusting are set, but generally what is seen as “disgusting” is set relatively early in life. Culture, learning and development all help shape disgust.
It’s just not natural!
In our study, we showed 510 adults pairs of “normal” and “alternative” products via an online survey, and asked them how much they would be willing to pay for the alternatives. We also asked them to rate which product was tastier, healthier, more natural, visually appealing and nutritious. Product pairs included:
shiny and typically shaped fruits and vegetables vs knobbly, blotchy, gnarled and multi-limbed examples.
plant protein foods vs insect-based foods
standard drinks vs drinks with ingredients reclaimed from sewage
standard medicines vs medicines with ingredients extracted from sewage.
Our results show that, even after statistically adjusting for obvious factors like pro-environmental attitudes, those with a greater “disgust propensity” are less willing to consume atypical (weird-looking) products.
This may seem rather obvious but most prior studies have muddled a food’s “novelty” with its possible disgusting properties (by asking people, for example, whether they’d eat bugs). By asking about really common fruits and vegetables, our study shows just how far disgust may reach in influencing what we consume.
As importantly, our results suggest evaluations of a product’s perceived naturalness, taste, health risk, and visual appeal “explains” about half of the disgust effect.
In particular, lack of perceived “naturalness” was a frequently reason for unwillingness to pay for product alternatives. This result was in line with previous studies that have looked attitudes to eating insects or lab-grown meat. This is a promising area for social marketing.
Given evidence about how much of what we consider disgusting is cultural and learned, marketing campaigns could help shift attitudes about what is “natural”. It has been done before. Consider this advertisement to naturalise sugar consumption.
Thinking differently about emotion-eliciting stimuli is termed “reappraisal”. Reappraisal has been shown to reduce disgust effects among those with obsessive compulsive disorder. Desensitisation (repeated exposures) seems less effective in reducing disgust (versus fear) among people with diagnosed phobias, but it may work better among the general population.
Of course, such speculations remain untested and their ultimate success remains unclear.
But it wasn’t so long ago that Western consumers turned their noses up at fermented foods, and the notion of “friendly bacteria” made as much sense as “friendly fire”. More than a decade ago the residents of a drought-stricken Australian town voted against recycling sewage for drinking water. Now the residents of an Australian city accept recycled sewage being pumped back into the city’s groundwater.
Given time, circumstance and a little nudging, a future meal at your favourite Thai restaurant may well involve ordering a plate of insects.
But more importantly for the koala, the nose is an important connection between this iconic marsupial and the world it lives in, from sniffing out toxins to saying hello.
And it starts right at birth. The tiny newborn koala, despite weighing only half a gram, already has the ability to smell and feel its way towards the milky scent of the pouch and its mother’s teats.
A koala’s nose knows how to sniff out toxins
Koalas, famously, spend most of their time sleeping or resting. When they’re not sleeping or resting, they are mostly feeding or moving between trees. In both of these activities – or in other words, for most of their waking hours – they follow their nose.
Koalas nearly always smell their food carefully before eating. So many koala experts were surprised to learn recently that koalas don’t have particularly many genes for olfactory receptors – the receptors found on nerve cells in the nasal cavity for detecting different smells.
This matches up with anatomical observations that also suggest that among marsupials, the koala’s sense of smell is probably relatively poor, partly as a result of features associated with conserving water.
Gum leaves are chock full of natural plant toxins and other unpleasant chemicals, and koalas choose trees that minimise their exposure to the worst of these.
But most of the toxins that influence koala feeding are not volatile – they have no smell. It falls to the koala’s sense of taste (and genes for taste receptors are especially abundant in the koala genome) to make a final decision on whether a leaf is safe to eat.
Fortunately for the koala, the only-slightly-toxic compounds called terpenes (the invigorating scent of Eucalyptus oil) are highly volatile and offer a useful cue to the levels of other toxins in a leaf.
And one advantage of being a specialist feeder with a basic diet, is that there are relatively few odour cues to learn. It’s also fortunate the leaves koalas are checking out are right in front of their noses!
The koala’s nose might not only smell plant toxins, it may also play a minor role in detoxifying them.
We know enzymes in our own noses can detoxify certain drugs, and in other specialist herbivores, such as woodrats, many of the same enzymes that detoxify natural plant toxins and drugs in the liver are also expressed in the lining of the nose.
These enzymes likely help stop the nose from becoming overwhelmed by odours and maintain sensitivity. Critically, they also protect the central nervous system, as nasal tissue is the only thing separating inhaled toxins from the brain.
A koala’s nose knows how to make friends
Sniffing out food is important, but it’s not the koala’s biggest forte. So why the big schnoz? The answer may lie with the importance of social communication.
Although the koala genome has relatively few olfactory receptors, it’s rich in vomeronasal receptors, which are expressed in cells in the nasal cavity that are sensitive to moisture-borne molecules like pheromones.
Koalas are generally solitary creatures, but that’s not to say they don’t know their neighbours. Along with the distinctive loud bellowing of male koalas during the breeding season, olfactory communication is what koalas use to find or avoid each other.
Koalas of both sexes often spend considerable time smelling the base and trunk of a tree before they decide whether to climb up or move on elsewhere. When they enter or leave a tree, koalas commonly dribble a stream of urine down the trunk, leaving a trail of chemicals that potentially reveal information about the koala’s sex, identity, dominance, relatedness to other koalas, readiness to mate, disease status and even what they’ve been eating.
But if koala urine is a book written in scent, the secretions of the male koala’s sternal gland are more like a barcode.
This gland is obvious as a yellow-brown stained patch of bare skin in the middle of male koalas’ chests, and offers a straightforward way to tell the sexes apart.
It secretes an oily mixture of fatty acids and other chemicals, which are then transformed into an even more complex chemical mixture by the unique bacterial community occupying each koala’s gland. The end result is a distinctive bouquet and an unmistakable badge of identity for each koala.
Nose kisses from a koala
Aside from these fascinating nasal abilities, there is one more thing that we love about the koala’s nose.
When wild koalas are brought into captivity, they continue to rely on their nose to learn about the strange new world around them – that includes their food and branches, but also the scientists and carers moving around them.
If we’re serious about feeding the world’s growing population healthy food, and not ruining the planet, we need to get used to a new style of eating. This includes cutting our Western meat and sugar intakes by around 50%, and doubling the amount of nuts, fruits, vegetables and legumes we consume.
These are the findings our the EAT-Lancet Commission, released today. The Commission brought together 37 leading experts in nutrition, agriculture, ecology, political sciences and environmental sustainability, from 16 countries.
Over two years, we mapped the links between food, health and the environment and formulated global targets for healthy diets and sustainable food production. This includes five specific strategies to achieve them through global cooperation.
Right now, we produce, ship, eat and waste food in a way that is a lose-lose for both people and planet – but we can flip this trend.
What’s going wrong with our food supply?
Almost one billion people lack sufficient food, yet more than two billion suffer from obesity and food-related diseases such as diabetes and heart disease.
The foods causing these health epidemics – combined with the way we produce our food – are pushing our planet to the brink.
One-third of the greenhouse gas emissions that drive climate change come from food production. Our global food system leads to extensive deforestation and species extinction, while depleting our oceans, and fresh water resources.
To make matters worse, we lose or throw away around one-third of all food produced. That’s enough to feed the world’s hungry four times over, every year.
At the same time, our food systems are at risk due to environmental degradation and climate change. These food systems are essential to providing the diverse, high-quality foods we all consume every day.
A radical new approach
To improve the health of people and the planet, we’ve developed a “planetary health diet” which is globally applicable – irrespective of your geographic, economic or cultural background – and locally adaptable.
The diet is a “flexitarian” approach to eating. It’s largely composed of vegetables and fruits, wholegrains, legumes, nuts and unsaturated oils. It includes high-quality meat, dairy and sugar, but in quantities far lower than are consumed in many wealthier societies.
The planetary health diet consists of:
vegetables and fruit (550g per day per day)
wholegrains (230 grams per day)
dairy products such as milk and cheese (250g per day)
protein sourced from plants, such as lentils, peas, nuts and soy foods (100 grams per day)
small quantities of fish (28 grams per day), chicken (25 grams per day) and red meat (14 grams per day)
eggs (1.5 per week)
small quantities of fats (50g per day) and sugar (30g per day).
Of course, some populations don’t get nearly enough animal-source foods necessary for growth, cognitive development and optimal nutrition. Food systems in these regions need to improve access to healthy, high-quality diets for all.
The shift is radical but achievable – and is possible without any expansion in land use for agriculture. Such a shift will also see us reduce the amount of water used during production, while reducing nitrogen and phosphorous usage and runoff. This is critical to safeguarding land and ocean resources.
By 2040, our food systems should begin soaking up greenhouse emissions – rather than being a net emitter. Carbon dioxide emissions must be down to zero, while methane and nitrous oxide emissions be kept in close check.
How to get there
The commission outlines five implementable strategies for a food transformation:
1. Make healthy diets the new normal – leaving no-one behind
Shift the world to healthy, tasty and sustainable diets by investing in better public health information and implementing supportive policies. Start with kids – much can happen by changing school meals to form healthy and sustainable habits, early on.
Unhealthy food outlets and their marketing must be restricted. Informal markets and street vendors should also be encouraged to sell healthier and more sustainable food.
Realign food system priorities for people and planet so agriculture becomes a leading contributor to sustainable development rather than the largest driver of environmental change. Examples include:
incorporating organic farm waste into soils
drastically reducing tillage where soil is turned and churned to prepare for growing crops
investing more in agroforestry, where trees or shrubs are grown around or among crops or pastureland to increase biodiversity and reduce erosion
producing a more diverse range of foods in circular farming systems that protect and enhance biodiversity, rather than farming single crops or livestock.
The measure of success in this area is that agriculture one day becomes a carbon sink, absorbing carbon dioxide from the atmosphere.
3. Produce more of the right food, from less
Move away from producing “more” food towards producing “better food”.
This means using sustainable “agroecological” practices and emerging technologies, such as applying micro doses of fertiliser via GPS-guided tractors, or improving drip irrigation and using drought-resistant food sources to get more “crop per drop” of water.
In animal production, reformulating feed to make it more nutritious would allow us to reduce the amount of grain and therefore land needed for food. Feed additives such as algae are also being developed. Tests show these can reduce methane emissions by up to 30%.
We also need to redirect subsidies and other incentives to currently under-produced crops that underpin healthy diets – notably, fruits, vegetables and nuts – rather than crops whose overconsumption drives poor health.
4. Safeguard our land and oceans
There is essentially no additional land to spare for further agricultural expansion. Degraded land must be restored or reforested. Specific strategies for curbing biodiversity loss include keeping half of the current global land area for nature, while sharing space on cultivated lands.
The same applies for our oceans. We need to protect the marine ecosystems fisheries depend on. Fish stocks must be kept at sustainable levels, while aquaculture – which currently provides more than 40% of all fish consumed – must incorporate “circular production”. This includes strategies such as sourcing protein-rich feeds from insects grown on food waste.
5. Radically reduce food losses and waste
We need to more than halve our food losses and waste.
Poor harvest scheduling, careless handling of produce and inadequate cooling and storage are some of the reasons why food is lost. Similarly, consumers must start throwing less food away. This means being more conscious about portions, better consumer understanding of “best before” and “use by” labels, and embracing the opportunities that lie in leftovers.
Circular food systems that innovate new ways to reduce or eliminate waste through reuse will also play a significant role and will additionally open new business opportunities.
For significant transformation to happen, all levels of society must be engaged, from individual consumers to policymakers and everybody along the food supply chain. These changes will not happen overnight, and they are not the responsibility of a handful of stakeholders. When it comes to food and sustainability, we are all at the decision dining table.
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.
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.
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%.
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.
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.
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.
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.