POINTS OF VIEW
Biodiversity & security
Biodiversity decline is not just an environmental issue. It has much wider implications, particularly when combined with population growth. By the middle of this century, there will be a projected ten billion people19 on Earth. This means increased pressure on natural resources such as food and water, an increase in risks to human health, and higher levels of migration as people seek healthier, more prosperous lives elsewhere. Researcher and author Dr. Jean-Michel Valantin and IRRI researcher Professor Rod Wing speak about biodiversity loss, the risks for humanity and the need to shift to more sustainable food production.
In terms of food production, where do you see the main threats to our agricultural systems?
Dr. Jean-Michel Valantin
The main pressure today on agriculture comes from a combination of factors: climate change, population growth and pollution, all putting pressure on the soil. Our soil is getting poorer while it contains 80% of the biodiversity on land. For the moment, crops are still growing but what will happen when the soil becomes too dry or too poor because of rising temperatures and more extreme weather? Furthermore, there are cascade effects between the land and sea biodiversity pressures. For example, the American Midwest has seen historic flooding this year. As a result, nutrients from fertilizers wash into the Gulf of Mexico where they cause algal blooms that absorb oxygen and create a ‘dead zone’, that is to say an area where the level of oxygen has become so low, because of excessive nutrient pollution, that it cannot support marine life such as plankton or fish anymore. However, climate related pressures take place everywhere, not just the Midwest. We had a severe drought in 2018 in Australia; and there have also been heatwaves in recent years in Europe and in the United States.
Could this affect food production and food security?
Dr. J.-M. V.
Yes, this can result in food production issues, in higher prices and, ultimately, social unrest. In 2011, some Arab countries saw a spike in bread prices as a result of poor harvests following the heatwaves in Russia and Ukraine. That triggered the ‘Arab Spring’. In Tunisia, the very first demonstration was about bread and the same thing happened in Syria. There is a clear connection between food prices and social stability. Can you imagine if this happened in China, a country of 1.4 billion people? Given the size of the country, food tensions could be enough to trigger global effects.
Overall, is there evidence that natural resources are becoming scarcer?
Dr. J.-M. V.
Around the world, we are seeing more competition for resources. Fishing fleets in the South China sea are being militarized. Resources are under pressure because of overfishing, pollution, acidification, the proliferation of dead zones. There are more people in the region competing for diminishing resources. For example, in the early 2000’s, Somalia was torn apart by civil war and drought, the state collapsed, trawlers came in to Somali waters from countries like Egypt, Iran and Spain and overfished, and Somali fishermen saw their own resources disappearing, so they bought weapons and attacked the trawlers. Because of scarcity, Somali fishermen became Somali pirates. Ship owners were forced to hire private security, an international military task force was created, insurance became very expensive and the cost of crossing the Gulf of Aden spiked.
Have we seen much reaction from governments to this shortage of natural resources?
Dr. J.-M. V.
One example is what happened in 2005 after a heatwave in southern China that seriously affected rice production. The Chinese government became more aware of food security. Part of their response has been to buy or rent arable land all over the world – in Argentina, for example. That could create new kinds of international tensions. We live in very interconnected societies, which can make us more vulnerable to environmental challenges
We are witnessing increased pressure on food supplies – is that a result of population growth?
Pr. Rod Wing
Our planet will have 2.5 to 3 billion additional people by 2050. That is a massive increase. As a consequence, we need to learn how to grow higher-yielding crops on more marginal land. Rice is one of the world’s most important food crops, if not the most important: it feeds the poorest of the poor. One of the most significant challenges of our lifetime has become to feed our world without destroying our environment. The fact is, we have to grow these crops sustainably. In the case of rice production, one course of action is to build the next generation of supercrops – ‘green super rice’ – basically, rice that can be grown with less water, less pesticide use, with higher yields and a lower environmental footprint. What is not widely known is that rice is a major contributor to methane emissions, a powerful greenhouse gas contributing to climate change, which makes the need for this green supercrop even more urgent
What is the role of research? Can we find a technical solution?
Pr. R.W.
At IRRI, we are working on gene sequencing, and isolating the ‘sustainable’ genes – the genes that make wild rice more resilient, better able to withstand heat or drought, for example. The idea would be to transfer these genes into cultivated rice. There are only two types of cultivated rice: the first was cultivated in China 10,000 years ago, the second, separately, in Africa, 7,000 years later. One wild species we are working with is Oryza coarctata, which can grow in salt water. Given rising sea levels, we are now trying to understand more about this species’ salt-loving genes. Ultimately, this will allow us to add more genetic diversity to the mega varieties that are grown around the world. Another option would be to domesticate Oryza coarctata, and to bring it into managed production.
There are millions of rice farmers around the world – what can they do?
Pr. R.W.
Most rice farmers are small-scale. About 80% of farmers worldwide sustain themselves and grow just enough food to survive. Not all farming practices and technologies are accessible to them although yields can be increased just by laser-levelling a field21. It is simple, but not all farmers have access to this technology, which takes a lot of training, education and outreach. That is also one of IRRI’s missions. We are building up gene banks with a total of around 700,000 types, or ‘accessions’, of Oryza sativa – the Asian cultivated rice – in China, India and at IRRI in the Philippines. We want to build IRRI’s digital gene bank so we can use the information to accelerate breeding of more resilient, more sustainable varieties.
+49%
In 2017, there were 258 million migrants worldwide, up from 173 million in 200020. According to the latest figures, refugees and asylum seekers make up just over 10% of all migrants
Source: UN International Migration Report, 2017
30%
Marine resources in the South China Sea have been fished down to between 5% and 30% compared with 1950s levels.
Source: University of British Columbia (Boom or Bust – The Future of Fish in the South China Sea), 2015
3.5 billion
Rice is an essential component of the diets and livelihoods of over 3.5 billion people..
Source: Nature Reviews Genetics: The rice genome revolution: from an ancient grain to Green Super Rice (Rod A. Wing, Michael D. Purugganan and Qifa Zhang), 2018
POINTS OF VIEW
Biodiversity & security
To further understand what is at stake in terms of biodiversity, security and potential solutions, we spoke to researchers working on the decline of pollinator populations, the impact of legacy pollutants from mining, and the over-use of fertilizers on our farms.
We are seeing a significant decline in populations of bees and other pollinators. What is happening?
Dr. Coline Jaworski
i It varies by species and by location. In Europe, one type of bee – the bumble bee – is doing very well overall, while the decline in bee populations in the United States is more serious. There are already noticeable effects on crop production which may be due to a combination of factors: more intensive farming practices, including the use of pesticides, climate change, or the fragmentation of habitats.
Is climate change an important factor?
Dr. C. J.
Climate change means plants will flower at different times, and that disrupts pollinators. It also means drier conditions, which leads to fewer plants and flowers. If plants are stressed, they produce less pollen and less nectar, which, in turn, means less food for pollinators. It also affects the color, size and scent of flowers. When looking for food, pollinators rely on floral scent. Recent research shows that when there is too much ozone, which happens often in the south of France, for example, pollinators cannot smell flowers properly anymore and are completely lost.
How resilient are pollinator populations? Can they adapt to these changes?
Dr. C.J.
Adapting to a change in floral scent may happen quite quickly, a matter of weeks. For a species to change geographical distribution takes much more time – years or decades. Some species will not be able to do this – they have very restricted areas: if a pollinator is dependent on a specific plant species, and this plant species does not move, then a pollinator cannot follow. They are stuck in a particular area – these are the pollinators the most at risk of extinction.
What happens if we do not tackle this problem?
Dr. C.J.
It is very location dependent. Some regions become unsuitable for agriculture because of a combination of climate change, the degradation of our ecosystems and biodiversity decline. Other regions might do well in terms of crop production, but incur other problems such as encouraging invasive species, especially pests.
This has serious implications for crop production…
Dr. C.J.
In the United States, we have seen crop yields go down. Apple and strawberry production now relies on farmers moving in bee hives. This is not yet the case in Europe. However, moving bees is not a sustainable solution since we have seen bee hives collapse because of disease linked to being moved. To limit the decline in pollinator numbers, we need to protect natural ecosystems – there is no other way around it. Interestingly, there are studies showing that pollinator populations are healthier in European cities than in the surrounding countryside. There are more flowers in cities, in private gardens and so on. In agricultural areas, some flowers have been wiped out, with smaller field margins and fewer wild habitats and forest areas. Most European cities have adopted pesticide-free zones, and we know pesticides can have a dramatic effect on insects. We need to reintroduce more flowers into the countryside in terms of both quality and diversity. Flowers are needed all year long and need to be diverse enough to support a variety of pollinator populations.
… and farmers need to consider changing their practices.
Dr. C.J.
Farmers are more aware now of the risks of pesticide use. One option is to allow more weeds; many weeds are flowering plants. It is not easy and it may mean a decline in yields because there is competition between crops and weeds. We also need strong scientific arguments to make the case as well as modelling and quantifying to show how much more sustainable this would be over the long term. Providing financial incentives to farmers to encourage them to maintain sustainable, healthy lands is another possibility.
1,220 tonnes
Artisanal and other small-scale mining released more than 1,200 tonnes of mercury into terrestrial and freshwater environments in 2015.
Source: UN Environment Programme (Global Mercury Assessment, 2018)
75%
More than three-quarters of global food crop types depend on pollinators, including fruit and vegetables and important cash crops like coffee, cocoa and almonds.
Source: IPBES (2019)
You have studied pollutants from historic mining sites – it seems that many pollutants remain hundreds of years after mines have closed.
Dr. Sophia Hansson
These are mainly heavy metals like lead and mercury – more often than not a by-product of mining. With gold mining, mercury is added to help purify the gold, which means a lot of mercury is released in the areas around these sites. It is a technique that has been around for a very long time; it is efficient, but it is also highly dangerous since it releases a lot of mercury into the environment. Recent work in Sweden showed that concentrations of mercury in the lake and the sediment increased almost a thousand-fold during the time the mine was in operation. Centuries later, this concentration has still not returned to its natural background level.
And these elements remain in the environment?
Dr. S.H.
The problem with lead and mercury is that they do not degrade. On a site that was active 500 years ago, lead is still just as toxic today. In fact, in the case of mercury, it can become more dangerous over time as mercury may become methylmercury22, which is very toxic. It can enter the bloodstream and from there get into the muscles, the brain and the nervous system, potentially causing a serious threat to health.
How do these pollutants end up in the water supply or the food chain?
Dr. S.H.
At mine sites, waste – rocks and tailings – erodes and the metals then slowly leach into the soil, then into the groundwater, and eventually reach lakes, rivers and, potentially, the ocean. The main exposure then occurs through drinking water and food products – fish and other seafood. Climate change increases the risks. In mountainous environments, for instance, very dry spells dry up the soil, which starts to crack and becomes less stable, especially if there is also less vegetation to hold the soil in place. When the rain finally comes, the soil may be flushed away from the mountain slopes, bringing old pollutants with it, and potentially affecting villages downstream from the original mine site. In 2013, in the Pyrenees, a mountain range extending along the border between France and Spain, a lot of material was washed into the streams and rivers – too much, too quickly.
It knocked out water supply to nearby villages because the water could not be cleaned quickly enough. The Pyrenees is an area where there is no industry today and you would think it should be pristine, but the majority of lead in the fish from the Pyrenees lakes comes from old mining activities – even though those mines closed down over a hundred years ago. It is still fine to eat the fish – we are not seeing dangerously high concentrations – but it is important that we understand how long these contaminants have been in the system. We have mine sites in the Pyrenees that go back a thousand years and we still see the impact in fish today.
What lessons are there for modern mining? Are we still putting these pollutants into the environment?
Dr. S.H.
We have more environmental regulations in place. Therefore, although the mining is occurring on a much larger scale, the environmental impact is smaller. Bigger mining companies – those that are well established and have sufficient funding – tend to follow the rules. Of more concern are the smaller mines, such as some of the artisanal mining that is occurring in South America and Africa, which are often illegal, and where there are no environmental controls at all. There, the pollution can be quite serious. Even if there is a small spill, it will stay – these metals will not just go away. The work we are doing on both old and modern mines shows the importance of regulations
What is the scale of the problem? Humankind has a long history of mining.
Dr. S.H.
It does. In Sweden and Greenland, you can still find lead from old Roman-era mining activities: metals were released into the air and travelled around the world. When it comes to legacy pollutants, the problem is that we do not know how much we are talking about overall. We performed a rough calculation and estimated that, for just the French side of the Pyrenees, there are at least 600 tonnes of lead stored in the soil. The first step is to build a risk assessment map: what stocks we are talking about, how mobile they are, how far into the food chain they have moved and what risks that entails for humans. The knowledge we develop for the Pyrenees can then be applied to historic mine sites elsewhere.
Note on Nitrogen Cycle
Nitrogen forms the basis for compounds essential to living organisms (air contains just over 78% nitrogen). Bacteria in soil and in the roots of leguminous plants convert atmospheric nitrogen (N2) to ammonia (NH3); this process is known as nitrogen fixation. Nitrogen is then taken up by plants; animals consume these plants and return the nitrogen to the soil through their excreta and when they die; in the soil, the ammonia is converted first to nitrite (NO2), then to nitrate (NO3) (nitrification), before being converted back into molecular nitrogen in the atmosphere (denitrification). Nitrous oxide is produced as part of this denitrification. Reactive nitrogen refers to nitrogen compounds transformed in the cycle; they include compounds that support plant growth (ammonia, nitrate).
POINTS OF VIEW
Biodiversity & security
Over the years, we have dramatically increased our use of fertilizers. How is this changing our soils and our environment?
Pr. Graeme Nicol
If you look at the figures, we are now adding more nitrogen to the soil through artificial fertilizer than is added through natural processes. In effect, we are doubling the input of what is called reactive nitrogen into the world’s soil – which is really quite extraordinary. We are not necessarily changing the nitrogen cycle, in terms of its chemistry – we are accelerating it. Because we are putting in a lot more ammonia through fertilizer use, we are producing a lot more nitrous oxide, which is a greenhouse gas. Since pre-industrial times, the concentration of nitrous oxide in the atmosphere has gone up by nearly 20%, and that is due to human activity.
What about the world around us – biodiversity? What is the impact from these fertilizers?
Pr. G.N.
When you add ammonium to the soil, more than half usually gets converted to nitrate. Plants can take up nitrate of course, but the problem is that nitrate has a negative charge and so does soil, so there is no electrostatic mechanism for it to remain in the soil, which means it is easily washed out. The result is nitrate pollution. You have run-off into waterways and coastal areas. And where you have high rates of nitrogen, you get eutrophication – unnatural or atypical blooms of growth, like algal blooms. When this organic matter sinks and dies off you encourage other bacteria, which use up oxygen that reduces oxygen levels and that is when fish and other marine animals start dying.
How do we combat this? Can we reduce fertilizer use?
Pr. G.N.
It is not necessarily the use of fertilizers, per se, that is the problem. It is how we apply them. If you put in a large amount of fertilizer, such as ammonium nitrate or urea, bacteria react and produce nitrous oxide, and that is the problem. You could use a slow-release fertilizer – the longer it is retained in the soil, the more the plants will take up and the higher your nitrogen-use efficiency. Basically, we are trying to stop the bacteria having a big party. The other option is to use a standard fertilizer and apply a chemical compound that inhibits the bacteria, but that is not the most natural solution.
Are there other possibilities?
Pr. G.N.
We have BNI – biological nitrification inhibition. Some plants produce inhibitors naturally. These inhibit bacteria – to give themselves a better chance of taking up the ammonia that is produced from decay and mineralisation. People have been trying to promote the use of BNI. Currently, a lot of commercial breeding strategies assume high levels of fertilizer use, but in certain systems – in pasture for grazing animals for example – you can get grasses that have a much higher BNI activity, so when sheep and cows excrete you can slow the process. There are also archaea23 in the soil, which we have known about since 2005. We have shown that these archaea also oxidize ammonia, but in doing so they produce half the amount of nitrous oxide. The trouble is, when you add ammonium fertilizer, the archaea do not really use it, it is the bacteria that use it. So, if you are using a slow-release fertilizer, what you are doing, in effect, is preferentially selecting for the archaea – the bacteria will be outcompeted because bacteria need higher concentrations.
How do we apply this practically?
Dr. D.N.
We know that currently, 35% of all nitrous oxide emissions come from agricultural systems and that is what we need to control. In Europe, we have the EU Water Framework Directive, which is in place to control nitrate levels in water, as nitrate is toxic at certain levels. There are nitrate-vulnerable zones where there are restrictions on fertilizer use. If we can increase our knowledge of the micro-biology present in a particular soil – soils will vary from place to place – then you can decide which fertilizers to use, and when.
200 million
Fertilizer use worldwide now exceeds 200 million tonnes – a more than seven-fold increase since 1960.
Source: FAO and International Food Policy Research Institute, 2020
20 Figures include all international migrants (those currently living outside their country of birth), including refugees, asylum seekers, economic migrants etc.
21 Laser land levelling is used to level fields by removing soil from high points of a field and depositing it at low points. The technology enables crops to mature uniformly, improves yields and reduces greenhouse gas emissions by saving energy, reducing cultivation time and increasing efficiency of fertilizer use.
22 Methylmercury is formed from inorganic mercury through the action of bacteria and other microbes in various environments, including lakes, rivers, wetlands, sediments, soil etc. If consumed in sufficient quantities, methylmercury has serious consequences for human health, particularly among children and pregnant women.
23 Archaea are microorganisms similar to bacteria in size, but radically different in molecular organization.
