How the Food System Threatens the Environment
So we have a big problem. The problem is how to grow enough food and the right kind of food for a healthy and growing population. And we’ve seen that the problem’s going to get tougher as the population grows. And as the environmental threats multiply in the coming years. But the problem’s even more complicated. And that is that agriculture itself is one of the major causes of environmental threat.
The agricultural sector is the single most important sector from the point of view of human-induced climate change, and other environmental damages to the planet. I always find this a little bit counterintuitive. I think the automobile age, that must be the big, damage to the environment the energy system and fossil fuels. Of course those are huge factors in climate change and in environmental costs. But if we look at a particular sector of the economy we come back to the original one, to food production itself. And to agriculture more generally as the key human activity that puts the most pressures on the planet. What kinds of pressures? I think it’s worth mentioning quickly, before delving more deeply into three of them, the range of pressures that the agricultural system and farm practices put on the planet. First is greenhouse gasses.
We’ll turn to this in some detail, but the farm sector is a major emitter of the three main greenhouse gasses; carbon dioxide, methane, and nitrous oxide. And this by itself means that farm practices need to be rethought as we desperately need to move to a low carbon and a low greenhouse gas emission world.
The second major impact Is through something very rarely discussed in in in the, the public but of increasing concern among specialists and that is on the nitrogen cycle. There’s a natural nitrogen cycle our atmosphere is 79% nitrogen in the form of N2. That kind of nitrogen is inert odorless without taste and not very useful, actually, for us. But nitrogen in it’s reactive forms of nitrates and nitrites and ammonia and ammonium, ion, and, its other reactive forms is absolutely vital for us and for all the rest of, living, species. Because nitrogen’s the backbone of amino acids and of proteins, it’s absolutely core to our metabolism, and to every aspect of our lives, including the ability to grow food. It’s for that reason we put a lot of nitrogen on the soil in the form of nitrogen-based fertilizers, to help feed the nutrients to our crops so that our crops feed us. But the damage of that human intervention into a natural nitrogen cycle is enormous. We’ll look at that in just a moment.
A third major way that the farm system impacts on the planet is the destruction of habitat for other species. Not entirely surprising when we consider that 40% of the total land area of the planet is agricultural land whether the arable land or the meadows and pasturelands. Humanity’s already grabbed so much of the land area for us, but it’s grabbing more, especially in the form of deforestation, and the rain forests that are at risk right now are places of incredible and irreplaceable biodiversity. And so one of the major ways that the earth is vulnerable to the sixth rate extinction wave that we have already discussed is through the tropical rain forest deforestation, which is part of the ongoing process of clearing lands for arable and for pasture land.
There are many other ways, which I’ve mentioned, where the environment is at threat from farming activity. The pesticides, the herbicides, the other chemicals that are used in farm production are a major threat to biodiversity. And especially the massive amounts of water that are used, around 70% of the total human use of fresh water goes through agriculture with only 10% going through household use and the remaining 20% or so for industrial processes. Agriculture is a voracious user of water and that water, itself, is under threat. So, for all of these reasons, the agriculture sector Is a key driver of anthropogenic environmental loss, and we’re going to need to change technologies and processes and patterns of land use to make the food system compatible with a sustainable planet. Let’s have a look at the first of those three drivers that I discussed. Climate change, nitrogen cycle, and land use where I want to look more deeply at the role of agriculture.
This pie chart shows us the estimated total amount of greenhouse gases that are emitted, allocated across the various sectors of the economy. The power sector for example, through the burning of coal, oil and gas, is responsible for a massive amount of CO2 emissions, and for an estimated 24%, roughly a quarter of the total greenhouse gas emissions.
The transport sector, the internal combustion engine in the cars and in the trucks, is responsible for an estimated 14% of total emissions. Industrial processes, for example, steel production or petrochemical production, another one-seventh or 14% of total greenhouse gas emissions. The non-energy sphere is responsible for around one-third of the total greenhouse gas emissions. That is CO2 emissions, methane, nitrous oxide, and chemical pollutants from specific chemicals like hydrofluorocarbons that are not the emissions from the combustion of fossil fuels. Within that category, agriculture plays a huge role. Of course, agriculture emits greenhouse gases in the transport sector in tractors and in transport of food. It emits greenhouse gases in the industrial sector for the production of chemical fertilizers. But there’s a massive amount of greenhouse gas emissions that is not directly from fossil fuels at all. This includes for example, the emissions that come from clearing forests. As the trees are chopped down, as they are burned, as they decay, CO2 that was sequestered in the forests are emitted into the atmosphere. And several billion tons every year of CO2 come from deforestation. Agriculture also is a major source, as I mentioned earlier, of the second and third ranking greenhouse gases. Methane, CH4, is emitted in certain crop productions such as paddy rice. And it’s also emitted through livestock, through the ruminants who through the natural processes of their digestion give rise to quite a lot of methane emissions, both from the front and the back of the animals, I should mention. And this also contributes to the increasing concentration of methane in the atmosphere, a very powerful greenhouse gas. Nitrous oxide, N2O, is also emitted from agriculture. It is one of the ways that nitrogen-based fertilizers degrade.
Instead of being taken up by the plants, they volatilize, go into the atmosphere, they go into the the water supply. And one of these parts of the nitrogen cycle is from, the livestock and from the fertilizer use, into increased emissions of nitrous oxide. And this also adds to the total amount of greenhouse gases that agriculture contributes to the overall process. When you look at it, more than one third of total emissions are due to land use change such as deforestation, and the direct emissions of greenhouse gasses from agricultural production.
It’s astounding. Roughly one third of total greenhouse gases directly come from the agriculture sector, and there are bits and pieces more through the fertilizer manufacturing and through the direct expenditure of fossil fuel based energy as inputs to agriculture on top of that one third. So we see that indeed the agriculture sector is a major contributor to greenhouse gases, and to climate change. As well as the first sector to lose from this. This is a terrible two-way problem that needs to be addressed through improved agricultural processes, as I’ll be discussing shortly. Let me turn to the nitrogen cycle. The nitrogen cycle vital for life has been overtaken by humanity. Absolutely extraordinary. In nature the N2 molecules in the atmosphere are converted into reactive nitrogen through various biological processes of nitrogen-fixing bacteria, as well as through physical processes, of lightning, for example, that breaks the very strong triple bond of the N2 molecule and by disassociating the N2 molecule, leads to the formation of ammonia and other reactive nitrogen. In that normal process the cycle from N2, to reactive nitrogen compounds like nitrates, nitrites and ammonia, and then back through respiration uh,and through through biological processes to back to N2 is a natural nitrogen cycle. But humanity is now creating even more reactive nitrogen than nature itself. We’re doing it in our industrial plants at a mega scale, 100 million tons or more per year of nitrogen-based fertilizers. Back in the early years of the 20th century, two great chemical engineers, Haber and Bosch, developed a process that some consider to be the single most important innovation of the 20th century, one that almost none of us has heard of, in fact, but changed the world. The Haber-Bosch Process, so called, is a way, through application of high amounts of energy and the use of various identified catalysts, to break that N2 bond to create in a chemical process in, in a factory basis, ammonia. And that ammonia can then be used to provide the base stock for urea and other nitrogen-based fertilizers. Up until the Haber-Bosch Process, the nitrogen that was deposited on the soils either came from the manures of farm animals or it came from the mining of excrement off the coast of Peru and Chile of bats and birds, the so-called guano which was being mined as a nitrogen source for fertilizer for Europe. But it was being quickly depleted.
And there was a crisis at the end of the 19th century, what are we going to do with the encroaching nitrogen scarcity? Along came Haber and Bosch, the Haber-Bosch Process, nitrogen-based fertilizer. And what was then a world population of under two billion became during the twentieth century a population of more than three times that, and now reaching 7.2 billion people. And it was the advent of nitrogen-based fertilizer, among other things and including, of course, the high-yield seed varieties and other agronomic advances, that made it possible to produce enough food to support 7.2 billion people, even if, I must add, a large number of them, 3 billion, are not well-nourished on that food supply. But, with all that nitrogen now being converted from N2 into reactive nitrogen, we have a mega problem.
And the mega-problem is shown in this complicated flow chart of what happens to that nitrogen when it is used in the farms and then it runs off. In some ways, it enters the water supplies, nitrates, causing a danger to the water supply. Some of it runs into the rivers and the sea and we’ve already seen how that leads to algal blooms and nutrification. some of it enters the atmosphere, no
t as N2O, but as NO2, which causes smog in our cities. And so from the fertilizer deposit come a host of problems. There’s addition to greenhouse gases. There is acidification of soils by the nitrogen that is put into the soils. There is the worsening water quality that comes from the nitrates and the nitrites running into the water supply. There is the damage to ecosystems of eutrophication of the estuaries. There’s the fall of air quality as the noxes, the NO2s, NO3s, and other, effects of the nitrogen enter the urban atmosphere to create smog, to create tropospheric ozone, and to create massive health hazards, in our cities. So here is a, a dilemma, that is a mega dilemma, and hardly discussed in our day to day life. We need the nitrogen for our food production, and yet the consequences of the nitrogen on the physical environment in multiple ways, from climate change to eutrophication to urban smog to poisoning of our water supplies, is growing. This map comes from a study showing estuaries around the world suffering from eutrophication, from nitrogen and phosphorous based fertilizers. A huge problem, these are the dead zones in our coastal areas, killing vital parts of the marine ecology. And the problem is growing and it is likely to get worse unless we address how to use nitrogen in a more responsible way.
Third area that I wanted to mention in-depth is the forests. And just to point out that the forest loss that is occurring in all of the great rain forest regions, in the Amazon and the Congo Basin and, and in the Indonesian Archipelago have multiple drivers that differ across regions. In the Amazon most of the loss of the rain forests has come through the clearing of the rain forest to make way for new pasture land and new farm land, or because of the building of infrastructure such as roads in the Amazon. In southeast Asia where there’s also a large loss, the drivers are somewhat different. The drivers there are logging for tropical hardwoods in huge demand for China’s booming economy, and also for clearing the rainforest to grow tree crop plantations, of which the fastest growing, taking over large areas in Indonesia and Malaysia, is palm oil. In Africa there is yet another driver and that is peasant small holder agriculture. Not clearing especially for tropical logging or for tree plantations or even for large pasture land, but just the spread of small holder farmers into the forest margin. And often a huge use of the forests, and an unsustainable use for fuel wood and for charcoal. In the wealthier regions of the Amazon in Brazil, and in in Southeast Asia, the fuel wood problem is not as severe because there are alternative energy sources. But in the Congo Basin for example, and in other forest areas of Africa where populations are very, very poor and where alternative fuel sources such as natural gas or or electricity are not available, charcoal is used in such large amounts that that is a key driver of the deforestation and a key driver of the loss of habitat. Clearly in each of these areas, in order to preserve habitat, protect biodiversity, reduce the greenhouse gas emission consequences of deforestation, actions are going to need to be introduced that are responsive to the particular challenges in those areas, and the particular needs of the local populations. This will play an enormously important roll in helping to reduce the rate of uh,climate change, but also will be absolutely vital if we are to succeed in heading off the massive loss of biodiversity