Arquivo de etiquetas: Ameaças Ambientais

Sustainable Food Supply and the End of Hunger III

How Environmental Change Threatens the Food System

So we have a problem. Here we are in the 21st century. And still around 40% of the world’s population is malnourished. And around 30% of the worlds population is undernourished, either in open flagrant hunger, nearly billion people, or another billion in addition to those also suffering from hidden hunger of micronutrient deficiencies. Farm systems everywhere are already under stress. Unable to provide the healthy diets and nutrition in economical way, to meet the needs of the world’s population. But, there are some big challenges ahead that are going to make all of these problems even tougher than they are now. The most direct of these challenges is the fact that the world’s population continues to grow and continues to grow relatively rapidly, even if not in percentage terms, in absolute terms. Every year another 75 to 80 million people add it to the world population. By 2025 we’ll reach eight billion people. By the early 2040s, nine billion people. And on the current medium forecast of The United Nations we’ve seen, almost 11 billion people by 2100. At the same time that we’ll be grappling with the challenge of feeding more and more people.

1031The current food supply, which is already putting so much stress on the world’s environment is also going to be stressed by another couple of features. One is that for those parts of the world getting richer. The tendency and we, we hope it’s a large part of the world I, I should quickly emphasize. The tendency will be to add more meat to the diet, even too much meat. Too much meat for for human health and well-being. But as meat is added to the diet that is a kind of amplifier of the demand for grain production, because for animals like cows and pigs which give us our beef and pork. For every kilogram of beef that we consume, there have been around 10, and in some farm systems, up to 15 kilograms of feed grain consumed by the cow to produce the 1 kilogram of beef. So there’s a huge amplifier as diets shift to meat in terms of the underlying demand for feed grains on the planet, and therefore for the total demand on the agricultural system. There’s a second major reason however, in addition to that stress and that is environmental change is going to make it harder and harder to grow food in many places in the world. So much so that we can’t really know in detail but we have major cause for worry. I’d like to discuss those environmental challenges to the food supply to the prospects for the increased food production that will be needed to feed a growing world population. These environmental threats the risks come in many shapes and forms start with climate change, the biggest of all. As the climate changes under the force of human emissions of green house gases, we know that the changes in the climate. Are complex and for many parts of the world at least highly adverse for food production, of course the dominant form of climate change is warming, warming of the planet that is already nearly 1 degree centigrade above the pre-industrial average temperature. But could, on our current trajectory, reach several degrees centigrade warmer than the pre-industrial earth. Higher temperatures, in general, are going to be harmful for food production. But especially in the warmer regions of the world. And that means ironically, especially in the poorest parts of the world, crops face many kinds of temperature stresses. At high temperatures crops may not develop at all. Seeds may become infertile. At higher temperatures plant respiration means a net reduction of yields of farm crops. Higher temperatures mean faster evaporation of water in the soils and more transpiration of water through the stomata of the leaves of plants. Combining those two factors of the ecologists call that evapotranspiration, but it means that moisture and water on the earth returns to the atmosphere as water vapor at a faster rate threatening the plants with the inad, inadequate amount of water supply. So, climate change threatens the soil moistures. Threatens the productivity of crops as result. Climate change of course, means more than warming. We know, it means changes in precipitation patterns. Many parts of the world will become drier. And many dry parts of the world will find it extraordinarily difficult, perhaps impossible, to grow a crop. If the general principle that the dry places will tend to get drier and the wet places tend to get wetter is valid as a very rough summary of the effects of human induced climate change. We can see the trouble ahead because places that are in the margin of crop growing right now, may find themselves pushed right over the edge. Where the growing seasons are too short, the rainfall too small, the precipitation too erratic. To be able to support farming in places where there are large numbers of people, right now. We know the climate change also means rising sea levels. It means the places that are farmed right now in lowland areas near the coast will be threatened. Places like Bangladesh, which are built on the deltas of the the great rivers, the Brahmaputra and the Ganges it can be completely inundated. And not only will sea level rise essentially force, major loss of cropland in such areas. But it will also mean many more floods and storm surges of the kind the New York City felt when it was hit by Superstorm Sandy in the fall of, of 2012. Because the sea level had already increased by nearly a foot. Compared to the century earlier. So climate change, it’s got it all. And it’s causing tremendous dislocation already. But with a lot more to come. We’ve already talked about the rising acidity of the oceans. But have a look at what that acidification means for another part of our food supply for marine life, for the shellfish. What you see here are tests of shellfish growing at different concentrations of carbon dioxide. And the higher the concentration, the smaller are the shellfish. Because these animals with the shells or with other kinds of exoskeletons. With the even the microscopic plankton that have calcareous shells can’t build their shells when the ocean is more acidic. Which changes the chemistry for them to be able to, to have the, the normal development of their exoskeletons or their shells. And this is also already causing destruction of many highly productive estuaries but there is a lot more to come. And so we see that again even aside from the climate change the rising carbon dioxide concentrations are a profound threat for us. In addition to climate change, ocean acidity, many other environmental changes already are degrading farmland and threatening agricultural productivity. Farmers use large amounts of pesticides and herbicides to grow the crops, but the poisoning of the soils and the environment is taking its toll, on biodiversity. We’re seeing a drop of significant biodiversity of many kinds of species, including pollinators, for example, like honey bees. And other pollinators that are vital for crop productivity for growing fruits and other kind of flowering crops. And this has led to alarming and so far, to an important extent, unexplained declines of biodiversity that we’re going to discuss later on. But this is another major threat to farm productivity. Invasive species, meaning when species are relocated from one environment to another environment. Sometimes intentionally because farmers have the idea that they’ll plant crops that have been grown in other parts of the world. But when, species are moved to new environments, perhaps not having, the predators, or the rest of the ecosystem, that holds them in check, there can be wild spread of weeds, super weeds in new environments, or rodents, or other kinds of pest and pathogens, that overtake farms. We’re seeing a lot of new pathogens emerging in many places, threatening major crops and we know throughout human history that potato blight and other pathogens can devastate crops and devastate populations. Farmland depends on water, of course rain fed and irrigation. And irrigation is the farm system of choice for farmers when they can afford it, because it offers the chance of water control. And multi-cropping years. In other words, rather than just one season depending on the rains. In warm climates, there can be two or three growing seasons, doubling or even tripling the amount of production coming from hectare of arable land. But the problem is that environmental stress also threatens our irrigated lands because our current irrigation depends on rivers on glaciers and on ground water all of which are threatened now. Glaciers are retreating. As they melt under the warming climate, the short response is more riverflow. This can give the impression of a boom, even the rivers flow as the glaciers melt in the, the, the warmer winter and spring days. But, when those glaciers disappear, the flow goes from excess to zero. And it can be, a devastating and dramatic loss to populations that depend on rivers fed by glacier melt. Many rivers they have been so overused at this point. Dammed and used for irrigation that they’re also not even flowing to the sea. And under the pressures of climate change, the natural forces will mean less river flow in addition. The Nile, for example which, on which hundreds of millions of people depend. Will have a most likely significant decline of river flow as a result of climate change. The Yellow River in North China another vital waterway for China and for farmers that are in the Yellow River Basin. Are experiencing the consequences of declining river flow, in a river that no longer reaches the ocean. And ground water that is pumped for irrigation, as it is in the U.S. Midwest, as it is in the Ganges Plains, face the terrible. Reality that the pumping to grow more crops for growing population is taking place far faster than the natural recharge of those aquifers. The groundwater is falling, and when it falls far enough, it no longer can be the basis for agriculture. So the environmental threats ahead of depleted fresh water supplies, weather from the glaciers that reduce river flow, or the depletion of groundwater is another extraordinarily serious menace. That threatens farming in many parts of the world. Under the pressures of intensive agriculture, often when farms have encroached on forest lands or in topography not really suitable for farms, the result is also rapid land degradation. Soil loss. Depletion of soil nutrients. And often after new areas are cleared for farmland or pasture land, say in the amazon, they’re abandoned a few years later because they were never suitable. But the consequences are very high, there’s been deforestation, loss of habitat, emission of carbon dioxide in to the atmosphere. People have depended on a short-term burst of farm productivity. And then that farm productivity quickly diminishes and then disappears, and the farm is abandoned. All of this emphasizes the fact that farm systems more than any other human activity are dependent on the climate we know, on the hydrologic patterns we know, on the ocean chemistry we know, all of which are under enormous human change. The anthropocene is creating a new world and it will be a dangerous one. Of course, there are possibilities for adaptation. Of course there are possibilities for more efficient resource use, but the inertia of the way we do things now and the instability that results when, we have the collision of nature and our current systems. Not leading to problem solving, but leading to crises and conflict. Need to make us sit up and realize how big the challenge will be. It was hard enough feeding a planet. The challenge we haven’t even accomplished with our current population, and our current technologies and our current environment, but now when we consider the rising populations and the growing environmental stresses, we realize how big the challenges are that lie ahead.

What is Sustainable Development? IV

Environmental Threats

One of the most important messages of sustainable development is that we’ve become a threat to ourselves. Economic production has become so large, our productivity in many ways so high, and the numbers of us on the planet so vast, that the effect of all this economic activity on the physical Earth itself has become overwhelming.

For the first time in human history, for the first time in the planet’s history, one species, that would be us human beings, are threatening the fundamental parts of the Earth’s own dynamics: the climate system, the water cycle, the nitrogen cycle, the ocean chemistry. Think about the basic arithmetic.

There are 7.2 billion of us on the planet now. On average, each individual is producing around $12,000 of output per year, rough number, averaged over the whole year. But with 7.2 billion people, an average of $12,000 per person, it means that the world economy as a whole, has an output of between 80 and 90 trillion dollars per year.

141Many times larger than ever in the past and continuing to expand rapidly. And the result of all of that, in the water we are using, the energy that we are burning, the land that is being devoted to feeding the planet, the chemicals that are being produced, and the pollution that results from that poisoning the air and the waterways, it’s leading to an unprecedented environmental crisis. One of things that’s notable about this crisis, is that it’s felt by rich and poor alike. Have a look my own city, swimming for survival during this super storm that we experienced in October and November, 2012, what we called Hurricane Sandy. But halfway around the world the same year, Beijing experienced massive flooding. Or take a look at Bangkok, in the astounding floods of October, 2011: again a major world city underwater, deluged by unprecedented rains and as in all of these cases, a huge setback for the economy, loss of life, massive loss of property, billions or tens of billions of dollars of damage, and an unsettled global economy, because a disruption in one part of the world, in a world of interconnected production of supply chains that stretch across the world. Mean that a flood in Bangkok can disrupt automobile production, or computer production, all over the world, because of components or factories that can’t get to market during these disasters.

The kinds of disasters that are being felt are varied, but what is clear, is that they’re rising in number. What we call hydrometeorological shocks or disasters: water, and weather related, whether it’s deluges, extreme storms, hurricanes and typhoons of, huge, impact, storm surges and floods, as swept over Manhattan or Beijing, or, Bangkok, massive droughts, droughts that lead to, the remarkable and shocking phenomenon you see here, of, terrible forest fires that spread across the American West in 2012.142

These kinds of varied storms, shocks, heat waves, droughts, floods have become the new normal for the world. In fact, it’s part of a world that is so new, and so tark that the scientists notably the geologists, have given our age even a new name. They call it the Anthropocene. A new word that comes from its Greek roots, anthropos and cene, anthropos meaning human Cene meaning epoch or age of the Earth. And what the scientists are telling us is that this is the human age of the planet. They don’t mean that in a good way. They mean it in it’s uniqueness and in a very dangerous way that humanity is changing the water cycle, the climate is warming the temperature is melting the glaciers is threatening the great ice sheets over Antarctica and Greenland, is causing the oceans to become more acidic, is threatening other species with survival in such a fundamental way that the planet behaves differently now, even from a geologic point of view, hence, the Anthropocene.

One of the main drivers of these changes is humanity’s massive use of coal, oil, and natural gas, the three energy sources we call fossil fuels. When we burn coal, oil, and gas to move our cars, heat our buildings, drive our industrial production, produce electricity, we end up with carbon dioxide emitted into the atmosphere. And carbon dioxide in the atmosphere changes the climate. This stark graph, which we will revisit, later on, shows the cycles of carbon dioxide concentrations in the atmosphere, shown here, over the last 800,000 years.143

Well, by natural processes mainly changes of, the earth’s, orbit, and the effects that that produced, carbon dioxide in the Earth’s history has gone up and down in kind of a wave like manner. But look at the recent few years, the, the blink of an eye in terms of the Earth’s history. Carbon dioxide has suddenly soared to levels of 400 parts per million in of CO2 in the atmosphere, something not seen on the planet, not for 800,000 years, indeed not for 3,000,000 years. And this is causing massive disruption of the climate system, global warming, and more extreme events like droughts and floods. We’ll be talking a lot about this and what could be done about it.

But it is a stark illustration of how humanity is changing the basic Earth processes. A group of scientists got together a few years ago. And noted that it’s not only the carbon dioxide in the air, but many other things that we’re doing. The way we’re using water the way that we’re putting nitrogen based fertilizers into the soil to help crop productivity. But putting it on in such large amounts that the nitrogen cycle, itself, is effected. The way that carbon dioxide in the atmosphere affects the ocean chemistry, making the ocean more acidic. The way we’re chopping down trees to make room for new pasture land and farmland. In other words, all the varied effects of a big crowded planet and a lot of economic activity, threatening the planet systems. And so this group of scientists said we are trespassing, boundaries that are safe for humanity. So these scientists said we need to identify the safe operating limits for the planet, we need to understand what those planetary boundaries are.


144And around the circle you see here is their visualization of those planetary boundaries. Have a close look: climate change, ocean acidification, ozone depletion, the nitrogen cycle, the phosphorous cycle, global fresh water use, changes in land use, loss of biodiversity, driving other species to extinction, that is, aerosol loading, the particles we’re putting into the atmosphere through industrial processes, and chemical pollution, poisoning air and waterways. These are planetary boundaries that we trespass at profound risk for ourselves and for our children.

A core goal of the science of sustainable development is to understand these risks and most importantly to determine what we can do so that we stay within the safe operating limits of humanity, we honor and respect these planetary boundaries, as we continue to improve our well being. It’s the combination of economic prosperity, social inclusion, ending poverty, and ensuring environmental sustainability, that is the holistic objective of sustainable development.