people and the biosphere espm 2 - nature.berkeley.edu · past, current and future state of the...

No discussion on the biosphere, its state and future can proceed without considering the impact of the human species.

Look at Science July 2011

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Too often population issues are viewed as ‘radioactive’ by those seeking solutions and setting goals for solving many of the world’s environmental problems, current and future. In this lecture we will see clearly we cannot ignore the issues associated with population if we are to maintain a habitable planet for us and future generations. The questions and answers are stark, not easy to navigate and have many complex cultural, ethical and economic ramifications, in addition to the environmental ones.

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This identity helps explain why population is central in ideas about environmental impact. So remember when you are asked at the grocery store, paper or plastic?, your impact on the planet will be great if you decide to have one child instead of two, or two instead of three.

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At Cal, there are faculty working on human population issues. One of the leading experts is Prof. Malcolm Potts. His activities are associated with the Bixby Center, another resource for learning and research

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In this lecture we will overview the issues associated with humans and the biosphere, past growth, our current and projections of our future population. We’ll identify the most pressing problems associated with humans and the biosphere. Bottom line if we can cause these problems we have the hope/potential to solve them with will power, political wlll, dollars and technology

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We are officially in a new geological era, the Anthopocene. I was associated with a advisory panel for the American Geophysical Union to consider new journals. The one that one the most support was on this topic, which we named Future Earth.

There have been many articles documenting the impact of humankind on the biosphere. Some call it the great acceleration due to the rapid rise in change in so many aspects of life on Earth since the industrial age.

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Many of the trends documented in the previous slide are backed up with data in this slide. More graphic is the great acceleration of such measures as population, water use, damming of rivers, consumption of raw material and economic growth

Steffen et al Ambio

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http://www.castor2.ca/nsc/01_Pollution/01_NA_Night/earth_night.jpg

The presence of humans on the landscape is ubiquitous It is so extensive we can see our ‘fingerprints’ at night by the observation of the lights of our homes and our cities from space.

Where is the impact greatest? Which parts of the planet are darkest? Are these areas dark due to lack of people or lack of fuel consumption and development?; or some combination of the two?

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Destruction or disrepair of the environment is associated with providing energy, food and resources to support our population, economies and life style. When populations were low we had the luxury of polluting our environment, as we could move on elsewhere. We don’t have the luxury today. We must develop a new land ethic to live sustainably into the future to enable future generations of humans to live a decent life.

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It is issues like this why I think it is so important for students like you to take a class like this. You must be aware of the issues and help forge solutions, both technically, economically and socially. The answers are complex, conditional, and grey, not black and white.

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The world is currently in the midst of the greatest demographic upheaval in human history. Dramatic reductions in mortality, followed (but with a lag) by equally marked reductions in fertility, resulted in a doubling of world population between 1960 and 2000. A further increase of 2 to 4.5 billion is projected for the current half‐century, with the increase concentrated in the world’s least developed countries. Despite alarmist predictions, historical increases in population have not been economically catastrophic. Moreover, changes in population age structure have opened the door to increased prosperity. Demographic changes have had and will continue to have profound repercussions for human well‐being and progress, with some possibilities for mediating those repercussions through policy intervention.

7 Billion and CountingDavid E. BloomScience 29 July 2011: 333 (6042), 562‐569. [DOI:10.1126/science.1209290]

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7 Billion and CountingScience 29 July 2011: vol. 333 no. 6042 562‐569

Another 2 billion people will be on the planet during your lifetime. Population in the more developed world is expected to remain stable, unless there is mass immigration/emigration from the less developed world. Current projects put the greatest growth in the less developed world with all its attendant consequences.

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9 Billion?Leslie RobertsScience 29 July 2011: 333 (6042), 540‐543. [DOI:10.1126/science.333.6042.540]

Notable is the rapid decrease in the interval between each increment of an additional billion people. It took until 1800 to reach the first billion.

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This simple differential equation defines the rate of change of population. Note the b times P, birth, is the birth rate. For example if b is 1% per year it is 0.01. But the main idea is that the growth due to birth is a function of the current population times the rate of birth, b. The same holds for death. It is the rate of death, d, times the current population. Additional population comes from immigration. Losses from emigration

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7 Billion and CountingDavid E. BloomScience 29 July 2011: 333 (6042), 562‐569. [DOI:10.1126/science.1209290]

Figure represents a stylized version of this framework under the assumption of zero net migration, showing the transition from a regime of high fertility and mortality to one of low fertility and mortality (with low population growth at both ends). A key feature of the transition is that the mortality decline (in brownish red) precedes the fertility decline (in green), the result being a transitional period of population growth (24–27).

You can have low population growth with high birth rates, if the death rate is high too. But to maintain stable population growth a reduction in birth rate needs to follow a decline in death rates, which occur with better medicine, nutrition and modern life.

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You may hear about exponential growth. In the next few slides we’ll examine this process in detail. Knowing about simple projections is important in planning.

The key point is the change in population, n, with a change in time is a function of the current population and its growth rate. If you project this idea on an excel spread sheet, adding the new increment to the old total you will soon see rapid and exponential growth.. This example shows how rapidly a population of 2 changes with 50% growth.

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Solving the differential equation for the time rate of change of a population or quantity leads to exponential growth. How fast that population doubles in size depends on its growth rate. Technically one can define this by the rule of 69..take 69 and divide it by the growth rate.

These ideas are important for thinking about how the rate of inflation my diminish your purchasing power or how fast money in your bank account will grow.

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What is the global population growth rate? Today it is about 1.2% per year. How many people are added to the world each year if the global population is about 7 billion?

How long would it take the population to double if this rate was constant and sustained?

Global fertility is declining

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Good news is population growth rates are decreasing and are projected to continue decreasing. Questions are what implication this may have on economic growth.

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9 Billion?Leslie RobertsScience 29 July 2011: 333 (6042), 540‐543. [DOI:10.1126/science.333.6042.540]

The disparity in population growth is regional, with the lead in Asia (India, China) and Africa

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Regionally population are and can growing much faster.

Fast growth is locale, too, but it can change by immigration and emigration

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By 2050, the human population will probably be larger by 2 to 4 billion people, more slowly growing (declining in the more developed regions), more urban, especially in less developed regions, and older than in the 20th century. Two major demographic uncertainties in the next 50 years concern international migration and the structure of families. Economies, nonhuman environments, and cultures (including values, religions, and politics) strongly influence demographic changes. Hence, human choices, individual and collective, will have demographic effects, intentional or otherwise.

Cohen

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JE Cohen ScienceHuman Population: The Next Half Century Joel E. Cohen, et al.Science 302, 1172 (2003); DOI: 10.1126/science.1088665

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Demographers use the Population period as a way to display population information. This figure shows the conceptual figures for different population dynamics.

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Population pyramid for the US

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Population projections with various growth scenarios.

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The urbanization of the world concentrates power, money and creative culture on one hand, like New York, London, Singapore, Shanghai

On the other hand, it also concentrates the poor and disposed in slums and flavelas

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Potts

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The discussion of population tends to be a radiatively hot topic. But in an discussion of the past, current and future state of the biosphere it must be considered in an intelligent and unbiased manner.

Some camps worry about discussions of population limits as racist or elitist. Others consider its necessity to main environmental justice, quality of life and a sustainable planet. Others say it is not an issue because we can feed the world if we make the effort.

Personally, I have experienced the world double in my lifetime and have seen both the benefits and consequences of a burgeoning population. More people, more diverisity and an interesing world. More consumers of our ideas and products. Too many people, crowded roads, classes, limitations of clean water, air pollution, increased CO2 and projections of global warming.

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The power of population is so superior to the power of the earth to produce subsistence for man, that premature death must in some shape or other visit the human race. The vices of mankind are active and able ministers of depopulation. They are the precursors in the great army of destruction, and often finish the dreadful work themselves. But should they fail in this war of extermination, sickly seasons, epidemics, pestilence, and plague advance in terrific array, and sweep off their thousands and tens of thousands. Should success be still incomplete, gigantic inevitable famine stalks in the rear, and with one mighty blow levels the population with the food of the world.—Malthus T.R. 1798. An essay on the principle of population. Chapter VII, p61[1]

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Population Bomb, 1968, Paul Ehrlich

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Dennis Meadows won the Japan Prize in 2009,, The report’s message was an enormous shock to a world in themidst of economic growth. It said that there are certain constraintson the Earth's physical capacity—including resources, environment,soil and so on—and if populations and economies were allowed tocontinue growing without restraint, humanity would face a crisis. Italso said that in order to mitigate these risks, it would be necessaryto aim at zero growth for population and the economy. Releasedduring a period that was even more growth‐oriented than today, thereport had many detractors.

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Paul Sabin teaches American history at Yale University and is the author of The Bet: Paul Ehrlich, Julian Simon, and Our Gamble Over Earth’s Future.

Gloomy forecasts for soaring resource costs reveal an all‐too‐common tendency to overlook how scarcity and abundance relate to each other. Scarcity, by leading to increased prices, spurs innovation and investment. Efforts to locate new resources and design cheaper methods yield new technologies. New periods of abundance occur, even overabundance or a glut. We see that abundance today in natural gas markets.Yet a bet on resource prices also is a poor measure for environmental well‐being or societal welfare. Sometimes resource prices are low because the environment is being degraded or is at risk. Mountaintop removal mining and deep‐water oil drilling both produce abundant fossil fuels and help keep energy prices down. But at the same time, they endanger entire ecosystems, from the blasted mountains of Appalachia to the polluted waters of the Gulf of Mexico. More broadly, the price of resources such as coal and oil do not reflect impacts that lie outside the market pricing system. Carbon dioxide pollution, for example, is particularly difficult to ameliorate because there is no price on carbon that might provide incentives for conservation, investment, or alternative energy.

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Optimist argue we always have and always will save ourselves with technology.Yet one reason we frame this course around the theme of complex systems is that the biosphere is not a clocklike mechanism that can be easily manipulated. It is a complex system with many desireable and undesirable feedbacks if pushed too far. It is important that we understand, accept and work within the limits of this new paradigm.

The factor I add is what about the quality of life..

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Foley, J. A., et al. (2011). "Solutions for a cultivated planet." Nature 478(7369): 337‐342.

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We need land for producing food and fiberAgricultural extentAccording to the Food and Agriculture Organization (FAO) of the United Nations, croplands cover 1.53 billion hectares (about 12% of Earth’s ice‐free land), while pastures cover another 3.38 billion hectares (about 26% of Earth’s ice‐free land)

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Rangelands are important too as they can be used to produce food in lands that are too steep or dry or unproductive to support production agriculture

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Biotechnology should not be taken off the table. But I understand many of the concerns that are associated with its use. Here is the case of the need for a scientifically literate electorate. Blanket restrictions of GMOs is not wise, nor a solution, either

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Seufert, V., et al. (2012). "Comparing the yields of organic and conventional agriculture." Nature 485(7397): 229‐232.

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Seufert, V., et al. (2012). "Comparing the yields of organic and conventional agriculture." Nature 485(7397): 229‐232

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Seufert, V., et al. (2012). "Comparing the yields of organic and conventional agriculture." Nature 485(7397): 229‐232.Numerous reports have emphasized the need for major changes in the global food system: agriculture must meet the twin challenge of feeding a growing population, with rising demand for meat and high‐calorie diets, while simultaneously minimizing its global environmental impacts1, 2. Organic farming—a system aimed at producing food with minimal harm to ecosystems, animals or humans—is often proposed as a solution3, 4. However, critics argue that organic agriculture may have lower yields and would therefore need more land to produce the same amount of food as conventional farms, resulting in more widespread deforestation and biodiversity loss, and thus undermining the environmental benefits of organic practices5. Here we use a comprehensive meta‐analysis to examine the relative yield performance of organic and conventional farming systems globally. Our analysis of available data shows that, overall, organic yields are typically lower than conventional yields. But these yield differences are highly contextual, depending on system and site characteristics, and range from 5% lower organic yields (rain‐fed legumes and perennials on weak‐acidic to weak‐alkaline soils), 13% lower yields (when best organic practices are used), to 34% lower yields (when the conventional and organic systems are most comparable). Under certain conditions—that is, with good management practices, particular crop types and growing conditions—organic systems can thus nearly match conventional yields, whereas under others it at present cannot. To establish organic agriculture as an important tool in sustainable food production, the factors limiting organic yields need to be more fully understood, alongside assessments of the many social, environmental and economic benefits of organic farming systems.

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Conversations with Claire Kremen stresses the point that comparatively little research has been applied to organic agriculture vs conventional. With more research yield gaps can close.

Also much limitations in food is associated with distribution of food and losses from insects and rodents, poor roads and rails, corruption and politics.

The results of our meta‐analysis differ dramatically from previous results6. Although our organic performance estimate is lower than previously reported6 in developed countries (−20% compared to −8%), our results are markedly different in developing countries (−43% compared to +80%). This is because the previous analysis mainly included yield comparisons from conventional low‐input subsistence systems, whereas our data set mainly includes data from high‐input systems for developing countries. However, the previous study compared subsistence systems to yields that were not truly organic, and/or from surveys of projects that lacked an adequate control. Not a single study comparing organic to subsistence systems met our selection criteria and could be included in the meta‐analysis.

Other questions relate to whether organic farming may be better and more resilient to extremes in climate with global warming. There is evidence in this direction.

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Seufert, V., et al. (2012). "Comparing the yields of organic and conventional agriculture." Nature 485(7397): 229‐232.

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Foley et al.

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Several studies have shown that global crop production needs to double by 2050 to meet the projected demands from rising population, diet shifts, and increasing biofuels consumption. Boosting crop yields to meet these rising demands, rather than clearing more land for agriculture has been highlighted as a preferred solution to meet this goal. However, we first need to understand how crop yields are changing globally, and whether we are on track to double production by 2050. Using ∼2.5 million agricultural statistics, collected for ∼13,500 political units across the world, we track four key global crops—maize, rice, wheat, and soybean—that currently produce nearly two‐thirds of global agricultural calories. We find that yields in these top four crops are increasing at 1.6%, 1.0%, 0.9%, and 1.3% per year, non‐compounding rates, respectively, which is less than the 2.4% per year rate required to double global production by 2050. At these rates global production in these crops would increase by ∼67%, ∼42%, ∼38%, and ∼55%, respectively, which is far below what is needed to meet projected demands in 2050. We present detailed maps to identify where rates must be increased to boost crop production and meet rising demands.

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World wide decline in fish catch, partly due to super trawlers over fishing to feed a hungry world, or a richer world wanting exotic fish higher up the food chain, like tuna

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Worm, B., et al. (2009). "Rebuilding global fisheries." Science 325(5940): 578‐585.

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Worm, B., et al. (2009). "Rebuilding global fisheries." Science 325(5940): 578‐585.

After a long history of overexploitation, increasing efforts to restore marine ecosystems and rebuild fisheries are under way. Here, we analyze current trends from a fisheries and conservation perspective. In 5 of 10 well‐studied ecosystems, the average exploitation rate has recently declined and is now at or below the rate predicted to achieve maximum sustainable yield for seven systems. Yet 63% of assessed fish stocks worldwide still require rebuilding, and even lower exploitation rates are needed to reverse the collapse of vulnerable species. Combined fisheries and conservation objectives can be achieved by merging diverse management actions, including catch restrictions, gear modification, and closed areas, depending on local context. Impacts of international fleets and the lack of alternatives to fishing complicate prospects for rebuilding fisheries in many poorer regions, highlighting the need for a global perspective on rebuilding marine resources.

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Here is the list of issues related to population. We will cover these topics during the lecture on the Anthropocene

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