Sustainability and the value of Eco-System Services
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| Composites Design and Manufacture (Plymouth University teaching support materials) Sustainability and the value of Eco-System Services |
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The World Commission on Environment and Development published Our Common Future: from one earth to one world (Brundtland report) [1] in 1987. The key phrase from the report was “Humanity has the ability to make development sustainable to ensure that it meets the needs of the present without compromising the ability of future generations to meet their own needs”. The Earth Summit (Rio de Janeiro ~ Brazil, 1992) adopted Agenda 21 [2] as a comprehensive plan to build a global partnership for sustainable development while improving human lives and protecting the environment. The United Nations unanimously adopted the Millennium Declaration [3] (New York ~ United States of America, 2000) which led to the eight Millennium Development Goals (MDG) aiming to reduce extreme poverty by 2015. The vision was expanded as 17 Sustainable Development Goals (SDG) in the 2030 Agenda for Sustainable Development [4] as a blueprint for peace and prosperity for people and the planet.
However, the SDG do not directly address population as the key driver of planetary systems in the twenty-first century. In 1968, Ehrlich [5] warned of major societal upheavals and mass starvation unless there was immediate action to limit human population. The position was updated in 2016 [6]. Ehrlich and Holdren [7] introduced Equation 1 to describe how environmental change or impact (I) depends on population size (P) and per capita consumption (F), with F now represented as the product of affluence (A) and technology (T).
I = P F = P A T (1)
The Limits to Growth (1972) [7] attempted to analyse the carrying capacity of the planet and concluded that the world’s population (then 3.8 billion) and economy were still comfortably within the planet’s carrying capacity with room to grow safely while longer-term options were examined. In the 1992 (world population 5.3 billion people) follow-up book, Beyond the Limits [9], they concluded that humanity is dangerously in a state of overshoot (Figure 1). Over an extended period, a number of studies have proposed that an optimal population for the earth, compatible with an acceptable and comfortable standard of living would not exceed 3 billion people [10-15]. On 15 November 2022, the world marked the milestone of a population of 8 billion people. That number of people is the most common figure from a survey of 65 estimates of earth’s carrying capacity, albeit perhaps with the majority of people close to subsistence levels [16].
Tucker [17] has suggested that an 18th SDG be added that calls for an end to the runaway population growth with a target Total Fertility Rate (TFR) of 1.5 by 2030. Basten et al [18] have suggested that with a world average TFR of just 1.5, it would take around 200 years for the population to fall back to around 3 billion people. The fractional ratio makes little sense in the context of a single family, but some siblings may choose, or default, to be “childfree”. Lianos [19] proposes that "population must be stable at a level that is compatible with ecological equilibrium at about three billion people. To achieve that the world population must be reduced drastically which might be achieved if each family is allowed to have less than two children. He proposes that a globally tradable system of reproductive “shares” could be developed with three “shares” allocated to each couple (or perhaps more tractable to each woman) with each share giving the right to half-a-child. This effectively realises a world average TFR of 1.5. Trading fertility shares would permit some females to choose to have a greater number of children. The system could potentially transfer wealth from the rich to the poor, but would require some form of internationally agreed regulation and monitoring.
Tucker [20] further stated that “An 18th SDG, focused on ending runaway population growth, stabilizing population, and decreasing it to a lower more sustainable population plateau would go a long way to helping in the achievement of the other 17 SDG”. Sir David Attenborough [21] has said “All of our environmental problems become easier to solve with fewer people, and harder – and ultimately impossible – to solve with ever more people”. Vollset [22] considered the factors driving population growth and determined that the education of girls and women, and improved access to modern contraception have resulted in the TFR declining more quickly than previously assumed.
Conly [23] has said "you simply can’t justify the claim that you have a right to have as many children as you want when that will be as harmful to others as this much overpopulation [the UNEP prediction of 11.2 billion people by the year 2100] is bound to be".
Global warming
Human development has been accompanied by the release of increasing quantities of carbon dioxide and methane (from burning fossil fuels and decomposition of organic materials) and other gasses which blanket the earth and trap solar radiation leading to global warming and climate change. Adisa Azapagic et al's environmental impact classification factors (EICF) provide a route to analyse these effects.
The biosphere is divided into kingdoms as a top level classification of the variety of all living things that inhabit the planet. The five kingdoms are Monera (bacteria), Protista (organisms that have a membrane-bound nucleus, eukaryotes, that are not in the higher kingdoms), Fungi, Plantae and Animalia. A key environmental concern is the loss of this diversity, albeit that there is a focus on the megafauna and pollinators.
4athews [23] has argued that biodiversity targets have "sold conservation disatrously short ... with the only evident constraint on the population of homo sapiens [being] that it should not be so large as to leave no room on earth for (minimum populations of) other species. Otherwise biodiversity specifies no limit [except to keep species at numbers that avoid extinction]". She introduces the precept of bioproportionality where there are "optimal population sizes for all species, including ours". Also "This short-termism, motivated by the short duration of most political offices, may unwittingly be increasingly compromising our long-term quality of life and survival prospects. Ergo, liberal democracy as we currently practice it is not conducive to environmental sustainability".
Burr et al [25] have said "To think that we might manage to somehow pull off some technological trick in the future so that billions of people could all have an equally good quality of life while preserving pristine environments and retaining species diversity is a logical absurdity". Also, in the context of population management, "This short-termism, motivated by the short duration of most political offices, may unwittingly be increasingly compromising our long-term quality of life and survival prospects. Ergo, liberal democracy as we currently practice it is not conducive to environmental sustainability"
Costanza et al [26] estimated the value of the non-marketed contribution of the world’s ecosystem services to human welfare at US$16-54 trillion per year (with a mean of US$33 trillion) in $1994. This figure was significantly larger than the corresponding global GNP at $18 trillion per year and was considered to be an underestimate. Toman [27] suggested that "economic assessment of ecosystem benefits and opportunity costs [are] one important element of the information set that must go into social decision making, even though a simple cost-benefit test cannot determine what actions are appropriate". He states that "a default value of zero for a difficult-to-measure ecological value, as is used (explicitly or implicitly) in a number of cost-benefit analyses, is no more defensible scientifically than a default value of infinity" which only reinforces the need to appreciate the context of the analysis. He then concludes that the fundamental problem with the analysis in Costanza et al [26] is "that there is little that can be usefully done with a serious underestimate of infinity"!
Imhoff and Bounoua [28] report that the human species constitutes around 0.5% of the total biomass of organisms that require organic compounds to get carbon for growth and development, yet globally they consume 20% of the net primary production from the land, i.e. the supply of food energy. Kern [29] has summarised the debate about food, feed, fibre, fuel and industrial products.
The United States Department of Agriculture defines soil quality/soil health as "the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans. This definition speaks to the importance of managing soils so they are sustainable for future generations. To do this, we need to remember that soil contains living organisms that when provided the basic necessities of life - food, shelter, and water - perform functions required to produce food and fiber" [30]. Montgomery [31] argues that "cultivated soils erode bit by bit, slowly enough to be ignored in a single lifetime but fast enough over centuries to limit the lifespan of civilizations", and "sees in the recent rise of organic and no-till farming the hope for a new agricultural revolution that might help us avoid the fate of previous civilizations". Tolputt [32] considers the remedy to be Five pillars for good soil:
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