Why Goals 14 and 15 of the SDGs are essential for sustainable development: Part I
When the Millennium Development Goals were agreed back in 2000, the target of a 'significant reduction in the rate of biodiversity loss' was included under Goal 7, explicitly recognizing that a surge in protected areas was needed to preserve ecosystems, species of flora and fauna that inhabit them, and their contribution to human societies.
After fifteen years, that target, which the vast majority of countries had in the meantime pledged to achieve by 2010 by committing to the Convention on Biological Diversity's Strategic Plan for Biodiversity 2002-2010, remains largely unmet, becoming one of the greatest failures of the MDGs. The fourth edition of the Global Biodiversity Outlook (GBO-4), in particular, recently maintained that actions must still be “stepped up and accelerated” if the goal is at least to be met under the new Strategic Plan for Biodiversity 2011-2020.
But why was that target added in the first place, and why it has now been reframed in great detail in Goals 14 and 15 of the Sustainable Development Goals, which are aimed at “conserving and sustainably using the oceans, seas and marine resources for sustainable development” and at “protecting, restoring and promoting sustainable use of terrestrial ecosystems, sustainably managing forests, combating desertification, and halting and reversing land degradation and halting biodiversity loss”, respectively? In other words, why is it important if species and ecosystems continue to disappear at an increasing rate, both on land and in the oceans, and why we should do something to reverse this process?
After all, extinction of a species or a group of species has been shown to be fairly common in Nature. Evidence suggests that even mass extinction events, defined by scientists as times when a loss of more than three-quarters of extant species occurs in a geologically short interval, are essential for subsequent evolutionary innovations. This is demonstrated, for example, by the recovery of greater levels of biological diversity after each of the 'Big Five' waves which struck in the past, including the one that led to the appearance of Homo sapiens when dinosaurs were wiped out during the Cretaceous period.
In addition, the average life-span of a species may vary considerably, even within natural background extinction rates (that is, normal extinction rates occurring during periods in between mass extinction events), with estimates ranging from about 1 million years for mammal species to 4-5 for marine animals and more than 10 for invertebrates and dinoflagellates. Non-catastrophic extinction events have thus happened, in the absence of human activity, at a relatively standard pace throughout history, not merely as an isolated result of competition and natural selection but rather as a gradual and continuous process that often leads to ecological cascades and influences ecosystem modification.
Should we really care, then, if mankind (through a combination of factors ranging from climate change to habitat loss, and including overexploitation, pollution, invasive species introduction, and so forth), jumps in and alters extinction rates to the point where the average live-span of species is dropping steadily (down to 200-400 years before the end of the century, for vertebrates) and the number of species that are classified as either 'vulnerable', 'endangered' or 'critically endangered' in the IUCN Red List of Threatened Species has increased from 6,343 in 1998 to 22,413 in 2014, with these changes in the conservation status of these species being reflected by a steep decline in population numbers?
The answer is YES, and it lies in the concept of ecosystem services, which can be broadly defined as the direct and indirect benefits that ecological systems provide to humanity annually. Benefits of the first kind are linked to direct human consumption or trade, while the notion of “indirect economic benefits” concerns those aspects of biodiversity (e.g. watershed protection, climate regulation) that perform a function which is valuable in itself and that can therefore be assigned an economic value even as no resource is destroyed or extracted in the process.
In 1997, a seminal study led by ecological economist Robert Costanza estimated that US $33 trillion per year is the average value of these renewable goods and services, and that figure was recently raised to US $125-145 trillion per year when Costanza used updated data to revise his own assessment. What is striking about them is that most are directly related to the role of living organisms within their ecosystem, such as nutrient cycling, pollination, biological control (which pertains to the trophic-dynamic regulations of populations), food production, raw materials, genetic resources, and so on. In other words, far from being a mere repository of aesthetic, recreational, cultural and educational values, biological diversity plays an essential role in sustaining human societies through both direct and indirect utilities, and has even been recognized as one of the planetary life-support systems, those natural systems whose maintenance is vital for human survival.
While I will examine these services more in depth in a series of future blog posts, it should already be clear that neglecting biodiversity's contribution to human life on Earth may ultimately compromise the sustainability of humans in the biosphere, prompting abrupt environmental change as the result of the crossing of the related planetary boundary and thereby causing staggering economic and well-being losses. The same 2014 paper by Costanza, for instance, hypothesized that the loss of ecosystem services caused by land use change may already be costing somewhere between US $4.3-20.2 trillion/yr, depending on which unit values are used. Now that the SDGs have been agreed to, it is thus time for global leaders to push for an effective implementation of the post-2015 agenda that reconciles economic development, social inclusion, and environmental sustainability: we simply cannot pursue prosperity and address inequalities within the economy and society if we don't have healthy ecosystems to support both of them.
Dario Piselli is the Project Lead for Solutions at SDSN Youth. All opinions expressed on the blog are the opinions of the author and not that of SDSN Youth
 CBD (2001) Decision VI/26, para.11
 Barnosky, AD et al. (2011) Has the Earth's Sixth Mass Extinction Already Arrived? Nature 471:51-57
 Keller, G (2008) Cretaceous Climate, Volcanism, Impacts, and Biotic Effects. Cretac Res 29:754-751
 May, RM et al. (1995) 'Assessing Extinction Rates'. In Lawton, JH and May, RM (eds.), Extinction Rates (Oxford, UK: Oxford University Press)
 Jablonski, D (1991) Extinctions: A Paleontological Perspective. Science 253:754-757; and Dunn, RR et al. (2009) The Sixth Mass Coextinction: Are Most Endangered Species Parasites and Mutualists? Proc R Soc Lond [Biol] 276:3037-3045
 IUCN (2014) The IUCN Red List of Threatened Species. Version 14.3. Available at:http://www.iucnredlist.org
 According to the Living Planet Index, which measures population trends for more than 3,000 vertebrate species based on 1970 levels, monitored amphibians have experienced an 80 percent fall in their population since 1970 (an average for all amphibian species indicate a 41 percent estimate), with freshwater fish (65 percent), marine fish (20 percent), and mammals (25 percent) enduring a similar destiny.
 Costanza, R et al. (1997) The Value of the World's Ecosystems and Natural Capital. Nature 387:253-260
 Costanza, R et al. (2014) Changes in the Global Value of Ecosystem Services. Global Environmental Change 26:152-158
 Rockström, J et al. (2009) Planetary Boundaries: Exploring the Safe Operating Space for Humanity. Ecol Soc 14(2):32