<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div style="margin: 0px; font-stretch: normal; line-height: normal;" class=""><span style="-webkit-font-kerning: none;" class="">Proceedings of the Royal Society B: Biological Sciences</span></div><div style="-webkit-text-stroke-width: initial; margin: 0px; font-stretch: normal; line-height: normal; -webkit-text-stroke-color: rgb(0, 0, 0);" class=""><span style="-webkit-font-kerning: none;" class=""><a href="http://dx.doi.org/10.1098/rspb.2012.2845" class="">http://dx.doi.org/10.1098/rspb.2012.2845</a> </span></div><div style="-webkit-text-stroke-width: initial; margin: 0px; font-stretch: normal; line-height: normal; -webkit-text-stroke-color: rgb(0, 0, 0); min-height: 17px;" class=""><span style="-webkit-font-kerning: none;" class=""></span><br class=""></div><div style="-webkit-text-stroke-width: initial; margin: 0px; font-stretch: normal; line-height: normal; -webkit-text-stroke-color: rgb(0, 0, 0);" class=""><span style="-webkit-font-kerning: none;" class="">Accepted: 7 December 2012</span></div><div style="-webkit-text-stroke-width: initial; margin: 0px; font-stretch: normal; line-height: normal; color: rgb(0, 111, 81); -webkit-text-stroke-color: rgb(0, 0, 0); min-height: 17px;" class=""><span style="-webkit-font-kerning: none;" class=""></span><br class=""></div><div style="-webkit-text-stroke-width: initial; margin: 0px; font-stretch: normal; line-height: normal; color: rgb(0, 111, 81); -webkit-text-stroke-color: rgb(0, 0, 0);" class=""><span style="-webkit-font-kerning: none;" class=""><b class="">Can a collapse of global civilization be avoided?</b> </span></div><div style="-webkit-text-stroke-width: initial; margin: 0px; font-stretch: normal; line-height: normal; color: rgb(0, 111, 81); -webkit-text-stroke-color: rgb(0, 0, 0);" class=""><span style="-webkit-font-kerning: none;" class="">Paul R. Ehrlich</span><span style="vertical-align: 5px; -webkit-font-kerning: none;" class="">† </span><span style="-webkit-font-kerning: none;" class="">and Anne H. Ehrlich </span></div><p style="-webkit-text-stroke-width: initial; margin: 0px 0px 12px; font-stretch: normal; line-height: normal; color: rgb(35, 31, 32); -webkit-text-stroke-color: rgb(0, 0, 0);" class=""><span style="-webkit-font-kerning: none;" class="">Department of Biology, Stanford University, Stanford, CA 94305, USA </span></p><div style="-webkit-text-stroke-width: initial; margin: 0px; font-stretch: normal; line-height: normal; color: rgb(35, 31, 32); -webkit-text-stroke-color: rgb(0, 0, 0);" class=""><span style="-webkit-font-kerning: none;" class=""><b class="">FULL PDF</b></span></div><div style="-webkit-text-stroke-width: initial; margin: 0px; font-stretch: normal; line-height: normal; color: rgb(0, 0, 238); -webkit-text-stroke-color: rgb(0, 0, 238);" class=""><span style="text-decoration: underline; -webkit-font-kerning: none;" class=""><a href="https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2012.2845" class="">https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2012.2845</a></span></div><div style="-webkit-text-stroke-width: initial; margin: 0px; font-stretch: normal; line-height: normal; color: rgb(35, 31, 32); -webkit-text-stroke-color: rgb(0, 0, 238); min-height: 17px;" class=""><span style="-webkit-font-kerning: none;" class=""></span><br class=""></div><p style="-webkit-text-stroke-width: initial; margin: 0px 0px 12px; font-stretch: normal; line-height: normal; color: rgb(35, 31, 32); -webkit-text-stroke-color: rgb(0, 0, 238);" class=""><span style="-webkit-font-kerning: none;" class=""><b class="">Abstract</b></span></p><p style="margin: 0px 0px 12px; font-stretch: normal; line-height: normal;" class=""><span style="-webkit-font-kerning: none;" class=""><font color="#231f20" class=""><span style="-webkit-text-stroke-color: rgb(0, 0, 238); -webkit-text-stroke-width: initial;" class="">Environmental problems have contributed to numerous collapses of civilizations in the past. Now, for the first time, a global collapse appears likely. Overpopulation, overconsumption by the rich, and poor choices of technologies are major drivers; </span></font><font color="#231f20" class=""><span style="-webkit-text-stroke-color: rgb(0, 0, 238); -webkit-text-stroke-width: initial;" class=""><span style="background-color: rgb(255, 251, 0);" class="">dramatic cultural change provides the main hope of averting calamity. </span></span></font></span></p><p style="-webkit-text-stroke-width: initial; margin: 0px 0px 12px; font-stretch: normal; line-height: normal; -webkit-text-stroke-color: rgb(0, 0, 238);" class=""><span style="-webkit-font-kerning: none;" class=""><b class="">Introduction </b></span></p><p style="-webkit-text-stroke-width: initial; margin: 0px 0px 12px; font-stretch: normal; line-height: normal; color: rgb(35, 31, 32); -webkit-text-stroke-color: rgb(0, 0, 238);" class=""><span style="-webkit-font-kerning: none;" class="">Virtually every past civilization has eventually undergone collapse, a loss of socio-political-economic complexity usually accompanied by a dramatic decline in population size [1]. Some, such as those of Egypt and China, have recovered from collapses at various stages; others, such as that of Easter Island or the Classic Maya, were apparently permanent [1,2]. All those previous collapses were local or regional; elsewhere, other societies and civilizations persisted unaffected. Sometimes, as in the Tigris and Euphrates valleys, new civilizations rose in succession. In many, if not most, cases, overexploitation of the environment was one proximate or an ultimate cause [3]. </span></p><p style="-webkit-text-stroke-width: initial; margin: 0px 0px 12px; font-stretch: normal; line-height: normal; color: rgb(35, 31, 32); -webkit-text-stroke-color: rgb(0, 0, 238);" class=""><span style="-webkit-font-kerning: none;" class="">But today, for the first time, humanity’s global civilization—the worldwide, increasingly interconnected, highly technological society in which we all are to one degree or another, embedded—is threatened with collapse by an array of environmental problems. Humankind finds itself engaged in what Prince Charles described as ‘an act of suicide on a grand scale’ [4], facing what the UK’s Chief Scientific Advisor John Beddington called a ‘perfect storm’ of environmental problems [5]. The most serious of these problems show signs of rapidly escalating severity, <span style="background-color: rgb(255, 251, 0);" class="">especially climate disruption</span>. But <span style="background-color: rgb(255, 251, 0);" class="">other elements could potentially also contribute to a collapse:</span> an accelerating extinction of animal and plant populations and species, which could lead to a loss of ecosystem services essential for human survival; land degradation and land-use change; a pole-to-pole spread of toxic compounds; ocean acidification and eutrophication (dead zones); worsening of some aspects of the epidemiological environment (factors that make human populations susceptible to infectious diseases); depletion of increasingly scarce resources [6,7], including especially groundwater, which is being overexploited in many key agricultural areas [8]; and resource wars [9]. These are not separate problems; rather they interact in two gigantic complex adaptive systems: the biosphere system and the human socio-economic system. The negative manifestations of these interactions are often referred to as ‘the human predicament’ [10], and determining <span style="background-color: rgb(255, 251, 0);" class="">how to prevent it from generating a global collapse is perhaps the foremost challenge confronting humanity. </span></span></p><p style="-webkit-text-stroke-width: initial; margin: 0px 0px 12px; font-stretch: normal; line-height: normal; color: rgb(35, 31, 32); -webkit-text-stroke-color: rgb(0, 0, 238);" class=""><span style="-webkit-font-kerning: none;" class="">The human predicament is driven by overpopulation, overconsumption of natural resources and the use of unnecessarily environmentally damaging technologies and socio-economic-political arrangements to service Homo sapiens’ <span style="background-color: rgb(255, 251, 0);" class="">aggregate consumption </span>[11–17]. How far the human population size now is above the planet’s long-term carrying capacity is suggested (conservatively) by ecological footprint analysis [18–20]. It shows that to support today’s population of seven billion sustainably (i.e. with business as usual, including current technologies and standards of living) would require roughly half an additional planet; to do so, if all citizens of Earth consumed resources at the US level would take four to five more Earths. Adding the projected 2.5 billion more people by 2050 would make the human assault on civilization’s life-support systems disproportionately worse, because almost everywhere people face systems with nonlinear responses [11,21 – 23], in which environmental damage increases at a rate that becomes faster with each additional person. Of course, the claim is often made that humanity will expand Earth’s carrying capacity dramatically with technological innovation [24], but it is widely recognized that technologies can both add and subtract from carrying capacity. The plough evidently first expanded it and now appears to be reducing it [3]. Overall, careful analysis of the prospects does not provide much confidence that technology will save us [25] or that gross domestic product can be disengaged from resource use [26]. </span></p><div style="-webkit-text-stroke-width: initial; margin: 0px; font-stretch: normal; line-height: normal; color: rgb(35, 31, 32); -webkit-text-stroke-color: rgb(0, 0, 238);" class=""><span style="-webkit-font-kerning: none;" class=""><b class="">FULL PDF</b></span></div><div style="-webkit-text-stroke-width: initial; margin: 0px; font-stretch: normal; line-height: normal; color: rgb(0, 0, 238); -webkit-text-stroke-color: rgb(0, 0, 238);" class=""><span style="text-decoration: underline; -webkit-font-kerning: none;" class=""><a href="https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2012.2845" class="">https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2012.2845</a></span></div><div class="">
<div dir="auto" style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div dir="auto" style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;">++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++<br class=""><br class="">"Direct effects of climatic warming can be understood through fatal decrements in an organism's performance in growth, <br class="">reproduction, foraging, immune competence, behaviors and competitiveness."<br class=""><br class="">Portner and Farrell. Physiology and Climate Change. Science October 31 2008</div></div></div></div>
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