The last post suggested that living more simply will be a necessary part of any transition to an ecologically sustainable society. To support the contention that current consumption patterns are unsustainable, and that low-consumption lifestyles are necessary, here is a brief scientific review of the ecological impacts of economic activity today.
The Living Planet Report 2008, based on the scientific research conducted by the Global Footprint Network, begins with the platitudinous reminder that our lives depend on the services provided by Earth’s natural systems; the report then proceeds to state its central finding: ‘we are consuming the resources that underpin those services much too fast – faster than they can be replenished. Just as reckless spending is causing recession, so reckless consumption is depleting the world’s natural capital to a point where we are endangering our future prosperity.’ The report goes on to add: ‘If our demands on the planet continue at the same rate, by the mid-2030s we will need the equivalent of two planets to maintain our lifestyles.’
This is hardly news, of course. There has long been a broad consensus within the scientific community that human economic activity is degrading Earth’s ecosystems. In 1992, for example, the Union of Concerned Scientists published their ‘Warning to Humanity,’ which was endorsed by 1,700 of the world’s leading scientists, including the majority of living Nobel laureates in the sciences. The warning begins:
Human beings and the natural world are on a collision course. Human activities inflict harsh and often irreversible damage on the environment and on critical resources. If not checked, many of our current practices put at serious risk the future that we wish for human society and the plant and animal kingdoms, and may so alter the living world that it will be unable to sustain life in the manner that we know. Fundamental changes are urgent if we are to avoid the collision our present course will bring.
More recently, the consensus surrounding the fact of ecological degradation has been exemplified by the United Nations’ publication of the Millennium Ecosystem Assessment in 2005, which was compiled and reviewed by over 2,000 leading scientists from 95 countries. This massive scientific study reveals that approximately 60 per cent of global ecosystems services ‘are being degraded or used unsustainably,’ resulting in ‘substantial and largely irreversible loss in the biodiversity of life on Earth.’ Looking uneasily toward the future, the study states: ‘The consumption of ecosystems services, which is unsustainable in many cases, will continue to grow as a consequence of a three- to six-fold increase in world GDP by 2050.’ This is particularly concerning given that the study also acknowledges that ‘the degradation of ecosystems services is already a significant barrier to achieving the Millennium Development Goals agreed to by the international community.’
A sampling of a few other recent scientific studies will serve to reveal the depth and extent of the ecological crisis. Mathis Wackernagel and colleagues have measured the ‘ecological footprint’ of humanity and compared it to the ‘carrying capacity’ of the planet. They concluded that the global ecological footprint exceeds sustainable carrying capacity by twenty per cent. In 2010, the World Wildlife Fund reported that humanity’s global ecological footprint is now exceeding sustainable carrying capacity by fifty per cent. Of similar concern, the United Nations Global Environment Outlook 2007 (GEO4) provides details on, among other things, the reality of climate change, reporting that 11 of the 12 years between 1995-2006 were the hottest since 1850. This rise in temperature has been strongly linked to greenhouse gases arising primarily from the human use of fossil fuels. In terms of loss of biodiversity, the Living Planet Index reveals that over the past 35 years alone, Earth’s wildlife populations have declined by approximately one third. This list could go on but the point is made. Evidence of environmental devastation and decline abounds.
Even this brief evidential review shows that there is a substantial body of scientific literature indicating that the high-impact, fossil-fuel-dependent, lifestyles practised in the developed world (and increasingly elsewhere) are environmentally unsustainable and certainly not universalizable. Leading environmentalist, Bill McKibben, even believes that the ‘consensus’ which has solidified over recent decades has transmogrified, in recent months, into something of a ‘panic,’ partly out of fear of approaching the ecological ‘tipping point’ beyond which feedback loops will be irreversible and unstoppable. But even leaving to one side the controversial possibility of a tipping point, the best available evidence illustrates that the global economy has physically grown to such a size that it now exceeds the regenerative and absorptive capacities of Earth’s ecosystems. That is, human beings are now consuming natural capital and diminishing the capacity of the planet to support life in the future.
 World Wildlife Fund (WWF), ‘Living Planet Report 2008,’ http://assets.panda.org/downloads/living_planet_report_2008.pdf at 15 march 2010.
 WWF, above n 1, 1.
 Union of Concerned Scientists, ‘1992 World Scientists Warning to Humanity’ <http://www.ucsusa.org/about/1992-world-scientists.html> at 15 March 2010.
 Millennium Ecosystem Assessment, Ecosystems and Human Well-Being (2005).
 Ibid 1.
 Ibid 2.
 An ‘ecological footprint’ is a measure of the amount of renewable and non-renewable ecologically productive land area required to support the resource demands and absorb the wastes of a given population or specific activity. See Mathis Wackernagel, ‘Tracking the Ecological Overshoot of the Human Economy’ (2002) 99(14) Proceedings of the National Academy of Sciences of the United States of America 9266.
 ‘Carrying capacity’ can be defined as the maximum population of a given species that can be supported indefinitely in a defined habitat without permanently impairing the productivity of that habitat. See William Rees, ‘Revisiting Carrying Capacity: Area-Based Indicators of Sustainability’ (1996) 17(3) Population and Environment 195.
 Wackernagel, above n 11.
 United Nations Environment Program, ‘Global Environment Outlook 4’ (2007) 59.
 See the Intergovernmental Panel of Climate Change, ‘Climate Change 2007 – The Physical Science Basis’ (2007) 112 (concluding that ‘Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations’).
 WWF, ‘Living Planet Report 2008,’ above n 1, 2.
 See Thomas White, ‘Sharing Resources: The Global Distribution of the Ecological Footprint’ (2007) 64(2) Ecological Economics 402. See also, United Nations Development Program, ‘Human Development Report’ (2007/8) 15 <http://hdr.undp.org/en/media/HDR_20072008_EN_Overview.pdf> at 10 September 2010 (noting that ‘There could be no greater challenge to our assumptions about progress than that of realigning economic activities and consumption with ecological realities’); Gro Brundtland, Oslo Symposium on Sustainable Consumption (stating, ‘It is simply impossible for the world as a whole to sustain a Western level of consumption for all’), quoted in James Salzman, ‘Sustainable Consumption and the Law’ (1997) 27 Environmental Law 1243, 1246.
 Bill McKibben, ‘Because the World Needs to Know’ (public lecture, University of Melbourne, 11 May 2009).
 On feedback loops and the tipping point, see New Economic Foundation, ‘100 Months: Technical Note’ (2008) <www.neweconomics.org> at 20 May 2009 (which calculates that 100 months from August 2008, atmospheric concentrations of greenhouse gases will begin to exceed a point whereby it will no longer be likely we will be able to avert potentially irreversible climate change). This indicates a much shorter period than previously thought in which to make the transition to a low-carbon economy.
 See Thomas Prugh and Robert Costanza, Natural Capital and Human Economic Survival (1995); Mathis Wackernagel, ‘National Natural Capital Accounting with the Ecological Footprint Concept ‘ (1999) 29(3) Ecological Economics 375.