policymakers demonstrate

280 Paul Ekins, Paul Drummond, and Jim Watson
arising from these activities: the degradation or unsustainable use of approximately
60 per cent of the ecosystem services (defined in Section 7.3.2) it examined;
evidence that changes being made in ecosystems were increasing the likelihood
of nonlinear changes in ecosystems (including accelerating, abrupt, and
potentially irreversible changes) that have important consequences for human
well-being; and the fact that the negative results of environmental degradation
were being borne disproportionately by the poor, ‘contributing to growing
inequities and disparities across groups of people, and sometimes the principal
factor causing poverty and social conflict.’ (MEA, 2005, pp. 1–2). Secondly, in
2009, Rockström et al. (2009) developed the concept of ‘planetary boundaries’,
which defined a ‘safe operating space’ for humanity within the environment,
and published evidence of human activities in relation to this space across nine
environmental issues. Their work suggested that for biodiversity loss, climate
change and the nitrogen cycle, human activities were already outside the safe
operating space (with the phosphorus cycle fast approaching this condition).
Thirdly, the Fifth Global Environmental Outlook of the United Nations Environment
Programme concluded that ‘As human pressures within the Earth System
increase, several critical thresholds are approaching or have been exceeded,
beyond which abrupt and nonlinear changes to the life-support functions of the
planet could occur. There is an urgent need to address the underlying drivers
of the human pressures on the Earth System’ (UNEP, 2012, p. 194). Finally,
in 2013 the Intergovernmental Panel on Climate Change (IPCC), in its Fifth
Assessment Report, gave its starkest assessment yet on the threats to humanity
because of its continuing large-scale emission of greenhouse gases (GHGs),
with five ‘integrative reasons for concern’, namely unique and threatened
ecosystems; extreme weather events; distribution of impacts; global aggregate
impacts, including extensive biodiversity loss; and large-scale singular events,
with risks of ‘tipping points’ (IPCC WGII, 2014, p. 12).
Limits to Growth
The first economist to make an unequivocal prognosis of the unsustainable
nature of human development was Thomas Malthus (Malthus, 1798). To summarize
drastically, he noted that human population had an exponential growth
trajectory, that agricultural productivity had a linear growth trajectory, and that
fertile land was absolutely limited. From this, he drew the conclusion that
human population growth would be brought to a halt by a shortage of food,
and that such population as remained would bump along between subsistence
and famine, disease and war. He considered that technology might increase the
productivity of land, but ruled out the possibility that it could do so sufficiently
to negate for long the difference between rates of increase of human populations
and agricultural production, which led him to his dismal conclusion. Malthus
was wrong, but that does not mean that this basic insight – that the physical