BES President Professor Georgina Mace talks to PLoS about Rio and progress in the 'limits to growth' debate

BES President Professor Georgina Mace yesterday talked to the Public Library of Science's (PLoS) Biology Podcast about the upcoming challenges faced at the Rio talks, and considered whether recent papers on environmental limits to population growth show progress in this decades-long debate.

The two papers in question were published by PLoS yesterday, and argue on either side of the classic discussion. In 'The Macroecology of Sustainability ', Professor Mace states that although the authors - Burger et al - start by adopting the traditional Malthusian perspective (which says that population growth will eventually be limited by finite resources), the paper goes on to extend the theory to a much more sophisticated level by considering how apparently sustainable local processes have impacts elsewhere in the global system. The authors state that this explains why we have rarely been observed to meet environmental limits in the past - in fact, in most cases, the impacts of human activity are actually displaced elsewhere, either spatially or temporally.

In the second paper, 'The Shifting Boundaries of Sustainability Science: Are We Doomed Yet? ', Matthews and Boltz echo the classic argument of Ester Boserup , stating that the 'limits to growth' theory championed by Burger et al is based on a very static view of the world which doesn't take into account changes in technology and innovation, the way resources are used and consumption behaviours. The authors give several examples of where apparent environmental limits have been overcome in the past.

Asked about how this debate may influence discussions at the Rio summit (currently taking place in Brazil), Professor Mace said that it is unlikely that the 'limits to growth' argument will be revisited in detail, but suggested that the issues will come to light in other areas of discussion. In particular, all nations are likely to agree that reducing absolute poverty is a priority goal for sustainable development, and Professor Mace anticipates that this will be linked to recognition that the only way to increase access to necessary material goods for the poorest will be to address excessive consumption at the top level - in a world of finite resources, we cannot increase consumption infinitely. Some attendees may echo Matthews & Boltz's argument that everyone's needs can be met by adopting new technological innovation and adjusting social systems to improve the efficiency of growth. Prof Mace anticipates that this discussion of 'green economic growth' will be a strong feature of the Rio meetings and that, although there remains much debate about the definition of a 'green economy', any discussion of the topic is positive as it will 'inevitably lead people to understand that economic growth is firmly rooted in environmental resources'.

Considering some of the reasons that, despite decades of international political debate on the subject, global environmental degradation is still occurring at a rapid rate, Professor Mace suggested that a continuing misconception of many people that humans are separate from ecological processes and the environment is a major cause of overexploitation; although we often have a good understanding of the macro-scale processes of issues such as climate change and biodiversity loss, we are less aware of how our actions at the scale at which we live our day to day lives leads to these problems. Similarly, the impacts of biodiversity loss are currently less obvious than factors linked to climate change such as rising sea levels and extreme weather, and there remains significant uncertainty both about what the implications will be, and how serious. An additional issue leading to inaction is that the causes and possible solutions to environmental degradation are not limited to the realm of natural sciences but rather involve governance and decision-making across policy areas, making cooperation difficult.

The strong political interests at play at international summits like Rio can also present barriers to real progress, said Professor Mace, and certainly, the recent history of this kind of discussion is 'not very positive'. However, she expressed optimism that one of the major outcomes of the Rio talks will be the development of new Sustainable Development Goals to replace the Millennium Development Goals. These, she says, will be more strongly based in social and natural sciences, and so 'will be achievable and won't conflict with each other', an issue she acknowledges has been one of the problems with similar international goals in the past.

Far greater interaction between social and economic scientists, already strongly involved in the sustainable development debate, and natural scientists, who have traditionally remained on the periphery, will be critical in devising solutions says Prof Mace. Working together, she says, these groups have the capacity to address some very difficult issues in the sustainable development debate, such as determining how adaptable and resilient systems are, and how far innovation and technology can help.

Professor Mace concluded that although progress has been slow in the past, finding solutions and harnessing political will to tackle environmental degradation and biodiversity loss on a global scale will be critical; 'if we don't do something soon, the effects for future generations could be quite profound'.

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