INTRODUCTION

Chapters 2 to 5 have set out theories and approaches to sustainability. Some of these are focused primarily on maintenance of production over time and what needs to be done to achieve that. Total factor productivity attempts to view production through the lens of all that is needed to produce an output, including man-made and natural inputs. Maximum sustainable yield is a theoretical basis for maintaining harvests from a dynamic population resource such as a fishery. In Chapter 4 we looked at industrial production and how we can envision production or the provision of a service in terms of energy and related concepts of emergy and exergy. We also explored ways in which industrial processes can be analysed through material flows and life cycles. In Chapter 5 we encountered economic approaches and the valuation of both man-made and natural resources, their consumption and degradation. The chapter ended with an introduction to the concept of sustainable livelihoods.

Therefore, in this book we have encountered a mixture of approaches employed to better understand sustainability and more applied studies intended to help with the achievement of sustainability through management or policy formulation. The two overlap of course; research designed to analyse the life cycle of a GM crop will add to human knowledge and give us a better understanding of the environmental costs associated with production of GM and non-GM varieties at farm level, but the findings can also feed into policy.