No such thing as a cheap lunch? Quantifying tradeoffs between yield and environmental externalities in food production systems

How can we feed a rapidly expanding human population without causing further grave damage to biodiversity? Many argue that the environmental impact of farming might be best limited by linking high farm yields, with sparing natural habitats elsewhere. However, there is a widespread if as-yet untested perception that high-yielding farming techniques involve larger environmental externalities (such as greenhouse gas emissions, nutrient and freshwater depletion) than lower-yielding methods, producing the same quantity of goods. This project, involving the University of Cambridge Department of Zoology, RSPB, the Sainsbury Laboratory and rhe University of Cambridge Veterinary School, will systematically test this proposition across four important agricultural sectors, identify especially promising farming systems characterised by relatively high yields but limited environmental costs, and develop and implement a novel technique for the robust integration of externalities into land-use planning.

This project is funded by the CCI Collaborative Fund for Conservation.

Project Aims

This project aims to test the idea that, per unit production, high-yielding farming imposes larger environmental externalities (eg greenhouse gas emissions, nutrient pollution, freshwater depletion) than lower-yielding methods. By collating and modelling published and unpublished data on four major farm sectors we will begin to answer three questions:

  1. Are tradeoffs (ie positive correlations) between yields and environmental externalities typical, and what are the key uncertainties?
  2. Are there current production systems which are particularly promising or especially unrewarding?
  3. How far are yields reduced, and hence the relative favourability of high- vs low-yielding approaches altered, once externalities are considered?

Key Activities

We will tackle these questions by bringing together a major new network of conservationists, agricultural experts and environmental scientists with experience in four globally significant sectors – (1) cereal and (2) dairy production in western Europe; (3) paddy rice cultivation in south and east Asia; and (4) beef production in tropical Latin America. Together we will collate and analyse state-of-the-art information on four major environmental externalities – GHG emissions, water use, N and P losses to air and water, and soil loss – before, during and after an intensive four-day, 25-person workshop in Cambridge.

Conservation Impact

This project is central to one of CCI’s core priorities –reconciling biodiversity conservation and food production. It is closely linked with the activities of Cambridge’s Global Food Security Initiative, and with the policy interests of both RSPB  (whose new agriculture strategy highlights better understanding of externalities as a key knowledge gap) and UNEP-WCMC (which seeks to offer governments policy advice and tools on issues such as agricultural development planning). It will be considered successful when its findings have informed the policies of key participating organisations.


  1. A new framework for capturing the most important elements of the environmental footprint of alternative farming systems – their yields and their externalities – alongside a new approach for estimating the costs of internalising major externalities.
  2. New collaborations at the conservation-agriculture interface – eg between CCI partners, Rothamsted and the International Rice Research Institute.
  3. Two peer-reviewed papers - one setting out key findings and a second detailing our new method for estimating the costs of agricultural externalities via on-farm internalisation.

CCI partners Involved

The University of Cambridge's Sainsbury Laboratory is a research institute funded by the Gatsby Foundation. The aim of the Laboratory is to elucidate the regulatory systems underlying plant growth...
The Royal Society for the Protection of Birds (RSPB) speaks out for birds and wildlife, tackling the problems that threaten our environment. It is the largest wildlife conservation organisation in...
The Department of Zoology carries out wide-ranging work in ecology and conservation including conservation science, aquatic ecology, pathogen evolution and evolutionary ecology. Research of the...
The Department of Veterinary Medicine at Cambridge is at the forefront of veterinary science and education and is a centre of excellence for teaching and research. We are a large, multidisciplinary...