The effort factor: Evaluating the increasing marginal impact of resource extraction over time

Concern for the increasing impact of human activities on Earth’s ecosystems has generated a growing effort to monitor those impacts and measure the success, if any, of mitigation measures. This contribution argues that ecological impact assessments that tend to rely primarily on the volume of natural resources produced and subsequently consumed overlook the degree to which ecological impact can vary significantly independently of production volumes, due to the varying impact that results from production effort. Production effort, in turn, is directly linked to the quality of raw materials, which inevitably tends to decrease over time. As a result, unless technological improvements were able to compensate for the resource quality decline indefinitely, we face a future of increasing marginal ecological impact over time. This is demonstrated here based on three resource extraction systems, coal mining in the UK, grain production in China, and global marine fisheries. 2014 Elsevier Ltd. All rights reserved.