Pharmaceutical residues in waterways, industrial waste lingering in soils, space debris in orbit for hundreds of years, nuclear waste requiring management for thousands of years, and greenhouse gases affecting carbon cycles subject to geologic time-scales: these pollutants are the potentially long-lasting side effects of modern, growing economies and the attainment of ever-better standards of living.
Policymakers seek to protect the public by balancing the costs and benefits of mitigation, remediation, and other strategies to control these problems. Unlike the case of many shorter-lived pollutants, however, these long-lived contaminants are particularly vexing for regulators and citizens alike. Indeed, these long-lived environmental issues could be thought of as a class of problems that are "forever ours," unique because of their almost unrestrained temporal scale. The contaminants may be present in trace amounts or have other effects that cause only small damages today; thus the public may not feel urgency to take action. But the contaminants may persist and, even worse, accumulate over time to create much greater damage, although in a perhaps very distant future. Some pharmaceutical residues, certain greenhouse gases, and space debris that self-collide to produce yet more debris are examples of pollution with cumulative effects that can worsen to create significant future harm.
