Water used by irrigated crops is obtained from three sources: local precipitation contributing to soil moisture available for root water uptake (i.e., green water), irrigation water taken from rivers, lakes, reservoirs, wetlands, and renewable groundwater (i.e., blue water), and irrigation water abstracted from nonrenewable groundwater and nonlocal water resources. Here we quantify globally the amount of nonrenewable or nonsustainable groundwater abstraction to sustain current irrigation practice.

It is widely held that humankind's destructive tendencies when exploiting natural resources leads to irreparable harm to the environment. Yet, this thinking runs counter to evidence that many ecological systems damaged by severe natural environmental disturbances (e.g., hurricanes) can restore themselves via processes of natural recovery. The emerging field of restoration ecology is capitalizing on the natural restorative tendencies of ecological systems to build a science of repairing the harm inflicted by humans on natural environment.

The Nuremberg Code, set up to protect the human subjects of research, is being routinely ignored, warns Harriet A. Washington.