The World Environment 1972-1992 offers a look at the environment from three perspectives. Ten introductory chapters detail the range of environmental threats and examine how they have unfolded over the past two decades. The threats include those that were well known two decades ago, such as toxic chemicals, air and water pollution, and land degradation (desertification, deforestation and soil loss). They also include those that have emerged over the period under review - stratospheric ozone depletion, loss of biodiversity and climate change.