Environmental problems, and our perceptions of their current and future health effects, have changed over the decades. About 20–40 years back, public health was most concerned about localised environmental degradation, as exemplified by air and water pollution. Although it was often difficult to measure the direct health effects, the paradigm of public health worked reasonably well to cope with these problems. As a result, some of the localised environmental problems of the 20th century have been solved, at least in the richer parts of the world.¹

We have since become aware, however, of the threats to human health which operate at a much larger geographical scale, and which, because of their non-localised character, are even more difficult to investigate. All these “global environmental changes” are due to increased human pressure on the environment, of which the main drivers are population growth and an increase in per capita resource use and waste production. Climate change and other changes to the atmosphere, land use changes and soil degradation, freshwater depletion and contamination, and biodiversity loss are four important categories of global environmental change, each of which form potential, although partly or largely unknown, threats to human health.² What should public health research do to help humanity cope with these new environmental problems?

WHAT IS KNOWN ALREADY?

A better understanding of the (potential) health effects of global environmental change is only just emerging, partly based on observations of current exposure–health outcome associations, partly based on scenario analyses, and in both cases surrounded by considerable uncertainty. These health effects are mediated by a number of causal pathways, of which the most important probably are heat waves and other extreme weather events, changes in the spread of micro-organisms, changes in biological productivity of land and water, …