The atmosphere, oceans and biosphere are global commons, changes in which affect all human society. There is no doubt that human activity has caused global atmospheric changes, but the effects of these upon climate, and hence upon land productivity, are not known. What matters is not the climatic changes themselves, but preparedness by countries at risk to meet them. Conservation of biodiversity – plant and animal species, ecosystems, and genetic resources – is both a national and a global concern. Ecosystem services, such as regulation of the atmosphere, water, and nutrient cycles, and filtration of wastes, provide benefits to human society of the same order of magnitude as the whole of the world's gross national product. In developing countries, land shortage puts pressures on protected areas, and still more on ecosystem conservation outside these. Whilst international efforts help in the short run, the long-term solution can only come from recognition of the value of conservation by national governments and their people.