Freshwater resources are of major environmental and economic importance. Their distribution varies widely among and within countries. In arid regions, freshwater resources may at times be limited to the extent that demand for water can be met only by going beyond sustainable use.

Fisheries make an important contribution to sustainable incomes, employment opportunities and overall food protein intake. On the other hand, overfishing of some species in some areas is threatening stocks with depletion. In certain countries, including at least two OECD countries – Iceland and Japan – fish is the main source of animal protein intake.

The amount of municipal waste generated in a country is related to the rate of urbanisation, the types and patterns of consumption, household revenue and lifestyles. While municipal waste is only one part of total waste generated in each country, its management and treatment often absorbs more than one third of the public sector’s financial efforts to abate and control pollution.

Carbon dioxide (CO2) makes up the largest share of man-made greenhouse gases. The addition of man-made greenhouse gases to the atmosphere disturbs the earth’s radiative balance (i.e. the balance between the solar energy that the earth absorbs and radiates back into space). This is leading to an increase in the earth’s surface temperature and to related effects on climate, sea level and world agriculture.

Atmospheric pollutants from energy transformation and energy consumption, but also from industrial processes, are the main contributors to regional and local air pollution and raise concerns as to their effects on human health and ecosystems.

Emissions of greenhouses gases (GHG) from human activities disturb the radiative energy balance of the earth's atmosphere system. They exacerbate the natural greenhouse effect, leading to temperature changes and other consequences for the earth’s climate.

Green areas such as parks and natural vegetation contribute to reducing pollution, improving the health and quality of life of residents, and making metropolitan areas more attractive to residents and tourists.