Modern environmental Problems

Together with many social and economic benefits of urbanization, there are also environmental problems. Cities comprise less than 3% of the Earth's surface, but there is an extraordinary concentration of population, industry and energy use, leading to a massive local pollution and environmental degradation. In the cities, approximately 78% of carbon emissions are due to human activities. The ecological footprints of cities go (through emissions, consumption and other human activities) far beyond their urban boundaries to forests, agriculture, water and other surfaces, which supply their residents so that they have an enormous impact on the surrounding rural, regional and global ecosystem.

Cities are therefore centers of consumption (energy, materials...), greenhouse gas production, waste and emissions of pollutants in water and air. Ecological and sociological footprints of cities have expanded over increasingly large areas and created urban - rural continuum of communities, who share similar aspects of individual lifestyles. There are less and less areas in the world which are not under the influence of the dynamics of cities.

The world faces enormous environmental challenges in terms of climate change, resource use and protection of the natural environment. Urban areas have a high environmental impact that can be felt globally, as well as within its own borders.

Ecological footprint

The environmental impacts of modern cities go beyond their surrounding regions. Size, rate, and connections of the modern metropolis show a global impact. The ecological footprint is one measure of these effects. The ecological footprint of cities is defined as the total amount of productive land needed to maintain current activities and the removal of waste. The ecological footprint of cities such as New York and Tokyo are hundreds of times larger than their actual size and are also faced with problems such as acid rain, reduction of the ozone layer and global warming.

Developing countries

In the cities of the developing world, where population growth is outpacing the ability to provide the necessary infrastructure and services, the most serious environmental problems are expected in the immediate vicinity, with serious economic and social impacts on the urban population. Inadequate water supply to households, the accumulation of waste and unhygienic conditions require large claims in terms of unnecessary deaths and illness of one billion of the world population who lives in slums. Cities in developing countries are also faced with the worst urban air pollution in the world, which occurs as a result of rapid industrialization and increased motorized traffic. It is estimated that worldwide urban air pollution is cause of one million premature deaths each year and costs 2% of the GDP in developed countries and 5% in developing countries

Developed countries

The urban population of developed countries, which is characterized by some of the highest rates of per capita consumption in the world is largely responsible for the resulting trends. US city with 650, 000 inhabitants requires approximately 30, 000 km2 to meet their needs, similarly big, but a less wealthy city in India requires only 2, 800 km2. Similarly, the urban population of the developed world produces six times more waste than urban dwellers in developing countries.
However, developing countries are becoming richer and urbaner, and their levels of consumption are close to those in developed countries. As a result, they rapidly and significantly contribute to the global problem of resource depletion and climate change. The need to change the cities into more efficient and less polluted areas is, therefore, more necessary than ever.

While cities of developed countries have adopted policies and technologies to improve many of their local environmental problems, it is growing recognition that human activities in urban areas have significant impacts at the global level. In fact, cities of the world represent 75% of global energy consumption and 80% of greenhouse gas emissions and a disproportionate share of resource use.