Environmental Problems of Modern Cities
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.
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.
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
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.
Environmental problems of modern cities
Urban environmental problems are mostly inadequate water supply, wastewater, solid waste, energy, loss of green and natural spaces, urban sprawl, pollution of soil, air, traffic, noise, etc. All these problems are particularly serious in developing countries and countries with economic transition, where there is a conflict between the short-term economic plan and the protection of the environment.
Pollution of the urban environment and its components is the total resultant of an excessive burden on the environment and the self-cleaning capacity. Environmental problems in urban areas are growing especially in cities in developing countries. Of greatest concern are the state of air quality, noise, and congestion. In cities of economically developed countries, the environmental problems related to industrial production, lodging, and basic infrastructure are reduced, however, the problems of consumption (increasing waste) and traffic problems have increased. Cities consume increasing amounts of natural resources, produce more and more waste and emissions, and all this have an impact on the regional and planetary environment. Air and water pollution and waste are the main environmental problems in most cities. The underlying causes of air pollution of the city are the processes that are associated with the burning of fossil fuels (production and consumption of energy for heating buildings, industrial activities, traffic). Noise is also a special form of pollution, which burdens the urban population. Urbanization causes numerous effects on water resources; these effects can change the hydrology, water quality and availability of aquatic habitats. Deterioration in the quality of ground and river water in the cities is mainly due to the water consumption of the population and industry. Contamination is usually caused by industrial activity as well as the disposal of waste, so in cities is dominated water pollution from municipal and industrial wastewater. The city is marked by large inputs of energy, water, food and a variety of raw materials, resulting in large quantities of goods, as well as waste, which means a huge loss of natural resources in the form of raw materials and energy. Urban ecosystems are indicated by a very high energy consumption and large amounts of solid waste that accumulate in certain places. In this way, they represent landscape degradation factor and adversely affect the quality of water resources and urban air.
Have you ever felt the polluted air in your city?
In most cities, a man transformed nature, vegetation was replaced with concrete, asphalt, and other surfaces, transformed or buried riverbeds, caused city climate and created huge artificial transfers of energy, water, and various substances. Growing cities are changing hydrological relationships and thereby influence the size and frequency of floods. Knowledge of urban hydrology and geomorphology is not only a key to good urban planning but should be available to each resident.
Cities have little direct impact on the global balance of radiation, but inside urban climate, generated by absorption and subsequent re-radiation of heat from built-up areas and emissions of artificial heat through combustion, creates the effect of the urban heat island. Cities are warmer at night than the surrounding countryside and often, especially in the higher latitudes, even during the day. In Tokyo, anthropogenically generated heat increases the temperature of the urban surface by about 1.5 ° C in summer and 2.5 ° C in winter, the effect of urban land-use raises the temperature by about 1 ° C in both halves of the year.
Even the hydrological cycle is increasingly under the influence of a man who uses water for different purposes and returns it to the water cycle contaminated. These changes are in urban areas so profound that we can speak of urban hydrology. Built-up areas create artificial impervious surfaces that reduce surface water supplies, infiltration is gone, surface flow, permeability, and erosion are increased, evaporation is reduced. In a wider range, it comes not only to qualitative but also quantitative consequences (regulation, dams, ...). However, human activity is reflected in the quality of water resources. The major problem present urban waste water and residues of pesticides and biocides, which pass through the surface and groundwater. Freshwater resources in urban areas are also threatened by the waste from transport, tourism, military activities.
Human activities have a negative impact on pedosphere; this is reflected in the increasing chemisation and mechanization of agriculture and in the cities, however, especially as poisoning the soil through contaminated air and precipitation and changes in the quality of land use for sealing.
Consequences and effects of urbanization
Knowing the problems of urbanization is not enough, it is necessary to understand their implications and the degree of social preparedness to deal with them. Consequences and effects of urbanization depend on many other factors and are operating in all segments of human activity and the environment. They can be divided into several groups:
1. Environmental problems due to the production and consumption:
- increasing energy consumption, which results in a reduction of non-renewable resources
- problems of infrastructure that does not follow the spread of urbanization
- high consumption of drinking water, which affects the lowering of groundwater levels
- excessive use of space
2. Pollution problems from major manufacturers and emissions problems due to the dispersed agents:
- pollution of water, air, soil due to industry and agriculture
- problems of waste disposal sites, particularly radioactive
- the problem of the concentration of population (air pollution, groundwater ...)
- a dense network of roads and increase in traffic (air pollution, noise, ...)
3. Social and environmental problems and the consequences of urbanization (differences between population groups, stress loads, accidents, disease, crime, ...)
4. The economic component of the effects of urbanization (accidents, the cost of building infrastructure, road network damage as a result of an interaction of a large number of factors which by themselves would not have negative effects on the environment, ...).
Where the cities trigger environmental problems, they also offer solutions. As 'hot spots' of production, consumption and waste generation, cities possess the potential, which can increase the energy efficiency and sustainability of society as a whole. Solving these problems is beneficial for the environment, and also improves the health and wellbeing of citizens and should be the basis of development that would make cities more attractive places for living and working.
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Air pollution in Beijing
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