Climate variability and extreme events due to intensification of the urbanization process–a study case at Oporto

Abstract: Oporto, a north-west coast Portuguese city of 300 000 inhabitants, has been the stage of an enormous economic growth during the two last decades. Especially after becoming membership of the European Union, in 1986, Portugal has constantly benefit from significant amounts of E.U. money in order to create and/or renew its productive tissue.

During this period we assist, in Oporto, at a considerable change in industrial and commercial location patterns and accessibility closely followed by the already expected reflexes in behaviour and mentalities. There was an enormous increase in the family incomes for the majority of the people, induced by this continuous afflux of money from E.U., immediately translated in a wild competition in an enlarged and more appellative market, which obviously carried at the same time some more negligent attitudes towards all the environmental components (eg. air, water, soil, etc.).

The economic growth of Oporto metropolitan area, as well as all the coastal cities from Braga till Setúbal, was one of the main responsible for the extraordinary national increase in energy requirements and emissions recorded after the 80's.

This poster tries to ilustrate, with some examples, that the Climatic System isn't immune to the increase on the amount and diversity of the outputs delivered by the Oporto urban metabolism to the atmosphere, especially during the last twenty years.

The presence of several intense Urban Heat Island(s) around Oporto show that all this modifications in the chemistry of the atmosphere emerge easily, at a local or regional scale level.

Nevertheless the shape and intensity of the Oporto urban heat island changed a lot, from one day to another, according with the weather type prevalent. The wind velocity and direction, the type and the vertical structure of the atmosphere have an effective control upon the thermal pattern within the city favorable to some factors more than others.

Having seen this we understand better that all the anthropic impacts due to an urbanization process may act as discontinuous but significant tensions on the Climatic System .

If we believe that the Climatic System 's preferred type of answer are the impulsive ones, we may conclude that a great number of extreme climatic events are no more than reorganisation mechanisms/processes connected to all the anthropic interferences in the Climatic System .