the evaluation of climate change risks

Nowadays, it is acknowledged that climatic changes represent a serious threat for the environment and, so, this problem has been approached at numerous conferences, conventions and summits. The climate is strongly influenced by the changes in the atmospheric concentrations of certain gases that hold the solar radiations on the Earth’s surface (the greenhouse effect). The water vapors and the carbon dioxide (CO2) present in the atmosphere have always generated a natural greenhouse effect, without which the Earth surface would be 33o C lower than it is today. Other greenhouse gases are: methane (CH4), nitrogen protoxide (N2O), and the halogenated compounds such as chlorofluorocarbons (CFCs). During the last hundred years, man’s activity has led to the increase of the atmospheric concentration of the greenhouse gases and of other pollutants, its consequence being the increase of the average global temperature. Although it has not been calculated exactly how much of this warming can be attributed to the greenhouse gases, there is evidence that human activity contributes to global warming. The main causes leading to the accentuation of the greenhouse effect are the burning of the fossil fuels, deforestations, cement production, waste disposal, refrigeration etc. The climatic changes triggered by the greenhouse gases will have consequences that have already made themselves visible, causing: the increase of the sea level and the possible flooding of the low areas; the melting of the icecap; the modification of the precipitations regime, with consequences like the increase of the floods and droughts frequency; changes in the occurrence of climatic extremes, especially in the occurrence of the high, extreme temperatures. All these will have a direct impact on ecosystems, health, some key economic sectors such as agriculture and on water resources.