State of Art in the Field

Effects of extreme events

Impacts of future climate change on climate variability will become a further major threat to the built cultural heritage [7]. Many processes affecting the conservation of archaeological and historic sites do not occur at regular intervals, but are concentrated in episodic outbursts related to the presence of extreme events, such as severe storms, carrying both water and dust. As examples, frequent repetition of floods and windstorms accompanied with landslides and fires have affected large and rich cultural heritage areas, e.g. in Italy, Turkey, Bohemia. The frequency of flooding will increase in many areas of Europe. Some extremes of weather and climate are predicted to increase in many areas, bringing a rise in average precipitation, higher maximum temperatures, more intense precipitation events or an increase in summer drying (drought and in the longer term desertification). In addition, current knowledge on future changes in extreme events, such as tropical cyclones, is still very limited.

Impacts of climate change on sea levels are well known. Low-lying areas, especially around seas with rising levels, will be particularly at risk and there is a wealth of heritage in such environments [8]. Sea level and climate change will affect terrestrial hydrology, also producing a potential alteration in groundwater and soil water level and chemistry. Soil water and ground water will be directly affected by global warming. In many low lying coastal areas groundwater levels will also rise as a consequence of increased intrusion of seawater into ground water areas. Changes in ground water, particularly the lowering of water tables, can lead to salinization, which will affect monumental structures.

An increasing number of historic buildings are subject to flooding, through river or sea flooding, or as a result of increased rainfall, inadequate roof drainage and poor surface water management. Increased winter rainfall and storminess, particularly in exposed areas, is resulting in water-saturated building fabrics.