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Climate change

Le dune di Porto Pino - foto di Roberto Agostinelli
According to the Intergovernmental Panel on Climate Change (IPCC) Fourth Technical Assessment Report (TAR) published in 2007, the 11 years from 1995 and 2006 were amongst the warmest since records of global temperatures began in 1850. The linear temperature increase from 1906 – 2005 was 0.74 [0.56 – 0.92] (the numbers in square brackets indicate the level of uncertainty around the best estimate) and is larger than the corresponding trend in the Third Technical Assessment Report (2002).
The main reason for the temperature rise is a century and a half of industrialisation: the ever increasing combustion of petrol, gas and coal, the cutting of forests and a rise in land used for agriculture

The definition of climate change used by the United Framework Convention on Climate Change (UNFCCC) is a change in the climate which is greater than those caused by natural variations observed in comparable periods of time. The variation is attributable to an alteration of the global atmosphere, directly or indirectly caused by human activity.
The evidence and the scenarios presented in the IPCC Fourth Assessment Report: Climate Change 2007 – AR4 have aroused considerable concern, in particular with regards to the possible implications for ecosystems, populations, and, above all, economic sectors which depend on specific climate conditions. From the main evidence emerging at a global level, the following phenomenon can be cited:
• an overall increase in global temperatures: the years from 1997 – 2008 were among the warmest on registered since global temperature measure began in 1850. 8 of the 10 hottest years have been recorded since 2001. The overall increase in global temperatures from the average of 1850 – 1899 and that from 2001 – 2005 was 0.76C;
• the thawing and resulting contraction ice covering land and sea: satellite observations since 1978 show how the annual average Arctic sea ice has reduced by 2.7% per decade, with even greater reduction in the Summer (7.4% per decade);
• sea level rise: average global sea levels increased by 1.8mm per year between 1961 and 2003. The rate of increased to 3.1mm per year from 1993 – 2003. We can expect territorial variations and more intense precipitation, as well as an increased frequency of extreme phenomena (flooding, drought, etc.).

According to the IPCC, changes to the atmospheric concentration of greenhouse gases and aerosols (small particles such as nitrates and dust, etc.), forest coverage and solar radiation are capable of altering the energy balance of the climate system, creating disorder. From 1970 – 2004, global emissions of greenhouse gases (GHG) increased by 70%. The largest sources of greenhouse gases come from energy production activities (26%), industry (19%), deforestation and land use (17.4%), agriculture (14%) and transport (13%).
The latest IPCC report confirms that future climate change will not be confined to rising temperatures, but will also produce a change in the whole climate system with serious repercussions for ecosystems and human activities. The scenarios outlined by the IPCC envisage a rise in global emissions of GHGs ranging from 9.700.000 to 36.700.000 metric tons of CO2-eq between 2000 and 2030. These changes have led to an increased loss of biodiversity, have placed considerable stress on land and marine ecosystems. Rising sea levels are of particular relevance to coastal area management. Analyses and observations of the changes that affect sea levels have become increasingly important, above all because of the potential impacts on populations living in coastal regions and islands.
There are two main causes of sea level rise: the thermal expansion of the oceans and the thawing of land ice. Since 1993 thermal expansion of the oceans has contributed around 57%, while the reduction of glaciers and the ice caps added 28%.

The main impacts of climate change on the coasts of Sardinia

The intensification of erosion is one of the most important observable impacts on the coastal areas of Sardinia. Reference to literature published on the subject can help establish the scale of the problem. For example, according to one study by the Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA) (2005), over the last 40 – 50 years Sardinia has lost around 107Km of coast. Studies by Gruppo Nazionale per la Ricerca sull’Ambiente Costiero (GNRAC) (2006) note the impact of erosion along 165Km of coast (or 35.9% of the sandy coast). Ranieri (2008) highlighted a loss of around 20m in only a few years in the coastal area of Porto Torres.

The following climate change related impacts on the coasts of Sardinia have been described in recent literature:
• increased frequency of extreme events linked to the weather, sea storms, increased wave energy and the effects of prevailing winds;
• increased sea levels (caused simultaneously be human and natural processes) and sea currents;
• a trend of decreasing levels of precipitation and resulting reduction of river sediments to the beach;
• increased risks of instability, erosion and coastal retreat, in particular for the North and North-West Sardinian coasts.

According to a 2007 study by the ENEA (the national agency for new technologies, energy and sustainable economic development), by the end of the century, the North-West of Sardinia, particularly the low valley of Coghinas and the coastal aquifers of Pilo lagoon, will be subjected to an average sea level rise of 0.31m. The sea level rise will accelerate the rate of erosion and degradation of the coastline, while salt intrusion could have a negative effect on coastal aquifers.
Beaches have become increasingly valuable tourist attractions, providing many leisure and recreation activities. Today’s bathing landscape is being modified, driven by a growing trend which is influenced by natural events and human intervention. In their natural state, the beaches have an intrinsic value, and a strong value added on the economic sustainability of the area. Studies suggest that, on average, each m2 of beach has a value between €800 and €2000.

According to a recent study (CIRCE, 2008) in a famous Mediterranean tourist destination, the number of people employed in the sector could reduce by 18%, solely because of erosion of the beach. This would cause a 0.3% loss of GDP for the same area. Currently there are no studies considering the impacts of climate change on Sardinia’s socio-economic system. Sea level rises could cause a reduced availability of land. Studies by Fondazione Eni Enrico Mattei (FEEM) and ENEA suggest a loss of land due to an average increase of the sea level in the Sangro river estuary (Abruzzi). In this case, the direct costs were estimated at €14 million (Breil et al, 2007) for the IPCC 2100 scenario. When the probability of an increased intensity of hydrological activity is added to the increased sea level, the costs rise to around €73 million.
Loss of land is not the only impact to be considered. We should also consider the potential number of people who would be flooded or forced to move.
Erosion will play a very important role, from desertification and tidal surges which will have serious impacts on agricultural production through the loss of cultivable land. This will have severe, indirect socio-economic impacts, such as a loss of productivity and an increase in unemployment in rural areas.

by Alessio Satta