Climate change in Italy: what do we really know?

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How will climate change in Italy? What will be the consequences for the country? Despite criticism by "climate deniers", a hundred of Italian scientists working in various capacities on climate change - from atmospheric physics to economics, have tackled the issue. The result is a volume of 590 pages which is under all respects the equivalent of the IPCC report for Italy. "Climate change in Italy: evidence, impacts and vulnerability, edited by Sergio Castellari and Vincenzo Artale (Euro-Mediterranean Centre for Climate Change - CMCC - Bononia University Press, 2010) is a mine of current data and projections on climate and its many and sometimes unexpected impacts. The nice thing about the Italian report is that "it does not make it a political issue," as the intent was not to define nor even to suggest answers to the now ascertained phenomenon of climate change.

The main objective of the report is to illustrate the state of the art in climate research in our country, a few bright spots in the gloom that still characterizes it. Despite themselves, climatologists are today in the same situation of nuclear physicists at the time of the Manhattan Project - said Anthony Navarra, president of CMCC (National Research Center on climate science and policy) at the book presentation in Venice on April 15 - They have been charged with a huge responsibility amid very high political tensions and expectations. Yet climate research is still underfunded, in Italy just as everywhere else. And with these resources it has trouble facing up to the great practical and theoretical challenges that lie ahead."
The report - the fruit of two years of work coordinated by Sergio Castellari of CMCC and Vincenzo Artale of ENEA (Italian National agency for new technologies, Energy and sustainable economic development) - could be the first of a series, with updates every three years. In 19 chapters, the book addresses climate issues in all their aspects, starting from the basic disciplines (meteorology, climatology modelling, atmospheric physics) and then moving on to the examination of the impacts (hydrological cycle, agriculture, desertification, forests, mountain, biodiversity, marine system , health, urban planning, energy, transport, economic system). Let's see how, gleaning from the abstracts of those researchers involved in the work:

Climate changes in the last two centuries

"It is especially interesting to note that the10 warmest years since 1800 in Italy are after 1990 and that, of these, six in 10 were after the year 2000. These data confirm the upward trend in temperature. Equally significant is the fact that 16 among the 20 warmest years took place after 1980. The top ten of temperature over the past two centuries is in fact the following: 2003, 2001, 2007, 1994, 2009, 2000, 2008, 1990, 1998, 1997. " write Teresa Nanni of the Institute of Atmospheric Sciences, of CNR (National Research Center) in Bologna and Maurizio Maugeri and Michele Brunetti of the University of Milan. "The mean anomaly of these first 10 years is 1.2 ° C higher than in the reference period, while the mean anomaly of the six years following 2000 is slightly higher than 1.3 ° C. Regarding rainfall, if we consider the period November 2008-April 2009, we hit a record: 54% more than the climatological average for the period 1961 to 1990, never in the past two centuries had so much rain fallen in Italy during the same period.
Maximum and minimum anomalies and average temperature in those 200 years for each month of the year also present an interesting picture. Excluding January, November and December (the hottest of these three months were, respectively, in 1804, 1926 and 1825) the maximum temperatures of all months have been recorded in recent years: in February 1990 with +2.93 ° C , March 2001 with 3.5, April 2007 with 3.13, September 1987 with 2.92 , October 2001 with 2.9. Then there is 2003, the warmest year in the last two hundred, a record achieved mainly because of an extraordinary heat wave in May and August, with significant and sustained positive anomalies, respectively 3.05, 5.12, 2 , 84, and 4.45 ° C above the 1961-90 average of each month. Conversely, it can be observed that the minimum temperatures of each month from January to December, were all in very far apart years: ten of them date back to 1800, September was in 1912 and October in 1974."

The future of climate in Italy

climate
#LLL#
Difference between the average
air temperature at
2 meters (T2M) in the period 2071-2100
and in the period 1971-2000 obtained
from simulations of the 20th century
and the 21st century (scenario A2
performed with the model SXG of CMCC
following the CMIP3 protocol
(Gualdi et al. 2008). The upper
panel shows the difference
for the winter (December,
January and February, DJF), while
the lower panel shows
the difference for the summer
(June, July and August, JJA).
The temperature is in ° C.

"According to the projections of climate change for the Euro-Mediterranean region obtained from global models, the region may be subject to a substantial warming, which in the Mediterranean basin would be more pronounced in summer and at the end of the twenty-first century it could reach a 4 ° -5 ° C increase in the seasonal mean surface temperature compared to the end of the twentieth century. " write Silvio Gualdi and Antonio Navarra of CMCC, and Filippo Giorgi of Abdus Salam International Centre for Theoretical Physics in Trieste. "The warming of the region would be accompanied by an increase in winter precipitation in the north of the Alps, while southern Europe and the Mediterranean region would suffer a drastic reduction in precipitation, more pronounced in summer (-25-30%).
In addition, the global projections indicate that the signal of climate change is clearly visible also in the variability among various years, which shows a marked tendency to increase as does the occurrence of extreme events (heat waves) and drought.
More specifically, for Italy, regional scale models indicate a warming in all seasons, although with a maximum during summer and a minimum in winter. Precipitation decreases heavily on the peninsula in the summer and, to a lesser extent, in spring and autumn. In winter precipitation increases in northern Italy and decreases in the south of Italy. This is accompanied by periods of drought and more frequent heavy precipitation events.
"The signs of change in precipitation and temperature show a fine pattern related to the topography of the peninsula. This is why a new generation of models is being developed that incorporates the Mediterranean Sea in an interactive manner, both in global and regional models. This will generate new ad hoc scenarios for the Mediterranean region for the 5th IPCC report, whose release is planned for the year 2013. " This is part of the agenda of the ambitious European project CIRCE.

Climate Extremes in Italy

"Currently, the Italian territory is experiencing an increase in daily maximum and minimum temperatures, connected to a shift of the entire statistical distribution of values towards warmer temperatures and thus an increase in average temperature. This trend is consistent with the increased frequency of heat waves (tripled in the last 50 years) and projections of climate models indicate that it will become progressively more marked during the 21st century, "write Piero Lionello of the University of Salento in Lecce and numerous colleagues who contributed to the chapter. The projections of climate change on a local scale for temperatures and precipitation for the period 2070-2100 show significant temperature increases.
Finally, Italy is experiencing a reduction in the number of days with little rain and an increase in days with heavy rainfall in some regions of northern Italy. Because of the strong intrinsic variability in precipitation regimes, however, statements about rains cannot be made with the same level of confidence as for temperatures. The results for Emilia-Romagna indicate that the minimum and maximum temperature will be significantly warmer in all seasons. The average increase for the maximum temperature reaches 5 ° C in summer, 3 ° C in spring and 2 ° C in the other seasons. The increase in minimum temperatures is more intense during the summer and fall, with values up to 4 ° C, while in winter the increase is about 3 ° C. As for the Italian Peninsula simulations foresee a reduction in the number of days with precipitation in all seasons, weaker in winter and more intense during the other seasons.

Clear, fresh (scarce) water

"According to the models included in the Fourth Assessment Report, the Mediterranean hydrological cycle will be significantly influenced by global climate changes forecast for the XXI century. In fact, projections show a decrease in average annual precipitation in the Mediterranean area by about 20% (SRES A1B scenario, anomalies in the period 2070-2099 compared to 1950-2000), "say Michele Vurro of the CNR and the other authors of the chapter. "In percentage terms, the anomalies are greatest in summer, which is also the period for which there is maximum consistency between models. A decrease in rainfall should be accompanied by an increase in evaporation in the Mediterranean region. With regard to the sea, this will mean an increase in surface water deficit. On land, most likely this will lead to a decrease in soil moisture, which will be particularly pronounced during the summer. In fact, considering the changes until 2050, the Mediterranean is among the regions for which the models show the greatest consistency, with a decrease of 10-30% of surface waters. The implications of these projections are that the Mediterranean region will suffer a decrease in water resources (this projection is given with a very high confidence level in the IPCC WG II, 2007), and the decrease in surface waters will be exacerbated by the decrease in groundwater.
These projections are affected by uncertainties related to the formulation of models (including the insufficient spatial resolution of the simulations) and scenarios of future emissions and other radiative forcings. In addition, the natural decadal variability will contribute to the anomalies of the hydrological cycle in the Mediterranean in the coming decades. "

How will agriculture and forestry change?

"There is now undeniable evidence that the Earth system (crops and forests) is responding to changes in environmental stimuli with increased productivity. The causes are not entirely clear, although it is reasonable to assume that the increase in atmospheric concentration of CO2, increased nitrogen deposition, changes in climate, changes in solar radiation and even changes in galactic cosmic rays associated to solar activity may explain the phenomenon. However, also the change in management systems can contribute to this extraordinary response. The consequences can be many, exceedingly complex and perhaps not entirely predictable, "explain Franco Miglietta and Francesco Vaccari, of CNR in Florence, and Marco Bindi of DISAT of Florence. "The first and perhaps the most obvious one, concerns the carbon cycle; if plants grow more, they fix more atmospheric CO2 removing it from the atmosphere and sequestering it in trees and soil organic matter. If plants grow more they place greater amounts of water vapor in the atmosphere, with potential consequences on rainfall. If plants grow more the soil is better preserved, as plants facilitate its permeability, reduce the amount of rainwater that quickly returns to the sea through surface runoff. Finally, food resources increase for a long chain of organisms that live on forest products: from microorganisms, worms, insects and all the way up to mammals. One may even go further and consider the hypothesis that biodiversity may eventually increase. The goal of research is to understand the causes and consequences of global change. We must make rapid progress in this area and exploit the great potential and great services that nature and woods are freely providing us. Once again nature proves our most important ally in the fight against climate change. It is our duty to help this ally, and help it in defending us from the damage that we may be causing to our planet.
On the other hand, as noted in another chapter by Riccardo Valentini of the University of Tuscia and the other authors, a possible increase in forest productivity could lead to a "gradual disruption of forest ecosystems, of which only a few will be able to migrate to areas more suitable to the changed climate scenarios, while most of them are destined to extinction, at least locally. An alteration of the balance with pathogens (with a possible increase in forest diseases) and an increase in forest fires are also expected, mainly because of temperature increase but also as a result of drought conditions.

The extinction of the glaciers and mountain ecosystems

The mountain environment seems to be one of the most affected by current climate change. "The data presented confirm that in the Italian Alps a widespread retreat of glaciers is under way since the mid-nineteenth century, with limited episodes of new advancements between the years 1970 and 1980 in the twentieth century and early '20s. This is consistent with what has occurred in general on the Alps (where the glacial coverage decreased from approximately 4474 km2 in 1850 to 2000 km2 in 2003 with a 55% reduction) and the evolution of the alpine climate of the last 80 years which recorded a temperature increase almost twice the global average, "write Luca Mercalli and Daniele Cat Berro of the Italian Glaciological Society, Giovanni Mortara of CNR in Torino Claudio Smiraglia of the University of Milan.

"Similar values of coverage retraction were recorded on the Italian mountain ranges: the glaciers of the Piedmont side of the Gran Paradiso had already lost 50% of their 19th century area in 1991 and have further contracted since then. On the Valsesian side of Mount Rosa, the reduction was 53% between 1850 and 2006. For the entire Valle d'Aosta the reduction of glacial coverage from the Little Ice Age is estimated at 41.5%, while for other mountain ranges of the Central Alps, such as Ortles-Cevedale the reduction has been of 47%. The reduction in the areas has been accompanied by a reduction in the lengths of the sides sometimes recording retractions of several kilometers if compared to the positions of two centuries ago (-1.6 km for the Lys glaciers of Mount Rosa, Pré de Bar on the Mont Blanc, Forni on Cevedale) . Since the mid-800 the thickness of the glaciers has been decreasing significantly as well, in some cases more than one hundred meters.

The disintegration of Alpine glaciers
Due to its intensity, the phenomenon taking place on the Italian Alps can be defined as a rapid "disintegration of the glaciers," a veritable "collapse" of the cryosphere, which results in the extinction of the smaller glaciers, the fragmentation of the major glaciers (e.g. Brenva on the Mont Blanc, Lys on the Monte Rosa, East Fellaria on Bernina), the emergence of ever larger rock "windows", the formation of numerous ice-contact glacial lakes and the increase of surface debris cover leading to the transformation of the Italian Alps glaciers from the classical "white" glaciers into "blacks glaciers, whose area of ablation is completely covered with debris thicker than 1 meter. This latter phenomenon is also linked to the increased dynamics of the slopes in relation to the melting of permafrost and buried ice lenses, which, together with concentrated precipitation, causes collapse events at high altitude (> 3000 m) even of considerable volume, sometimes with exposed ice and the imbibition of melted glacial deposits resulting in the formation of mud flows and debris.
As a result of this development the hydrological regimes will change, initially recording summer peaks with greater water flows, followed in relation to the reduction of glaciers, by increasingly smaller flows and thus greater exposure to summer droughts.
If considerable changes in climate trends do not take place in the next few decades (future scenarios proposed by the numerical models show increases in summer temperature of about 3 to 6 ° C by 2100 in the Alps), the extinction of glaciers situated below of 3500 meters will be likely."

Also the Alpine and Apennine ecosystems are at risk. "The lowering of groundwater levels and the contraction of the period of snow are among the direct causes of the collapse of forest ecosystems and those of high altitude of the Apennines, which do not seem able to recover, given the speed of climate change under way and the unavailability of appropriate genetic resources within easy reach, "writes Bruno Petriccione of the State Forestry Corps. "The first symptoms of these processes are already verifiable. Studies carried out on the Central Alps show a gradual shift towards higher altitude areas of plant species of high altitude, while observations made in the Central Apennines show a trend of adaptation of high altitude ecosystems to increased aridity: in these cases, the specific composition has changed in the last ten years, by around 10-20%, with worrying signs of a degenerative process already taking place (increase in plant species better adapted to aridity and stress and parallel decrease of those better adapted to greater water availability, low temperatures and more snow). Over the next 100 years a gradual destruction of forest ecosystems is to be expected, of which only a few components will be able to migrate to areas better suited to the changed climate scenarios, while most of them are destined to extinction, at least locally. "

Climate and biodiversity

"In response to global warming, species may be able to adapt or they will move to other areas to remain under the same climate conditions or they will be doomed to extinction. Global estimates indicate that the risk of extinction by 2050 due to climate change will be between 18% and 35%, depending on whether climate change will be limited or significant. Even if these studies were wrong by an order of magnitude and the loss of species were equal to 1.8 to 3.5% instead of 18-35%, hundreds of thousands of species would still be lost, "write Marino Gatto and Giulia Fiorese of the Politecnico of Milan, Adriana Zingone of the Dohrn Zoological Station in Naples and Giulio De Leo of the University of Parma.

The effects on the Mediterranean Sea

"In recent years the Mediterranean was always consistently above average climatology, particularly over the last ten years, and some basins like the Adriatic Sea and the Tyrrhenian Sea are showing peaks of surface temperature anomalies (the difference between the average temperature observed in the last thirty or forty years and the temperature observed on the day or month under consideration) during the summer of more than three-four degrees" writes Vincenzo Artale of ENEA and the other authors of the chapter. "The analysis of data collected during the course of numerous oceanographic cruises in the last century and beyond, show a gradual increase in temperature of surface, intermediate (the famous Levantine water) and deep water. This increase in temperature is accompanied by a simultaneous increase in salinity: the warmer the water the greater its ability to dilute salt.
However, the observed variability of temperature, salinity and elevation of the surface of the Mediterranean is fairly complicated. A large spatial variability, due the combination of various effects adds up to changes in trends (sometimes not understood) on a relatively short time scales and changes in hydrological characteristics over a long time (probably due to global warming) combine with events that are faster and more 'dramatic' in terms of circulation change. "

Global warming is also changing the chemistry and ecosystems of the Mediterranean. Because of lower rainfall and lower contribution of river water, the Mediterranean is expected to become more nutrient-poor, although other effects may counteract this trend. This phenomenon, combined with warming, is already causing a tropicalization of the basin, with the arrival of species accustomed to warmer climates. 

Will cities adapt to the temperature increase?

Cities are the places most vulnerable to climate change. The coastal areas and their infrastructure (including ports) are particularly at risk (for the rise of the sea). The changing rainfall regime will instead impact on sewerages and water treatment plants. Finally, the heat waves (like the well known of 2003), which are likely to intensify in the coming decades, will especially affect the weak and the elderly in the urban population.
"The evidence highlights the urgent need to develop - as it has already been done in many foreign situations - both incisive urban policies aimed at energy saving (in terms of city, neighborhood, individual buildings) and veritable plans involving administrators and citizens in what is emerging as the biggest challenge that awaits the urban realities in the twenty-first century "conclude the town planners at the University of Rome, who are the authors of this part of the Report.

The transport system as well- as noted by Stephen Caserini of the Politecnico of Milan and Roberta Pignatelli of ISPRA Rome - will be affected.
"The intensification of climate change will impact on transport infrastructure, mainly in terms of stability of road, rail or port manufactured goods or the resistance of asphalt roads and railway tracks, but will also impact more broadly on the dynamics of the industry, in terms of distribution of urban and maritime transport, "the authors write. "For example, the market of commercial shipping in the Mediterranean will be affected by the increased competitiveness of the new routes that will open in the coming decades through the Arctic Sea, compared to traditional routes between Europe and the Far East, which currently pass through the Channel of Suez to the Mediterranean ports. Indirect impacts must also be considered, including for example changes in atmospheric dispersion characteristics that can make the impact of transport on air quality in urban areas even more critical"

The costs of climate change

"Italy will face costs as a result of climate change," explains Carlo Carraro, Alessandra Sgobbi and Jacopo Crimi of the Fondazione Eni Enrico Mattei. "Considering the redistributive effects among the different Italian economic sectors in the scenario of a temperature rise of 0.93 ° C in 2050 compared to 2001, the sectors that show a greater reduction in the physical quantity produced are utilities (-0, 71% to -0.87%), and some of the energy sectors (oil -1.88%, gas-3.72% ). These reflect a decline in world demand for oil and gas, mainly due to lower winter heating needs, while the demand and production of electricity increase (+1.8%), including for the increased use of air conditioners. In an Italian scenario where climate change will combine with increased desertification, agriculture would of course record a sharp drop in production, especially as regards the production of wheat (-1.45%) but also fruit and vegetables. A significant reduction in the production of capital goods is also observed. However, this phenomenon is related to the decline in investment, which takes place in Italy but not in all countries of the world.
Thus, considering the redistributive effects of climate change at the national level, this could cost the Italian economy between 0.12 and 0.16% of GDP in 2050, representing a reduction in national income of about Euro 20/30.000 million , the equivalent of a major government financial intervention on the budget. Figures that in 2100 may record a sixfold increase"

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