Nature-Based Solutions as Climate Change Adaptation and Mitigation Measures In Italy

Glovanna Grossi, Stefano Barontini, Francesca Berteni, Matteo Balistrocchi, and Roberto Ranzi

University of Brescia

Introduction

Water resources availability and distribution depend on hydrological processes (evaporation, infiltration, runoff, etc.) featuring the natural water cycle, which is so important for the life of vegetation, animals, and people. In the last decades, land-use changes and urbanization occurring worldwide have affected the natural water cycle by changing the hydrological properties of the soil. On the other hand, hydrological processes depend also strongly on climatic features (air temperature, precipitation, etc.), which are observed to be changing and projected to change even more in the future. The natural water cycle is, therefore, changing its features locally, both because of human activity and because of the changing climatic features. Unfortunately, the more the water cycle is far from its natural conditions, the less it is resilient to climate change, which means that it is more vulnerable to climate change. Namely, the enhanced flood risk in urban areas observed in many parts of the world is in most cases due to the combination of land-use change and climate change.

To protect cities and increase their resilience to climate change, nature-based solutions aiming at restoring, maintaining, and sustainably using natural ecosystems can be very helpful (Naumann et al., 2014). These solutions are also known as ‘eco-system based approaches’ and they include several measures (Naumann et ah, 2011). Besides, in the built environment, construction of more energy-efficient buildings, installation of hard defense structures (e.g. sea walls to buffer against coastal flooding), reduction of impermeable surfaces, installation of green roofs and vertical gardens, and use of ecosystem-consistent materials (e.g. barriers for water retention in wetlands constructed with wood and peat from the site instead of concrete) could be implemented. Concerning the urban and regional planning, land-use zoning, increased use of green infrastructure and spaces (e.g. green roofs, urban tree planting, parks/recreational areas, green belts, etc.), increase in blue infrastructure and spaces (lakes and ponds), increase in soil infiltration in parks, parking lots, and green curbs could be adopted.

They can be considered as climate change mitigation measures because they use ecosystem services to reduce greenhouse gas emissions and to conserve and expand carbon sinks. On the other hand, they can also be considered as adaptation measures because they preserve ecosystem services and reduce the impact of the effects of climate change, by providing water storage opportunities both to rout peak flows and to delay water use and by improving the local climate by increasing the vegetated land. These solutions have been proposed recently in several international frameworks, including UN-Water projects. The United Nations World Water Development Report 2018 (WWAP, 2018) is dedicated to these solutions when dealing with water challenges in a wide sense. The milestones in the European water policies are the European Water Framework Directive (Directive 2000/60) and the Flood Directive (Directive 2007/60), leading member countries to act in the direction of sustainable water resources management and control. Studies carried out by the European Commission on water policy options include a support study on the effectiveness of natural water retention measures (European Commission, 2012).

At the national level, some countries have already started to deliver guides, for example, Canada (CSA, 2012). Germany has developed guidelines for stormwater percolation, holding, and management facilities (ATV - A 128 E, 1992; DWA - A 138-E, 2005; DWA - A 117-E, 2006). Italy has mentioned nature-based solutions as promising approaches in its national adaptation strategy to climate change (MATTM, 2019).

The Italian Climate

The Italian territory spans from 36°30' to 46°30' latitude North and from 6°30' to 18°30' longitude East, including several climate types. The northern boundary is delimited by the Alps, which strongly influence the climate because of their rapidly changing topography reaching more than 4000 m a.s.l. According to the Koppen climate classification (see Figure 7.1), based on the monthly temperature and precipitation, the climate of Northern Italy ranges from a humid subtropical climate (Cfa) to humid continental (Dfb), turning to cold continental (Dfc) in the highest elevation band. In the rest of Italy, the climate is similar to the Mediterranean type (Csa), including some transition types due to the effect of the Apennines. Between the north and the south, air temperature can be very different, especially during winter. In the northern areas, summer precipitation usually occurs as storms in the afternoon/night hours with a few wet days. A dry and sunny summer is on the other hand typical of the southern regions.

Beck et al. (2018) present new high-resolution global maps of the climate classification at a 1-km resolution for the present day (1980-2016) and projected future conditions (2071-2100) under climate change. In their work, the present-day map is derived from an ensemble of four high-resolution, topographically corrected climatic maps. The future map is derived from an ensemble of 32 climate model projections (scenario RCP8.5), by superimposing the projected climate change anomaly on the baseline high-resolution climatic maps. In the northern hemisphere, the projected map shows a shift to the north of the climate types. This is true also for Italy, where the specific features of the mountain regions turn out to be at least partially smoothed.

Brescia (Regione Lombardia), which herein provides a suitable test case, is located in an area currently featuring a humid subtropical climate. Table 7.1 shows the main climate statistics for the period 1982-2012.

The last assessment report on the climate indexes for Italy provided by the National Agency for the Protection of the Environment (ISPRA, 2019) describes both the status of the climate in 2018 and the climatic trends observed in the last decades. In 2018, the average annual air temperature was 1.7°C higher than the average in the reference

Climate classification in Italy (Beck et al., 2018)

Figure 7.1 Climate classification in Italy (Beck et al., 2018).

Table 7.1 Brescia’s climate data in the period 1982-2012: monthly temperature T and rainfall depth P

J

F

M

A

M

J

J

A

S

0

N

D

Mean T (°C)

l.l

3.7

8.2

12.3

16.5

20.3

22.8

21.9

18.8

13.2

7.2

2.4

Min T (°C)

-2.4

-0.7

3.1

7

II.1

14.7

17.1

16.6

13.7

8.7

3.6

-0.6

Max T (°C)

4.6

8.1

13.3

17.6

22

26

28.5

27.2

23.9

17.7

10.8

5.5

P (mm)

53

51

55

73

82

82

68

84

80

96

90

63

Source: Retrieved from climate-data.org.

period 1961-2000, while the annual precipitation was 18% higher than the average in the same reference period, but a different behavior between northern and southern regions w'as observed, as well as season by season. At the national level, the updated seasonal temperature trends show the highest positive rates for spring and summer, while the seasonal precipitation trends turn out to be not significant, even if weak positive values in spring and the fall and weak negative values in winter and summer are observed. In the period 1970-2000, the annual sum of the daily precipitation higher than the 95th quantile (R95) does not show any significant trend in the medium-long term, even if positive anomalies appear to be more than the negative ones in the last decade.

The National Adaptation Strategy and the Nature-Based Solutions

In 2015, the Italian Ministry for the Environment, Land and Sea (MATTM) approved the National Adaptation Strategy to Climate Change (MATTM, 2015). The document stems from the guidelines for national adaptation strategies set by the European Commission (2013) and includes sustainability principles contained in the Water Framework Directive and the Flood Risk Management Directive. Strategic actions are classified into specific soft, green, and grey measures.

Soft measures do not require direct structural operations, even if they might be preliminary to structural interventions, enhancing resilience through a deeper knowledge and a more favorable organizational, institutional, and legislative framework. Soft actions may be dealing with information, organizational and participatory processes, and governance. Structural measures can be green or grey. Green measures differ from grey measures because they are ‘nature-based’, that is, they use or sustainably manage natural services, including the ecosystem ones, to mitigate the impact of climate change. The Directorate-General for Climate and Energy of MATTM is currently working for the implementation of the strategy through the Italian National Adaptation Plan for Climate Change (MATTM, 2019), developed with the support of the Euro-Mediterranean Centre on Climate Change (CMCC). The plan provides institutional guidance to national and local authorities for the elaboration of regional strategies or plans and the integration of climate change adaptation within spatial and sectoral planning. Based on a robust climate, land, impact, and expected risk analysis for each of the key sectors reported in the strategy, it suggests preferential adaptation actions according to well-established criteria for each of the Italian climatic homogeneous regions.

The final definition and implementation of actions need to be focused on the local scale, as climate impacts and consequently adaptation benefits are directly and mainly perceived at the local scale. Furthermore, local political and developmental strategic objectives, together with a deeper analysis of the specific climatic features, need to be addressed through the engagement of all the local actors and stakeholders. Regional climate projections show a potential decrease in summer precipitation all over the country, while the winter precipitation is expected to increase in the northern regions. On the other hand, regional climate models do not agree on the effects of climate change on precipitation extremes, and detailed analysis of the local conditions is suggested to detect current and future trends.

 
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