Climate change and their impacts in the Balearic Islands: a guide for policy design in Mediterranean regions.

Understanding the local effects of global warming-derived impacts is important to island systems due to their fragile environmental conditions. This is especially true when it comes to Mediterranean insular regions as they are climate change (CC) hotspots where adaptation and mitigation policy design is an urgent matter. Looking at 2030 as a time horizon for climate action and focusing on the Balearic Islands, this paper reviews the physical changes projected for the coming decades as a result of CC and analyses their impacts on regional environmental, economic and social variables. Mitigation and adaptation measures are also proposed based on the identified priority impacts. The fact the Balearics are a top world holiday destination allows the analysis to serve as a guide to other Mediterranean islands with tourism-based economies facing similar CC scenarios. Results show the projected rise of temperature and sea level; the reduction of the average precipitation and increase in evapotranspiration, the droughts and the increase in ocean acidification and deoxygenation are the main threats faced by the Balearics, this putting their economy at risk due to the high tourism's vulnerability to CC. Mitigation and adaptation action on terrestrial and marine ecosystems, water resources, energy, infrastructure and urban planning, human health, economy, law and education is recommended. Sustainable mobility and waste managing are also viewed as important fields for mitigation action. Conclusions show that diversifying the current socioeconomic model is needed to increase the community and territory resilience. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10113-021-01810-1.

Introduction

Since the beginning of the twentieth century, the increase in human-induced concentrations of greenhouse gases (GHG) in the atmosphere has raised the planet’s mean temperature (IPCC 2018). In this context, understanding the local effects of global warming-derived impacts is especially important to islands due to their fragile environment. This is particularly true in the Mediterranean Basin as it is a climate change (CC) hotspot (Giorgi 2006; MedECC 2020). Accordingly, both the review of CC-related current and projected physical changes and the analysis of their derived impacts on environmental, economic and social variables represent the starting point for developing adequate policies in insular territories. Though these changes will be most noticeable in the second half of the twenty-first century (Klausmeyer and Shaw 2009; Lelieveld et al. 2012; Cramer et al. 2018; Kaniewskia et al. 2020), designing measures to mitigate and adapt to CC becomes today an urgent task since the islands especially need preparedness given their vulnerabilities.

In 2018, responding to the interest of the regional government to assess the economic, social and environmental prospects for the Balearic Islands by 2030, the Economic and Social Council (ESC) requested to the Interdisciplinary Lab on Climate Change of the University of the Balearic Islands (LINCC UIB) a study about climate change (CC). In particular, the ESC commissioned the LINCC UIB to evaluate the CC impacts on the insular territory and give guidance on the implementation of mitigation and adaptation policies to address them. This resulted in chapter 5 of the ‘Study on the Economic, Social and Environmental Prospects for the Balearic Islands for the 2030 Horizon’ report. This chapter attempted to assist the government in the identification of all the relevant CC-related issues to be included in mitigation and adaptation plans before 2030 (De Vílchez et al. 2019). This paper upgrades and extends the research undertaken in such a report. However, for space limitations, it only presents the CC impacts considered of priority for the Balearic Islands1 and briefly discusses the importance of designing mitigation and adaptation measures. The fact the Balearics are a world top holiday destination makes relevant this discussion as it can serve to give guidance to other Mediterranean territories with tourism-based economies facing similar CC threats. The high vulnerability of tourism to CC (Simpson et al. 2008; Bujosa et al. 2015; Factor CO2 Ideas 2015; Lee et al. 2018; González et al. 2019; Arabadzhyan et al. 2020) makes these regions even more fragile thus calling for an urgent change of their socioeconomic model. The analysis presented here also wants to serve as a wake-up call for initiating such a change.

The paper is structured as follows. The next section describes the methodology used to evaluate the CC-related physical changes and their derived impacts, which is based on an ad hoc expert opinion elicitation procedure. “Physical changes” and “From physical changes to impacts on ecosystems” discuss the priority physical changes and expected impacts on ecosystems, respectively, while “From physical changes to impacts on human systems” revolves around the priority impacts on human systems. “Climate policy for the Balearic Islands” comments on the importance of mitigation and adaptation and recommends a series of policies within each field. A “Conclusions” section ends the paper.

Methodology

To evaluate the CC-related physical changes and impacts (both referred to as hazards from now on) in the Balearic Islands, a LINCC dedicated working group was created including nine experts from different academic disciplines such as physics, engineering, biology, oceanography, economics and law. Based on their expertise, they reviewed existing research on hazards in both the Balearics Islands and other Mediterranean regions sharing similar environmental and/or socioeconomic characteristics, thus facing analogous CC threats. In cases where information on hazards was scarce for the region of interest, the experts reviewed related research focusing on other places elsewhere.2 Regarding the identified impacts, they were classified into two groups: (i) impacts on ecosystems, divided into the categories ‘terrestrial’ and ‘aquatic’ and (ii) impacts on human systems, divided into the categories ‘water resources, energy and infrastructure’, ‘human health’, ‘economy’ and ‘human rights, society and the political system’. Impacts on terrestrial ecosystems were further divided into ‘natural’ and ‘agricultural and livestock’ systems, and those on aquatic ecosystems were classified into ‘marine’ and ‘freshwater’. Likewise, economic impacts distinguished between ‘general impacts’ and ‘sectoral impacts’ (including tourism, agriculture, livestock, fishing, construction, real estate and public sector).

An expert opinion-based assessment was conducted according to an ad hoc methodology based on a qualitative informal knowledge elicitation (Gavrilova and Andreeva 2012; O’Hagan 2019).3 Considering the nature of and the available time for the exercise, a round table–focused collective knowledge elicitation was carried on where all of the experts had equal rights to answer. A consensus combination of collective elicited judgements was adopted after a facilitated discussion among experts during a series of meetings to determine the relevance of each identified hazard and the available documented evidences. For each hazard, the experts were asked to answer the following questions: (1) ‘Is there any chance the hazard will occur in the Balearic Islands during the 2050–2100 period?’ and, if so (2) ‘Which is the expected variation in its magnitude and the associated probability of occurrence for this period?’ Such a time frame was chosen because changes due to CC were expected to be exacerbated in the second half of the twenty-first century and hence easily distinguishable from changes related to the natural (in case of physical changes and ecosystem impacts) or usual (in case of human system impacts) variability. Three different levels of magnitude variation were defined according to the comparison between the expected change in the intensity, duration and/or frequency of the hazard due to CC and the variation registered during the last 30 years. So, if the CC-related expected change in magnitude was much larger or larger than the variation occurring due to natural/usual variability, it was assigned the levels high or medium, respectively. In contrast, if the expected magnitude change was slightly above the natural/usual variation, it was considered low. The probability of occurrence (i.e. the confidence on the projection) was also assigned the levels low, medium or high depending on the extent to which the expected magnitude variation was likely to happen.4

To evaluate the expected magnitude and associated probability of occurrence for each hazard, the experts reviewed literature published from 2003 onwards and considered different criteria depending on whether they were assessing a physical change, an ecosystem impact or a human system impact. Thus, to determine the expected variation in the magnitude of a physical change and its probability of occurrence, they considered information on the observed and projected climate at regional scale. For the impacts on natural and human systems, they took into consideration the expected magnitude variation of physical changes and its probability of occurrence, the environmental and socioeconomic conditions of the islands and their expert knowledge on both the system and its resilience in terms of vulnerability.5 For the human system impacts, they also considered the expected magnitude variation of ecosystem impacts and its probability of occurrence.

As a final step for the elicitation, the experts defined different categories for the hazards being likely to happen in the Balearic Islands. Hazards were considered of priority when both their expected magnitude variation and its probability of occurrence were medium or high. In contrast, they were considered of no priority when either (i) their expected magnitude variation was low and its probability of occurrence was medium/high or (ii) their expected magnitude variation was medium/high and its probability of occurrence was low. When both the expected magnitude variation and its probability of occurrence were low, the hazards were assumed to be of no concern for the islands (Table 1).6

Table 1

Categories of climate change-related hazards being likely to happen in the Balearic Islands according to their expected magnitude variation and its probability of occurrence

Probability of occurrence	Expected magnitude variation
	Low	Medium	High
Low	Of no concern	Of no priority	Of no priority
Medium	Of no priority	Of priority	Of priority
High	Of no priority	Of priority	Of priority

When the existing research was not enough to draw conclusions about whether the hazard would occur or not due to CC, it was classified into a ‘not enough information’ category. This category was also applied to hazards being likely to happen but whose expected variation in its magnitude and/or its probability of occurrence were difficult to determine according to existing data (e.g. decrease of the market value of coastal properties due to a loss of aesthetics caused by beach erosion).7

Once the different types of hazards being likely to happen in the Balearic Islands had been identified, the experts proposed a series of mitigation and adaptation measures which could be implemented.

Physical changes

From 1975 to 2015, maximum and minimum air temperatures have risen at a rate of 0.44 and 0.37 ºC/decade, respectively (Herrera et al. 2016). The winter-summer transition has become more abrupt (0.86 ºC/decade) due the spring warming (Jansà et al. 2017). Since 1970, the Western Mediterranean sea temperatures have also increased at a rate of 0.25 ºC/decade in the upper 80 m of the water column (Vargas et al. 2008). Sea level records also show an upward trend of 1.3 cm/decade for the twentieth century (similar to the global one).

Climate projections suggest temperatures will increase by 3–5 ºC by the end of the twenty-first century compared to 2010 if GHG emissions follow current trends (Adaptecca 2018), and by 1.75–2 ºC under a moderate scenario. This will lead to longer and more intense heat waves. Mean precipitation will decrease by 20% in 2100 under a pessimistic GHG emissions scenario and by 10% under a moderate one, and the severity of droughts will be enhanced. There are some results projecting a slight increase of extreme precipitation, but there is little consensus among models. Also, wind intensity and the number of cyclones will likely decrease on average, while the intensity of the intense events could slightly increase.

Depending on the GHG scenario, the mean sea level will increase between 37 and 90 cm (MedECC 2020). The intensity and frequency of marine storms will slightly decrease, although their impact will increase due to the rise of the mean sea level. The sea temperature will also rise between 2 and 4 ºC in the upper layers (Soto-Navarro et al. 2020), leading to stronger marine heat waves. Also, the vertical stratification will be enhanced and the available dissolved oxygen reduced, thus diminishing the ventilation of intermediate and deep layers. Though there are not robust estimates for this yet, more atmospheric CO2 might provoke higher ocean CO2 absorption and ocean acidification.

From physical changes to impacts on ecosystems

Impacts on plant and animal biodiversity

Terrestrial ecosystems are suffering from rising temperatures and reduced rainfall-derived impacts. Both factors combined will lead to an increase in evapotranspiration that will reduce the area occupied by forests of Quercus ilex (holm oaks), which will not be able to subsist in the spaces that currently represent their climatic limit. In turn, there will be an increase in the forests and maquis of Olea europea var. sylvestris (olive tree) and Pinus halepensis (pine tree). On the other hand, forest fire risk will be higher due to a greater number of days with high temperatures and low humidity. All these factors combined can lead to forest decline and make them more sensitive to pests and pathogens. Consequently, their capacity to sequester carbon will be reduced.

It is also expected that some threatened plant species may become extinct when their habitat disappears such as plants living in fountains, torrents or simply wet soils. Naufraga balearica, a critically threatened endemic monotypic plant genus, is paradigmatic in this sense (Cursach et al. 2018). In contrast, some exotic species are becoming dangerous invaders by finding a more favourable climate, such as some cultivated plants natives from dry tropical zones (Lantana camara, Opuntia spp., Agave spp., etc.). Finally, changes in phenology of flowering and fruiting could result in ruptures of mutualisms, for instance with their pollinator and dispersant animals. On the other hand, sea level rise and extreme meteorological events will have an important impact as well, since beaches and coastal dunes will reduce its extension, and in some places, they may disappear. Likely some rare psammophilous plants and animals could be extinct at the local level. Also, coastal wetlands will suffer salinization, with dramatic changes in these ecosystems. It is also expected that temporary ponds and torrents will reduce the time they are flooded; even some could disappear. It could also threaten some plants and animals which live in this habitat, for instance, the endemic and endangered amphibian Alytes muletensis or the very rare fern Marsilea strigosa.

Even if there are not specific studies in the Balearic Islands about the CC effect on animals, it is expected that animal biodiversity and populations are also affected by alteration of distribution, seasonality, growth, reproduction, migration and synchrony of life cycles among animals and/or plants. Temperature increase is currently changing distribution of birds, insects and mammals to northern latitudes (Feehan et al. 2009) as well as contributing to the extinction of some species of mammals (Thomas et al. 2004). CC effects are expected to be more severe on those species with a restricted distribution, such as the endemic ones (i.e. A. muletensis in the Balearic Islands). On the contrary, invasive species (i.e. insects such as Aedes albopictus and Rhynchophorus ferrugineus) will be favoured by higher temperatures thus increasing its distribution. There are also evidences of global insect decline due to CC (Habel et al. 2019; Harris et al. 2019; Powney et al. 2019). Indeed, indicators of decline in lepidoptera populations were found in Menorca and attributed to changes in the phenology of host plants (Colom et al. 2019).

Impacts on wild plant and animal health

CC is expected to cause a weakening of trees and a reduction of their defences against phytophagous insects and pathogens that will experience favourable periods for proliferation. Currently, severe outbreaks of bark beetle species (Tomicus destruens and Orthotomicus erosus) and pine processionary (Thaumetopoea pityocampa) on the populations of P. halepensis have been observed in the Mediterranean region (Spathelf et al. 2014). Meanwhile, Q. ilex forests are increasingly affected by high abundance of the lepidopteran pest Lymantria dispar. Thus, holm oaks weakened by insects or unfavourable weather are more vulnerable to the spread of pathogenic fungi, such as Botryosphaeria corticola and Biscogniauxia mediterranea (Moralejo 2010, unpublished work).

Recent emerging plant vector borne diseases such as the bacterium Xylella fastidiosa found in the Balearics in 2016 (Olmo et al. 2017) will increase its distribution in Europe because of the temperature rise according to model scenarios for 2050 and 2100 (Bosso et al. 2016). CC will also affect the wild animals’ health by favouring reproduction and distribution of parasites (i.e. gastrointestinal nematodes) and increasing the presence of emerging diseases (Altizer et al. 2013). In the Balearics, some introduced parasites are affecting key endemic species (i.e. chrytidiomycosis in A. muletensis) (Fisher et al. 2012). The effect of tropical parasites species (e.g. Angiostrongilasis in the hedgehodge Atelerix algirus) on some vertebrates is also an example (Paredes-Esquivel et al. 2019). Pollinators (bees) are a key group of animals affected by CC. Indeed, it directly impacts their life cycles and indirectly affects them via diseases and parasites such as fungi Nosema spp., the mite Varroa destructor and the coleopteran Aethina tumida (EFSA 2015).

Impacts on marine ecosystems

Global warming has multiple effects on marine ecosystems, including biodiversity loss, changes in ecosystem functioning and proliferation of invasive species.

The coastal ecosystems of the Balearic Islands are dominated by the endemic seagrass Posidonia oceanica, which is a key species providing multiple services thanks to its high productivity: it increases water transparency and biodiversity; produces oxygen and acts as an important carbon sink, absorbing 7% of carbon emissions of the islands (Marbà, personal communication). However, these meadows are very sensitive to global warming as it produces physiological stress, stimulates bacterial activity, changes ecosystem biodiversity and increases flowering events and plant mortality (Marba and Duarte 2010). As a result, both the seagrass and its services could disappear by 2040–2060 in the shallowest areas (Jorda et al. 2012), this shaping the future of Mediterranean coastal ecosystems.

Benthic filters are another Mediterranean sensitive community to global warming. During summer, high temperatures enhance stratification, reducing food-supply to bottom waters, and benthic filtering communities die of starvation. This phenomenon has already caused mass mortality events of different invertebrate groups, such as gorgonians and corals (Garrabou et al. 2019).

Migration and distribution of fish communities can also suffer from CC impacts. Since 1960, global warming produced a migration of ocean isotherms of 50 km/decade in the Mediterranean Sea (Burrows et al. 2011) altering distribution of fish species, with some species migrating northwards seeking for refugee in colder waters.

The proliferation of tropical species is leading to the Mediterranean tropicalization (Bianchi and Morri 2003). Some invasive species will benefit from warmer waters (Raitsos et al. 2010). The invasive macroalgae Halimeda incrassata has rapidly colonized sandy habitats since 2011 (Alós et al. 2016) leading to changes in abundances and distribution of fishes (Vivo-Pons et al. 2020). Another invasive species that could benefit from CC are the rabbitfish (Siganus luridus and S. rivulatus). These species negatively affect rocky ecosystems leading to deforestation, due to their highly herbivore rates (Vergés et al. 2014a). At the moment, thermic tolerance of these species limits their distribution to the Eastern Mediterranean, but CC might allow to broad its distribution western-wards with isotherm migration (Vergés et al. 2014b).

CC can also alter trophic interactions as a consequence of the presence of new species with warmer thermal windows and due to changes in the nature or strength of existing interactions due to warming responses. Species interactions can dramatically alter species responses to CC. The exact consequences for focal species are unknown and dependent on multiple interacting factors (Gilman et al. 2010; Zarnetske et al. 2012).

CC also impacts marine biogeochemical cycles and organisms’ metabolic rates. Temperature raises both respiration (oxygen consumption) and photosynthetic (oxygen production) rates although respiration increases faster than primary production (Brown et al. 2004; Vaquer-Sunyer and Duarte 2013). This could lead to a decrease in oxygen content in coastal waters with negative consequences for marine benthic communities, very sensitive to deoxygenation (Díaz and Rosenberg 2008; Vaquer-Sunyer and Duarte 2008). This situation has been already reported for a Balearic enclosed bay (Vaquer-Sunyer et al. 2012). CC will also aggravate negative effects of deoxygenation as organisms increase their oxygen requirements at warmer waters at the time that warming accelerates oxygen depletion (Vaquer-Sunyer and Duarte 2011).

Ocean acidification decreases survival, calcification, growth, development and abundance of a broad range of marine organisms. However, the magnitude of these responses varies among taxonomic groups. Molluscs larvae are specially sensitive to acidification, whereas in other taxonomic groups, it is not clear that early stages are more sensitive than adults. The variability in the species’ responses is enhanced when multi-species assemblages are assessed. Elevated water temperature enhances organisms’ sensitivity to acidification (Kroeker et al. 2013).

Impacts on agricultural and livestock systems

Climate prediction models indicate warming will cause substantial changes in global agriculture (IPCC 2014) which will be of particular importance in Mediterranean regions (del Pozo et al. 2019; Santillán et al. 2020; Varotsos et al. 2021). Temperature increase, changes in precipitation distribution and more intense and frequent extreme events (e.g. severe drought periods, heat waves) can cause important quantifiable impacts on agriculture. On the one hand, crop productivity can be reduced due to prolonged drought (Fraga et al. 2019). Evaporative demand and plant transpiration rates can also raise this leading to greater direct evaporation of soil water and reduction of availability of water for crops, respectively (López-Urrea et al. 2012). In addition, modification of phenology of cultivated species (advance of budburst, lengthening of phenologic cycles, delays in dormancy of buds) can happen (Ramos 2017; Lorite et al. 2020), and a reduction of chill hours can affect physiology, such as flowering (Ashebir et al. 2010), dormancy and latent periods. The severity and frequency of heat waves will also influence the physiology of plants causing a loss of production (DaMatta et al. 2010). Changes in chemical composition of crop products and its derivatives due to light spectrum modification (greenhouse effect), and high temperatures will be another CC impact on agriculture. Such changes will have negative effects on products’ taste and nutritional properties (Lorite et al. 2018; del Pozo et al 2019). Finally, new pests might cause significant economic costs, and even the infeasibility of certain crops. Milder winter periods will also intensify local pest–derived impacts due to more annual generations and favour the emergence of new invasive plant pest and diseases (Civantos et al. 2012).

Extreme heat waves are considered the most important CC direct impact on livestock production (Thornton et al. 2009), while the loss in the quality of pastures due to rainfall reduction would be the main indirect impact. New vector borne diseases are also expected as shown by those having occurred in Europe in recent years such as Lumpky Skin Disease in Greece and East Europe. Diseases transmitted by Culicoides spp., such as bluetongue (Miranda et al. 2003), have also occurred in Spain and the Balearics Islands. Though bluetongue was initially considered to be restricted to southern latitudes, it has surprisingly reached North European countries, such as Germany, Deutschland and UK. This is viewed as an example of the global warming–derived effect on the insect vector competence (Purse et al. 2015) (Table 2).

Table 2

Priority impacts on ecosystems derived from priority climate change-related physical changes expected for the Balearic Islands during the 2050–2100 period

Priority physical changes	Types of ecosystems
	Terrestrial ecosystems				Aquatic ecosystems
	Natural systems		Agricultural and livestock systems		Marine ecosystems	Freshwater ecosystems
Sea level rise	• Beach surface decrease, dune system loss and increase in coastal erosion • Decrease in population and local extinction of rare psammophilous species					• Increase in the salinization of aquifer and coastal wetlands
Air and sea temperature increase Increase in the number, length and frequency of atmospheric and marine heat waves	• Emergence and spread of invasive plants and animals	• Changes in the distribution of the main forest communities • Increase in wildfires • Increase in forest pests and pathogens due to the weakening of the main tree species • Decay and defoliation of forests • Reduction of forest carbon sink capacity • Insect decline		• Changes in plant physiology due to heat waves • Changes on chemical composition of fruit and by-products • Increase in morbidity and mortality of animals caused by heat waves • Emergence of vector borne diseases	• Loss of Posidonia oceanica meadows and the services provided by the planta • Increase in organisms migration • Increase in the abundance and number of invasive species of tropical origin • Trophic interactions disruption • Increase in mass mortality events (i.e. benthic filters)a
Reduction of average precipitation and increase in evapotranspiration Increase in the number, duration and intensity of droughts			• Reduction of crop yields			• Increase in the salinization of aquifer and coastal wetlands • Local extinction of plant and animal species from seasonal aquatic environments

aCoastal protection, wave’s velocity and intensity reduction, water transparency, carbon sinks, oxygen sources, biodiversity hotspots and sand sources are examples of services provided by the plant

From physical changes to impacts on human systems

Impacts on water resources, energy and infrastructures

CC is expected to reduce the fresh water resources due to a reduction of precipitation and an increase in evapotranspiration. Specifically, the more pessimistic emission scenarios show reductions greater than 55% (Pulido-Velazquez et al. 2015). In addition, a significant increase of water demand by the residential, service and industrial sectors (Milano et al. 2013) would lead to future lower water availability. The Balearic Islands’ water reservoirs get their minimum levels during summer, in particular in August due to the tourism activity, which is one of the biggest contributors to local water demand (Garcia and Servera 2003). The monthly mean water demand by the region’s population is 1.7 hm3, which almost doubles during the peak season when an increase between 0.9 and 1.4 hm3 is produced. This will undoubtedly impact water distribution and collection systems (Loftus et al. 2011). Increased water demand will also contribute to raise the pollutant concentrations in the water reservoirs and aquifers’ salinity (Fader et al. 2020).

Such a water scarcity scenario will also lead to raise the demand for desalination which will increase energy consumption. The Balearic Islands have 8 desalination plants (3 in Mallorca, 3 in Eivissa, 1 in Menorca and 1 in Formentera) based on reverse osmosis. Although this is said to be an efficient technology, it requires at least 5 kWh to desalt 1 m3 of sea water (Shemer and Semiat 2017). Energy consumption from water desalination rose by 37.4% during the 1999–2017 period (GOIB 2016; ABAQUA 2019; Vaquer-Sunyer et al. 2021).8

As water demand, energy demand will be higher in summer (Valor et al. 2001), especially at nights (Papakostas and Slini 2017), while it is expected to be lower in winter (Giannakopoulos et al. 2009). Thus, the annual average demand might remain unchanged at current energy consumption levels. However, as peaks of summer demand will be higher due to cooling systems, polices oriented to either increase the power generation capacity or implement energy saving will have to be undertaken, which will involve higher generation costs (Elimelech and Phillip 2011).

Action on infrastructures will also be needed in the face of global warming. Higher temperatures might also deteriorate the infrastructures due to dilatations/thermal contractions and induce acceleration of corrosion processes. More CO2 concentration involves a higher carbonation rate, this deteriorating existing concrete infrastructures (Stewart et al. 2011; Ekolu 2020). Although corrosion might be viewed as a minor issue, current estimates indicate that the global cost of corrosion represents the 3–4% of the GDP in industrialized countries, or equivalently $US1.8 trillion (Schmitt 2009). The huge magnitude of the direct and indirect corrosion costs allows anticipating that a slight CC-derived acceleration of this process could lead to important global economic costs.

On the other side, the expected rise in the sea level will reduce the height of the coronation level of the breakwaters in harbours and other maritime infrastructures, increasing the risk of failure under the occurrence of potential high waves. In addition, extreme rainfall episodes may increase which would lead to more floods, and therefore, larger drainage requirements such as slopes, elements of transverse drainage on roads or bridges, among others, may be needed locally to avoid aggravating the flooding effect at certain points (CEDEX 2013; Cramer et al. 2018).

Impacts on human health and the economy

Although at the global level it is expected CC will cause deaths due to heat stress, poor nutrition and malaria between 2030 and 2050 (WHO 2014), heat waves will represent the major direct CC human health impact in Western societies. The one occurring in Europe in 2003 was estimated to increase the probability of death between 20 and 70% in large cities (Mitchell et al. 2016). In the Balearic Islands, elders suffering from cardiovascular or respiratory diseases as well as outdoor workers are expected to be the most vulnerable population segments. On the other side, the most important indirect CC human health impacts will be vector-borne diseases and the rise of allergy episodes. Invasive species of vectors (i.e. Aedes albopictus) and imported diseases (i.e. dengue) will also increase the transmission risk, as already confirmed in Spain in 2018 (ECDC 2018). In addition, higher temperatures may modify the transmission capacity of autochthonous vectors, such as Culex pipiens and West Nile virus, as confirmed in the recent epidemic in Andalusia (ECDC 2020). Higher pollen concentrations will also provoke allergy-related respiratory problems.

CC is also expected to substantially affect the economy, thus leading to a decrease in social welfare (IPCC 2014). On the one side, production costs of all sectors will be affected by some physical changes. Indeed, higher temperatures and more frequent heat wave episodes will lead to a lower labour productivity mainly affecting the most vulnerable people and the employees’ mental and physical health (Kjellstrom et al. 2016). In addition, the capacity of facilities and infrastructures can also be reduced by increased temperatures, which can lead to a growing risk of fires affecting infrastructures’ logistics. The electricity generation and/or distribution systems will also experience more pressure due to the potential rise in summer energy demand. Utilities of provision and treatment of water for consumption can suffer from overload not only due to higher water demand but also due to lower precipitation. Some facilities might also have to be repaired or forced to close due to the sea level rise (Linnenluecke et al. 2011; Factor CO2 Ideas 2015).9 Production costs will further increase because of a potential rise in water prices due to both the increase in the demand of water and its use rivalry between sectors (e.g. tourism, agriculture, industry). The agro-product prices might also increase due to a reduction of agro-systems productivity which, together with insularity costs, can increase imports of agro-products and their price (MedECC 2020). A higher energy demand can also lead to a rise in the energy prices which could be further exacerbated due to the peak oil, gas and coal phenomena.

On the other side, CC will also impact ecosystems’ capacity to provide goods and services (Torres and Hanley 2017) especially affecting tourism, livestock and agriculture sectors. Warming and frequent heat waves are expected to affect the Balearic Islands’ attractiveness (Bujosa et al. 2018) leading to a seasonal and geographical redistribution of tourists’ flows, which will look for higher latitude, cooler regions (Bujosa et al. 2015). They are also expected to cause a loss of environmental quality, this making the islands even less attractive. Indeed, higher temperatures will increase the risk of fires (Fernández-González et al. 2005) and provoke the loss of seagrass Posidonia oceanica (Marba and Duarte 2010) affecting two recreational services provided by this plant: (i) the quality and transparency of coastal waters (Torres et al. 2009) and (ii) the recreational fishing of species which the plant serves as habitat to.10 Warming can also lead to a higher frequency of jellyfish outbreaks (Canepa et al. 2014) and a loss of landscape values due to the further spread of the plant pathogen Xylella fastidiosa. New pathogens could also affect the destination attractiveness through vector-borne diseases or pandemics caused by other types of viruses like Covid-19.11 On the other side, the sea level rise will also affect the environmental quality through the reduction of beaches’ width (Enríquez and Bujosa 2020). Warming and lower precipitation will also impact the livestock and agricultural sectors’ benefits (Factor CO2 Ideas 2015; Institut d’Estudis Catalans and Generalitat de Catalunya 2016) as they will lead to a lower availability of fodder and grasses, this causing a reduction in milk and cheese production, lower yields and increased irrigation costs.

As a result of general and sectoral impacts, a rise in governments’ budget deficit is expected due to the potential growth in public spending associated to energy and health systems, fighting against pests, port infrastructures and water collecting and distribution utilities.12 The expected economic losses will also lead to an income reduction and hence less public revenues, this further contributing to raising the deficit.

Impacts on human rights and socio-political systems

CC can also lead to serious consequences upon citizens, society and the democratic institutions. Even from a legal perspective, the interdependence between nature and human beings is becoming increasingly clear. Since the 1972 Stockholm Declaration on the Human Environment, there has been a growing awareness that a clean and healthy environment is indispensable to the enjoyment of human rights. This has been clearly stated by the most recent reports of David R. Boyd, the current Special Rapporteur on Human Rights and the Environment,13 and recognized by an increasing number of courts, both at the domestic14 and international level.15

Accordingly, it is expected that CC will affect the human right to life, health, private and family life, property, food, water and housing, which have been established in several international instruments to which Spain is Party16 and according to which Spain is obliged to interpret the fundamental rights set forth in its own Constitution.17 This is especially true when it comes to consider the CC impacts on the most vulnerable, lower-income and marginalized sectors of society which are expected to be the most affected ones (O’Brien and Leichenko 2000; MedECC 2020). The encroachment of legally established human rights is likely to produce a surge in legal actions directed either against public authorities or private actors contributing to global warming, as is already happening in many countries (UNEP 2020).

Moreover, the dire CC impacts, together with a probable increase in the flux of migrants from Northern Africa (Cramer et al. 2019), will also likely deteriorate social stability and increase an already growing disaffection towards the democratic institutions that has fuelled the surge of a xenophobic and extreme-right party in the 2019 local, regional and nation-wide elections (Tables 3 and 4).18

Table 3

Priority impacts on water resources, energy, infrastructures and human health derived from priority climate change–related physical changes expected for the Balearic Islands during the 2050–2100 period

Priority physical changes	Types of human systems
	Water resources, energy and infrastructuresa			Human health
Sea level rise	• Impacts on port infrastructures		• Increase in the penetration of salt water into aquifers leading to a reduction of the quality of water supply
Air and sea temperature increase Increase in the number, length and frequency of atmospheric and marine heat waves	• Increase in infrastructure deterioration due to thermal deformations	• Decrease in water availability • Increase in seasonal demand for water resources • Increase in the interconnections of the water distribution infrastructures to deal with droughts • Reduction in the replacement flow and increase in the concentrations of pollution in the aquifers • Increase in summer energy demand peaks •Increase in the base power generation to meet the peak demand, due to the HVAC in summer period • Increase in the energy demand linked to desalination • Increase of the risk of wildfires and other types of fires linked to construction or exploitation of infrastructures		• Increased morbidity and mortality • Increase of vector-borne diseases
Reduction of average precipitation and increase in evapotranspiration Increase in the number, duration and intensity of droughts

aIt is worth noting that the rise in atmospheric CO2 concentration will also accelerate corrosion processes in concrete and steel structures, an impact on infrastructures which is also exacerbated by the increase in the air temperature

Table 4

Priority impacts on the economy, human rights, society and the political system derived from priority climate change–related physical changes expected for the Balearic Islands during the 2050–2100 period

Priority physical changes	Types of human systems
	Economy				Human rights, society and the political system
Sea level rise	• Impacts on public sector (expenditure on infrastructures)	• Impacts on tourism sector		• Increase in production costs due to decreased capacity of facilities and infrastructures	• Right to property	• Right to private and family life and housing		• Right to water • Increase in the number of legal actions against public administrations and private corporations • Impacts on the insurance sector and existing contracts • Growing social unrest and lack of confidence on the political system
Air and sea temperature increase Increase in the number, length and frequency of atmospheric and marine heat waves	• Decreased labour productivity • Impacts on public sector (expenditure on energy, health and fight against pests)		• Increase in prices of water, energya and agro-products • Impacts on agriculture and livestock sectors		• Right to life and health		• Right to food
Reduction of average precipitation and increase in evapotranspiration Increase in the number, duration and intensity of droughts	• Impacts on public sector (expenditure on energy and water collecting and distribution systems)

aIt is to say energy prices are also expected to rise due to the peak oil, coal and gas phenomenon, this further increasing the production costs of all the sectors

Climate policy for the Balearic Islands

Given CC cannot be avoided, prevention is not seen as a policy option, and climate policy usually revolves around two types of action: mitigation and adaptation. While adaptation is oriented to enhance the resilience of the ecosystem and society for them to better cope with the expected CC impacts, mitigation pursues to diminish GHG concentrations in the atmosphere to reduce the global temperature increase and hence its derived impacts. The IPCC strongly recommends reaching net zero emissions by 2050 to limit the temperature increase to 1.5 ºC (IPCC 2018). On the other side, the EU has reached an agreement on the European Commission’s proposal for the first European Climate Law, which aims to write into law the goals of the European Green Deal, establishing a GHG emissions reduction target of at least 55% by 2030. This is consistent not only with the Paris Agreement’s recommendation to reach net zero emissions by 2050 but also with some studies pointing to the need to raise the ambition level up to a 55–65% reduction in an attempt to ensure the net zero emissions objective (ECF 2018).

Mitigation is urgently needed to avoid the further exacerbation of the economic and social costs linked to emissions reduction within a shorter time period. Starting mitigation now can also avoid a reduction of both the set of feasible emissions reduction options and the social capacity for response.

Mitigation policy recommendations

Mitigation policies can be viewed as an opportunity to diversify the Balearic Islands economy as they can lead to create new job opportunities in high value-added technological sectors requiring skilled labour and being hard to delocalize. Mitigation can also help to strengthen local economic sectors such as agriculture, fishing, arts and crafts and natural resource management. In a CC context, diversification becomes a necessity for a tourism-based economy due to the intensive use of fossil fuel energy and materials by the tourism sector which converts it into a big contributor to CC (Simpson et al. 2008; Torres and Moranta 2021). Indeed, tourism carbon footprint rose from 3.9 to 4.5 GtCO2e at the planetary level between 2009 and 2013 accounting for the 8% of global emissions (Lenzen et al. 2018). As stated by Cadarso et al. (2015, 2016), tourism is responsible not only for direct, indirect and imported emissions but also for emissions associated with the capital investments required to supply tourism goods and services, which are mostly linked to the construction sector (e.g. hotels, restaurants, transport infrastructures).

Accordingly, it is highly recommendable to design a Plan for Mitigation to reach by 2030 the emissions reduction targets set by the Climate Change and Energy Transition Law launched by the Balearic Islands Government at the beginning of 201919 in accordance with EU goals. Although mitigation in a broad set of areas is required, it is worth noting the importance of acting on the energy and transport sectors as they represent almost 80% of total direct emissions in the territory (40% and 37%, respectively, in 2016). Implicitly, this involves reducing the mass tourism–induced human pressure which an economy’s diversification built on promoting activities having a lower carbon footprint will undoubtedly contribute to. Within a framework of a more diversified economy, the tourism sector’s strategies aimed at reducing its emissions are also necessary. In this sense, some airlines, cruise liners and establishments are already committed to achieve carbon neutrality by putting emphasis on reducing energy consumption through efficiency improvements and a rise in renewable energy use. The case of Artiem Hotels in Menorca is outstanding in this regard. This family enterprise has reduced by 14% the CO2 emissions of all its establishments in 5 years and pursues to reduce them by 80% in an 8-year time period.20 However, technological innovation will not be sufficient to effectively decarbonise tourism as behavioural and structural changes at a large scale are required (Simpson et al. 2008; Becken 2019). In line with this, latest debates on tourism, which have been intensified by the Covid-19 pandemic, interestingly advocate for relocating tourism in search of other alternatives involving a reduction of the ecological and social conflicts associated with the exponential growth of the sector (Cañada 2014). Labelled as ‘proximity’, ‘low-carbon’ or ‘slow’ tourism, such alternatives aim to rethink tourism to make it more sustainable (Becken 2017; Lee et al. 2018; Gössling and Higham 2020; Romagosa 2020).

In this context, both designing an R&D&I Plan oriented to acquire knowledge on potential mitigation strategies and developing a system to measure emissions also become essential to achieve mitigation targets.

Table 5 reports the mitigation policies which are recommended to effectively address all the impacts considered of concern:

Table 5

Recommended mitigation measures to address the identified priority climate change impacts to be included in mitigation plans before 2030

Policy area	Mitigation measures
Terrestrial and marine ecosystems	• Protect and promote the increase of natural areas such as forests and Posidonia oceanica seagrassesa • Calculate emissions associated to different land uses to complete the information of the Balearic Islands emissions inventories • Regulate biomass forest extractions to reduce the associated emissions • Implement an agricultural land and grazing management plan to reduce emissions • Promote soil uses and crops which better act as carbon sinks and preserve them through adequate waste management
Water resources	• Increase efficiency in water collection, distribution and consumption to reduce the need for desalinization as well as energy consumption
Energy	• Reduce energy demand in end-use sectors, especially in services and residential sectors, mostly through increasing buildings’ energy efficiencyb • Generate renewable energy together with both an adequate territorial planning and environmental impact assessmentsc • Promote changes in consumption patterns • Give up oil/gas exploratory drillings • Promote decentralized electricity generation • Define areas with a higher potential to facilitate access to electricity systems, thus being more suitable to allow for installation of renewable energy infrastructures • Use of smart-grid electricity techniques to allow for distribution of renewable energy generation • Promote district-heating networks in tourist coastal areas
Infrastructure and urban planning	• Promote urban planning which makes unnecessary or less necessary the use of private vehicles, thus reducing the pressure on the current transportation network as well as emissions and land consumption • Ensure compulsory sustainable parameters are established such as energy and water consumption and climate control systems in the construction sector • Implement plans for building restoration aimed at extending the useful life of buildings to avoid energy losses • Make urban areas greener through tree planting and green roofs to reduce the temperature and absorb CO2 as well as maintain them through a more sustainable water use
Sustainable Mobility	• Establish a public transport network with affordable prices, not based on fossil fuels and adapted to each island avoiding the use of private vehicles • Promote foot and bicycle mobility within urban areas by making easy and safe the use of the public space • Promote shared mobility mechanisms and small electric vehicles • Initiate debate with national and local institutions about the need to reduce substantially emissions of flights, prioritizing their public service character, and evaluate the need of designing emission compensation mechanismsd
Human health	• Promote consumption of local products as they have a lower carbon footprint • Promote more sustainable mobility systems (foot and bicycle mobility)
Economy	• Promote disinvestment in fossil fuel and high carbon activities • Apply the Polluter Pays Principle and introduce a carbon tax as well as incentives to reduce emissions • Support those companies which want to develop a low carbon activity • Promote the development of a proximity economy specifically through regulation of the hotel and restaurant sectors as well as sustainable public purchases • Implement a circular economy system and reduce production and consumption of goods • Develop alternative types of tourism such as ‘proximity’, ‘slow’ or ‘low-carbon’ tourisme
Waste	• Reduce waste generation especially that concerning food, packaging and textile • Extend the useful life of goods and facilitate their repair and exchange (eliminate planned obsolescence) • Promote circular economy in such a way waste can be converted into resources to be used in production processes • Increase recycling rates • Use of compost to reduce the emissions associated to its discharge and to increase the carbon amount in soils
Law	• Promote initiatives aimed at changing the Spanish state regulation of high carbon activities in which the Balearic Islands don’t have any (or have a partial) power such as those related to energy, ports, airports, waste and construction
Education	• Incorporate into formal education curricula new contents relating to climate change issues • Identify jobs/sectors which need to be trained more urgently in relation to climate change and design specific education programmes for them • Establish a team work with the General Direction of Environmental Education, Environmental Quality and Waste, the Education Department of the Balearic Islands Government and the University of the Balearic Islands to deal with educational issues relating to climate change

aIn 2017, terrestrial ecosystems captured a CO2eq amount equal to 11% of the annual GHG emissions of Spain. It is estimated the Balearic Islands forests could store up to at least 5% of the annual islands emissions. On the other side, it is expected that Posidonia oceanica seagrasses, currently excluded from national emissions inventories, can store up to a 10% of the annual islands emissions. They could retain in their sediments an amount of CO2eq corresponding to 100 years of emissions

bThe efficiency increase should be at least equal to 27% according to EU goals set in 2014 for the 2030 Climate and Energy Framework. This target was raised to 32.5% in June 2018. It is possible that it will be updated again in June 2021

cA target of at least a 35% share of renewable energy by 2030 would be necessary, in line with the goals set by the EU 2030 Climate and Energy Framework (32% by 2030). It is highly possible that the EU target will be raised in June 2021, with speculation that it could reach between 38 and 40%

dAir transport’s energy consumption represents about 30% of total energy consumption by transport. All these mitigation measures should also be adapted and applied to the maritime sector

eThese types of tourism have to be understood within a framework of economy’s diversification based on promoting activities with a lower carbon footprint

Adaptation policy recommendations

Adaptation policies should serve to make more resilient the ecosystems, the economy and the society of the Balearic Islands as well as to acquire knowledge oriented to keep or even increase social welfare. Such policies have to be adequate to cope with the expected priority CC impacts by 2030. So, the design of a Plan for Adaptation based on specialized research on both the CC effects on natural and human systems and the vulnerability of the different socioeconomic sectors is highly recommendable. The plan should be focused on the impacts requiring most urgent action such as temperature increase, sea level rise, threats to biodiversity, human health, water resources and risks related to infrastructures, and be built on an in-depth analysis about which activities can better adapt to CC.

In this sense, the high vulnerability of tourism to global warming emerges as another argument in favour of the economy’s diversification. Put it another way, diversifying the economy also represents a necessary adaptation strategy for the Balearic Islands to become more resilient. Even more, basing diversification on the promotion of activities with a lower carbon footprint (as explained in “Mitigation policy recommendations”) can further increase the destination’s resilience. In parallel with such a diversification process, it is also recommendable the different sectors engage in adaptation strategies to better cope with CC. And tourism is not an exception. Accordingly, retreat measures or relocating coastal firms, infrastructures and facilities and even residential populations from one area to another one are examples of adaptive responses to CC (Wall and Badke 1994; Linnenluecke et al. 2011; Mycoo 2013; Fatorić et al. 2017) which become interesting strategies to follow in ‘sun and beach’ tourism destinations. Creating shadow areas to counteract the expected tourists’ thermal discomfort due to the increase in the temperature (e.g. designing green environments surrounding the buildings) or diversifying the tourism product in favour of less climate-dependent activities (e.g. conservation strategies of natural assets or improvement of the cultural offer) are other examples of adaptation strategies which could also be undertaken (Bujosa et al. 2018).

Undoubtedly, creating an Observatory of CC Impacts to better forecast the expected impacts and closely monitor the actual ones upon all relevant sectors would be very helpful. Such an Observatory would provide essential data to devise efficient policies to prevent and address the deleterious CC effects. Designing an R&D&I Plan allowing for the development of adaptation policies being suitable for the Balearic Islands would also be recommendable.

The adaptation policies recommended to cope with CC are reported in Table 6:

Table 6

Recommended adaptation measures to address the identified priority climate change impacts to be included in adaptation plans before 2030

Policy area	Adaptation measures
Terrestrial and marine ecosystems	• Strengthen forest fire prevention systems and regulate biomass extractions both to prevent fires and to ensure carbon capture and storage by forests • Identify threatened species and design strategies for their conservation • Design a biosecurity strategy, adapt the existing laws to it and generate an alert system to manage the introduction of alien, potentially invasive species • Generate management systems for beaches allowing for their conservation and recreational use • Implement Posidonia oceanica seagrasses protection measures • Design plans for adaptation taking into consideration key threats such as water resources deficit and pollution, soil mineralization reduction and vulnerability of certain crops to climate change • Increase efficiency in the water use both in irrigated and non-irrigated lands • Implement a fishing plan aimed at dealing with fish species being most vulnerable to climate change • Design plans for adaptation of livestock to climate change, including adaptation of facilities and management (i.e. foraging alternatives)
Water resources	• Manage water demand in an integrated way to adapt it to water availability through saving mechanisms, use of alternative local drinking fountains and especially reuse of regenerated waters whenever is possible in agricultural and tourism activities • Revise and adapt water collection and distribution systems to optimize the volume of ‘recuperated water’ and reduce water losses • Protect aquifers from overexploitation and prevent the coastal ones from salinization derived from sea level rise • Elaborate a plan to identify nitrate pollution sources of aquifers and implement policies to restore the polluted ones • Promote housing water reuse systems • Promote housing water efficiency consumption • Educate and increase social awareness about water as a scarce resource • Revisit and adapt water treatments
Infrastructure and urban planning	• Analyse infrastructure vulnerability and adapt current and planned infrastructure to temperature rises (in case of terrestrial infrastructures) and sea level rise (in case of maritime infrastructures) • Redesign urban planning by creating shadow areas and green passages (trees, green roofs, vegetation) to reduce urban heat island effects • Incorporate climate variables into infrastructure design • Consider bioclimatic issues in urban planning • Promote the energy efficiency in buildings to reduce the need of climate control systems
Energy	• Assess vulnerability and use potentiality of electricity systems
Human health	• Improve prediction systems and provide knowledge about CC risks especially those related to heat waves and vector borne diseases • Design and strengthen prevention programs for the most vulnerable people • Increase capability of healthcare workers and adapt the health system to identify and address CC human health risks
Economy	• Reduce the need to import goods and services • Diversify the economy
Education	• Incorporate into formal education curricula new contents relating to climate change issues • Identify jobs/sectors which need to be trained more urgently in relation to climate change and design specific education programmes for them • Establish a team work with the General Direction of Environmental Education, Environmental Quality and Waste, the Education Department of the Balearic Islands Government and the University of the Balearic Islands to deal with educational issues relating to climate change

Conclusions

For the Balearic Islands, this paper discusses the observed and projected changes in the most relevant atmospheric and marine variables due to the higher GHG emissions concentrations in the atmosphere. It also analyses the derived priority impacts on natural and agricultural and livestock systems, water resources, energy and infrastructures, as well as on human health, the economy, human rights and the socio-political system. Though all these hazards are expected to be more intense in the second half of the twenty-first century, it is argued a fragile territory such as the islands should design mitigation and adaptation plans before 2030 on the basis of the priority impacts identified in this paper for them to better cope with CC.

The analysis presented here shows higher temperatures, heat waves, the reduction of the average precipitation, the increase in evapotranspiration, the droughts, the sea level rise and the increase in ocean acidification and marine deoxygenation as the main CC-associated threats. The high vulnerability of the islands’ ecosystems and the human systems depending on them calls for an urgent set up of CC policies if welfare of current and future generations is to be ensured. We identify important threats for the insular economy as it strongly depends on mass tourism, which is not only highly vulnerable to CC and pandemics but also a big contributor to the planetary environmental problems due to its high ecological footprint. This can put into risk the islanders’ wellbeing if the economy is not diversified in an attempt to make it more resilient and lesser emitter of GHGs. CC will have an important impact on biodiversity and the supply of services by terrestrial and marine ecosystems which importantly contribute to the current sun and beach tourism model of the Balearic Islands (e.g. landscapes, forests, sandy beaches, Posidonia oceanica meadows).

Under recognition that ecosystems provide the society with goods and services that are not only economically valuable but especially crucial for life reproduction, the economy’s diversification should be oriented to promoting an economic system which is environmentally friendly and protects the islands’ heritage and idiosyncrasy. Diversification of the current socioeconomic model will facilitate the implementation of the needed adaptation and mitigation measures. In this sense, we identify ten areas which should be object of mitigation action related to terrestrial and marine ecosystems, water resources, energy, infrastructure and urban planning, sustainable mobility, human health, economy, waste, law and education. Terrestrial and marine ecosystems, infrastructure and urban planning, energy, human health, economy and education have also been identified as major areas for adaptation action.

Though the analysis has been focused on the Balearic Islands, their Mediterranean environmental conditions, and hence the particular CC threats they face, also make it interesting to other Mediterranean insular regions, and in particular, to those that also have a mass tourism–based economy. So, the conclusions drawn here can serve as a guide for them when it comes to design CC mitigation and adaptation policies.

Below is the link to the electronic supplementary material.

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