Water Sustainability and Climate Change in the EU and Global Context – Policy and Research Responses

ABSTRACT

Climate change impacts on the hydrological cycle (e.g. effects on atmospheric water vapour content, changes of precipitation patterns) have been linked to observed warming over several decades. Higher water temperatures and changes in extremes, including floods and droughts, are projected to affect water quality and exacerbate many forms of water pollution with possible negative impacts on ecosystems and human health, as well as water system reliability and operating costs. In addition, sea-level rise is projected to extend areas of salinisation of groundwater and estuaries, resulting in a decrease of freshwater availability for humans and ecosystems in coastal areas. Besides this, changes in water quantity and quality due to climate change are expected to affect food availability, water access and utilisation, especially in arid and semi-arid areas, as well as the operation of water infrastructure (e.g. hydropower, flood defences, irrigation systems). This chapter discusses how climate change might impact the reliability of current water management systems on the basis of expert reports prepared at global or EU level, namely reports of the Intergovernmental Panel on Climate Change (IPCC) and guidance documents of the Water Framework Directive Common Implementation Strategy. Examples of international research trends are described to illustrate on-going efforts to improve understanding and modelling of climate changes related to the hydrological cycles at scales that are relevant to decision making (possibly linked to policy).

1 Introduction

According to the Technical Paper VI of the Intergovernmental Panel on Climate Change (IPCC), observational records and climate projections provide abundant evidence that freshwater resources are vulnerable toward climate change, with wide-ranging consequences for human societies and ecosystems in Europe and worldwide. In particular, observed warming over several decades has been linked to changes in the large-scale hydrological cycle (e.g. effects on atmospheric water vapour content, changes of precipitation patterns with consequences on extreme floods and droughts). Higher water temperatures and changes in extremes, including floods and droughts, are projected to affect water quality and exacerbate many forms of water pollution from sediments, nutrients, dissolved organic carbon, pathogens, pesticides and salt, with possible negative impacts on ecosystems, human health, and water system reliability and operating costs. In addition, sea-level rise is projected to extend areas of salinisation of groundwater and estuaries, resulting in a decrease of freshwater availability for humans and ecosystems in coastal areas. Besides this, changes in water quantity and quality due to climate change are expected to affect food availability, stability, access and utilisation, especially in arid and semi-arid areas, as well as the function and operation of water infrastructure (e.g. hydropower, flood defences and irrigation systems).

The consequences of climate change may alter the reliability of current water management systems. While quantitative projections of changes in precipitation, river flows and water levels at the river-basin scale remain uncertain, it is very likely that hydrological characteristics will change in the future. Adaptation options are currently designed to ensure water supply during average and drought conditions, while mitigation measures are also developed to reduce the magnitude of impacts of global warming on water resources, in turn reducing adaptation needs (with, however, possible negative side effects such as, for example, increased water requirements for bio-energy crops, reforestation, etc.). The options to respond to climate change are closely linked to a range of policies covering different sectors, e.g. energy, health, food security, water and nature conservation. This requires that adaptation and mitigation measures are evaluated across multiple water-dependent sectors.

2 Climate Change Impacts on Water

There is far-reaching consensus among scientists that climate change is, at least to a certain extent, caused by human activities. According to the terminology of the EU Water Framework Directive (2000/60/EC) or WFD discussed in section 3, direct climate change impacts on water resources should not be classified as an "anthropogenic pressure" in the narrow sense, since they cannot be mitigated by water managers' action. However, climate change impacts interact with and potentially aggravate other anthropogenic pressures and could therefore be considered as an anthropogenic pressure. For example, changes in precipitation and hotter/drier summer periods alter both the availability of water and the demand for water for uses such as agriculture. Lower water levels as a result of climate change may lead to an increase in the concentration of pollutants (less dilution). In addition, pressures on water from human activities may change as a result of climate change mitigation efforts, e.g. targets for bioenergy production to reduce CO2 emission from burning oil tend to increase pressures on water in several places while, on the other hand, the requirement of cleaner production techniques to reduce CO2 emission might also support the development of more water-protective technologies.

With the change of rainfall patterns, seasonality and spatial distribution, impacts of climate change are reflected in influences on the quantity and quality of water resources and impacts on their uses, e.g. abstraction of both surface and ground waters. Sustainable water resource management is hence closely connected to various drivers, including climate change, land cover and increasing water consumption (see Figure 1).

Long-term threats to groundwater resources could be linked to intense rainfalls, resulting in surface flooding rather than infiltration to groundwater. Water quality will also be affected in that run-off takes nutrients and pesticides from agricultural land and transfer them into rivers and lakes, for instance. Less availability of water resources will mean lower quality in some cases, e.g. droughts can have an impact on the ecology of rivers. Extremes may also have adverse effects on aquatic ecosystems, turning into not only a water shortage problem but also into a large environmental problem (up to desertification in some areas). Possible impacts to be anticipated also concern issues of water demand (increased demand and/or differing patterns), water infrastructures (e.g. in low-lying and coastal areas prone to flood risks, soil movement, effects on water treatment, etc.), sewer network operations (e.g. disruption due to extreme rainfalls with risks of pollution in industrial areas), threats to economic development of the water sector, etc.

The assessment of climate change impacts on water resources implies a good knowledge of their global/regional distribution. The most sensitive hydrological systems should also be identified at the scale of river basins (this is linked to WFD river basin management principles, see section 3). This means that climate-induced changes in hydrological systems and processes should be better understood, in particular, variables such as river flows, groundwater and lake levels, soil moisture, evapotranspiration, snow cover, glacier extent, permafrost, etc., as well as impacts on biodiversity. Besides impacts on natural conditions, climate change impacts on sectoral water uses should also be evaluated, e.g. on agriculture (rain-fed and irrigated), forestry (including forest fires and deforestation), hydropower, navigation and water supply (domestic, agricultural and industrial). Furthermore, water-related impacts on infrastructure, health, transport, financial services (e.g. insurance sector), energy and tourism should also be reviewed. This should be done in an integrated way in order to tackle multi-risk evaluations at the river basin scale, distinguishing land-use changes due to human activities from climate-induced changes.

While climate change and climate change impacts research are progressing fast, there is still a lot of uncertainty, particularly with regard to water-related changes. There is also large uncertainty about future projections of climate change impacts on waters during the forthcoming decades. Over this timeframe, mean temperatures are expected to continue to rise but large year-to-year variations in precipitation probably will mask underlying regional trends for several decades. This implies that temperature-dependent processes (such as seasonal snowmelt, species' distribution and phenology, etc.) probably will manifest change in the first instance. An increase of extreme events (floods and droughts) is also likely to occur. Uncertainties stem from different sources, e.g. difficulties in predicting future socio-economic development (scenario uncertainty), unsatisfactory model resolution and insufficient mathematical description of all global circulation processes (model uncertainty, especially for precipitation), lack of local hydrological localised models, etc. Attributing these hydrometeorological extremes to climate change is still uncertain because of a lack of accurate data and full scientific understanding of the functioning of the climate system.

3 Policy Background

3.1 Introduction

The need for policy responses to tackle climate change impacts on water is recognised worldwide. This is extensively expressed in the IPCC Technical Paper on Water, which is addressed primarily to policy-makers engaged in all areas related to freshwater resource management, climate change, strategic studies, spatial planning and socio-economic development. This Technical Paper evaluates the impacts of climate change on hydrological processes and regimes, and of freshwater resources (availability, quality, uses and management), at a worldwide scale, and highlights their implications for policy, looking at different sectors. In particular, it provides recommendations regarding adaptation measures in regions prone to climate-change-related extremes about water resource management, ecosystems, agriculture and forestry, coastal systems, sanitation and human health. Some statements issued from the IPCC Technical Paper are summarised in Table 1. This short introduction only serves to highlight that awareness for policy actions is growing worldwide but that, to date, no legal framework is in place to tackle climate change impacts on water at a global scale.

3.2 EU Policies

Compared with many international river basins worldwide which have no legally enforceable management framework, the situation in the European Union is developing towards a robust integrated water resources management system, with legal instruments being in place or in development. This section examines concrete policy steps that are either implemented or being developed in Europe. In the first place, EU water managers are currently implementing the Water Framework Directive (WFD), which is the main legislative instrument for water protection. Details about operational policy measures related to this directive can be found in the literature. The basic feature to be kept in mind in the context of this chapter is that the WFD is built upon the principles of river basin management planning (see Figure 2), considering all types of waters and pressures that may affect them, and designing programmes of measures (supported by extensive monitoring) to achieve "good status" objectives by 2015 (this concerns chemical and ecological status for surface waters, and chemical and quantitative status for groundwater). Climate change might affect and interact with all steps of WFD implementation, and thus on the status objectives, and this has been subject to in-depth discussions within the policy and scientific communities over the years 2008–2010 as reflected in the literature and in a guidance document of the WFD Common Implementation Strategy examining river basin management in a changing climate.

The WFD does not explicitly refer to risks posed by climate change to the achievement of environmental ("good status") objectives. However, several articles provide a framework to include climate change impacts into the planning process. In particular, the Annex II of the directive stipulates that "Member States shall collect and maintain information on the type and magnitude of the significant anthropogenic pressures to which the surface water bodies in each river basin district are liable to be subject". With the far-reaching consensus that climate change is at least to a certain extent caused by human activities, climate change impacts could fall into the category of "anthropogenic pressures". It should be highlighted that these impacts cannot be classified sensu stricto as anthropogenic pressure in the context of the WFD since they cannot be mitigated by water managers' actions. However, climate change might interact with and potentially exacerbate other anthropogenic pressures and should therefore be considered within the policy framework. For example, changes of precipitation patterns and drier summer periods might alter both the availability of water and water demands for agriculture and other uses, lower water levels might lead to pollution increases (less dilution), etc.

The climate sensitivity of the WFD has hence been studied in detail to evaluate the possible impacts on policy implementation. The main considerations are summarised below:

• Characterisation of water bodies and pressures. In the context of the WFD, this involves a review of the impact of human activities (and related pressures) on the status of surface and groundwaters. Several factors used in this review are based on water system typologies that are themselves variables according to the climate (hence to climate change). This includes, for instance, river flow categories, energy of flow, precipitation patterns, water level fluctuations, etc., with indirect impacts on pollution patterns (affecting both point and diffuse sources through changes of flows, run-offs, etc.). This means that some characteristics of water bodies might be modified owing to climate change, with effects on their status.

• Risk assessment. The characterisation of water bodies is an essential part of the WFD as it aims to forecast risks and calculate costs and benefits of the programme of measures. As expressed above, modifications of water bodies' characteristics due to climate change could lead to potential impacts on "good status" achievements (due to, for example, changes of water temperature, decreased dilution capacity of receiving waters, exceedence of water quality standards, changing metabolic rates of organisms, fish migration patterns, increased eutrophication, changes of river flows, etc. – the list is not exhaustive).

• Prevention of status deterioration. Changes in the flow regime and physico-chemistry of rivers could have significant impacts on key species that could alter ecological status achievements, in particular in protected water bodies, e.g. effects on spawning conditions for salmons, climate-driven shifts in species and community composition, etc.

• Achievement of "good status". Following on from the above, shifts in surface water bodies' characteristics might have effects on WFD status achievements, in particular concerning compliance to environmental water quality standards (chemical status), impacts on fish mortality and biota composition (ecological status), etc. At the other end of the spectrum, increased flood frequency might also impact on status objectives through increased sediment loads and mobilisation of contaminated sediments. Groundwater bodies may also be affected, e.g. through base-line shifting from natural conditions, enhanced downward migration of, for example, agricultural pollutants, saline intrusions in coastal aquifers due to rising sea levels, reduced groundwater recharge (with effects on quantitative status), etc.

• Programmes of measures necessary to deliver WFD objectives may also be affected directly or indirectly as these depend upon the above operational steps (characterisation, and analysis of pressures and impacts, in particular). The success of the programmes of measures will be closely related to the accurate characterisation in the first place, and flexibility to future changes in climate. The programmes should also accommodate possible changes in behaviour ahead of climate change, such as adaptation mea- sures in spatial strategies.

• Monitoring efficacy to check compliance to WFD objectives might also be affected by shifts in water body characteristics, e.g. increased river flows with greater dilution making sites more "compliant" towards environ- mental quality standards. Also, impacts of extreme events may be problematic at low monitoring frequencies. Monitoring strategies in the light of possible impacts of climate change would hence need to be reviewed at regular intervals (this is actually foreseen under the WFD framework).