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Focus: adaptation to climate change

According to one particular study, the Region will be confronted with potentially negative impacts if the anticipated climate change occurs, predominantly related to the environment and health, in particular as a consequence of an increased risk of extreme events (heatwaves, floods, etc.) As a city, the Region is particularly vulnerable due to various factors: a high degree of urbanisation and soil sealing, a high population concentration of which a considerable proportion is made up of vulnerable households, clustering of infrastructure and material assets, etc.

Mitigation and adaptation, complementary aspects in the fight against climate change

Climate policies include two complementary aspects: firstly, the prevention of climate change - or mitigation policy - which aims to reduce the emissions of greenhouse gases and secondly, adaptation to the impacts of climate change (both in terms of the environment and the economy and society in general). Most of the measures which were initially taken in the area of climate policy at the international, European and national levels focused on mitigation. Today, these policies also emphasise the adaptation which is necessary to confront the negative consequences which have already been observed, and which may be in the future.

At the international level, the United Nations Framework Agreement on Climate Change (UNFCCC) has established a binding framework for adaptation policies. At the European level, a process of reflection which began in the early 2000s culminated in April 2013 with the adoption of the European strategy on adaptation to climate change, which created a framework and mechanisms intended to significantly increase the European Union's degree of readiness in the face of current and future climate change.

At the Belgian level, a national adaptation strategy was adopted in 2010. Following the adoption of this strategy, a draft national adaptation plan was finalised in 2015 by the "Adaptation" task force of the National Climate Commission. It has not yet been approved at this stage.

However, the three Regions and the Federal State have drafted their own adaptation plan, in their respective fields of competence. For the purposes of the future Air-Climate-Energy plan (which is in the process of being adopted), Brussels Environment commissioned a study in 2012 on the Region's adaptation to climate change. This focus presents the main results for the environment and for society.

Evaluation criteria of the risks related to climate change

The final objective of the study was to identify the main regional vulnerabilities in the face of climate change, in order to formulate action plans for the regional strategy in a second phase. 'Vulnerability' refers to the Region's degree of exposure to the potentially harmful effects of climate change. The study also brought to light several opportunities related to climate change, although these are limited and would only be short-lived.

Diagram of the evaluation of the risks related to climate change for human and natural systems
Source : Brussels Environment, 2015

The risk identification is based on three criteria (cfr. chart above):

  • 1. The level of exposure to climate hazard, based on observations of the evolution of the past climate in the Region (Royal Meteorological Institute of Belgium, Report “Vigilance climatique” (Climate Vigilance), 2008 & see the documented climate sheet n°2) and on the prospects of future evolution (climate forecasts up to 2030, 2050 and 2080). Needless to say, that a degree of uncertainty generally accompanies these forecasts.
  • 2. The susceptibility of the Region: evaluation of the impact on water resources, biodiversity and forests, energy, health, territorial planning and infrastructure, tourism (the latter sector is not included in this focus). The urgency of managing the situation is also taken into account with respect to the expected impact.
  • 3. The Region's current or potential adaptation capacity is examined in relation to society's degree of awareness, the level of management in the existing planning documents and the regional expertise on the subject.

The risk evaluation and the highlighting of the Region's vulnerabilities are based on a series of indicators whose prioritisation and weighting have been established by experts: there is consequently a degree of subjectivity in the vulnerability analysis.

Likely future evolution of the climate in the Brussels Region

In the long run, the likely future evolution of the climate in the Brussels-Capital Region can be succinctly characterised as follows (RMI-IRM-KMI, Report “Vigilance Climatique” (Climate Vigilance) 2015 & see the documented climate sheet n°2) :

  • A warmer climate;
  • A seasonal character which is stronger marked by rainfall: less in summer and more in winter;
  • An increase in the frequency or intensity of extreme events (heavy rainfall in winter, heavy storms in summer, heatwaves in summer).

Main vulnerabilities of the Brussels Region

The amplification of the urban heat island effect (see the focus devoted to this subject) entails health risks for the population. This phenomenon actually strengthens air pollution by increasing the formation of ozone, which can be particularly dangerous for the most vulnerable people and children. The heat island effect has the potential to occur mostly in the urbanised city centre of the Region, where refuge areas (green spaces) are even more rare, the habitat is poorly adapted and there is a high concentration of vulnerable populations. Although new studies by the RMI (Hamdi et al., 2013) confirm temperature increases in the future, they nonetheless qualify the future evolution of the urban heat island effect: it would occur during the night, but would likely reduce during the day (due to an increase in rural temperatures) (see the focus devoted to this subject).

The increase in heatwaves and temperatures would also have health repercussions for the entire Brussels Region: firstly via the deterioration of air quality (increased occurrences of ozone peaks) and subsequently via a growing risk of allergies and infectious diseases or diseases which are transmitted by carriers.

Increased heat in the city risks an increased use of air conditioning in buildings: however, given the impact of air conditioning on the greenhouse effect, this response would counteract the mitigation policies carried out at the same time.

In terms of transport and infrastructure, a permanent risk of transport disruption during extreme meteorological events has been identified, as well as increased vulnerability and the poor adaptation of transport and building infrastructure to heatwaves and droughts, with an expected strengthening of the urban heat island effect.

One of the other vulnerabilities of the Region is its increasing exposure to flood risk (see the focus devoted to floods) due to growing urbanisation and soil sealing. According to climate models, winter rainfall would increase, leading to a higher risk of flooding during this season. On the other hand, if summer rainfall would tend to decrease, the higher temperatures might create unstable air masses and result in more storms: even if this scenario is full of uncertainties, a precautionary approach should prompt awareness of a flood risk which is also higher in the summer season.

Another notable impact of climate change concerns river flows, groundwater recharge and the quality of surface water and groundwater. The decrease in spring and summer rainfall linked to an increase in temperatures would accentuate evapotranspiration. The consequence for surface water would be more severe low-flow levels (in other words a decrease in the minimum flow in rivers), which would result in pollutants becoming less diluted in rivers and consequently, a deterioration in the quality of surface water. There would also be a risk of greater eutrophication of water in ponds and lakes. With regards to the recharge of groundwater, this could be compromised in the event that the supply shortage in the spring would not be compensated by the increase of supply in the winter. What is particularly at stake here is the Brusselian groundwater body, which is used for the production of drinking water.

The final major threat which has been identified is the impact on biodiversity and the Sonian forest. Firstly, the forest stands could suffer from poorer root anchorage (following water stress, a reduction in the number of days of frost, etc.) and be less able to withstand strong winds. But above all, climate change could alter the adaptation of species within their environment and distributional range. In the case of the Sonian forest, this impact would affect both the timber species and the related animal or plant species (for example, during the pollination process or regarding the transmission of diseases) (see "Sonian Forest and risks associated with climate change" in the State of the Environment 2007-2008 & "Health of the Brussels Sonian Forest" from the State of the Environment 2011-2014). The lack of connectivity between the habitats accentuates the vulnerability of the species found in the Brussels Region (see "Fragmentation and isolation of green spaces" from the State of the Environment 2011-2012). Finally, invasive species could become more numerous and reproduce more actively (see "Invasive exotic species" from the State of the Environment 2011-2014).

The table below illustrates the various vulnerabilities of the Region.

Main vulnerabilities and opportunities of the Brussels Region following the expected evolution of the climate
Source: Extract from the executive summary of the study into the adaptation to climate change in the Brussels-Capital Region (excluding impacts on tourism), 2012

Some opportunities

The identification of the positive aspects of climate change has also been taken into consideration in the work on adaptation by the IPCC in their regional exercises, whatever the spatial or institutional level.

The opportunities identified in the study essentially arise from the expected decrease in cold snaps and the number of days of frost:

  • Firstly, the decrease in heating requirements for buildings would entail a reduction in energy consumption and the associated emissions of atmospheric pollutants during the cold season;
  • Next, the improvement in air quality (discussed previously) as well as the decrease in cold snaps would reduce health problems during the cold season;
  • Finally, damage due to frost would decrease both in forest stands and on road transport, railway, or electricity network infrastructure.

Another opportunity has been identified, this time related to the presumed increase in temperature: an increase in plant growth, and in particular, forest growth.

However, the work reiterates the fact that these opportunities would be temporary, and with limited scope: with the expected extent of climate change still to come, thresholds would be reached which would destroy them (Factor-X, Ecores, TEC, 2012).

Which adaptation policy for the Brussels Region?

The regional adaptation policy is multi-disciplinary. It is not only limited to environmental measures. In fact, social and socio-economic measures also make it possible to reduce the exposure of populations, species and infrastructure to the harmful effects of climate change and therefore their vulnerability in the face of these changes.

The main strands of the regional adaptation policy are set out in the integral Air-Climate-Energy plan. Some adaptation measures are also included in the draft management plans for water (including the risk management plan for floods) and the nature plan. Among the key adaptation measures there are the reduction of the population's exposure to flood risk, the fight against the harmful effects of soil sealing on the environment, the development of a green network, blue network (surface hydrographical network) and grey network (sewage system) or even energy-efficient building renovation. More often than not, the emphasis is placed on the most vulnerable populations. Furthermore, the future management plan for the Sonian forest will include measures making it possible to increase the resilience of the forest to climate change (diversification of timber species, etc.).

The adaptation measures are referred to as "no regrets" measures, in other words measures with wider-ranging environmental and social benefits than simply adaptation to climate change. They are clearly favourable to the development of natural ecosystems, social cohesion and quality of life, regardless of climate change.

Date de mise à jour: 06/12/2017

Study(ies) and report(s)

FACTOR-X, ECORES, TEC, July 2012. « L’adaptation au changement climatique en Région de Bruxelles-Capitale : élaboration d’une étude préalable à la rédaction d’un plan régional d’adaptation ». Study performed on behalf of Brussels Environment. 252 pp. (.pdf, in French only)

FACTOR-X, ECORES, TEC, October 2012. Executive summary of the study « L’adaptation au changement climatique en Région de Bruxelles-Capitale : élaboration d’une étude préalable à la rédaction d’un plan régional d’adaptation ». Study performed on behalf of Brussels Environment. 7 pp. Restricted.

ROYAL METEOROLOGICAL INSTITUTE OF BELGIUM (RMI-IRM-KMI), May 2015. « Vigilance climatique 2015 ». 87 pp. (.pdf, in French and Dutch only)

HAMDI, R., VAN DE VYVER, H., DE TROCH, R. and TERMONIA, P. (RMI-IRM-KMI), June 2013. « Assessment of three dynamical urban climate downscaling methods: Brussels's future urban heat island under an A1B emission scenario ». International Journal of Climatology (2013), 34: 978–999. DOI:10.1002/joc.3734. 22 pp. (.pdf)