Climate change impacts and vulnerability in Europe 2016

Multi-sectoral vulnerability and risks
6.6 Vulnerability to climate change in urban regions
Key messages
• The climate resilience of Europe's cities, which accommodate almost three-quarters of the European population, is
decisive for their functioning and for Europe's growth, productivity and prosperity.
• Cities face specific climate threats. The urban heat island effect exacerbates the impacts of heat waves and is increasingly
also affecting cities in central and north-western Europe.
• Almost 20 % of the 411 cities that were considered were continuing to spread into areas potentially prone to river floods
during the period 2006–2009, thus increasing their sensitivity to the impacts of flooding.
• Urban sprawl with low-density housing has led to a growing intermingling of wild land and urban areas, which has
increased the risk of forest fires in many residential areas over recent decades, in particular around cities in Portugal,
Greece, southern France and Italy.
• European cities in general are less vulnerable to climate change than cities in other regions of the world owing to them
having a relatively high response capacity. However, further action is needed in line with the changing climate to sustain
this high degree of preparedness.
Cities are important for Europe. They accommodate
around three-quarters of its population and produce
a major proportion of Europe's wealth. Metropolitan
regions alone generate almost 70 % of Europe's GDP.
The proportion of the European population that is urban
is likely to increase further to 80 % by 2050 (EC, 2014).
Among other challenges, climate change impacts can
substantially affect the quality of life in and productivity
of cities. Well-functioning and climate-resilient cities are
therefore key for a climate-resilient Europe.
6.6.1 Climate risks to urban areas
While, in principle, cities face the same climate risks as
their surrounding regions (see Chapters 4 and 5), they
also face specific risks, which can be altered by urban
design.
The impact of heat waves is felt particularly intensely
in cities and towns. The 'urban heat island' (UHI) effect
increases the temperature of urban air compared
with the air of rural surroundings. The temperature
difference can be up to 10 °C (Oke, 1987). The UHI
effect is particularly significant at night, when high
temperatures are generally most problematic for human
health (Grinze et al., 2005). Zhou et al. (2013) found
that the effect is positively correlated with city cluster
size, but there are considerable deviations in size and
experience of UHI effect. This suggests that factors
other than size can influence the UHI effect, such as
topography, the form and size of green infrastructure,
building material or ventilation corridors. Furthermore,
in terms of health effects, thermal comfort is more
relevant than air temperature. Outdoor thermal
comfort is linked to the UHI effect, but also depends
on wind speed, humidity and radiation, factors that are
influenced by urban design (van Hove et al., 2015).
Map 6.8 shows city-specific values of the outdoor
thermal comfort index, which combines air temperature,
the relative humidity of the air and average wind speed
(EEA et al., 2015). The average values for the current
period show that most cities in Europe experience nights
of thermal discomfort, in particular in the south. The
UHI effect causes a significant increase in the number
of nights of thermal discomfort compared to using
standard rural data without UHI correction (EEA, 2015).
The number of nights of thermal discomfort is projected
to increase, and the part of Europe where people
experience nights of thermal discomfort is projected
to extend further. A specific regional analysis for cities
in the Randstad area in the Netherlands (Amsterdam,
Rotterdam and The Hague) indicates that, even in cities
currently experiencing hardly any warm nights, heat
stress at night could add up to more than a month per
year in the period around 2050 (KPSA, 2014). As many
buildings in these cities are not yet adapted to keep the
heat out or cool effectively, indoor thermal discomfort
is likely to increase and could threaten people's health.
In addition, energy consumption for cooling might
increase.
A recent assessment in the EU RAMSES project
used heat wave risk scores that also included
socio-economic information to assess vulnerability.
306 Climate change, impacts and vulnerability in Europe 2016 | An indicator-based report