Heat stress increase under climate change twice as large in cities as in rural areas: A study for a densely populated midlatitude maritime region

Abstract

Urban areas are usually warmer than their surrounding natural areas, an effect known as the urban heat island effect. As such, they are particularly vulnerable to global warming and associated increases in extreme temperatures. Yet ensemble climate‐model projections are generally performed on a scale that is too coarse to represent the evolution of temperatures in cities. Here, for the first time, we combine unprecedented long‐term (35 years) urban climate model integrations at the convection‐permitting scale (2.8 km resolution) with information from an ensemble of general circulation models to assess temperature‐based heat stress for Belgium, a densely populated midlatitude maritime region. We discover that the heat stress increase toward the mid‐21st century is twice as large in cities compared to their surrounding rural areas. The exacerbation is driven by the urban heat island itself, its concurrence with heat waves, and urban expansion. Cities experience a heat stress multiplication by a factor 1.4 and 15 depending on the scenario. Remarkably, the future heat stress surpasses everywhere the urban hot spots of today. Our results demonstrate the need to combine information from climate models, acting on different scales, for climate change risk assessment in heterogeneous regions. Moreover, these results highlight the necessity for adaptation to increasing heat stress, especially in urban areas.

Megacity-Induced Mesoclimatic Effects in the Lower Atmosphere: A Modeling Study for Multiple Summers over Moscow, Russia

“…In contrast to a number of studies, focusing on micrometeorological regime canopy layer and considering its features as a function only from land-use and building parameters (e.g., [91][92][93]), we show that the megacity climate features are expressed as mesoscale phenomena and affected by tropospheric feedbacks, including advection, diffusion, urban-induced mesoscale circulations and perturbations of atmospheric convection. These findings are in good agreement with previous modeling studies reporting the presence of non-local mesoscale feedbacks to urban expansion [7,30]. The revealed Coriolis-forced veering of the UHI downwind shift by the Ekman layer wind rotation and amplification of cyclonic vorticity seems to be a new finding, not shown in existing studies, which requires more detailed investigation.…”

“…Thus, urban-induced processes should be essentially considered in air quality forecasts for urban areas, e.g., in COSMO-ART model [99], which is now used for this purpose for Moscow region [100,101]. It is also important to take them into consideration in high-resolution weather forecast for urban areas, biometeorological applications and in downscaling of climate change scenarios as shown in [7,102].…”

“…Investigation of these effects and taking them into account within the framework of different weather and climate services is especially important due to their significant environmental and social impacts. In general, such impacts are considered as negative due to urban-caused acceleration of climate warming in the cities [1][2][3] and amplification of the heat waves [4,5] and related heat stress [6,7] affecting the human health and even mortality rates [8][9][10]. The drivers of urban-rural temperature and humidity differences and their near-surface climatology are well-studied for a big variety of cities all over the world (see classic studies [11,12] and review papers [13,14]).…”

City life on fast lanes: Urbanization induces an evolutionary shift towards a faster lifestyle in the water flea Daphnia

“…This prediction is in line with the temperature–size rule (Atkinson, ; Forster, Hirst, & Atkinson, ; Hoefnagel & Verberk, ) and complements the earlier observation that small organisms have a higher thermal tolerance, as was also reported for Daphnia (Brans, Jansen, et al., ; Geerts et al., ). The occurrence of disturbances linked to management (e.g., clearance of the litter layer on the bottom of the pond and addition of water; Hassall, ; personal observations) and extreme temperature events in cities (Brans et al., ; Ward et al., ; Wouters et al., ) might also select for a fast life cycle (Atwell et al., ; Charmantier et al., ; Evans, Boudreau, & Hyman, ). Alternatively, the limited availability of oxygen in aquatic systems and the increased oxygen demand at higher temperatures (Bozinovic & Pörtner, ; Chown & Duffy, ; Horne, Hirst, & Atkinson, ) might lead to the expectation of lower metabolic rates and thus a slower lifestyle in urban compared to rural populations of ectotherms (Angilletta et al., ; Tüzün, Op De Beeck, Brans, Janssens, & Stoks, ).…”

Numerical Simulation of the Period 1971–2100 over the Mediterranean Area with a Regional Model, Scenario SRES-A1B

“…For example, the heat waves, unusual in the present climate, are expected to become very common due to the increasing mean temperature, and could occur in any country of the Mediterranean area. Additional trends in extreme temperature may play a significant role in the tendency of heat waves, as documented e.g., in [40]. Since the resilience measures have already reached their limits, especially over northern Africa [41], climate projections of extreme events could be useful to address sustainable solutions for local adaptation.…”