Observed Changes in Long-Term Climatic Conditions and Inner-Regional Differences in Urban Regions of the Baltic Sea Coast

Abstract

This paper presents research outcomes from an investigation into climate change and urban impacts on climate development in urban regions of the Baltic Sea coast. The cities considered were Rostock and Stockholm, and their surrounding regions. The objectives were: 1) to determine whether significant changes in temperature and precipitation have occurred and, if so, to what extent; and 2) to establish whether there is a noticeable urban heat island effect in Stockholm and the medium-sized city of Rostock. Climatic trends were detected by linear regression and the MannKendall test. Different precipitation trends were detected over the whole period of observation. Average annual temperatures increased significantly in both case studies, particularly from the 1970s with highest trends in winter and lowest in autumn (Rostock) and summer (Stockholm). Although changes in temperature extremes were detected for both regions, no overall long-term trend for precipitation extremes was observed. The average temperature in the city of Rostock (Stockholm) was approximately 0.3˚C to 0.6˚C (1.2˚C) higher than in the surrounding rural areas had seasonal variations, with maxima in the warm season. The main outcomes were that significant changes in climatic conditions, particularly temperature patterns, have been occurring in the case study regions since the 1980s, and that there is a considerable urban heat island effect in both Stockholm and Rostock. This could encourage urban planners to consider specific climatic conditions and small-scale climatic influences also in relatively small coastal urban conglomerates in mid latitudes which can follow from land use changes.

Assessing urban climate effects on Pinus sylvestris with point dendrometers: a case study from Stockholm, Sweden

“…Over the whole monitoring period, urban sites are characterized by an average temperature difference of 1.3 °C and a 10% lower air humidity compared to the rural location, capturing the magnitude of the UHI in the region (Richter et al 2013). Our analysis confirms that these microclimatic differences affect urban trees radial growth as well as their climatic response, especially under drought-stress conditions.…”

“…Benefiting from urban planning practices focused on ecological preservation since the early 1900s, several patches of indigenous forests can still be found in many urban areas across Sweden. With an urban heat island (UHI) effect of 1.2 °C (Richter et al 2013), an increasing trend for urban expansion, and the location in a drought-sensitive region (Linderholm et al 2004;Seftigen et al 2013), Stockholm's urban area provides a good research opportunity on native trees' growth response to the ongoing climatic changes in addition to the urban climate effects. We hypothesize that in urban environments, increased temperatures may lead to enhanced growth relative to the natural forest stands, but that tree growth might be more sensitive to drought periods and heatwaves.…”

Socio-economic Impacts—Urban Climate

“…It is most pronounced during calm nights with clear skies (e.g. Schlünzen et al 2010;Richter et al 2013). This is important because higher night-time temperatures can cause discomfort and increase mortality rates during prolonged hot summer periods, as found for example for London (Armstrong et al 2011).…”

Is It Possible to Distinguish Global and Regional Climate Change from Urban Land Cover Induced Signals? A Mid-Latitude City Example

“…In radiation intensive, weak wind steady weather situations, the UHI is most pronounced [19]. Thus, UHIs are particularly distinct in calm summer nights with a clear sky (e.g., [20][21][22]). …”