Large-scale warming is not urban. Nature

Hadley Centre, Meteorological Office, Exeter EX1 3PB, UK.
Nature (Impact Factor: 41.46). 12/2004; 432(7015):290. DOI: 10.1038/432290a
Source: PubMed


Controversy has persisted over the influence of urban warming on reported large-scale surface-air temperature trends. Urban heat islands occur mainly at night and are reduced in windy conditions. Here we show that, globally, temperatures over land have risen as much on windy nights as on calm nights, indicating that the observed overall warming is not a consequence of urban development.

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    • "Cities accommodate over 50% of the world's population (Jansson, 2013). While some may have suggested that urbanisation has limited to no effect with respect to climate change (Parker, 2004; Peterson, 2003), some others indicate that cities are effectively capable of responding to it (Emmanuel & Krüger, 2012; Hoornweg, Bhada, Freire, Trejos, & Sugar, 2010; Moss, 2009). Nevertheless , cities now contribute to 60–85% of the world's energy consumption (Kamal-Chaoui & Roberts, 2009; Nakicenovic & Swart, 2000) and it is not credulous to expect that concentration of energy consemption activities on an over-crowded high-density area of land, have an impact on at least local, if not global, warming . "
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    ABSTRACT: Urbanisation may have been shown to have no effect on climate change, but some researchers suggest that cities are fully capable of responding to it. Urban Heat Islands (UHIs) represent dense urban areas within cities where the temperature is recorded to be higher than the neighbouring areas or those located in suburbia. Mitigation of UHI effects can help diminish detriments of climate change. This paper sets out to establish UHI mitigation strategies, their effectiveness and resilience to help provide recommendations for application of such strategies in future. Existing literature suggest that UK is facing with growing problem of UHI effects and sustainable development at urban scale can be improved if proportionate measures are taken to mitigate those effects. The lack of guidance for designers and planners with regards to UHI mitigation is also indicated in the literature where trees, shrubs and grass (TSG), use of high albedo materials (HAM) in external building surfaces and urban inland water bodies (UIWB) are identified as effective measures to mitigate UHI. This research identifies and tests resilience and effectiveness of UHI mitigation strategies, using ENVI-met simulations and through Urban Futures Assessment Method (UFAM). Assessed mitigation strategies (TSG, HAM, UIWB) are shown to have a similar level of resilience which could be improved if proper future-proof measures are taken in place. As a result, some practical suggestions are provided to help improve the resilience of tested UHI mitigation strategies in this study.
    Full-text · Article · Jun 2015
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    • "Given that there are different opinions on whether the measurements carried out in these areas affect the image of climate changes in a wider area (the view that such influence does not exist or is insignificant and that the techniques of eliminating the influence of the heat island on data seriesare adequate suggest e.g. Parker, 2004; Hansen, Ruedy, Sato, & Lo, 2010, while the opposite view is represented by Yang, Hou, & Chen, 2011; Lim, Cai, Kalnay, & Zhou, 2005), it seems important to answer the following questions: 1. What is the spatial distribution of air temperature changes in Serbia? 2. What is the intensity of the Belgrade urban heat island? "

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    • "Greenhouse gas emissions are embedded in climate models for IPCC climate change assessments, and land-cover changes in forcing scenarios for future climate change studies are also documented (Feddema et al., 2005). In recent years, there has been growing interest in land-use/land-cover change and its effect on climate change (Kalnay and Cai, 2003; Roy et al., 2003; Parker, 2004; Pitman et al., 2004; Feddema et al., 2005; Lobell et al., 2006a, 2008; Kueppers et al., 2007; Deo et al., 2009; Hu et al., 2010). "
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    ABSTRACT: Irrigation and urbanization, two widely occurring land-use/land-cover changes, have important influences on regional climate, especially on temperature. The effect of irrigation and urbanization on temperature is separately documented in several studies. However, there are few studies analysing the combined effects of irrigation and urbanization on temperature. In this study, changes in surface temperature were analysed in relation to irrigation and urbanization on the Huang-Huai-Hai Plain of China from 1955 to 2007. To better characterize the combined effects of these two processes on temperatures, long-term weather observations are used along with irrigation and urbanization data sets. The results indicated that irrigation had a significant cooling effect of 0.17–0.20 °C decade−1 on average daily maximum temperature of the hottest 1, 5, and 30 d of each year on the Huang-Huai-Hai Plain. Compared with the reference conditions, irrigation also indicated a cooling effect of 0.12 °C decade−1 on summertime daily maximum temperature. In contrast to its effect on maximum temperature, irrigation appeared to induce a warming effect of 0.43 °C/decade on average daily minimum temperature of the coldest 1 d of each year. Where irrigation interfaced with urbanization, the urbanization warming of extreme daily maximum temperature seemed to only partly counteract the irrigation cooling effect. The findings of this study deepen our insight into the effects of irrigation and urbanization on temperature dynamics, and the combined implications for regional climate change. Further efforts to understand irrigation and urbanization effects on climate should not only use observations, but should also be coupled with dynamic land-use and regional climate models to understand the complex processes and controlling mechanisms.
    Full-text · Article · Mar 2014 · International Journal of Climatology
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