Abstract
Extensive analyses of trends in mean annual and mean seasonal minimum and maximum temperatures and relative humidity were examined for Bawku East, northern Ghana, for the period 1961 to 2012. Mean monthly maximum and minimum temperatures were used to analyse and establish recent temperature trends on an annual and seasonal basis. The year was divided into rainy and dry seasons for the seasonal trends. Mean monthly relative humidity at 6 am and 3 pm from 1961 to 2012 were considered to show recent trends in humidity since temperature and humidity interact to determine the heat exposure for outdoor workers. Regression analysis was used to illustrate trends and calculate mean yearly and seasonal rate of change. A Durbin-Watson statistical test was employed to verify autocorrelation of the residuals of the trend models and none was detected. Results showed a gradual and statistically significant rise in both mean minimum and mean maximum temperatures at two stations (Manga and Garu). There was an inconsistent pattern of trend observed at the third station (Binduri). Declining trends in relative humidity were observed at 6 am and 3 pm at seasonal and annual levels at Binduri and Garu, while there was a rising trend in relative humidity at Manga. The importance of this study hinges on the linkage between heat exposure (temperature and air humidity) and human health in the wake of climate change on outdoor farmers in developing countries who spend many hours doing manual work in the heat. On the whole, the rising temperature has impacted on ecosystem services in the study area.
Highlights
The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) revealed an increasing trend in global average temperature since 1850 and recognised that of the last years (1995–2006) before the publication of the report were ranked among the warmest years on instrumental record (Christensen et al, 2007; Jones et al, 2007; Pachauri, 2007; Trenberth et al, 2007)
Extensive analyses of trends in mean annual and mean seasonal minimum and maximum temperatures and relative humidity were examined for Bawku East, northern Ghana, for the period 1961 to 2012
In the time frame from 1961–2012, in Bawku East of northern Ghana, Garu recorded a significant rise in mean temperatures above the national annual average of 0.027 °C per year
Summary
The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) revealed an increasing trend in global average temperature since 1850 and recognised that of the last years (1995–2006) before the publication of the report were ranked among the warmest years on instrumental record (Christensen et al, 2007; Jones et al, 2007; Pachauri, 2007; Trenberth et al, 2007). The IPCC noted that the predicted increase in average global temperature was highly likely due to emissions of anthropogenic greenhouse gases (Hegerl et al, 2007). The regional projections of IPCC indicated that the West African region is likely to sustain a 3–4 °C increase in temperature over the period 1900–2100. Within this region a 3°C rise is predicted to occur in the coastal and equatorial areas, while the western Saharan region is predicted to experience an increase of 4 °C (Christensen et al, 2007). Temperature affects evaporation and availability of water (Glantz, 1992), and regulates physiological processes in humans (Parsons, 2003), animals and crops (Collins, 2011), so rises in temperatures are likely to have wide-ranging impacts
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