Within century (1906–2005) temperature linear movement of 0.74 °C is noticeably lesser than the associated trend of 1980 to 2012, which is 0.85 °C Intergovernmental Panel on Climate Change (IPCC) 2014. Indeed climate change has been affecting communities in different ways and climate extremes are aspect of the most confusing challenges of climate change. The changes in the climate implies changes in the spatial extent, in the frequency, the intensity, the duration, and the time frame of climate events and this can lead to ground-breaking extreme weather and climate events (IPCC 2012). There are different climate extremes that affect communities in different ways: storms, flooding, drought and heat waves. The latter may seem to be the less dangerous among them but the recorded impacts worldwide have been dreadful compared to the other ones during the last decades (Balogun et al. 2016; Ceccherini et al. 2016, Russo et al. 2014, 2015; Nkrumah et al. 2011).
From droughts to flooding rains and damaging frosts to heat waves, it is obvious that climate extremes are very important and must be considered in every society (Alexander 2016); especially in tropics (direct hit of sunshine) where the west Africa countries are located. Over the years, people’s exposures to heat wave as a result of climate change have attracted a lot of concern due its frequent occurrence globally. It is a period of marked unusual hot weather over a region persisting for at least three consecutive days (Dawson RJ, Johns Det al. 2016).Scientists have agreed that climate change is happening, and that it is largely due to anthropogenic emissions of greenhouse gases (GHGs) (IPCC 2007).
Heat waves occur when high pressure rise upward in the higher atmosphere above the earth, from 3000 to 7600 m, gain strength and stays over an area for days and sometimes weeks in the same place. This physical process is frequently observed in summer (in each of the hemispheres) as the jet stream motion with the sun [National Oceanic and Atmospheric Administration (NOAA), 2015]. Anticyclones with low-level thermal low (transient anticyclones) can alter the jet stream’s normal path and block synoptic weather systems and allow heat waves to build in an area. This is a complex system that includes many factors such as tropical convection (Horton et al. 2016).
Human activities such as (industrialization, Urbanization and increased population) are capable of altering the carbon cycle by adding more Carbon dioxide (CO2) into the atmosphere, and this emission of carbon dioxide comes from a variety of natural sources; but human-related emissions are responsible for the increase land atmospheric temperature that has occurred since the industrial revolution (USNCDC, 2013). Histories have it that extreme temperature events such as (heat wave, flood, drought and many more) are increasing in their frequency, duration, and magnitude globally. Between 2000 and 2016, it was observed that the number of people exposed to heat waves increased by around 125million globally (IPCC, 2014).
The effect of heatwave may be aggravated in the cities, due to the urban heat Island (UHI) effects, deforestations, anthropogenic heat release from industry, businesses and transport; reduced cooling due to hindrance to airflow from buildings, and absorption and release of energy by dark surfaces like roads. The livelihoods and wellbeing of non-urban communities can also be severely disrupted during and after periods of unusually hot weather (Santamouris et al, 2007; Akbari and Oke 1987).
According to World Health Organization (W.H.O), 2008; Heatwaves can burden food and livelihood security i.e. its occurrence can make farmers lose their crops and livestock due extreme heat. It can also burden Health and emergency services; increase strain on water, energy and transportation resulting in power shortages or even blackouts. The health impact of a heatwave depends on the intensity and duration of the temperature, the acclimatization and adaptation of the population, and the infrastructure and preparedness (Hulmeet al, 2011).
Exposure to heatwave causes severe symptoms, such as heat exhaustion and heat stroke-a condition which causes faintness, as well as dry warm skin, due to the inability of the body to control high temperatures. Other symptoms include swelling in the lower limbs, heat rash on the neck, cramps, headache, irritability, lethargy and weakness. Heat can cause severe dehydration, acute cerebro vascular accidents and contribute to thrombogenesis (blood clots). People with chronic diseases that take daily medications have a greater risk of complications and death during a heatwave, most especially older people and children. (Miles2009; W.H.O, 2009)
Bringing it down to Africa, the continent is not left out of the severe impact of global warming, as it was deemed to be one of the most vulnerable regions to weather and climate variability despite having contributed little to its cause. Africa vulnerability to the dynamics of climate is as a result of its high exposure and low adaptive capacity (IPCC, 2014). In the past few decades Africa was said to have suffered 27% of the world reported fatalities from natural catastrophes(614,250 people) and experienced 1560 weather-related catastrophe such as heatwave, storms and floods(Munich Re 2011).
Land surface temperatures have increased in Africa by 0.5 degrees Celsius or more during the last 50-100 years. For instance, it was observed that in 2002 north-eastern Nigeria suffered one of the hottest and driest spells in living memory, with recorded temperatures above 50 degrees Celsius and dozens of people dying as results of the heat wave (http://news.bbc.co.uk/2/hi/africa/2038164).
Nigeria has been experiencing unprecedented climate change due to the way the country urbanizes coupled with the fact that Nigeria has a tropical climate with two precipitation regimes: low precipitation in the Northeast and high precipitation in the part of Southeast and Southwest. This can lead to aridity, drought and desertification in the north; and rise in sea level, heatwave, flooding and erosion in the southeast (Abdulkadir et al; Akande et al, 2017; ebele and Emodi 2016; Federal Ministry of Environment, 2014)
It was also highlighted that In Nigeria, When you have heatwave the body is dehydrated, the young, the elderly people that live sedated live-are the kind of people that will have immediate health reactions to heat wave said Environmental expert (Oluwafemi Akinbode 2020);
So since the study area (Enugu State) falls within the humid tropical rainforest belt of south-eastern Nigeria, there is every tendency that heatwave may affect the inhabitant of the Enugu. So therefore, there is every need for this research.
1.1 Statements of the Research problems
There will be over 200 million people living in Nigeria by the end of 2020 and one-half of them may be urban dwellers (Sada, 2015). With increased urbanization, temperatures tend to rise and this often has adverse effects on thermal comfort of people through the imposition of increased climate stress on such urban dwellers. The Intergovernmental Panel on Climate Change (IPCC) in their special report (Suzanne, 2018) suggests that risks with increased warming are particularly higher in urban areas due to the heat related effect. Today we hear frightening statements such as; intense heat-waves could become annual events by the year 2075.
Enugu metropolis is the centre of Enugu State, and it has recorded high increase in urbanization. The high tempo of temperature raise in Enugu metropolis is something to worry about because it affects the social life of the citizens within the urban (Adinna et al. 2009). The town is geographically positioned in the Tropical Rain forest area with high heat (Adinna et al. 2009). Also owing to the city’s urbanization, factors that mostly contributed to the temperature’s reduction of the region like plantation of tress and forest are gradually being removed due to deforestation and anthropogenic activities. The health of human beings and animals especially in Enugu metropolis is directly or indirectly influenced by the weather. Temperature, sunshine and oxygen have direct effects while the indirect effects are far greater (Odemoerbe, 2018). In Enugu, high temperatures combined with high humidity very often lead to the outbreak of “pricky heat” which is only cured by moving the person to a healthier environment, heat strokes occur when the temperatures become unbearable.
Climate change, population growth and urbanization are instrumental at increasing exposure to extreme temperatures. The effects of climate change are felt specifically in countries with tropical climate which are characterized by high humidity and very high temperatures. Countries in these regions especially in Africa are experiencing heavy urbanization and socio-economic development, leading to an explosion in the size of urban populations (Dao, 2012). A combination of these two factors is having a major impact on the living conditions of city dwellers in Enugu, especially in terms of exposure to extreme- or even- lethal temperatures. A critical threshold is usually considered to be 40.6 degrees centigrade taking humidity in to account (Guillaume 2019). High outdoor humidity levels can disrupt human ability to thermo-regulate with a potentially fatal consequences.
In Enugu heat is usually seen as normal. The general perception is that people are adapted to cope with it. One reason for this is that most elderly people may not see themselves as old and therefore don’t recognize the increased risks to heat waves (Gwimi, 2010). Heat waves are among the most dangerous natural hazards, but rarely receive adequate attention because their death tolls and destruction are not always immediately obvious. Weather phenomena can cause mass fatalities in vulnerable groups such as the elderly, young children and out- door workers. Though heat-waves are easily predictable, heat is often a silent killer. Sadly too, when there is a combination of poverty and high heat, it can be deadly. We need to develop a conceptual approach to understand the consequences of Heatwave in the Enugu city center and reconsider city plan strategy and what are the implementation measures. Therefore the majority of citizens are suffering from outdoor environment discomfort and this issue has a deeper and problematic dimension in the study of Enugu, particularly in the metropolis. This research is an effort to recognize the radical effect of Heatwave in Enugu and will suggest some appropriate recommendations to solve this matter.
The research aim of this research is to examine the effect of Heatwave phenomenon on Enugu metropolis.
The objectives of the research are:
- To investigate the change detection in the area over a period of time.
- To investigate climate change variables.
- To analyze the increase in surface and air temperature of the area over a period of time.
- To analyze the thermal comfort of the area.
The study investigated the impact of Heatwave in Enugu metropolis from 2000 and 2020 by means of remote sensing data, Landsat imagery gotten from the United States Geological Survey Site, and Air temperature, relative humidity and rainfall data from 2000 and 2019 which was procured from the Prediction of Worldwide Energy Resource (POWER) site ( https://power.larc.nasa.gov/data-access-viewer/)
1.5 Significant of the Study
The purpose of this research is to study the impact of heat wave in the study area. Heat waves have always been a silent natural disaster but the most impactful, especially on health and agriculture (IPCC, 2007). Globally, extreme weather events such as heat wave have strong implications for socio-ecological, biophysical and human system (IPCC, 2007).
High intensity of land atmospheric temperature as a result of heatwave has led to the prevalence of diseases such as heat stroke, body dehydration, heat rashes, meningitis and other chronic diseases in the state. Due Poor health care system, lack of access to credit facilities, poverty, inequitable distribution of natural resources, cultural practices, violent conflict and low educational background; both the inhabitants and farmers in Enugu state lack the adaptive capacity to cope and adjust to the effect of heatwave in Enugu (Duncan, 2007).
Other physical weather event that have occurred in Enugu metropolis as a result of regional urbanization over the years includes; flood, increased temperature (heat wave), gully erosion, increase in frequency and intensity of storms, late and early cessation of rain and frequent dry spell during farming season. Such impacts combined with high dependence of poor healthcare system and poor farmers with natural resources and rain-fed agriculture exposes these farmers to high impact of heatwave.
This Study therefore is out to show that heat wave portent serious danger to the people of Enugu metropolis especially in the areas of life, food, health, water, and social infrastructural security. The insecurity posed by climate change means that Nigeria at large and Enugu state in particular must rise up to these challenges by building climate resilient country in ways of adopting efficient mitigation and adaptation measures.
The metropolitan City of Enugu provides an excellent environment for a study like this due to a number of reasons. First the City was an administrative headquarters of Nigeria’s Eastern provinces in 1929. The rise of Enugu as a modern city began with the penetration of the British Colonialists in the first quarter of 20th Century. The British mining Engineers discovered real sub-bituminous coal which led to the establishment of a colliery and railway line linking Enugu with the coast to transport mined coal (Ayaode, 2018). As a result of this, many people drifted to the new town in search of livelihood. Heat waves associated with an increase in temperature are on the increase in many parts of Nigeria and highly pronounced in the Eastern part of the country (Odgie, 2010). Recent studies (Russo, 2019) also revealed among other things that:
- Enugu is one of the most spectacular classes of Nigerian cities which owed their growth and development to European influence.
- Enugu is a typical African city in the South East of Nigeria with rapid rate of increase in socio-economic activities and problems alike.
- With increase in urbanization and expansion in cities around Enugu metropolis, there is high rate of deforestation, and bush burning and clearing where vegetation had largely been replaced by buildings and roads thereby altering the energy balance.
These therefore provide the justification of this research.