CAUSES OF GLOBAL WARMING AND CLIMATE CHANGE IN NIGERIA

CHAPTER THREE:  METHODOLOGY

CAUSES OF GLOBAL WARMING AND CLIMATE CHANGE IN NIGERIA

Increasing temperature (global warming) and decreasing precipitation in most parts of the world are the greatest impacts of climate change. These bring about either negative or positive ecological impacts in different parts of the world. The increasing temperature has led to increased land based ice instability and its melting. The thawing of the Arctic, cool and cold temperate ice, the increasing rainfall in some parts of the world and expansion of the oceans as water warms has started impacting on sea level rise, coastal inundation and erosion.  The current global estimate of sea level rise is 0.2 m and it is projected to increase to 1 m by the year 2100 (Hengeveld et al. 2002; Hengeveld et al. 2005).  The implication is that the present 0.2 m sea level rise has inundated 3,400 km2 of the coastal region of Nigeria, and if the sea level rise attains the projected 1m on or before 2100 then 18,400 km2 of the coastal region may be inundated (NEST 2003). Coastal settlements like Bonny, Forcados, Lagos, Port Harcourt, Warri and Calabar among others that are less than 10 m above the sea-level would be seriously threatened by a metre rise of sea-level. The sea incursion due to sea-level rise means salt-water intrusion into the fresh water, invasion and destruction of mangrove ecosystems, coastal wetlands and coastal beaches.  The worst impact is population displacement, which may result in communal crisis.  The coastal inundation and erosion with their associated population displacement are currently major environmental problems in Nembe, Eket and other coastal settlements in Bayelsa, Delta, Cross River, Rivers,

and Lagos States of Nigeria. It is estimated that a metre rise in sea level will displace about 14 million people from the coastal areas of Nigeria (Abu 2007). Young (2006) also observes that sea-level rise up to a metre will displace 10, 13 and 72 million people in the coastal areas of Egypt, Bangladesh and China respectively. The increasing temperature and decreasing rainfall have led to frequent drought and desertification. The Sahara desert is observed to be expanding to all directions trying to engulf the Sahellian region of Africa with annual expansion of 1-10 km (Odjugo and Ikhuoria 2003; Yaqub 2007). Odjugo and Ikhuoria (2003) also observe that Nigeria north of 12oN is under severe threat of desert encroachment and sand dunes are now common features of desertification in states like Yobe, Borno, Sokoto, Jigawa and Katsina.  The migrating sand dunes have buried large expanse of arable lands, thus reducing viable agricultural lands and crops’ production. This has prompted massive emigration and resettlement of people to areas less threatened by desertification.  Such emigration gives rise to social effects like loss of dignity and social values. It often results in increasing spate of communal clashes among herdsmen and farmers and such clashes resulted in the death of 186 people in six northern states of Nigeria between 1998 and 2006 (Yugunda 2002; Yaqub 2007).  Akonga (2001) also shows that most of the destitute that emigrated as a result of drought and desertification usually move to nearby urban areas to beg for alms thereby compounding the already tense urbanization problems. Climate change will alter all aspects of the hydrological cycle ranging from evaporation through precipitation, run off and discharge (Mcguire et al. 2002). The global warming and decreasing rainfall together with the erratic pattern of rainfall produce a minimal recharge of groundwater resources, wells, lakes and rivers in most parts of the world especially in Africa thereby creating water crisis.  In Nigeria, many rivers have been reported to have dried up or are becoming more seasonally navigable while Lake Chad shrunk in area from 22,902 km2 in 1963 to a mere 1304 km2 in 2000. This shows that what is left of Lake Chad in the year 2000 is just 5.7% of 1963 (Odjugo 2007). Awake (2009) also confirms the fact that Lake Chad has shrunk by 95% since the 1960s and Aral Sea in Central Asia was the fourth largest lake in the planet in 1960.                   The water scarcity will create the tendency for concentration of users around the remaining limited sources of water.  Under such circumstances, there is increased possibility of additional contamination of the limited sources of water and transmission of water borne diseases like cholera, typhoid fever, guinea worm infection and river blindness. Odjugo (2000) and DeWeerdt (2007) note that the increasing temperature will mean northward migration of mosquitoes and malaria fever which will extend from the tropical region to warm temperate region while the sporogony of the protozoa causing the malaria accelerates from 25 days at 10^OC to 8 days at 32^OC. This paper also conceptualizes the relationship between climate change and human health(Fig 4). As shown in figure 4, the excessive heat, increasing water stress, air pollution and suppressed immune system occasioned by climate change will result in increasing incidence of excessive death due to heat exhaustion, famine, water related diseases (diarrhoea, cholera and skin diseases), inflammatory and respiratory diseases (cough, and asthma), depression, skin cancer and cataract.

One of the greatest impacts of climate change is the worsening condition of extreme weather events like drought, flood, rainstorms, windstorms, thunderstorms, landslides, avalanches and tsunamis, among others (Odjugo 1999, 2001b; Changnon 2001). Odjugo (2008) notes that the frequency and magnitude of wind and rainstorms did not only increase, they also killed 199 people and destroyed property worth N85.03 billion in Nigeria between 1992 and 2007. Buadi and Ahmed (2006) had similar result when they reported that rainstorms claimed 42 lives in southern Cameroon between 2000 and 2005. Between 1950 and 2000, the increasing frequency and intensity of rainstorms have created enormous damages estimated at $87 billion in property losses, $19 billion in crop losses and losses of over 12,000 human lives in the United States of America alone (Changnon 2001).

Climate change has started to, and will continue to impact negatively on agriculture and food security especially in tropical and subtropical regions because greenhouse gas emissions would increase the risk of hunger by additional 80 million people by 2080 in Africa and southern Asia (Odjugo 2001a; DFID 2006; Nwafor 2006, 2007; DeWeerdt 2007). Odjugo (2008) shows that climate change has led to a shift in crops cultivated in northern Nigeria. The paper (Odjugo 2008) quoting Ahmed (1978) reveals that as at 1978, the preferred crops the farmers cultivated were guinea corn followed by groundnut and maize, but due to increasing temperature and decreasing rainfall amount and duration occasioned by climate change, the farmers as a means of adaptation in 2007  shifted to the production of millet followed by maize and beans. Another major problem to agriculture in Nigeria due to climate change is the reduction of arable lands. While the sea incursion is reducing the arable land of the coastal plains, the desert encroachment with its associated sand dunes is depriving farmers of their agricultural farmlands and grazing rangelands. Moreover, the frequent droughts and lesser rains have started shortening the growing season thereby causing crops failure and food shortage. It has been shown that drought, desert encroachment and coastal inundation have started affecting the country’s ecosystem leading to ecological destabilization due to climate change impact in the semi-arid region of Northern Nigeria (Odjugo and Ikhuoria 2003 ; Ayuba et al.  2007).

         

The Climate Change Phenomenon

A drastic change in the climate system either due to natural forces or unsustainable human activities results in climate change. The later is regarded as the basic cause of on-going climate change and the climate and the advanced countries are most responsible (DeWeerdt, 2007). IPCC (2007) shows that observe red climate data from developed countries reveal significant change in response to global warming but there is remarkable lack of geographic balance in data and literature on observed changes with marked scarcity in developing countries. It is on this premise that this chapter is structured to assess the causes, rates and effect of climate change and global warming with emphasis on Nigeria.

The developed nation emits more of GHGs. While they accounted for over 75% of the total emissions, the developing nations are responsible for less than 25%. Industries, water pollution and agricultural production to a large extent and vehicular fumes to a lesser degree are the major sources of greenhouse gas emissions in the developed world. Nigeria like most developing countries is not like an industrialized nation so automobiles are therefore the major sources of air pollution in the urban areas. This is because most vehicles imported into the country are either fairly used or old ones which emits lots of carbons into the atmosphere. Carbon emissions from motorcycles are even worse than those from vehicles in Nigeria.  Most commercial motorcycle riders in Nigeria usually add engine oil to the petrol, which automatically turns the petrol into gasoline. Although gasoline burns slower than petrol, it emits more carbons. The motorcycle riders save fuel at the expense of the environment. The failure of the power holding company of Nigeria (PHCN) to provide efficient and effective electricity has resulted in majority of Nigeria buying generators to provide individual thermal electricity, and these do not only constitute noise pollution but also emit a lot of carbon into the atmosphere. Gas flaring is another source of GHGs emission in Nigeria. Nigeria is the largest gas flaring nation in the world. She flares more than 70% of hr natural gas (odjugo, 2007).

Impact of climate change in Nigeria

Impact as used may be negative or positive or combination. Climate change has stated imparting and will continue to affect global temperatures, water resources, ecosystems, agriculture and health among others. Continued GHGs emission at or above the current rate would cause further warming and induced many changes in the global climate system during the 21^st century that would very likely be larger than those observed during the 20^th century.

In Nigeria temperatures has been on the increase. The increase between 1901 and 1938 was not much. The increase became so rapid since the early 1970s. The man temperature between the 1901 and 1938 was 26.04 while the man between 1971 and 2008 was 27.83. this indicates a mean increase of 1.78C for the two climate periods. This is significantly higher than the global increase of 0.74C since instrumental global temperature measurement started in 1860. Should this trend continue unattended to, Nigeria may experience high temperature increase between the middle (2.5C) and high (4.5C) by the year 2100. The result is a clear indication that Nigeria is experiencing global mean temperature (Odjugo, 2010). The observed temporal increase is also evident in the spatial increase. Between 1901 and 1938, the southernmost part of the country was marked by 25.5C isotherms while the northernmost was 28.5C. With the global warming becoming more pronounced, the southernmost part was marked by 26.5C isotherms and the north 30C. This study also noticed that the increase in temperature is more in the northern part of the country than in the southern part.

The temporal rainfall pattern in Nigeria shows a declining trend. Between 1901 and 1938, rainfall decrease was negligible by 1971- 2008 the decline became so pronounced. The mean rainfall value for the 1901 -  2008 was 1571mm while it deceased to 1480mm in 1971-2008 this shows a decrease of  91mm between the two climate periods. The decreasing rainfall and increasing temperatures are basic features of global warming and climate change (odjugo, 2005).

In the 1901-1938 climate periods, the 600mm isohyets engulfed nguru, but it was replaced by 500mm during the 1971-2008 climate periods. Moreover, prior to 1938, the 1200 mm isohyets that found close to Kaduna, has dropped to Minna axis.

Another prominent change in rainfall pattern in Nigeria is that the areas experiencing double rainfall maximal is undergoing gradual shift in the short-dry season (locally referred to as August break) from the month of August to July. The short-dry season is a brief period of low rainfall (dry spell) that separates’ the two rainfall peak. In 1901-1938, the short-dry season occurred 31 years in the month of August and 7 years in July. By 1971-2008, the short-dry season occurred 11 years in the month of August, 23 years in the month of July and four years for both months. This implies that the dry spell which used to occur in the month of August followed by heavy rains in the month of September (1901-1938) now shifted to July followed by wet period in the months of August and September (1971-2008).