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ALL through history, change is a fact of life. Scientific and historical evidences attest that climate has changed over time. What has informed contemporary worry about climate change is the rapidity of recent changes as compared to the past and the frequency and intensity of climate events that threaten human and environmental security, safety and livelihoods. But climate change is not climate variability.

One is long lasting; some will say with a minimum of 30 years, with seeming permanency while the other is short term and may be cyclical in nature. With the later, the common established pattern of climate may re-establish in a short while, while with the former a new pattern emerges, to which we have to adapt.

Scientific evidences abound of these changes. We will come to some of that later, but we may be reminded that in the course of our pursuit of livelihood we already experience these in Nigeria. When the harmattan becomes less obvious in terms of the temperature (not being as cold as was the case), when the harmattan/sand dust (wind) from the Sahel reaches the Atlantic Coast consistently in March not December as was familiar, a new pattern can be said to have emerged.

When the bimodal rainfall peak in the rainforest areas which deeps in August, and we call that 'August' break is no longer discernible, and is seemingly consistently so, that is a change. When the number of days with average temperature over 45 degrees in the Sahel region around Maiduguri has significantly increased, and becomes persistent compared with was known, that is a change.

When the number of rainy days significantly reduces, but the aggregate volume of rain each year is unchanged around the rainforest areas of southeast Nigeria, and remains constantly so, that is a new pattern, not a short-term variability. These we encounter in various ways across Nigeria with implications for agriculture, transport, industry, commerce, health, migration, settlement and housing, and in several other ways, as we shall shortly present. But let us return to some evidences from natural and physical sciences.

An recent interim report by the Climate Systems Advisory Group (CSAG) at the University of Cape Town in South Africa, one of NEST partners; changes in climate variables (temperature and rainfall) were analyzed and presented in spatial and temporal forms over the country at national, ecological zones and station levels. The impact of the climate change scenarios on onset and cessation of rainfall, length of rainfall periods, dry-spells, drought, and heat waves occurrences are quantified. Some preliminary results are:

There is suggestion of warmer climate in the future.  Temperature increases of about 0.02oC to 0.04oC per year from now till 2050, then about 0.08oC till 2100 are predicted. Spatial distributions show a consistent increase in temperature over the entire country. However, the coastal regions are projected to warm less than the interior regions, because of the cooling effects from the Atlantic Ocean. The highest increase occurs in the northeast.

The projected changes in precipitation vary across the country with a wetter climate in the south along the coast, but a drier climate in the northeast during the two future periods. This is consistent with the increase in temperature, because the increase in temperature along the coast would make the atmosphere to evaporate more water from the ocean and produce more rainfall over the coastal region, provided there are mechanism to trigger the precipitation process. The warmer climate in the semi-arid region (i.e. northeast) would decrease the atmospheric humidity, and thereby reducing the chance of cloud formation and rainfall.

The models ensemble suggests a peak increase of about 2 mm/day in August over Mangrove and Rain forest zones and about 1 mm/day in the same month over Short grass savannah and tall grass savannah zones. In general, the increase in temperature is uniform for all the months over the Mangrove and Rain forest, but shows a tendency to be higher in February and March over Tall grass savannah and Short grass savannah.

The distribution over the Mangrove and Rainforest suggest that an increase of 4 mm/day is plausible over the zone. Moreover, over the zones, the temperature change distribution has its highest probability frequency in the positive values, and further suggests that a temperature increase of 7oC is a possibility by 2081-2100.

The extreme events considered here are temperature-based and rainfall-based events. Over Mangrove, Rain forest and Tall Grass savannah, the scenarios project earlier onset dates and later cessation dates, hence longer rainfall season than normal. The increase in the rainfall season could be up to 2 weeks. On the hand the models project a shorter rainfall season over Short grass savannah, and the decrease could be more than one week.

Furthermore, the model suggests more rainy days and more days with of extreme rainfall amount (amount >50 mm/day or > 100m/day; hence flooding) over Mangrove, Rain forest and Tall Grass savannah; meanwhile, over Sahel, there could be less of these events.

The changes in temperature-based extreme events are more pronounced than that of rainfall. Both scenarios project more of hot extreme event in the future. For instance, the models suggest that days with temperature reaching 38oC (or more) could increase by more 7, 22, 40 and 82 days per year in 2046-2065 over Mangrove, Rain forest and Tall grass savannah and Short grass savannah respectively, and by more than 46, 69, 96 and 151 days, respectively. The number of days with heat waves could increase exponentially as well. The numbers of extreme cold event are projected to reduce.

There are consequences of these changes for every facet of life and livelihood. A few include: In light of this predicted results, increase in temperature in the Sahel and Guinea will increase the occurrence of cerebro-spinal diseases, skin cancer as well as increase incidences of cardiovascular respiration disorders.

The intense rainfall will increase the risk of flooding which introduces chemicals, pesticides, and heavy metals into water systems thus increasing the risk of water-borne diseases outbreak. WHO (1996) noted that with global climate change, outbreaks of food and water-borne infectious diseases such as diarrhoea, Typhoid and rotavirus are projected to increase. These diseases occur as a result of the contamination of water supplies through the disruption of water and sanitation systems, which can be caused by toxic runoff from increased rainfall and flood. Increased rainfall may favour breeding of mosquitoes, which implies high occurrence of Malaria, especially in the coastal, and rainforest zones where increased rainfall is predicted.

Nigeria is prone and will be prone to a wide variety of climate change-induced hazards and disasters. Floods, storms, ocean surges, droughts, erosion, heat stress cause extensive losses to livelihoods and property, and claim many lives. In 2009, a total number of 331 cases of disasters were recorded by Nigeria Emergency Management Agency (NEMA) in Nigeria. Out of the total, fire claimed the highest number with 123 cases representing 37.16per cent, followed by rainstorm (29.91per cent), flood (19.95per cent), communal/religious crises (8.46 per cent), erosion (2.72 per cent), oil spillage and boat mishap 0.60 per cent while epidemics and bomb explosion claimed 0.30per cent each . This means that there will be increased demand for disaster relief and emergency relief in the country. Pressure on disaster and emergency management facilities will intensify.

Climate change will modify existing risk characteristics in disaster management, migration and security through:

• Increased frequency and intensity of climatic hazards

• Increase reach of climate hazards. As a result, impacts in these areas are indirect - stemming primarily from direct impacts on agriculture, water resources, settlements and health.     Combined, all of these impacts result in increased stress on Nigeria's disaster management, migration and security systems.

Diverse effect of raising temperature and water stress for agriculture in the Sahel and possibly in the savannah. This will require efforts in biotechnology especially for drought-resistant varieties of crops. Livestock production will be under stress from water scarcity and heat in the Sahel and savannah regions. Drying aquifers have consequences for irrigation facilities and created more pressure for additional irrigation facilities.

Migration of people to lower temperature areas especially from the Sahel down to the savannah and rainforest. This can lead to resource induced-conflicts.

Rising sea levels and coastal erosion may have consequences for Nigeria-s industrial and economic base, as well as the transport, shipping, energy sectors as well as human settlement.

According to NEMA, of a total of 87,864 people affected by various disasters in 2009, 36,146 were displaced by floods, 19,418 were affected by rainstorm, while fire and erosion accounted for the displacement of 5,860 and 3,638 people respectively. In the coastal area of the Niger Delta, it is estimated that with a climate change induced accelerated sea level rise (ASLR) of about 0.5m could lead to the disastrous submergence of about 35 per cent of the delta, turning about 2.1 million people into environmental refugees.  These are not exhaustive.

There are still gaps to be filled especially as the subject of climate change evolves and is dynamic (not static). There are needs for studies that are more intensive in the observations of climate parameters over the Nigeria space. There are currently not enough weather observation centres in the country.

The economics of climate change and adaptation measures in Nigeria is still at a very peripheral stage. Studies are required on this. Biotechnology has been relatively behind in our continent compared to others. The need for breeders to factor in climate change factors is even more challenging than hitherto.

Till now the focus on irrigation in Nigeria has been in the savannah areas, and not often suited for smallholding farming. There is a need for design and development of irrigation facilities adequate for the coastal and rainforest areas that harvest water for household and occupational uses.

There is need for continual development of strategies, programmes and projects adequately relevant and considering geographical circumstances, as Nigeria is a fairly large and diverse area in terms of ecology and cultures.

Finally, it is proper that climate change and effects are receiving so much attention - but it is meaningless if we do not act with the knowledge we are gaining. We must work together to help fellow Nigerians be aware and adapt to climate change. But we most also ourselves adapt. We can drive less. Take public transport like the bus, if the opportunity is there. Try accumulating multiple errands into one trip, walking or taking the bicycle instead of driving the car. At home, we should turn off lights, appliances, televisions and computers when not in use.

At the work place, we should turn equipment off like computers, photocopiers and coffee makers, particularly overnight and on weekends. Use as little paper as possible, printing, photocopying and faxing.   Communicating electronically through email and fax is less expensive, more productive and healthier for the environment. Use recycled paper whenever possible, and print on both sides of the paper. We need to reduce, reuse, and recycle, keep containers, bags for future use, use cloth towels and napkins instead of paper napkins, use rechargeable batteries instead of disposable ones, discourage junk mail by not subscribing into mailing lists, reuse plastic carrier bags. Keep one or two in your pocket for your next impromptu shop, recycle all your cans and glass bottles, recycle your inkjet cartridges and mobile phones, recycle clothes or take them to a charity shop, compost your kitchen and garden waste.

We should harvest/collect rainwater for use in the garden, planting improved crop varieties (drought resistant, salt tolerant, heat tolerant, flood tolerant) changing planting dates, changing tillage operations, soil conservation techniques. We should embark on water management, water harvesting, and small irrigation methods.

We should engage in reforestation and forestation. Even in our indigenous systems and cultures there were measures to ensure these. There should be sensitization on preventive and curative medicine should be focused upon. We should promote access to both primary and secondary health care facilities. Health education strengthened in schools.

We should raise climate change awareness through the formation of clubs, and education of our peers. These issues should be incorporated into curriculum in schools at all levels.

• Professor Nwajiuba is the executive director of the Ibadan-basedNigeria Environment Study/Action Team (NEST)