Table of Content forward introduction

1. 
   Introduction
   

2. 
   Evidence of Climate Change
   

2.2 Hail Frequency

2.3 Mean Temperature

3. 
   Synoptic Features
   

3.2 Inter-Tropical Discontinuity (ITD)

3.3 El-Nino
4.0 Temperatures

4.1 Hot Season Maximum Temperatures

4.2 Hot Season Maximum Temperature Anomaly

4.3 Cold Season Minimum Temperatures

4.4 Cold Season Minimum Temperature Anomaly

4.5 Annual Mean Temperature Anomaly

6.1 Cumulative Annual Rainfall

6.2 Rainfall Anomaly

6.3 August Rainfall Anomaly

6.4 Rainfall Months

6.5 Little Dry Season

8.1 Wind Speed

8.2 Temperature

8.3 Rainfall

9.1 Agriculture

9.2 Health

9.3 Education

9.4 Hydrology

9.5 Aviation

10. 
    Summary
    

10. 
    Climate outlook 2013
    

12.1 Lagos State

12.2 Nigeria


13.0 Sample Flood Pictures
12.3 Global

FOREWORD

Climate change is real and its consequences will be with us for the greater part of this century. If appropriate measures are taken now to stem the increase in the emission of Green House Gases (GHG) into the atmosphere that is responsible for the global warming then there will be a reversal of the consequences. The Intergovernmental Panel on Climate change (IPCC) has established through its science based research that the effect of global warming will linger for longer period if the present trend of GHG emission is not curtailed. The Intergovernmental body has also shown that the anthropogenic activities has contributed significantly to the variations and changes observed in the world climate system since the post industrial revolution era apart from the contributions of natural climate modifiers such as continental drift, volcanoes, ocean currents, earth’s tilt, comets and meteorites. All living things are affected by the climate systems and in particularly by the climate extremes which threatens safety of lives and property and sustainability of socio-economic activities. Since weather and climate know no natural, geographical, political or disciplinary boundaries, cooperation amongst relevant institutions become very necessary to put in place a robust and effective mitigation and adaptation measures to the variability and change of the climate systems in order to achieve the much desired stabilization. It is therefore not surprising that climate change remains one of the greatest challenges of our time towards attainment of sustainable economic development and calls for reinforced interdisciplinary cooperation to stem its devastating consequences.

The synoptic features indicated dominance of the subtropical high pressure systems at the beginning of the year, leading to the raising of dust particles at the surface in the Sahara Desert and subsequent transportation and reduction of horizontal visibility across the country. The southwesterly winds gained momentum at the coast and progressively moved inland at the end of first quarter of the year. The monsoon trough remained very active across the country till the end of the third quarter, and this brought about enhanced rainfall and thunderstorms, flash flooding and the associated impacts.

The seasonal and meridional oscillations of the Inter-Tropical Discontinuity (ITD) attained a peak position of about latitude 18.8^oN in August. In addition, the dynamics of the atmosphere showed unusual surging and pulsation of the ITD, such that severe storms were experienced over the coast as early as February in 2012, particularly over Lagos. Further scientific studies are presently being undertaken to understand the causative factors.

Rainfall amounts were normal to above normal with high intensity rainfall duration in some occasions leading to flooding during the months of July, August and September. It is important to note that for the first time since 2008, the northeast had rainfall more than normal values in more than ten consecutive years. Widespread flooding peaked between September and mid-October across the country and was particularly severe in the northcentral and coastal states. Nigeria experienced the worst flooding in 2012 for more than a century.

The hot season in 2012 was warmer than normal in the north but normal in the south except over the extreme southeast which was colder than normal. The comfort index anomaly showed greater than normal discomfort during the hot season in the north but other regions were comfortable over the same period. The August break of 2012 over southwest Nigeria lasted for about two weeks at Ibadan and five weeks at Ikeja. The phenomena lasted till the first week in September.

Extreme weather and climate events in 2012 led to significant socioeconomic impacts. Strong winds in the magnitude of 60-70knots were experienced in the south and the north for the months of February and June respectively. Daily maximum temperatures of 40.0^oC and higher were experienced in the northern part of the country and in some places for sixty days, although the days were not consecutive. High impact daily rainfalls of 100.0mm and higher values were recorded in the year between May and August.

The onset of the rainy (wet) season between 1941 and 1970 was mostly from “early to normal” (Fig. 1a). Isolated places around Sokoto, Maiduguri, Owerri, Port Harcourt and Calabar had late onset of the rainy season. However, increasingly late onset of the rainy season characterised later years such that by 1971-2000 a vast portion of the country now experience late onset of the rains (Fig. 1b).

Similarly, the cessation of the rainy season in the country transformed from being generally “normal” between 1941 and 1970 (Fig. 2a) to “early cessation” during the 1971 – 2000 period (Fig. 2b).

The period of the rainy season in the country has been reduced from 1941 when the onset and cessation were generally normal to 1971 when signals of late onset and early cessation of the rainy season set in. Since then, the length of the rainy season has remained shrinking while annual total rainfall is about the same, thereby giving rise to high impact rainfall, resulting in flash floods.

Temperatures across the country show an increasing trend from mid 20^th century to date. The mean temperature anomaly (Fig. 4a) shows clearly the prevalence of warming in the country. Temperatures have increased from 0.2 – 0.5C in the high ground areas of Jos, Yelwa and Ilorin in the north and Shaki, Iseyin and Ondo in the southwest to 0.9 - 1.9C over the rest parts of the country.

During the months of February and March, the positions of the ITD were above normal (Fig. 6). This accounted for the early onset of rainfall in the south in February. However, it was below normal throughout the rest of the year.

The La Niña condition which prevailed during the later months of 2011 continued in early 2012 with below average sea surface temperatures (SSTs). However, the SST in the Niño-3.4 region which was near –1.0°C began to warm and by the end of February, the La Niña weakened to near –0.5°C below average SSTs (Fig. 7). This trend continued in March, April and May, with large scale atmospheric circulation anomalies and the Southern Oscillation Index (SOI) indicative of a transition from La Niña to ENSO-neutral condition.

The second half of 2012 clearly showed warm-neutral ENSO condition. Upper and lower-level zonal winds were near average, and convection was slightly suppressed over most of the tropical atmosphere.

Maximum temperatures during the hot season (February and March) in the south and (March and April) in the north, showed that temperature ranged between 30.1 – 40.0°C (Fig. 8). The maximum temperature gradually increased inland from the coastal areas, with the exception of Jos and its environs. The southeast coastal areas had mean maximum temperatures of 30.0 – 33.0°C, while the coast of the southwest and the inland cities of the south recorded maximum temperatures between 33.0 – 36.0°C. Maximum temperatures over the central areas and the north central parts ranged between 36.0° -38.0°C during the period except for Jos and its environs which had mean maximum temperature ranging between 30° -36°C. Jos recorded the lowest maximum temperature of 30.1°C. Elsewhere in the north, maximum temperatures were between 38.0° - 40.0°C.

The hot season in 2012 was warmer than normal in the northern parts of the country with maximum temperature departures ranging from 0.5 - 2.5°C (Fig.9). Normal temperature conditions were experienced at the southern and central parts of the country in the year, except for Makurdi and Bida where maximum temperatures were 0.5-1.5°C higher than normal maximum temperatures. On the other hand, Calabar, Uyo and Eket, in the extreme southeast coast, recorded maximum temperatures lower than normal by 0.5 - 2.5°C.

Monthly minimum temperature across the country during the cold season (January) showed that low minimum temperatures, between 10.0 - 14.0°C, were recorded in the northeast, Kano, Katsina and the areas around Jos in the central region (Fig. 10). The remaining parts of the north experienced season minimum temperatures between 14.0 -18.0°C while cold season minimum temperatures ranged between 18.0 – 22.0°C over the northcentral and the south except at the coastal cities which experienced the highest temperatures range of 22.0 – 24.0°C. The highest cold season minimum temperature in the south (24.1°C) was recorded at Eket.

Cold season minimum temperatures in 2012 were generally normal across the country when compared with 1971 – 2000 average values (Fig. 11).