LAGOS FLOODING AND THE SCIENCE OF CLIMATE CHANGE: LET OUR TALK BE BASED ON SCIENCE.

“You cannot keep waste in your drains and canals all week and months and when the rains come and flood the city, you blame it on climate change. We have not experienced climate change. When you witness the effects of extreme tropical rainfall, then can we begin to truly know what climate change is?”

Is there any common sense in the saying that “climate change is the major factor that contributes to the serious flooding issues facing Lagos now?”

To me the answer is capital NO. Like a Yoruba saying” Ọbun rí ikú ọkọ dirọmọ òní tí kò bá jẹ́ ikú ọkọ òun, òun oba tí wẹ láti ijeta.

In the past weeks people who should ordinarily keep their mouths shut are now calming to be Climatologist while some are now self-acclaimed Environmentalists. I am not saying climate change is not real, I have written on the effects of climate change on Lagos environment and also had a photo exhibition of the effects of climate change on Lagos environment in the past 20years. 

(See http://ladedoyin.blogspot.com/2017/10/coastal-erosion-and-lagos-coastline.html ) and http://ladedoyin.blogspot.com/2017/07/torrential-rainfall-like-lagos-like.html ).

In my opinion, human factors such as lack of regulatory enforcement, wrong timing of interventions etc. contributes to the flooding in Lagos than climate change. How do you keep waste in your drains all month without clearing and expect rain not to be on the road and you say its climate change?

Lagos is not the only low-lying city in West Africa, a major reason for saying that climate change contributes less to our flooding than our common Nigeria lazy man and inability to manage our common heritage. Like other coastal cities in West Africa, Lagos is subjected to many types of flooding. Examples are riverine flooding since we are located in low-lying areas of lower reaches of rivers, coastal flooding due to storm surges and tidal effects at the estuarine reaches, pluvial flooding mainly because of insufficiency of the drainage network capacity or due to lack of cleaning and maintenance of the existing drainage facilities. Flooding by seepage occurs when the water level rises in the wetlands that surround the buildings, the overflow of the water table infiltrates into houses especially where the level of the floor is not raised enough and/or the floor is not well tiled.  

I have often said we are the architect of our own misfortune.  Let’s talk briefly with facts and figure and allow science to direct our reasoning. Abidjan, with around 1700 mm of rainfall per year, has a tropical rainforest climate like Lagos. As the graph below displays, it has a twin-peak regime with a major peak in June and a smaller peak in October/November  

Source: www.climate-data.org

It is on the Gulf of Guinea coast and is therefore influenced by hot, humid air for most of the year. This results in a higher total annual precipitation and a greater number of rainy days. The twin precipitation peaks happen because the Intertropical Convergence Zone (ITCZ) moves north in the early part of the year, bringing rainfall and then south later in the year, again bringing rainfall. Like Abidjan, Lagos shares similar climate derivatives with Abidjan. However, unlike Abidjan our annual rain rainfall never exceeded 1693mm.

www.weather-nga.com

A critical look at the two datasets, the precipitation in Abidjan is more than that of Lagos but it is not that the city is not affected by flooding.   Heavy rainfall has been observed in parts of Cote D’Ivoire in the month of October 2019. On 11 to 13 October 2019, the rainfall intensified and resulted in flooding in six cities; Abidjan, Aboisso, Grand Bassam, Ayamé, and Man causing significant damage and loss of lives.

What I want to bring out from the data is that naturally our precipitation is high in our two peak periods. However, our normal African lifestyle, we blame God and nature. Weather and climate data are not represented by a few days figure but rather years. For those saying climate change is the main cause of the flooding, we have the precipitation data in Lagos for the past 20 years. Please kindly find the difference in our precipitation in the last 20 years and use the Intentional Meteorological Organisation guide to define your Lagos flooding as climate change. (see guide: (In the International Meteorological Vocabulary (WMO-182), heavy rain is defined only as “rain with a rate of accumulation exceeding a specific value.”  It is recognized generally that when a precipitation event is considered to be extreme, it relates to one of the following two contexts: (i) a precipitation event is considered to be extreme when it exceeds a certain  threshold that has a certain associated impact, i.e. a fixed threshold, or (ii) a precipitation event is considered to be extreme due to its rarity, i.e. a percentile-based threshold. The rarity of occurrence tends to take the form of upper 90th, 95th, and 99^th percentile of precipitation. Such percentile-based threshold is usually derived from statistical cumulative density function or some conceptual distributions for precipitation extremes (such as Generalized Extreme Value, GEV), guidelines on the definition and monitoring of extreme and climate events.

So, if anyone can help me with this, I will accept that our flooding is climate change related if not let’s do our part or rather ask for help.

Research and Studies, when it pertains to weather and climate issues in Lagos and Nigeria, seldom focus on research as majority of our programme are ceremonial based. Most studies on flooding and sea level rise in Lagos are either carried out by international expert or funded by them. You see Senate and House committee spend millions of naira on visit and talk without proper data. They believe an expert from abroad than a local researcher who has worked and seen the trend.  Some of the mitigation approaches that should be adopted urgently are:    

1.      Land-use control and catchment management:  urban planning policies are towards money making rather than environmental protection. We sand fill lagoon and wetland without adequate environmental management plan. We allocate wetland for housing projects in the city when lands are available in Badagry, Epe and Ikorodu without damaging the environment.

2.       Preparedness and planning for events and disaster: it is in our character not to plan. We don’t plan. Presently, we don’t have a working early warning system for any form of weather event. So, if we have occurrence more than usual. My people will say its climate change. I can recollect following my grandma to Oja Ejirin (ejirin market in Ikosi ejirin LCDA). Local boat people know when the water is full and how change in tides can affect transportation. Those periods the passenger’s capacity is reduced due to the tidal change. Now, because of our greed, they will have full capacity and kill people and blame it on climate change.

3.      Adaptation capacities at individual, household and community level: we all know that most part of Lagos is wetland and the water needs time to percolate. We are not building to fit our environment. Now, everybody uses paving stones for beatification and landscaping. The bad part is we use polythene materials for undercover and this prevents percolation. We need to change the way we treat our environment. Most bridges in Lagos are design as deck on pile. They are constructed with the ability to serve has water reservoir. Now we allocate them for different forms of business and recreation. Sorry to tell you they are not for that.     

TO BE CONTINUE ……………………………………….