Ozone, vegetation and our health

Ozone is a gas that is closely related to oxygen - yes, the gas we breathe in.  Is Ozone good or bad for us?  Well, it is both good and bad.  Ozone is a very bad gas to our health when it exist close to the ground.   However, beyond this region it is very good as it protects us from the harmful effect of the sun.    So, we want ozone in the upper atmosphere but not in the lower atmosphere.

There are a lot of things that remove ozone from the upper atmosphere.  One of them is the amount of trees or vegetation we have on the ground.  This is one of the reason people concerned about the environment ask that we plant trees around us.  How exactly does the amount of trees affect the total ozone in the atmosphere?  This was the focus of the research by Ogunjo and other researchers [1].

To do this, there is the need to assign numbers to trees.  Impossible? Using satellite data, regions with very high amount of trees and vegetation are given the number 1 while places with no trees or vegetation get the number 0.  This method constitute the Normalized Difference Vegetation Index (NDVI).   From a similar satellite, the amount of ozone in the atmosphere was also gotten.  The authors now conducted an analysis over West Africa.  Their result can be seen in the figure below.

Figure 1:  Linear relationship between NDVI and total ozone column [1]

The authors found out that as we cut and burn trees in West Africa we reduce the amount of ozone available to protect us.  It could be seen from their figure that if the amount of vegetation increases, the total ozone column also increases and vice versa.   They discovered that regions with high amount of vegetation also have high amount of ozone.    The rapid population growth in West Africa (especially Nigeria) is increasing the demand for housing, clothing, feeding, and other necessities.  All these place demand on our vegetation.    The best time to plant a tree was 20 years ago, the next best time is NOW!  There is the urgent need to protect our future by increasing our vegetation.  This is not a job for one but for all.

References

[1]  Ogunjo, S., Fuwape, I., Rabiu, B., Oluyamo, S., & Owoola, E. (2019). Assessing the Impact of Vegetation Cover on Total Column Ozone Over West Africa. In Advances in Remote Sensing and Geo Informatics Applications (pp. 231-233). Springer, Cham.

Lagos: Any respite from the floods?

Any story about Nigeria without Lagos is incomplete.  Lagos has a significant role in the past and future of the country.  it is regarded as the commercial nerve centre of the country.  However, the beautiful city of Lagos is not without her own peculiar challenges.  The population of Lagos is on the increase, no thanks to the allure of "gold on the street" sold to rural dwellers.  This growing population is impacting on the existing infrastructure within the city.  In recent times, another challenge is coming to light - flooding.  Being a coastal city, Lagos is prone to heavy rainfall.   Heavy rainfall coupled with improper planning and waste disposal, flooding is becoming pronounced in different parts of the State.  Will the flooding stop any time soon?

Not according to Prof. Abiodun and his colleagues.  According to their report "A decrease in annual precipitation is projected over Cape Town, Maputo and Port Said, whilst an increase is projected over Lagos, where the water surplus from the more extreme precipitation events exceeds the deficit from the less wet days" (Abiodun et al, 2017).  How was this conclusion reached?  The authors used two future climate scenarion (RCP4.5 and RCP8.5)  to compute moderate extreme events.  The moderate extreme events computed include the total number of days for which rainfall is greater than 1mm, the total number of days in a year when the rainfall on a given day is above 20 mm and twelve other indices.  This analysis was done for four coastal African cities - Cape Town, Maputo, Port Said and Lagos.  The authors found that the number of wet days in a year in Lagos will reduce but the total precipitation will increase.  This means we will be having fewer rainfall but those rains will be very heavy.  An implication of this is the increase in number of dry days.  This will affect agricultural products at planting and harvesting.  It also means we are going to have hotter days.  Lagos was found to be an exception to most of these results.  

Projected percentage changes in extreme precipitation indices over the four cities (a Cape Town, b Maputo, c Lagos and d Port Said) in the two future periods (2046–2065 and 2081–2100) under RCP4.5 and RCP8.5 scenarios. The changes are calculated with reference to the past climate (1986–2005) and are averaged over the neighbourhood of the city(Abiodun et al, 2017)

What can Lagos State do about these results?  While it can be argued that not much is going on in terms of agriculture in Lagos, the little agriculture we can lay claim to is under threat.  Will the current structural and environmental plan be viable in the future under higher flood? There is no doubt that the Lagos State government has a lot to do in terms of planning.  Recent land reclamation activities along the coastal areas should be reconsidered in light of these results.

Reference

Abiodun, B.J., Adegoke, J., Abatan, A.A. et al. Climatic Change (2017) 143: 399. https://doi.org/10.1007/s10584-017-2001-5
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

No good news for African crops under climate change

Climate change came into global focus again as the world, without the United States of America, affirm their readiness to combat it's effect on planet earth.   The effect of climate change will be felt in different dimensions across different countries.  It is going to affect tourism, communication, agriculture, health and economy.  World leaders considered the effect of climate change far greater than any singular economy or cross border politics.  Differences were put aside as all signed the agreement.  I am glad Nigeria signed that agreement.

The effect of climate change has been discussed on this blog under the topic "Climate change and maize shortages in Africa by 2050".   There is the need to revisit this issue as a new research by Challinor and his team has again brought to fore the dangers climate change poses to our agricultural production.  In their research, Challinor et al (2016) examined the implication of global warming on the breeding, delivery and adoption of new maize varieties using five different climate forecast over Africa.  The authors investigated the point at which the time from germination to maturity become significantly different from what we have currently now.  From their results, the impact of heat stress was significant.  From Figure 1, the RCP 8.5 data predicts that the effect is upon us faster than we think.

Time at which the climate change signal for crop duration is detected. The specified year refers to the midpoint of the 20-year period in which the median crop duration falls below the 25th quantile of the baseline period (1995–2014). Grey cells indicate that the crop duration remains within the 25th–75th quantile until at least 2038—the latest possible delivery date for a BDA cycle beginning in 2004 (see Table 1).

Our focus as an agrarian nation has to move from the challenges of bad roads, access to markets, fertilizers, irrigation that has been plaguing us for ages into developing seeds and methods that will beat the effect of climate change. Any strategic plan for sustainable agriculture in Nigeria that does not consider climate adaptation strategies such as novel seeds cannot stand the test of time.  The best time to start the process is now!

References

[1] A. J. Challinor, A.-K. Koehler, J. Ramirez-Villegas, S. Whitfield, and B. Das, “Current warming will reduce yields unless maize breeding and seed systems adapt immediately,” Nat. Clim. Chang., vol. 6, no. 10, pp. 954–958, 2016.

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Is Solar energy predictable?

If you start a journey from point A at time T₁ and get to point B at time T_n. We say the "system" is linear if the arrival time is a function of the start time e.g. If you start at T₁₊₁, you get there at time T_n+1 or generally, if you start at T_a+1 you arrive at T_n+a.    Not all journey are smooth, there might be delay due to traffic and other unforeseen circumstances.  Let's call the addition of all possible delay on the route d.  If you take off  at time T₁, your arrival time due to delay on the route will be T_n+d.   We refer to this "system" as a stochastic system.     However, if the arrival time cannot be predicted based on the take off time T₁ due to conditions around the starting conditions, we say the "system" is chaotic.  Long term prediction of chaotic system is not possible.  Chaos in this case does not mean random or disorder but sensitivity to initial starting conditions.

Chaos is aperiodic time-asymptotic behaviour in a deterministic system which exhibits sensitive dependence on initial conditions (http://farside.ph.utexas.edu/teaching/329/lectures/node57.html).

 

Initially, studying chaos was limited to complicated differential equations but in recent times, natural phenomena has been investigated for chaos.   Many systems such as menstrual period (Derry and Derry, 2010), rainfall (Sivakumar, 2001), temperature (Fuwape et al, 2015), stock market (Fuwape and Ogunjo, 2013) have been found to be chaotic.  To investigate chaos, tools such as correlation dimension, Lyapunov exponent, and other tools have been developed.  Is chaos good or bad?  This will be the subject of another post.  In light of current agitation for use of renewable energy instead of fossil fuels, there is the need to study the predictability of the proposed energy systems.  

Ogunjo, Adediji and Dada from the Department of Physics, Federal University of Technology, Akure investigated if solar radiation available at Akure, Southwestern Nigeria for a period of two years.   The researchers found that the solar radiation at Akure during the dry season is more chaotic than during the wet season.  This means that it is easier to predict the solar energy available in the location during the wet season than during the wet season of the year.  

Figure 1:  Phase space reconstruction of solar radiation data from Akure  (Source:  Ogunjo et al. 2014)

The Nigerian government is currently on a drive to provide off-grid power based on solar energy. From the results presented by the researchers, it is imperative that the chaotic nature of solar energy over Nigeria be investigated and taken into consideration before large scale deployment.  There is the need to further study the variation of incident solar radiation in different parts of the country for the most cost effective and reliable solar energy solution.  For instance, further studies will give insight into the feasibility of combining solar energy with wind or other forms of energy for better reliability.  Also, the possibility of solar panels that can track the rising and setting of the sun need to be investigated.

References

Derry, G., & Derry, P. (2010). Characterization of chaotic dynamics in the human menstrual cycle. Nonlinear Biomedical Physics, 4(1), 5. http://doi.org/10.1186/1753-4631-4-5

Fuwape, I. I. A., & Ogunjo, S. T. (2013). Investigating Chaos in the Nigerian Asset and Resource Management (ARM) Discovery Fund. CBN Journal of Applied Statistics, 4(2), 129–140. article.

Fuwape, I. A., Ogunjo, · S T, Oluyamo, · S S, Rabiu, · A B,  (2016). Spatial variation of deterministic chaos in mean daily temperature and rainfall over Nigeria. Theoretical and Applied Climatology, In Press. http://doi.org/10.1007/s00704-016-1867-x

Ogunjo, S. T., Adediji, A. T., & Dada, J. B. (2015). Investigating chaotic features in solar radiation over a tropical station using recurrence quantification analysis. Theoretical and Applied Climatology. http://doi.org/10.1007/s00704-015-1642-4

Sivakumar, B. (2001). Is a chaotic multi-fractal approach for rainfall possible? Hydrological Processes, 15(6), 943–955. http://doi.org/10.1002/hyp.260

Climate change and maize shortages in Africa by 2050

From your observations of the December-January weather over the years, do you think the harmattan is getting stronger, weaker or just the same?  If you can give an answer, then you have witnessed climate change!   According to IPCC, climate change refers to a change in the state of the climate that can be identified (e.g. using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer.   Monitoring climate change over time helps us measure its impacts on our life, however, we need to predict the possible future effects on our lives for proper planning and adaptation.  If our weather is chaotic and difficult to predict as reported by Fuwape and her team, how do we know tomorrow's weather?

Models are abstract representation of real life events.  Using past weather records, scientists have developed models to predict future weather conditions for different regions of the world.  These models use previous patterns and other factors affecting weather to predict future weather conditions.  Predicting future climates will help in quantifying the effect of tomorrow's weather on different aspects of our lives.   Burke and his colleagues tried to determine how future weather conditions will affect agriculture, specifically cereals production, in West Africa using a model developed by the Intergovernmental Panel on Climate Change Fourth Assessment Report (AR4).   The authors concluded that "the majority of African countries will have novel climates over at least half of their current crop area by 2050."  This means that by 2050, many parts of Africa will have climatic conditions that is different from what they have now and the future climate will not support half what is grown now.   Specifically, only 14% of temperature in African countries that grow maize will be similar to what we are experiencing now.  This is expected to reduce to 3% by the year 2075.  The temperature will be hot such that maize will not be able to grow.   Similar results was obtained for millet and sorghum over Africa.  This portends a problem for agriculture in Africa especially Nigeria where cities have been eating into agricultural farmlands (see report here).

Several attempts have been made by organizations and bodies within Nigeria to draw a plan or strategy for climate change.  Elias and Omojola after examining the plan of Lagos state towards climate change concluded that "these efforts are haphazard, largely top-down, uncoordinated and fragmented."  There is a recent plan by the Federal Ministry of Agriculture towards mitigating climate change which i currently do not have access to.  The authors concluded that "increased understanding of the substantial threat climate change poses to agriculture has not been met with a similarly improved understanding of how best to respond."  There is the need for Federal and State governments to work with Agricultural Scientists, meteorologists and other relevant researchers in academics to work towards a plan.  The plan should include development of a genebank for suitable crops.

References

Burke, M. B., Lobell, D. B., & Guarino, L. (2009). Shifts in African crop climates by 2050, and the implications for crop improvement and genetic resources conservation. Global Environmental Change, 19(3), 317–325. http://doi.org/10.1016/j.gloenvcha.2009.04.003

Peter Elias, Ademola Omojola (2015) Case study:  The challenges of climate change for Lagos, Nigeria,  Current Opinion in Environmental Sustainability, Volume 13, April 2015, 74 - 78, http://dx.doi.org/10.1016/j.cosust.2015.02.008

 

Fuwape, I. A., Ogunjo,  S T., Oluyamo,  S S., Rabiu,  A B (2016). Spatial variation of deterministic chaos in mean daily temperature and rainfall over Nigeria. Theoretical and Applied Climatology, In Press. http://doi.org/10.1007/s00704-016-1867-x