Growing more plants and trees can cut down the heat in Nigerian cities

(Originally published in www.theconversation.com)

Nigeria is regarded as a hot country. Average maximum temperature can reach 38℃ - one of the hottest in sub Saharan Africa. In the last few years extreme heat and intense heatwaves have become a common experience in both rural and urban areas, showing that the country is getting hotter. This year, the Nigerian Meteorological Agency has warned of an “above danger heat stress”.
These experiences are in line with projections that the mean temperature of the planet is increasing, and expected to go on doing so. In Nigeria, the average air temperature is expected to rise by between 0.2 and 2.5℃ over the next five decades, according to the UN’s Intergovernmental Panel on Climate Change.
These increases cannot be overlooked. The effect is already being felt in cities which have developed what is known as “heat islands”. These are urban areas that have higher temperatures than surrounding rural areas due to the fact that natural landscapes have been replaced by paved surfaces and buildings.
Some predict that Nigerian cities may become too hot to live in.

Practical solutions are needed. One approach that’s been shown to work elsewhere is urban greening. This involves introducing trees and plants in places such as parks and gardens, streets, on walls and on top of roofs. By constantly releasing moisture into the atmosphere through their leaves, plants and trees cool themselves and the surrounding environment. This helps to reduce heat. This principle is well known and has been implemented in many European and North American cities.

We studied the temperatures inside and around two typical buildings in Akure, Nigeria. One of the buildings had trees around it while the other had none. The study was carried out for six months and spread across the two seasons (rainy and dry). It showed that tree shading had an impact on thermal conditions in buildings and their surroundings.

This evidence, alongside other research, shows that plants and trees need to be grown in the country’s cities. And everyone must play a part - individuals, households, communities, cities and states.

Reducing temperatures and energy saving

Our study showed that air temperature was higher and stayed that way for longer inside the building without vegetation, with indoor–outdoor temperature reaching a peak of 5.4°C for the unshaded building and 2.4°C for the tree-shaded one. The outdoor area around the tree-shaded building was cooler than around the unshaded one, irrespective of the season.
But the impact of the trees went beyond just the temperature. The cooler temperatures meant that there was less demand for indoor cooling like air-conditioners.
Two separate studies done in Nigeria show that greening buildings can reduce the use of air-conditioning, leading to annual savings of about 34,500 NGN (US$218) in Akure and 17,255 NGN (US$162) in Owerri. These cities are in two different regions of Nigeria yet the results were similar.
Other studies support our research findings. A difference in the average temperature of 7.5°C between spaces with trees and those without was recorded in Enugu, a city in South East Nigeria. In Abuja, researchers found that bare surfaces and built-up areas had higher land surface temperatures while green surfaces maintained lower land surface temperatures.

Vertical greening systems like green walls in Lagos was found to have around 0.5°C reduction in temperature.

What must be done

State and local governments have the main responsibility of introducing policies that would lead to more greening in Nigeria’s cities. In the last ten years some states and the Federal Capital Territory have built urban parks. But much more needs to be done to significantly increase the amount of vegetation and green spaces in the country’s cities. Urban tree planting projects should be promoted on streets and beyond.

There should be programmes to plant trees in neighbourhoods and to create vegetated play parks, community gardens and other forms of green open spaces. Plants should also be planted in road setbacks and spaces within dual carriage ways. Vacant lots and derelict buildings can also be purposefully vegetated.

There should also be a push for gardens to be created – for food as well as aesthetic reasons – inside houses, on the roof or on the walls. Densely packed built environment in cities make space a challenge. But this can be overcome through plant growing techniques that use up little or no space. Good examples of vertical greening systems are available in Mexico City.

These examples provide proof that vegetation at the household and community level can directly influence temperature in the neighbourhood. We believe urban greening is a task that can, and must, be done.

Academic Reading

New words

Et al 

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The five most addictive substances on Earth – and what they do to your brain

(The passage was originally published in The Conversation on March 2, 2016 by Eric Bowman. He is a lecturer in Psychology and Neuroscience at University of St Andrews. See, https://theconversation.com )

What are the most addictive drugs? This question seems simple, but the answer depends on whom you ask. From the points of view of different researchers, the potential for a drug to be addictive can be judged in terms of the harm it causes, the street value of the drug, the extent to which the drug activates the brain’s dopamine system, how pleasurable people report the drug to be, the degree to which the drug causes withdrawal symptoms, and how easily a person trying the drug will become hooked.

There are other facets to measuring the addictive potential of a drug, too, and there are even researchers who argue that no drug is always addictive. Given the varied view of researchers, then, one way of ranking addictive drugs is to ask expert panels. In 2007, David Nutt and his colleagues asked addiction experts to do exactly that – with some interesting findings.

1. Heroin

Nutt et al.’s experts ranked heroin as the most addictive drug, giving it a score of 3 out of a maximum score of 3. Heroin is an opiate that causes the level of dopamine in the brain’s reward system to increase by up to 200% in experimental animals. In addition to being arguably the most addictive drug, heroin is dangerous, too, because the dose that can cause death is only five times greater than the dose required for a high.

Heroin also has been rated as the second most harmful drug in terms of damage to both users and to society. The market for illegal opiates, including heroin, was estimated to be $68 billion worldwide in 2009.

2. Cocaine

Cocaine directly interferes with the brain’s use of dopamine to convey messages from one neuron to another. In essence, cocaine prevents neurons from turning the dopamine signal off, resulting in an abnormal activation of the brain’s reward pathways. In experiments on animals, cocaine caused dopamine levels to rise more than three times the normal level. It is estimated that between 14-20m people worldwide use cocaine and that in 2009 the cocaine market was worth about $75 billion.

Crack cocaine has been ranked by experts as being the third most damaging drug and powdered cocaine, which causes a milder high, as the fifth most damaging. About 21% of people who try cocaine will become dependent on it at sometime in their life. Cocaine is similar to other addictive stimulants, such as methamphetamine – which is becoming more of a problem as it becomes more widely available – and amphetamine.

3. Nicotine

Nicotine is the main addictive ingredient of tobacco. When somebody smokes a cigarette, nicotine is rapidly absorbed by the lungs and delivered to the brain. Nutt et al’s expert panels rated nicotine (tobacco) as the third most addictive substance.

More than two-thirds of Americans who tried smoking reported becoming dependent during their life. In 2002 the WHO estimated there were more than 1 billion smokers and it has been estimated that tobacco will kill more than 8m people annually by 2030. Laboratory animals have the good sense not to smoke. However, rats will press a button to receive nicotine directly into their bloodstream – and this causes dopamine levels in the brain’s reward system to rise by about 25-40%.

4. Barbiturates (‘downers’)

Barbiturates – also known as blue bullets, gorillas, nembies, barbs and pink ladies – are a class of drugs that were initially used to treat anxiety and to induce sleep. They interfere with chemical signalling in the brain, the effect of which is to shut down various brain regions. At low doses, barbiturates cause euphoria, but at higher doses they can be lethal because they suppress breathing. Barbiturate dependence was common when the drugs were easily available by prescription, but this has declined dramatically as other drugs have replaced them. This highlights the role that the context plays in addiction: if an addictive drug is not widely available, it can do little harm. Nutt et al’s expert panels rated barbiturates as the fourth most addictive substance.

5. Alcohol

Although legal in the US and UK, alcohol was scored by Nutt et al.‘s experts 1.9 out of a maximum of 3. Alcohol has many effects on the brain, but in laboratory experiments on animals it increased dopamine levels in the brain’s reward system by 40-360% – and the more the animals drank the more dopamine levels increased.

Some 22% of people who have taken a drink will develop dependence on alcohol at some point during their life. The WHO has estimated that 2 billion people used alcohol in 2002 and more than 3m people died in 2012 due to damage to the body caused by drinking. Alcohol has been ranked as the most damaging drug by other experts, too.

Thanksgiving Day

    Over the river and through the wood,
    To grandfather’s house we’ll go.
        The horse knows the way
        To carry the sleigh
    Through the white and drifted snow.

    Over the river and through the wood,
    To have a first-rate play,
        Hear the bells ring,
        “Ting-a-ling-ding!”
    Hurrah for Thanksgiving Day!

    Over the river and through the wood,
    Now grandmother’s cap I spy!
        Hurrah for the fun!
        Is the pudding done?
    Hurrah for the pumpkin pie!

      --Lydia Maria Child

What is it to be helpful?

To have willing feet
A smile that is sweet,
A kind, pleasant word
For all that you meet--
hat’s what it is to be helpful.