What is the Inter-tropical Convergence Zone?
What is the Inter-Tropical Convergence Zone (ITCZ)? Why do I need to know what it is? What is its relevance to water, development and environmental change in Africa? These are all questions I asked myself. This post aims to answer all three. I am someone with a brief scientific background and, therefore, will attempt to provide a simplified overview of the ITCZ, El Niño and La Niña in an understandable manner.
The ITCZ is a band of low pressure close to the equator, where the northern and southern trade winds meet. The band is not stationary; it migrates north during July and August and south throughout January and February to follow the sun's natural overhead position. The climate of Eastern Africa is significantly controlled by the ITCZ (Taylor, 2016). It determines the annual seasonality of rainfall, which can potentially lead to extreme weather events. Seasonal shifts impact annual rainfall patterns, hence why East Africa has bimodal precipitation, whereas the sub-tropics have unimodal precipitation. Longer-term trends in the ITCZ can lead to both severe drought and severe flooding, location-dependent.
I am unable to talk about the ITCZ without also mentioning El Niño and La Niña. In summary, El Niño results in wetter, shorter rains, whereas La Niña is associated with drier, shorter rains (Palmer et al., 2023). Currently, in East Africa, there has been a three-year-long period of La Niña. This has resulted in prolonged, devastating droughts. Many suspect that El Niño is looming, which would bring the rains to a rain-starved region, but this could also be detrimental. Flash flooding caused by extreme weather events could further harm agriculture by washing away what remains of the topsoil.
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| Figure 1: A map of East Africa showing anomalies in accumulated precipitation in the period March to September 2022. In East Africa, there have been five consecutive failed rain seasons between 2019 and 2023. The majority of the population of these nations are employed in the agricultural sector, and as few communities have long-term water storage, the rain is vital to their livelihoods. Not only have the ramifications of the drought been economic but also social. More than 3 million people are facing an emergency level of food insecurity, and 1.3 million people have been made climate migrants. This drought was the worst drought in the last 40 years. Anthropogenic climate change has increased the likelihood of these intense drought events; they are 100 times more likely to occur.  |
| Figure 2: A diagram showing different outcomes of the same drought if global temperatures were decreased by 1.2 degrees Celsius. |
Hi Charlotte! I really appreciate how your detail and research on the ITCZ, El Niño and La Niña help to contextualise the climactic context of the different regions of Africa. I also found it shocking to see how much social impact climate change is causing through the statistics you provided, which discuss exacerbated food and water insecurity. I was curious to understand the extent to which you think understanding these terms and seasonal climate situations can lead to better water management. Which stakeholders or groups need to hear this information the most?
ReplyDeleteHello again Safiyah, I really appreciate you keeping up with the blog posts and so glad you enjoyed it! I think it is vital to understand these processes to lead to better water management. It can indicate when communities would need to replenish long-term water storage and when they need to utilise stored water. This information is vital, particularly for the local people, many of which rely on agriculture for their livelihoods (both employment and food source). It is also important information for local governments and NGO's to understand which interventions are most valuable to these communities given rainfall patterns.
DeleteHi Charlotte, I really like your use of figures, and your specific focus on the ITCZ is really interesting. Have you considered the implications that these global events might have on the question of conflict and water scarcity? The reason I ask this question is because it is always really interesting to think about the ways in which global processes have local implications. With that idea in mind, what made you choose this specific topic? And how significant is environmental change to the future of local water scarcity?
ReplyDeleteHello, thank you so much for your comment. For me personally, my passion was ignited during the first year module "environmental change" and as a human geographer I don't get many opportunities to explore this topic in depth. I think environmental change is the most important factor effecting the future of water scarcity due to its unpredictable and unfair nature. Climate change has or will impact every aspect of daily life, and for those who already are socio-economically disadvantaged, these consequences will be felt disproportionally. These type of events that I discussed with undoubtedly fuel water scarcity and conflict. This is because they will increase the frequency and intensity of extreme weather events, therefore drastically changing patterns of river discharge and accessible, clean and safe water.
ReplyDeleteHi Charlotte! Your explanation of the ITCZ and El Nino/La Nina was super clear and concise! for someone who isn't very strong at physical geography your explanation helped me follow your post very well! I also liked how you contexualised it into Africa's context. Eg: "Currently, in East Africa, there has been a three-year-long period of La Niña" <-- this really helped me understand the how significant the ITZC really is!
ReplyDeleteHello Sarah, thank you so much for your kind words, I am so glad that my blog helped you understand these very complex geographical processes, that was my goal! Please follow along as I delve deeper into the implications of environmental change on water and development in Africa!
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