The US government body, the National Oceanic and Atmospheric Administration (NOAA), has said that the natural climate pattern, El Nino, is likely to emerge between May and July this year.
Although its peak is undetermined, the global effects have been well documented, and in the case of a strong El Nino, the outcome could be catastrophic.
May was 0.5°C above the 1991-2020 average worldwide, and high temperatures are currently on the way in the Northern Hemisphere. Cities alert the population to take necessary precautions, but which cities are actually prepared for this scenario, and how much at risk is their population?
Researchers at the University of Oxford mapped heat risk globally in cities with populations with more than one million across three major components: hazard exposure, vulnerability and lack of coping capacity. Among the top 10 are one Iraqi city, Basra; two Indian cities, Ahmedabad and Nagpur; two Pakistani cities, Faisalabad and Hyderabad; four African cities, Bamako in Mali, Lagos, and Kano in Nigeria and Conakry in Guinea; and Barranquilla in Colombia. In total, there are more than 37 million people at risk
Hazard exposure
Hazard exposure is the combination of land surface temperature, air temperature, humidity, wind speed and temperature of the surfaces surrounding a person, such as walls, floors, and windows, also called radiant temperature. It is the most scattered component, and where cities close to the equator and in hot-arid regions dominate the most.
Because the metric uses humidity and radiant load rather than air temperature alone, it pushes humid-tropical cities high even where the thermometer reading is not extreme.
Exposure is necessary but not sufficient. For example, Jeddah in Saudi Arabia ranks highly for exposure, however, it is not at the top of the composite risk because the other two components offset it.
Vulnerability
It measures how susceptible the exposed population is to harm and takes into account GDP per capita, share of young children and old adults and air-conditioning penetration. It is intensely sub-Saharan African concentrated.
Youthful populations, low GDP per capita, and low air-conditioning penetration make these populations physiologically and economically exposed regardless of absolute temperature. In this aspect, Jeddah completely shifts in the ranking, while Kano, Nigeria, leads the ranking.
Lack of coping capacity
Lastly, city infrastructure also dictates the index. It shows the deficit in infrastructure, ecological buffers and financial means to manage heat. This component takes into account the vegetation and tree cover, and electricity prices as a proxy for cooling affordability.
This is an arid and semi-arid characteristic: sparse vegetation compounded by high electricity prices, making active cooling unaffordable. Where vulnerability is about who is exposed, coping capacity is about the physical and financial systems available to blunt the heat, and those are thinnest across arid South and West Asia.
How components work together
The central message is that hazard exposure is not the entire story. A city reaches the highest-risk tier when it scores poorly across all components, or when two components are high. Hot cities such as Bangkok, Jeddah, and Kuala Lumpur rank at the top of hazard exposure, but have strong coping capacity (more urban greenery or cheaper energy).
As mentioned at the beginning, one Iraqi city in this study is at greater risk. Basra is described as experiencing 'compounded risk across hazard exposure (0.96), vulnerability (0.83), and limited coping capacity (0.73)', and it is one of the few cities appearing in both the hazard and vulnerability top tens with a coping deficit, resulting in the highest composite score.
One caveat the authors note is that a low risk index does not mean the absence of harm. In any city, residents of low-income and informal settlements can still face severe risk.
Finally, by combining these three components, the policymakers have a diagnostic tool to tackle the heat issue for current and future generations.
