What is a heat wave?
A heat wave corresponds to the observation of abnormally high temperatures over several consecutive days. It can be caused by dry and clear weather or by persistent winds from hot regions like the Sahara. These extreme climate events pose a threat to health, biodiversity, and the Moroccan economy. It is predicted that these events will be more frequent and more intense over the coming century.
Projection to 2050 in Morocco
Today, Morocco experiences on average 20 days per year of heat waves. We are already seeing an increase in their frequency and intensity, with the heat wave experienced in May 2022 in several provinces of the Kingdom. For a warming scenario of 2.5°C by 2050 — aligned with current projections — it is estimated that this number would increase to 60 days per year. For a warming scenario of 4.5°C by 2050 — continued increase in greenhouse gas emissions — it would reach 100 days per year.
Visualization of the number of heat wave days per year for warming of 2.5°C (current projections) and 4.5°C (increased emissions) by 2050
Vulnerability and health risks
Among the populations most vulnerable to heat waves are the homeless, people in poor health, workers overexposed to heat, infants, and the elderly. If we do not drastically reduce our greenhouse gas emissions, then situations of thermal discomfort will become the norm for all these populations by the middle of the century. There is a projected multiplication of heat-related illness risks caused by extreme thermal discomfort during summer (thermal discomfort = perceived temperatures above 32°C) by the end of the century.
Beyond creating discomfort, heat waves pose health risks. The human body must remain at its normal temperature (approximately 37°C). During a heat wave, it must therefore exert effort to return to this temperature. If this effort is too great, it can lead to cardiovascular effects, effects on breathing, digestion, or cognitive abilities. Thus, it is estimated that the risk of mortality in people over 65 in 2050 under extreme heat conditions would be multiplied by a factor between 2 and 5 for warming of 2.5°C. For warming of 4.5°C by 2050, this factor increases to between 3 and 8. And we must expect that people capable of assisting the most vulnerable will also be in difficulty.
Vulnerable populations and different risk levels depending on heat intensity. Source: u003ca href=u0022https://forumeteoclimat.com/wp-content/uploads/2021/05/fim-2021_colloque_pascal_compressed.pdfu0022u003e Heat waves and health, Mathilde Pascal 2021 u003c/au003e
Urban heat island effect
In urban areas, the effects of heat waves are amplified. The lack of vegetation, high human activity, and heat capture by urban materials are factors that contribute to increasing the intensity of heat waves. This effect is called urban heat island effect. Conversely, plant transpiration in vegetated areas helps cool the atmosphere and compensates for heat. Thus, the difference in nighttime temperature between a city and the countryside can reach 10°C in summer during a heat spell.
Illustration of factors contributing to the urban heat island effect, Source: u003ca href=u0022https://www.apc-paris.com/system/files/file_fields/2018/11/07/icu-brochureapc-mf.pdfu0022u003eParisian Climate Agencyu003c/au003e
The absence of vegetation in the arid zones of the kingdom also has an amplifying effect. Indeed, as in urban areas, the absence of vegetation due to soil dryness reduces the cooling effect that could have been obtained through plant evaporation and transpiration.
Economic consequences
Heat waves also have economic consequences. For example, it is projected that for a warming scenario of 4.5°C by 2050, thermal discomfort would lead to a reduction in work capacity of 20% in 2050 and 40% in 2100 during the hottest months of the year.
When they become too long and intense, heat waves also threaten agricultural crops and livestock. Prolonged exposure to abnormally high temperatures — combined with a drought situation — leads to the loss or malformation of hectares of cereal crops, as was the case in
What is a heat wave?
A heat wave corresponds to the observation of abnormally high temperatures over several consecutive days. It can be caused by dry and clear weather or by persistent winds from hot regions like the Sahara. These extreme climate events pose a threat to health, biodiversity, and the Moroccan economy. It is predicted that these events will be more frequent and more intense over the coming century.
Projection to 2050 in Morocco
Today, Morocco experiences on average 20 days per year of heat waves. We are already seeing an increase in their frequency and intensity, with the heat wave experienced in May 2022 in several provinces of the Kingdom. For a warming scenario of 2.5°C by 2050 — aligned with current projections — it is estimated that this number would increase to 60 days per year. For a warming scenario of 4.5°C by 2050 — continued increase in greenhouse gas emissions — it would reach 100 days per year.
Vulnerability and health risks
Among the populations most vulnerable to heat waves are the homeless, people in poor health, workers overexposed to heat, infants, and the elderly. If we do not drastically reduce our greenhouse gas emissions, then situations of thermal discomfort will become the norm for all these populations by the middle of the century. There is a projected multiplication of heat-related illness risks caused by extreme thermal discomfort during summer (thermal discomfort = perceived temperatures above 32°C) by the end of the century.
Beyond creating discomfort, heat waves pose health risks. The human body must remain at its normal temperature (approximately 37°C). During a heat wave, it must therefore exert effort to return to this temperature. If this effort is too great, it can lead to cardiovascular effects, effects on breathing, digestion, or cognitive abilities. Thus, it is estimated that the risk of mortality in people over 65 in 2050 under extreme heat conditions would be multiplied by a factor between 2 and 5 for warming of 2.5°C. For warming of 4.5°C by 2050, this factor increases to between 3 and 8. And we must expect that people capable of assisting the most vulnerable will also be in difficulty.
Urban heat island effect
In urban areas, the effects of heat waves are amplified. The lack of vegetation, high human activity, and heat capture by urban materials are factors that contribute to increasing the intensity of heat waves. This effect is called urban heat island effect. Conversely, plant transpiration in vegetated areas helps cool the atmosphere and compensates for heat. Thus, the difference in nighttime temperature between a city and the countryside can reach 10°C in summer during a heat spell.
The absence of vegetation in the arid zones of the kingdom also has an amplifying effect. Indeed, as in urban areas, the absence of vegetation due to soil dryness reduces the cooling effect that could have been obtained through plant evaporation and transpiration.
Economic consequences
Heat waves also have economic consequences. For example, it is projected that for a warming scenario of 4.5°C by 2050, thermal discomfort would lead to a reduction in work capacity of 20% in 2050 and 40% in 2100 during the hottest months of the year.
When they become too long and intense, heat waves also threaten agricultural crops and livestock. Prolonged exposure to abnormally high temperatures — combined with a drought situation — leads to the loss or malformation of hectares of cereal crops, as was the case in
A heat wave corresponds to the observation of abnormally high temperatures over several consecutive days. It can be caused by dry and clear weather or by persistent winds from hot regions like the Sahara. These extreme climate events pose a threat to health, biodiversity, and the Moroccan economy. It is predicted that these events will be more frequent and more intense over the coming century.
Today, Morocco experiences on average 20 days per year of heat waves. We are already seeing an increase in their frequency and intensity, with the heat wave experienced in May 2022 in several provinces of the Kingdom. For a warming scenario of 2.5°C by 2050 — aligned with current projections — it is estimated that this number would increase to 60 days per year. For a warming scenario of 4.5°C by 2050 — continued increase in greenhouse gas emissions — it would reach 100 days per year. Among the populations most vulnerable to heat waves are the homeless, people in poor health, workers overexposed to heat, infants, and the elderly. If we do not drastically reduce our greenhouse gas emissions, then situations of thermal discomfort will become the norm for all these populations by the middle of the century. There is a projected multiplication of heat-related illness risks caused by extreme thermal discomfort during summer (thermal discomfort = perceived temperatures above 32°C) by the end of the century. Beyond creating discomfort, heat waves pose health risks. The human body must remain at its normal temperature (approximately 37°C). During a heat wave, it must therefore exert effort to return to this temperature. If this effort is too great, it can lead to cardiovascular effects, effects on breathing, digestion, or cognitive abilities. Thus, it is estimated that the risk of mortality in people over 65 in 2050 under extreme heat conditions would be multiplied by a factor between 2 and 5 for warming of 2.5°C. For warming of 4.5°C by 2050, this factor increases to between 3 and 8. And we must expect that people capable of assisting the most vulnerable will also be in difficulty. In urban areas, the effects of heat waves are amplified. The lack of vegetation, high human activity, and heat capture by urban materials are factors that contribute to increasing the intensity of heat waves. This effect is called urban heat island effect. Conversely, plant transpiration in vegetated areas helps cool the atmosphere and compensates for heat. Thus, the difference in nighttime temperature between a city and the countryside can reach 10°C in summer during a heat spell. The absence of vegetation in the arid zones of the kingdom also has an amplifying effect. Indeed, as in urban areas, the absence of vegetation due to soil dryness reduces the cooling effect that could have been obtained through plant evaporation and transpiration. Heat waves also have economic consequences. For example, it is projected that for a warming scenario of 4.5°C by 2050, thermal discomfort would lead to a reduction in work capacity of 20% in 2050 and 40% in 2100 during the hottest months of the year. When they become too long and intense, heat waves also threaten agricultural crops and livestock. Prolonged exposure to abnormally high temperatures — combined with a drought situation — leads to the loss or malformation of hectares of cereal crops, as was the case inWhat is a heat wave?
Projection to 2050 in Morocco
Vulnerability and health risks
Urban heat island effect
Economic consequences