Observations that have been conducted around the world since the 1950s show that climate change has increased the frequency, strength, and duration of heat waves. According to projections of the Intergovernmental Panel on Climate Change (IPCC), this trend is expected to continue even more forcefully in the coming decades.
In Israel, as well, there has been a substantial growth in the frequency of heat waves in the past two decades relative to the previous ones. The National Emergency Management Authority (NEMA) in the Ministry of Defense and the Israel Meteorological Service recently published a comparative scenario for incidents of heat waves that showed the implications of the population’s exposure to high temperatures due to prolonged heat waves. In Israel, a heat wave is defined as at least three consecutive days with abnormally heavy burden of heat including at night. The concept of the burden of heat is a combined measure of air temperature and humidity. Heat waves usually last between a week and ten days with temperatures that are hotter than the multi-year average.
It is worthwhile understanding the physiological implications of such events. When the human body is exposed to high temperatures, it preserves the body’s normal temperature (between 36.1 and 37.8 degrees Celsius) through evaporation of perspiration, convection through water or air circulating across the skin, conduction through cooler objects in direct contact with the skin, and radiation from the skin. Exposure to extreme heat causes significant physiological stress that impacts all the bodily systems, primarily the heart. In order to cool the body, the vascular system generates a massive flow of blood to the skin, through increased heart activity at the expense of other systems and perspiration. When the body does not succeed in cooling itself, or when the humidity in the air is so great that perspiration is ineffective, the internal body temperature rises. This situation is especially dangerous for adults, infants, individuals with chronic illnesses like diabetes and heart conditions as well as individuals who take medications that affect the nervous system. A rise in body temperature can cause a variety of physiological effects, the most severe being heat stroke that can lead to death. For example, research done at Haifa University found that a rise in temperature of one degree increases the likelihood of stroke by 10%. Other data indicate that heat waves are related to additional risks of 11.7% in mortality from heart disease and an increase of 0.8% in morbidity. In addition, heat waves have a notable impact on daily life — for example through reduced physical activity, depression, anxiety, and increases in violent behaviors.
In Israel, the number of premature deaths due to the burden of heat is higher than the OECD average, although it is smaller relative to other countries with similar climate and advanced healthcare systems. Various evaluations suggest that Israel is harmed less by heat waves due to a higher number of air conditioning units in homes, vehicles, and at recreation and employment sites. Nevertheless, there are populations at heightened risk that are not protected by air conditioning, like outside workers (construction, agriculture, infrastructure, sanitation), the unhoused, and populations living in poverty. According to the alternative poverty report produced by the Latet organization in 2022, more than 50,000 households in Israel live in “energy” poverty and are connected to an electricity meter that they prepay and which is likely to disconnect when there is exceptional use over the prepaid amount. Another influence of heat waves is the possibility of disruptions in the electricity supply due to the difficulties of the system in meeting increased demand.
Many countries deal with the dangers of the climate crisis through legislation to decrease greenhouse emissions and to help the population adapt to climate change. In Israel, despite the country’s commitment to decrease emissions and repeated attempts to advance climate legislation, no laws have as yet been passed. The good news is that during the previous government’s administration, in advance of the Climate Change Conference in Sharm el-Sheikh, the government passed a decision initiated by the Ministry of Environmental Protection that obligates government offices to propose programs of climate change preparedness by the end of 2023. The decision defined the climate crisis as a threat to national security and as such, it should be included in scenarios of the National Security Council. Security agencies have already begun to analyze climate risks that Israel faces and prepare programs.
Dealing with climate change has an additional important perspective — management of land resources. The OECD sees land and soil resources as an essential component of economic activity and economic growth, and notes that the ways in which the resource is used and managed influences all the components of environment quality, beginning with biodiversity and ecological system services, through to water, air, and soil quality, and finally to ground temperature and urban heat islands and greenhouse emissions. Therefore, the effects of climate change in general — and heat waves, in particular — on human health is linked in part to how land resources are managed. The combination of rapid population growth in Israel and its geographic location, which is especially sensitive to climate change, presents significant challenges and obligates wise, evidence-based planning.