Heat waves


Text Arend Hoogervorst Photograph Unsplash

Climate extremes

During 2021 and 2022, the Earth has experienced extremes of climate, which have significantly affected human life and activities. Whether this is caused, directly or indirectly, by climate change is not up for debate here. However, it is important to understand climate extremes, in particular, extremes of heat, in modifying our behaviour patterns to adapt sustainably to these inevitable and significant changes.

Heat wave?

2022 has been a bad year for heat waves. So, what is a heat wave? A heat wave is a period of abnormally hot weather generally lasting more than two days. Heat waves can occur with or without high humidity. They have the potential to cover a large area, exposing a large number of people to hazardous heat. The South African Weather Service is a little more specific: “…If the maximum temperature at a particular town is expected to meet or exceed 5 degrees C above the average maximum temperature of “the hottest month” for that particular place, as well as persisting in that mode for 3 days or more, then a heat wave may be declared….”

Health impacts

Extreme heat events can be dangerous, and even fatal, to human health. They can result in increased hospital admissions for heat-related illnesses and cardiovascular and respiratory disorders. These heat events can trigger various heat stress conditions, such as heat stroke. Heat stroke is the most serious heat-related disorder. It occurs when the body cannot control its temperature: Body temperature rises rapidly, the sweating mechanism fails, and the body cannot cool down. This condition can cause death or permanent disability if emergency treatment is not given. Small children, the elderly, and certain other groups, including people with chronic diseases, low-income populations, and outdoor workers, have a higher risk for heat-related illness. Higher temperatures and respiratory problems are also linked, particularly where the heat wave may be linked to increases in air pollutants.

Infrastructure impacts

Extreme heat also impacts societal infrastructure, from transportation to utilities, to clean water and agriculture. High heat can deteriorate and buckle pavements, warp or buckle railway tracks, and exceed certain types of aircraft operational limits. Electricity usage increases as air conditioning and refrigeration units in homes and offices work harder to keep indoor areas cooler. Transmission capacity across power lines is reduced during high temperatures, further straining the national and international electrical grids. Water resources are also strained as conventional, coal-fired power plants require large quantities of water for cooling, and crops increase water consumption and irrigation demands. People also increase their water consumption to stay hydrated and cool. Heat can have lasting impacts as crops may be damaged, reducing production, leading to food security problems and increased production costs for farmers and consumers.

Deadly statistics

From 1998-2017, more than 166 000 people died due to heat waves, including more than 70 000 who died during the 2003 heatwave in Europe. Heat waves across Europe started in June 2022 and continued throughout July into August. They caused continent-wide wildfires, with thousands dying due to heat-related causes. Other heat waves have been felt throughout the year, including in the Americas, China, Africa, Australia and the Indian subcontinent. Globally, extreme temperature events are observed to be increasing in frequency, duration, and magnitude. Between 2000 and 2016, the number of people exposed to heatwaves increased by around 125 million.

South Africa

A significant heat wave affected parts of South Africa in the first week of October 2022. On October 4, Pretoria reached a maximum temperature of 35 °C, with Vereeniging also reaching a high temperature of 35 °C.

United Kingdom

A heat wave beginning on July 8 2022 in the United Kingdom saw the first red extreme heat warning to ever be issued in the country. This was declared a national emergency on July 15. An unconfirmed report from the UK’s Meteorological Office on July 19 indicated a new record temperature for the United Kingdom, 40.3 °C. This is the first documented time the temperature exceeded 40 °C in the United Kingdom.

USA & China

An intense, potentially fatal, heat wave swept through the United States in July 2022. More than 100 million people were put on heat alerts, and over 85% of the country had temperatures at or above 32 °C. A catastrophic heatwave affected South China in October. On October 3, Qingyang reached a record high of 41 °C. The southern provinces of Guangdong, Guangxi, and Fujian also set a new monthly record high.

Looking forward

It is clear that heat waves are becoming a more established part of global climate patterns. Rather than arguing about what has or hasn’t caused the heat wave, it is more important to review preparations and responses when heat waves occur.

Own preparations

Are you ready for the potential increase in occurrence of heat waves in years to come? Have you considered how you would react to the warning of an on-coming heat wave at your home? Have you considered the preparations that could be taken to minimise the impacts on your family and pets? Think about some of the suggestions listed below. The South African Department of Health has produced a Guide to Extreme Heat Planning in South Africa for the Human Health Sector, which contains more detailed information and helps in planning and responding to heat waves.

Some preparations and responses to a heat wave

  • At home, if possible, shade or cover windows that are exposed to direct sunlight.
  • If the air inside feels cooler than outside, close the windows and try to keep the cooler air inside. If not, keep doors and windows open when outside temperatures are cooler.
  • If possible, work around the heat. It is advisable that you do your best to complete errands before the midday sun and temperatures peak, or later in the day when temperatures begin to drop.
  • Avoid cooking. Instead, prepare cool, light meals that will require little to no use of the stove and oven.
  • Incandescent light bulbs, produce a lot of heat. Switching to energy-efficient light bulbs may keep your home cooler and help you reduce energy costs.

About the author

Arend Hoogervorst is an environmental scientist with 40 years of experience in South Africa in environmental management and sustainable development in local and central government, commerce and industry and private practice.

© Arend Hoogervorst, 2022. Used with permission.