As many parts of the United States enter another day of high heat and humidity, we’re reading about the first ever heatwave warning guidelines issued by the United Nations earlier this month.
The guidelines are intended to alert the general public, health services and government agencies via the development of so-called heatwave early warning systems that should ultimately lead to actions that reduce the effects of hot weather extremes on health.
As the foreword to the publication states:
Heatwaves are a dangerous natural hazard, and one that requires increased attention. They lack the spectacular and sudden violence of other hazards, such as tropical cyclones or flash floods, but the consequences can be severe.”
In their joint guidance, the World Health Organization (WHO) and the World Meteorological Organization (WMO) note that heatwaves are becoming more frequent and more intense as a result of climate change.
According to the Intergovernmental Panel on Climate Change, the length, frequency and intensity of heatwaves will likely increase over most land areas during this century.
Recent world heatwave events come to mind:
Both India and Pakistan were hit by deadly heatwaves in the first half of 2015, leading to 3,600 fatalities, according to Munich Re. Temperatures were exceptional, climbing as high as 47 °C and accompanied by high humidity which compounded the effect.
European heatwaves in the summer of 2003 led to the deaths of tens of thousands of people, as did the Russian heatwaves, forest fires and associated air pollution in 2010. In fact, the Russian heatwave of 2010 still ranks among the top 10 deadliest world catastrophes 1970-2014.
The UN guidance makes the case that one way to manage the risk of heat-related health effects is through the development of a Heat Health Warning System (HHWS) as part of a broader Heat Health Action Plan (HHAP).
Of primary concern in an HHWS, it notes, is how to assess the level of heat stress associated with the meteorological or climate forecast, translate this into an estimate of a likely health outcome and identify a critical heat-stress threshold for a graded plan of action.
Typically, HHWSs are composed of a number of elements, including:
- Weather forecasts of high temperatures that may also include humidity;
- A method for assessing how future weather patterns may evolve in terms of a range of health outcomes;
- The determination of heat-stress thresholds for action;
- A system of graded alerts/actions for communication to the general population or specific target groups about an impending period of heat and its intensity and to government agencies about the possible severity of health impacts.
A number of cities and countries around the world have developed these early warning systems, including Canada, England, France, Germany, Italy, the United States and Australia.
The first HHWS was actually implemented in the city of Philadelphia in the United States in 1995. In this system, local city staff work with the National Weather Service (NWS) to determine when a heatwave is imminent.
After an alert is issued, the Philadelphia Health Department contacts news organizations with tips on how vulnerable individuals can protect themselves. People without air conditioning are advised to seek relief from the heat in shopping malls, senior centers and other cool spaces.
Friends, relatives, neighbors and other volunteers are also encouraged to make daily visits to elderly people during the hot weather, ensuring the most susceptible individuals have sufficient fluids, proper ventilation and other amenities to cope with the weather.
After the success of Philadelphia, similar tailor-made systems are being implemented for the 50-60 cities in the U.S. with a population of more than 500,000 and a local meteorological office, the guidance notes.
The NWS reports that heat is typically the leading cause of weather-related fatalities each year.
Check out Insurance Information Institute (I.I.I.) facts and statistics on drought and heatwaves here.