How has the behavior of heatwaves changed globally?
Historically, extreme heat events have occurred once or twice a year, with their effect being limited to a couple of countries and geographic areas within these countries. However, between the years 2000 and 2018, an increase in the magnitude, duration and intensity of heatwaves has been observed globally.
Between 2000 and 2016, the number of people exposed to heatwaves in the world has increased by at least 125 million, while the duration of the average heatwave is 0.37 days longer compared to the period 1986-2008. In 2015 alone, 175 million people were exposed to 627 heatwaves. (The Lancet Countdown on health and climate change: shaping the health of nations for centuries to come).
Figure 2. Percentile of temperatures on land and ocean, January to June 2018, registered by NOAA. Data source: GHCN-M version 3.3.0 & ERSST version 4.0.0
Source: NOAA, 2018
What are the most recent heatwaves that caused the most damage?
The mega heatwave that affected Europe in 2003 hit 16 countries and caused the death of at least 70,000 people. During this event 15,000 deaths occurred in France while 4,000 deaths occurred in the United Kingdom. This event confirmed the threat of heatwaves to life and health and emphasized the need for preparedness.
What was the human impact of heatwaves in the Americas?
The impact of heatwaves on human lives is unknown and due to the information available, any attempt to estimate it is an underestimation of the number of people affected. This is due to the lack of awareness of the problem, the lack of capacity to manage this threat by health personnel, the absence of operational definitions, the fact that health monitoring systems in countries do not look at deaths and disease caused by heat (with the exceptions of the USA, Canada and Mexico), the worsening of chronic diseases as a result of heat, and the inadequate coding of contributing conditions on death certificates.
To document the effects of heatwaves on health in the Americas, a review of news and reports available on the web was carried out. The analysis generated the following preliminary results, which need to be validated by the national authorities:
- The largest heatwave registered affected Argentina in 1900 and caused 478 deaths.
- More recently, heatwaves were recorded in:
o Brazil in 2010, mainly affected Rio de Janeiro and caused 735 deaths,
o Argentina in 2014, affected several provinces and caused 1877 deaths,
o Peru in 2016, due to El Niño-Southern Oscillation, caused the death of eight infants in Piura,
o Nicaragua in 2017, caused four deaths,
o Mexico and Paraguay in 2018 with 26 (7 more than in 2017) and four deaths respectively.
What happened in the region between 2018 and 2019?}
From the beginning of the Austral Summer in December 2018, six countries in the southern hemisphere declared a heatwave alert, plus one in the northern hemisphere, in the mid of the Boreal Winter. There are more countries affected but they did not declare an alert.
During the months of January and February 2019, the City and Province of Buenos Aires (Argentina) faced temperatures above 40oC.Hospitals, and health centers reported attending to patients with heat stroke, heat fatigue and associated diseases.
Meanwhile, during the month of January 2019, Paraguay registered temperatures between 30 and 43oC, resulting in the media attributed the deaths of two people to heat. In February, Uruguay registered a heatwave with temperatures above 40ºC. An increase in the number of visits to health facilities was reported, due to arterial hypotension, malaise, and decay. In Peru, temperatures were recorded above 33oC in Lima and 43oC, in the North with the possibility of high temperatures extending until April.
Meanwhile, in the northern hemisphere, Mexico had temperatures of up to 39oC in the Federal District and up to 45oC in Hidalgo.