Climate change multiplies the number of deaths from excess heat

Climate change is increasing the number and intensity of heat waves globally.

A group of researchers into environmental health and pulmonary diseases at the University of Oulu, Professor Jouni Jaakkola, Associate Professor Yuming Guo, and Dr. Niilo Ryti took part in a worldwide study evaluating the impact of heat waves on mortality, and predicting an increase in deaths caused by hot spells by the year 2080.

Climate change is increasing the number and intensity of heat waves globally. According to a model developed by an international group of researchers, the worst-case scenario is that mortality caused by heat waves in Finland could increase by 242% between 2031-2080 compared with the level in 1971-2020. If easing climate change and adapting to it prove successful, Finland could get by with a six percent increase in mortality. The Finnish material in the international study was based on more than 139,000 deaths in the Helsinki region between 1994 and 2011.

The impact will be worst near the equator. In Columbia, for instance, mortality caused by heat could increase by 2,000% if preventative measures are not enacted. Even in the most optimistic forecast, the increase will be 23%.

The study was based on 79 million deaths in 20 countries in a total of 412 cities or regions. In the first stage the impact of heat waves between 1984 and 2015 on mortality was evaluated on a local level. These impact evaluations were then used to predict the effects on mortality in different climate change scenarios. The scenarios were based on four alternate trajectories ranging from the successful fight against climate change to an increase in accordance with present growth.

In addition to the climate change scenarios, the forecasts also took into account the predicted changes in the age distribution of the population and measures aimed at adapting to the situation.

"The number and intensity of heat waves will increase over the coming decades, but fortunately the size of the change depends on the success of measures taken to control it. The health hazards of heat waves will also increase significantly if we are not successful in adapting to the heat both on an individual level and in communities", says Jouni Jaakkola, Professor of Public Health.

The most vulnerable sector of the population are children and the elderly, as well as those suffering from chronic illnesses whose ability to adapt to the heat is weaker than with healthy adults. Especially those suffering from cardiovascular diseases, pulmonary diseases, and diabetes are among those who are particularly vulnerable, who need to be efficiently targeted by preventative measures.

The harm caused by heat waves can be reduced through changes in the behaviour of individuals, cooling homes, making public cool spaces available, and the development of warning systems based on weather forecasts.

The study was published in the journal PLOS Medicine on 31. July, 2018. The project received funding from the Academy of Finland.


Last updated: 8.8.2018