By Neena Bhandari

Sydney, 12.07.2021 (SciDev.Net): Asia accounts for more than half of the over five million global deaths attributed to ambient cold and hot temperatures, according to an international study. But many governments are failing to prioritise health in their climate change strategies, experts warn.

The study, published 1 July in The Lancet Planetary Health, found that mortality rates in low-lying and crowded coastal cities in East and South Asia were particularly affected by temperature.

Researchers found that 9.4 per cent of global deaths from 2000 to 2019 could be attributed to non-optimal temperatures, with most of those caused by exposure to cold. However, this is predicted to change as global warming increases heat-related deaths.

“Over 2.4 million people died annually due to cold in Asia, followed by 1.18 million cold related deaths in Africa. But our findings show that in the long-term global warming is expected to increase the heat-related mortality burden,” says lead author of the study Professor Yuming Guo from Monash University’s School of Public Health and Preventive Medicine in Australia.

The findings come as the Global Climate and Health Alliance warns that governments are not doing enough to prioritise health in their national climate commitments ahead of COP26, the UN climate change summit, later this year. This is despite extreme temperatures, resulting in heatwaves, forest fires and cold snaps, having severe impacts on health.

The Global Burden of Diseases, Injuries, and Risk Factors Study 2019 showed that non-optimal temperatures were among the 10 leading causes of death worldwide.

“Understanding the geographic patterns of temperature-related mortality is important for future climate change and health related policies and strategies”, says Professor Guo. “During the 20-year period (2000-2019), earth’s temperature increased by 0.26 degree Centigrade per decade. This reduced cold related deaths by 0.51 percent and increased heat related mortality by 0.21 percent, which led to a reduction in net mortality due to hot and cold temperatures.”

The study also calculated global annual excess death ratio and excess death rate (per 100,000 residents) to systematically evaluate the geographical variation in temperature-related mortality burden.

“Sub-Saharan Africa had the world’s highest cold-related excess death rate (132 excess deaths per 100,000). On the other hand, Eastern Europe had nearly five times higher heat-related excess death rate (24 excess deaths per 100,000) than the global average”, says Dr Qi Zhao from China’s Shandong University and the study’s first author.

Of all excess deaths, 51·49 percent occurred in Asia, 23·88 percent in Africa, 16·44 percent in Europe, 7·70 percent in the Americas, and 0·48 percent in Oceania.

Dr Zhao notes that while people are more vulnerable to extreme temperatures which may cause lots of deaths, “they are a rare occurrence and last for a shorter duration. So, the cumulative death from moderate temperatures is much higher.”

Researchers used baseline data of 43 countries, comprising nearly half the world’s population, with different climates, socio-economic and demographic conditions, and differing levels of infrastructure and public health services. While predicting the local temperature-mortality relationships, they took into account GDP per capital.

The mortality data from this study is significantly higher than the second-largest study published in 2015, which had estimated 7.7 percent of deaths were related to cold and hot temperatures across 13 countries.

Fiona Armstrong, Executive Director of the Climate and Health Alliance says, “This study confirms that we can expect more deaths worldwide from heat exposure driven by climate change, which poses a threat to people’s health in the short and long term. Nations must urgently prepare their health systems to cope, not only with the increased illness and deaths from heat, but with all climate-related health impacts — extreme weather, novel infections and vector-borne diseases, mental distress, food and water insecurity, and more”.

“Wealthy countries, like Australia, must bear their fair share of the global responsibility for reducing emissions and supporting lower-income countries to make the transition, accounting for historic emissions and health equity”, Armstrong tells SciDev.Net.

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