More than five million extra deaths a year can be
attributed to abnormal hot and cold temperatures, according to a world
first international study led by Monash University.
The study
found deaths related to hot temperatures increased in all regions from
2000 to 2019, indicating that global warming due to climate change will
make this mortality figure worse in the future.
The international research team, led by Monash University’s Professor Yuming Guo, Dr Shanshan Li, and Dr Qi Zhao from Shandong University in China – and published today in The Lancet Planetary Health
– looked at mortality and temperature data across the world from 2000
to 2019, a period when global temperatures rose by 0.26C per decade.
The
study, the first to definitively link above and below optimal
temperatures (corresponding to minimum mortality temperatures) to annual
increases in mortality, found 9.43 per cent of global deaths could be
attributed to cold and hot temperatures. This equates to 74 excess
deaths for every 100,000 people, with most deaths caused by cold
exposure.
The data reveals geographic differences in the impact of
non-optimal temperatures on mortality, with Eastern Europe and
Sub-Saharan Africa having the highest heat and cold-related excess death
rates.
Importantly, cold-related death decreased 0.51 per cent
from 2000 to 2019, while heat-related death increased 0.21 per cent,
leading to a reduction in net mortality due to cold and hot
temperatures.
The largest decline of net mortality occurred in Southeast Asia while there was temporal increase in South Asia and Europe.
Professor
Guo, from the Monash University School of Public Health and Preventive
Medicine, said this shows global warming may “slightly reduce the
number of temperature-related deaths, largely because of the lessening
in cold-related mortality, however in the long-term climate change is
expected to increase the mortality burden because hot-related mortality
would be continuing to increase”.
Professor Guo said previous studies had looked at temperature-related mortality within a single country or region.
“This
is the first study to get a global overview of mortality due to
non-optimal temperature conditions between 2000 and 2019, the hottest
period since the Pre-Industrial era,” he said.
“Importantly, we
used 43 countries’ baseline data across five continents with different
climates, socioeconomic and demographic conditions and differing levels
of infrastructure and public health services – so the study had a large
and varied sample size, unlike previous studies.”
The mortality
data from this groundbreaking Monash study is significantly higher than
the second-largest study published in 2015, which was based on 74
million deaths across 13 countries/regions and estimated 7.7 per cent of
deaths were related to cold and hot temperatures.
Professor Guo
said that showed “the importance of taking data from all points of the
globe, in order to get a more accurate understanding of the real impact
of non-optimal temperatures under climate change”.
Of the global deaths attributed to abnormal cold and heat, the study found:
- More than half occurred in Asia, particularly in East and South Asia
- Europe had the highest excess death rates per 100,000 due to heat exposure
- Sub-Saharan Africa had the highest death rates per 100,000 due to exposure to cold
Professor
Guo understanding the geographic patterns of temperature-related
mortality “is important for the international collaboration in
developing policies and strategies in climate change mitigation and
adaptation and health protection.”
ANNUAL DEATHS DUE TO ABNORMAL TEMPS BY REGION:
- Africa – 1.2 million
- Asia – 2.6 million
- Europe – 835,000
- South America – 141,000
- UK – 52,000
- US – 173,600
- China – 1.04 million
- India – 74,000
- Australia – 16,500
ANNUAL DEATHS DUE TO COLD TEMPS BY REGION:
- Africa – 1.18 million
- Asia – 2.4 million
- Europe – 657,000
- South America – 116,000
- UK – 44,600
- US – 154,800
- China – 967,000
- India – 655,400
- Australia – 14,200
ANNUAL DEATHS DUE TO HIGH TEMPS BY REGION
- Africa – 25,550
- Asia – 224,000
- Europe – 178,700
- South America – 25,250
- UK – 8000
- US – 18,750
- China – 71,300
- India – 83,700
- Australia – 2300