Source:
https://scmp.com/comment/letters/article/3051700/climate-change-and-coronaviruses-warming-world-encourages-emergence Letters
Climate change and coronaviruses: a warming world encourages the emergence and spread of new infectious diseases
- Rising global temperatures will shorten winter seasons, which benefit potential disease-carrying agents and enable them to spread further north
- Climate change may also make habitats unsuitable for animals, forcing them closer to urban areas and increasing the risk of transmission of zoonotic diseases
Ash from wildfires forms patterns at Narrawallee Beach, located near the town of Milton in New South Wales, Australia, on January 13. The Australian fires have burned across an area twice the size of Switzerland while claiming at least 28 lives and destroying thousands of homes. Photo: Bloomberg
Since the coronavirus outbreak started over a month ago, over 75,000 people around the world have been infected with Covid-19. This is not the first time the world has dealt with a global outbreak in recent history – there was the severe acute respiratory syndrome in 2003, the Zika virus in 2015-16 and Middle East respiratory syndrome coronavirus that was first diagnosed in 2012 – and this coronavirus is unlikely to be the last.
In 2007, the World Health Organisation warned that emerging infectious diseases are becoming a growing threat in the face of increasing urbanisation, antimicrobial resistance and climate change.
While the relationship between the new coronavirus and climate change is tenuous at best, a warming climate will exacerbate the emergence of other novel infectious diseases in the future.
Rising global temperatures will shorten winter seasons – in 2019, Hong Kong experienced only three days when temperatures dropped to 12 degrees Celsius or below. Certain infectious diseases like dengue and malaria thrive better in warm temperatures.
Milder and shorter winters also benefit potential disease-carrying agents, such as mosquitoes and rats, as they can stay active and breed for longer and earlier in the season. Warmer climates also allow them to travel further up north and to higher altitudes, bypassing borders and bringing diseases to new places.
Compounding a warming climate is the change in the water cycle. Heavy rainfalls and floods will become more likely and intense. Heavy precipitation forms pools of stagnant water, which are prime breeding grounds for mosquitoes.
Lastly, climate change may also make habitats unsuitable for wildlife through warming temperatures and sea level rise. Along with other ecological disturbances, such as urbanisation and deforestation, wild animals may be forced to seek refuge in urban areas, bringing themselves and potential novel diseases into closer contact with domestic animals and us.
This is a particular problem as nature is a reservoir of potential human diseases: 60 per cent of all recognised human diseases and 75 per cent of emerging infectious diseases in the last few decades were zoonoses or transmitted from animals to humans.
So long as people live close together and global travel is easy, disease outbreaks are unavoidable. The emergence and re-emergence of infectious disease is, however, just one of the many health risks that climate change will bring about.
Climate change is predicted to cause 250,000 more deaths per year from infectious diseases, non-communicable disease like heat stress, waterborne diseases like cholera, and many more. World leaders and governments must address our warming climate if they are to safeguard our health.
Wendell Chan, programme officer, Friends of the Earth (HK)