As the world enters the climate emergency, an intensified and unpredictable El Niño weather event has been declared in Australia. El Niño is a climate event originating in the Pacific Ocean, and that has wide-ranging consequences for weather around the entire globe.

The warming climate conditions of El Niño is the most significant fluctuation on the planet and Australia is particularly vulnerable to its impacts (Haines, Lam 2023).One of the most concerning effects on public health during heightened El Niño periods is through extreme weather and weather disasters.

El Niño is associated with an increased risk of drought, catastrophic bushfires, and severe storms. These disasters can damage infrastructure, disrupt the delivery continuity of healthcare services, lead to displacement and directly harm lives (Kovats et al 2003).The most serious health challenges that will arise from El Niño here in Australia for the foreseeable future will include from:

• intense heatwaves
• increased severity of bushfires and air pollution impacts from smoke, and
• food insecurity due to drought effects on agriculture.

El Niño can also directly affect the transmission of some infectious diseases. For example, warmer temperatures and increased rainfall can create more favourable conditions for mosquitoes, which transmit diseases such as Ross River fever and Japanese encephalitis (Kovats et al 2003).

Some specific examples of the impact of El Niño on public health in Australia will come from a catastrophic bushfire season. Smoke from biomass burning, bushfires, contains pollutants harmful to health, including particulates. Particles less than 2·5 m in diameter that can penetrate human lungs and cause serious short- and long-term health effects (Islam et al 2022).

Air pollution can significantly increase cardiopulmonary risks, as well as impact people with respiratory diseases such as asthma, as well as cause death. It has been shown that during El Niño intensified bushfire seasons there are increased deaths compared to La Niña years (Johnston et al 2012). Moreover, the continuity of general and emergency health service delivery is impacted by heatwaves and bushfires that affect air quality (Islam 2022).

It is important to understand that while the dual weather events of La Niña and El Niño are natural phenomena, both the intensity and effects of the weather changes have been increasingly amplified by human made climate change (Haines 2023. El Niño significantly impacts public health, both directly and indirectly. As the WHO has so urgently declared, we need to do all we can to mitigate and stop runaway climate change to protect health. El Niño is a threat to public health, and we need to take action to address climate change now.

References:

• Kovats RS, Bouma MJ, Hajat S, Worrall E, Haines A. El Nino and health. Lancet 2003; 362: 1481–89.
• Haines, A., & Lam, H. C. (2023). El Niño and health in an era of unprecedented climate change. The Lancet.  S0140-6736
• Islam, M. S., Fang, T., Oldfield, C., Larpruenrudee, P., Beni, H. M., Rahman, M. M., ... & Gu, Y. (2022). Heat wave and bushfire meteorology in New South Wales, Australia: air quality and health impacts. International journal of environmental research and public health, 19(16), 10388.
• Johnston FH, Henderson SB, Chen Y, et al. Estimated global mortality attributable to smoke from landscape fires. Environ Health Persp 2012; 120: 695–701.