In May 2020, cyclone Amphan unleashed its fury on West Bengal, Odisha and Bangladesh. The Sundarbans delta was especially badly hit. At that time, India and Bangladesh were in lockdown with Covid-19 having acquired pandemic proportions and been declared a global public health emergency.
The pandemic had already affected livelihoods when the cyclone arrived to destroy natural resources. Access to even easily available resources was greatly restricted by the impaired human mobility caused by both the pandemic and the cyclone. Persons displaced by the cyclone also risked being infected by the SARS-CoV-2 virus as they huddled together with other evacuees in crowded shelters.
Elsewhere in the world too, a similar calamitous conjunction of the virus and extreme wet weather was taking place. In East Africa, vast hordes of locusts swarmed over the fields. Evoking comparison with the Biblical plague, they were linked to the warm seas which generated extreme wet weather that is highly suitable for the proliferation of locusts. In the Pacific islands, a category 5 cyclone of April 2020 colluded with the pandemic to damage the tourism-dependant economies of those islands. All of these were effects of climate change with global warming.
A recent report by the United Nations Office for Disaster Risk Reduction (UNDRR, 2022) describes how climate change and pandemics are combining to severely threaten human security. Providing global narratives of the threats posed by this dangerous duo, the report declares that “the climate emergency and the systemic impacts of the Covid-19 pandemic point to a new reality”. That self-evident truth is that humanity does not have the luxury of time to deal with these two threats separately and sequentially. It is no mere coincidence that these two mainly anthropogenic disasters are simultaneously demonstrating their sinister strengths through the prolonged Covid pandemic and unprecedented levels of global temperature rise, noted since 2020.
Climate change, with a fusillade of extreme weather events and high temperatures, leads to migration not only of humans, but also of both wild and domesticated animals. Viruses and other microbes can travel with them and find ample opportunities to find new susceptible hosts or even jump species. This can aggravate an existing epidemic or trigger a new one. As drought hits parched farm lands and people struggle to find drinking water, climate refugees will rise in numbers and epidemic risks too will rise alongside.
Covid-19 is not the only infectious disease whose threat is amplified by climate change. On a more regular basis, even after this pandemic subsides, we can expect a rise in vector-borne diseases. Diseases transmitted by mosquito bite will increase, as the insects can rise to higher altitudes and spread farther afield wherever the warmer weather suits them. Dengue already posts a threat to vast swathes of the global population, while malaria still piles up deaths in Africa and Asia. Add Chikungunya and Zika to that list of mosquito-borne diseases that will find global warming to their liking.
India is already experiencing this spurt and spread of vector-borne diseases. New states in north and north-east India are becoming malaria-prone. Malaria is also spreading from central Indian states to the south-western coastal states of Maharashtra, Karnataka and Kerala. Malaria would also have a longer transmission window, increasing from 7-9 months to 10-12 months in the north-eastern states. Dengue will have a shorter extrinsic incubation period. In Kerala, this period is now as short as 9-14 days and the state has been experiencing a rise in dengue cases even before the pandemic.
Climate change also brings with it a rise in water-borne diseases as extreme weather events and unseasonal rains can cause flooding and open the channels for cholera and other water borne microbes. The threat of other water-borne infections may be compounded by droughts where clean drinking water will become scarce, forcing people to drink contaminated water. Extreme weather events also disrupt health services and diminish the capacity to provide the raised level of health system response required in pandemic conditions.
Agriculture and food systems will be affected by rising temperatures, with decrease in production of both staples and non-staples, while fruit and vegetables will ripen early and rot faster. Nutrient quality of staples like rice and wheat will decrease, with a reduction in zinc, iron and protein levels. Since these are nutrients needed to promote innate immunity, vulnerability of people to infections will increase. Pandemics like Covid disrupt agricultural and food industry operations, apart from disrupting national and global supply chains. Even food aid gets interrupted. Both Covid and climate change have contributed to growing global food insecurity in the past 30 months.
The clock is ticking fast on the climate front. Covid-19 has sounded the alarm that many dangers created or accelerated by human folly need a determined response to reduce their impact. Will we heed that warning, before it is too late?
Cardiologist and epidemiologist and President, Public Health Foundation of India