THE devastating floods in Pakistan are a manifestation of climate change. Whatever development gains had been made over the decades in the flood-affected districts were washed away within a few days. Pakistan will take years to recover from this deluge.

The nature of various manifestations of climate change in the form of frequent extreme weather events — heavy and prolonged rains, cloudbursts, flash floods, heatwaves, wildfires, catastrophic storms, tsunamis, cyclones, droughts — make the future highly unpredictable. So, we don’t know when and where the next climate change disaster will hit. Obviously, this makes preparations to respond to these events extremely difficult, and never enough.

A lot has been written about the causes of climate change and how those who pollute the least are affected the most, environmental injustice and ways to deal with unabated fossil fuel extraction, greenhouse effects, global warming, melting glaciers and rising waters.

For almost three decades, the United Nations has been bringing together member states for global climate change summits. During this period, climate change has taken centre stage, globally. In 2015, the historic Paris Agreement was adopted by 196 world leaders with the aim of containing the increase in the average global temperature to below two degrees Celsius, above pre-industrial levels, and to pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels, recognising that this would significantly reduce the risks and impacts of climate change (Article 2).

The 27th Conference of Parties is going to start this Sunday in Sharm El Sheikh, Egypt, where 45,000 participants have registered to discuss climate change issues. In the words of the president-designate of COP27, “… climate crisis is existential, overriding and ever present, adverse climate impacts are increasing in frequency, intensity and impacts”.

Climate change affects human health in many direct and indirect ways. Primarily, climate change and its various manifestations occur due to the rise in global temperatures. As a result, the frequency and intensity of heatwaves are increasing.

Prolonged exposure to high day and nighttime temperatures produce cumulative physiological stress on the human body which exacerbates the top causes of distress and death globally, including respiratory and cardiovascular diseases, diabetes mellitus and renal disease. And every physical stress also results in mental distress and emotional disorder.

Rising temperatures are changing ecosystems which are favourable to the survival of many insects and pathogens. Mosquitos and ticks, for example, thrive in warmer environments. Climate change pushes animals to new habitats as natural habitats disappear, which leads to new interactions between animals and humans, giving rise to the spread of zoonotic diseases, for example, rabies. Ebola, Lassa fever, Rift Valley fever and monkeypox are examples which are known to spread more and widely under the effect of rising temperatures.

America’s CDC speculates that “as the difference between environmental temperatures and human body temperatures narrows, new fungal diseases may emerge as fungi become more adapted to surviving in humans”.

Environmental factors alone take the lives of around 13m people annually around the globe.

Apart from the heat factor, there are also a number of direct effects of climate change depending upon its manifestation at a given time and space.

Read more: Pakistan to take up climate financing issue at COP27, says minister

In these pages, I have written, for example, on the five groups of medical and healthcare problems during the floods and the need for and challenges of corresponding healthcare provision — ie injuries, waterborne diseases, exacerbation of existing chronic conditions, mental health issues and special needs of vulnerable groups like women and young children, old people, the disabled, etc.

Addressing these problems in emergency settings on a large scale and over a period of time puts huge stress on healthcare systems which themselves are badly affected. Pakistan is passing through such a situation, which the WHO has characterised as “public health crises”. Climate change effects such as rising sea levels, collapsing ice shelves, and greater volcanic activity are linked to the increased threat of tsunamis. The 2004 tsunami alone caused 227,000 deaths and unfathomable misery.

The indirect and insidious health effects of climate change work through raising the level of risks to health by negatively affecting the determinants of health. The discourse on the determinants of health is vast and there are many ways of looking at these.

One way of understanding the determinants of health is to see them as social, economic and political determinants. Another lens shows them as distal and proximal determinants in terms of their effect on health, and yet another dichotomy groups them into environmental and behavioural determinants. Whichever way we appreciate these factors, the fact remains that improvement or decline in them affects human health in a positive or negative way.

Another important feature of this discourse, from a policy perspective, is that these are factors which are not typically in the control of health ministries and hence necessitate inter-sectoral collaboration.

Take the example of education. Pradhan and others (2017) have concluded that the approximately 14 per cent and 30pc decline in under-five and adult mortality between 1970 and 2010 resulted from improvements in education levels, and that female education is far more important than male education for reducing both adult and child mortality.

Water is another critical determinant of health. The WHO estimates that almost one-tenth of the global burden of disease could be prevented by improving water, sanitation and hygiene. The list of health determinants is long and varied.

Climate change and a plethora of its manifestations influence most determinants of health. Displacements, families sliding into poverty, lack of proper nutrition due to wiped-out crops and seeds, lack of access to safe drinking water, disruption in schooling, air pollution, disrupted access to healthcare, unattended and prolonged mental stress are all determinants which are negatively affected by climate change.

Their combined and cumulative impact seriously affects human health and contributes heavily to morbidity and mortality. Environmental factors alone take the lives of around 13 million people annually around the globe while morbidity is uncountable.

The WHO rightly calls climate change the single biggest health threat facing humanity. Like always, the most vulnerable are the most affected.

The writer is a former SAPM on health, professor of health systems at Shifa Tameer-i-Millat University and WHO adviser on UHC.

zedefar@gmail.com

Published in Dawn, November 4th, 2022