Beating the heat: Protecting kidney health in a warming world
Climate change is making extreme heat events more common, more intense and longer lasting. Even if countries meet today’s climate pledges, the world is on course for much higher temperatures by the end of the century. Heat is not just an environmental concern, it is an all-of-society one.
The report explores how heat stress can become kidney stress, the scale and distribution of this emerging health burden and the people most at risk. It also assesses the policy responses needed to protect kidney health in a warming world. These include whole-of-government initiatives and action by health systems, public health authorities, employers, workers and researchers, which together can reduce the effects of heat on kidney health.
“Policymakers should view the kidneys as a barometer for the overall impact of heat on human health, seeing them as the canary in the coal mine.”
-Professor Vivekanand Jha, executive director of The George Institute for Global Health, India
The kidney health crisis is colliding with a rapidly warming world, as extreme heat amplifies an existing global burden where nearly 1 in 7 adults—788 million people—live with chronic kidney disease. This condition is already the ninth-leading cause of mortality globally and projected to become the fifth-leading cause of death worldwide by 2040. Climate change is adding to this burden. It now drives 84% of global heatwaves and the share of the world's population exposed to extreme heat stress has climbed from 15.9% in the 1970s to 21.9% in 2015-24—a figure projected to rise. Rising temperatures are no longer just an environmental issue but a severe physiological strain. For instance, one study found the odds of an acute kidney injury incident rose by 3.8% for every 1°C increase above 25°C.
This compounding impact is already devastating vulnerable populations, including older adults, those living with pre-existing chronic diseases, workers and those living in poorer regions (see Figure 1). Extreme heat amplifies kidney risk in individuals already living with diabetes, cardiovascular disease, and pre-existing kidney conditions; as Dr Ben Caplin, professor of nephrology at University College London, warns, “If you’ve got pre-existing kidney disease, even with a ‘normal’ GFR and no proteinuria, you are still at much greater risk of acute kidney injury.”
“People in the public health and clinical communities may recognise diabetes as a risk factor for kidney diseases but not that heat exposure can amplify risk too. We need to raise awareness [among them].”
— Dr Shuchi Anand, associate dean for global health and professor of medicine, UC Davis Health, US
Figure 1: At-risk groups for heat-related kidney injury
Workers are also a key at-risk group. In certain communities across Central America and Asia, heat-related kidney disease affects up to 14% of rural male laborers. Simple, low-cost measures such as shade, water, rest breaks and early heat warnings already save lives and protect worker productivity, often paying for themselves.
To systematically tackle this challenge, the report argues for an overarching heat-kidney framework that moves beyond diagnosis by exclusion to recognize heat exposure and the full spectrum of heat-related kidney injury across diverse populations. This issue needs an immediate multisectoral response where governments, health systems, employers, employees and researchers work together now to curb rising heat-related kidney risks before they become harder to manage or become irreversible (see 'Summary of actions for key stakeholders').
Summary of actions for key stakeholders
At-risk individuals: people need to understand the extent to which they are vulnerable to kidney disease and how exposure to high levels of heat might exacerbate that. Prevention works best when those at risk are on board.
Healthcare systems: awareness of CKD, its risks and the possible effects of heat on patients needs to improve among healthcare professionals. Using this better knowledge as a foundation, health systems should engage in appropriate individual patient education as well as opportunistic diagnosis interventions where merited.
Public health: officials in this field should consider what population-wide interventions might be useful in their jurisdictions, in particular appropriate education initiatives (about kidney health and the health dangers of heat), as well as possible cost-effective targeted screening programmes.
National and local governments: beyond healthcare programmes and ministries, governments need to develop plans to prepare for heatwaves and climate change more generally. Any strategy must consider how such events will increase the burden of specific diseases, including those affecting the kidney. Officials also need to create regulations that can reduce heat’s effect on health across various fields, going from employment law to building regulation.
Employers and employees: these groups should work together, bringing in experts where helpful, to design workplaces and work practices that minimise the heat dangers arising from their employment activities.
Academics and researchers: these should address the many scientific gaps, discussed elsewhere, in our current knowledge of how heat and kidney health interact. Funders should consider ways to support these endeavours, including prioritising studies that answer practical policy questions, such as which populations need early detection and what heat-risk thresholds to use, as countries define heatwaves differently according to local conditions.
Beating the heat: Protecting kidney health in a warming world