Unrelenting heat: Ten trends shaping heat action

Extreme heat is a defining challenge of our time: in all regions of the world, it is deepening vulnerabilities, widening inequalities, and straining social, environmental, and economic systems that are already under pressure.  

Responding to this challenge requires acceleration of coordinated action across borders and sectors: no single country, institution or sector can solve this challenge alone. The Global Heat Health Information Network (GHHIN) experts – policymakers, scientists, and practitioners – have identified ten key trends influencing heat action, driving the focus and prioritizing action for the Network and its numerous global, regional and national partners. 

1. Evidence on heat impact is increasing, but so is misinformation

Public attention to extreme heat has grown rapidly, yet misleading or oversimplified narratives increasingly shape the debate. Clear, consistent communication grounded in the best available science is now as important as science itself.

Research, advocacy, and media coverage on extreme heat keeps expanding. But alongside solid evidence, mis- and disinformation is increasingly shaping perceptions, derailing climate action, undermining trust and slowing urgent action – especially when heat deaths are under‑ or mis‑attributed.  

Attribution science – understanding how human‑driven climate change influences the likelihood or severity of weather events, like extreme heat – is advancing rapidly. But when communication is inconsistent, it can create confusion. Decision makers, funders, media and the public need clear and transparent information based on the best available science. As legal and financial responsibilities grow, and courts and insurers increasingly require evidence of climate‑related impacts, reliable information is essential for good governance and public confidence in heat action.

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2. Heat early warning systems are saving lives, but many are not built for extremes  & multi-hazard realities

Early warning systems remain among the most effective tools for protecting people and their health, yet many are still calibrated to historical conditions. Stress-testing and scenario planning are no longer optional – it is something every country needs to apply. 

Heat early warning systems (HEWS) are among the most effective tools for preventing heat‑related deaths, but many were not built for the record‑breaking extremes we see today. Many systems also focus only on temperature forecasts, telling people how hot it will get, but not how dangerous that heat will be, or what to do about it.  

Stress‑testing, scenario planning, and simulations can help identify weaknesses before a crisis hits. Without these improvements, warnings risk being ignored or may cause confusion, undermining public trust. Flexible, impact‑based systems that link forecasts to clear guidance and practical actions, are essential to ensure alerts lead to appropriate responses.

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3. Access to cooling and water has become a public health equity issue 

Cooling is no longer a matter of comfort but of survival. Access remains deeply unequal, conditioned by income, housing quality, energy costs, and water availability. Expanding affordable, low-carbon cooling and water-secure infrastructure is now a critical priority for adaptation.

Cooling is essential for public health and climate adaptation, yet access to safe, affordable cooling and clean water remains unequal, leaving low‑income households, informal workers, and marginalized groups at high risk. Rising energy and water costs often force people to forgo even basic safety measures, while reliance on energy‑intensive options such as diesel‑powered cold chains and air‑conditioning that vents hot air into public space, adds to emissions and strains power systems. 

Proven passive solutions remain underfunded, from shading and reflective materials to urban greening, improved ventilation and thermal insulation, and water‑sensitive design. Occupational cooling standards are urgently needed in agriculture, construction, and delivery work, and many health facilities, care homes, and schools still lack adequate cooling and water access. Expanding low‑carbon, equitable cooling and water access is essential for long‑term resilience.

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4. Heat impacts cut across sectors, but heat policies remain siloed and disjointed

Heat simultaneously disrupts various sectors: health, labour, education, transport, housing, tourism, energy systems and the economy. When these sectors plan in isolation, risks and life-threatening failures cascade and amplify. Stronger coordination across sectors and levels of government will ensure that these compounding risks don’t amplify one another. 

When extreme heat hits, impacts cascade: outdoor work slows, children miss school, urban services are disrupted, transport systems fail, and energy demand surges, straining power grids. Yet, responses remain siloed: ministries of health, education, labor, housing, transport, and energy often work separately, leading to gaps or conflicting or overlapping actions.  

 Strong coordination mechanisms that integrate heat considerations across all sectors are essential to avoid fragmented responses, and to ensure that the social and economic vulnerabilities increased by extreme heat aren’t overlooked. Practical, tailored guidance should support schools, workplaces, care facilities, and local governments so they can protect communities in ways that reflect local realities.

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5. Much heat information still does not reach decision-makers in a form they can use 

Large volumes of climate and health data exist, but they are often difficult to interpret for local authorities and practitioners. Science must be translated into timely, locally relevant, and actionable information – and digital tools can help close the gap. 

Much of the existing heat impact data remains difficult for communities and local authorities to use. Many do not have the tools to interpret complex datasets, and in the absence of clear communication, misinformation can spread. Science offers strong evidence of how heat affects people and systems, but these findings must be translated into formats that support effective policymaking and accountability.  

New technologies, including artificial intelligence, can help make information more locally relevant, interactive, and accessible to non‑technical audiences. Ensuring that data is timely, clear, and actionable is essential for preventive action. Without this, valuable information risks going unused while communities remain unprotected.

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6. The true impacts and burden of heat are still underestimated 

Mortality statistics are often the most compelling consequence of heat, but they capture only part of the impact. Expanding data collection beyond mortality to capture heat’s wider health, social and economic impacts will strengthen investment, action, and long-term resilience planning. 

Mortality reflects only a fraction of the true burden of heat. The bigger, less visible story is morbidity: heat worsens chronic illness, disrupts sleep, reduces productivity, and affects mental health – with pregnant women, newborns, and young children and older persons especially at risk. People in informal settlements face compounding exposure from poor ventilation, lack of green space, and inadequate housing. 

These consequences also translate into economic ones, from rising healthcare spending to lost working hours and from reduced productivity to food insecurity or reduced lifespan of equipment. Yet these costs remain poorly measured in most contexts. Closing this measurement gap, across mortality, morbidity, and economic loss, is essential to mobilize resources, support comprehensive resilience strategies and propel action. 

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7. Heat remains weakly embedded in climate and development policy 

Despite recognition of the risk, heat is still treated superficially in many national commitments and adaptation plans, building codes, and urban policies, and receives limited sustained attention in major political forums. Heat must be integrated into national and global policy agendas as an issue of urgent concern.

Extreme heat is still poorly reflected in national climate and adaptation policies. Many National Adaptation Plans (NAPs) and Nationally Determined Contributions (NDCs) mention heat only in broad terms, without clear targets or accountability. At state and local levels, housing policies, building codes, public space and urban planning regulations also rarely include heat‑risk or resilience standards, leaving major gaps in implementation, and limiting opportunities for investment.  

Integrating heat into these frameworks would strengthen visibility, ensure sustained financing, and support coordinated action across sectors. Elevating heat in global discussions such as G20 and COP negotiations, with strengthened policy-integration, is essential to shift it from a marginal issue to a central adaptation priority.

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8. Short-term and fragmented funding won’t help address a long-term problem. 

Many heat and initiatives rely on time-limited grants, making it difficult to sustain or scale effective interventions. More stable, coordinated financing from governments, development banks, and philanthropic actors is essential to move beyond pilot projects toward durable solutions for heat resilience. 

Heat action continues to be limited by fragmented and short‑term funding. Many initiatives rely on small, time‑bound grants, causing programmes to stall or end when funding cycles expire. This instability means successful projects often can’t be scaled, and new projects revisit work already done, duplicating efforts. In today’s geopolitical context, underfunding is not unique to heat and health – many sectors face similar pressures – making it even more important to concentrate and coordinate efforts across organizations and disciplines.  

The absence of institutionalized, long‑term financing leaves research institutions, civil society, and public agencies dependent on unreliable support. Philanthropies, bilateral donors, and development banks can help shift this pattern by backing coordinated, sustained financing strategies. Without such reform, progress on heat resilience will remain fragile and uneven. Long‑term, predictable investment is essential to build durable institutional capacity and protect communities from rising heat risks.

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9. Current approaches often miss rural, informal, and Indigenous communities 

Current approaches often miss rural, informal, and Indigenous communities  
Heat strategies tend to focus on cities, where data and resources are more readily available. Community-led approaches and social protection mechanisms need to be strengthened to reach those most exposed. 

Current heat responses often focus on urban areas and cities, where visibility and resources are greater. However, rural communities, Indigenous peoples, migrants, refugees, people living with disabilities, and informal workers face significant risks yet are frequently left out of formal strategies. Many work or live in conditions where social protection and occupational health systems do not reach them. Community‑based approaches that draw on local knowledge remain underused, despite their proven value in protecting vulnerable groups.  

Ensuring these communities are represented in heat strategies, social programmes, and governance processes is essential to designing solutions that reflect their realities. Addressing these gaps is critical to achieving equity in heat resilience and ensuring that all people – regardless of where they live or work – are protected from rising temperatures.

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10. Extreme heat is increasingly a risk to stability and security 

Heat disrupts food production, supply chains, labour markets, and public events, and can intensify social and political stress, making it a growing concern for stability and governance. Heat must be treated also as an issue of stability and security.

Extreme heat is no longer only a climate or health issue; it is a growing threat to global stability. The 2025 Global Risks Report identifies extreme weather events, including heatwaves, as the second most critical global risk in the near term, highlighting their capacity to disrupt economies, infrastructure, and governance systems.  An IFRC–OCHA analysis further warns that heatwaves will increasingly exceed human and social limits, driving humanitarian crises, displacement, and widening inequalities.  Yet response efforts still focus largely on environment and health sectors.  

Treating extreme heat as a cross‑government stability and security challenge is essential to prevent cascading disruptions, strengthen preparedness, protect vulnerable populations, and reduce systemic risk in a rapidly warming world. This means engaging finance ministries, security and defense institutions, infrastructure agencies, and other actors outside the climate and health community of practice.

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