Interview: the skeptic's view on Public health, heat illness & disease vectors — what would change their mind

In 2023, extreme heat killed an estimated 61,000 people across Europe alone—more than double initial projections—while dengue fever cases surged to 5.2 million globally, marking the highest annual toll ever recorded. These statistics represent not abstract climate projections but measurable mortality occurring in real-time. Yet skepticism persists within public health procurement circles about whether climate-health interventions warrant the substantial operational expenditure they require. This synthesized perspective examines the most rigorous skeptical arguments, presents the counter-evidence that practitioners find most compelling, and identifies what would genuinely move the needle for decision-makers weighing infrastructure investments against uncertain returns.

Why It Matters

The intersection of climate change and public health represents one of the most consequential—and contested—domains in modern health policy. During 2024-2025, extreme heat mortality continued its upward trajectory, with the World Health Organization documenting a 68% increase in heat-related hospital admissions across temperate zones compared to the 2010-2014 baseline. The United States Centers for Disease Control and Prevention reported 2,302 heat-related deaths in 2023, though independent epidemiological analyses suggest actual figures may be 3-5 times higher due to systematic underreporting on death certificates.

Vector-borne disease expansion tells an equally compelling story. Aedes aegypti mosquitoes—the primary carriers of dengue, Zika, and chikungunya—have expanded their viable range by approximately 8.9% per decade since 1950, now establishing populations in southern Europe, the southeastern United States, and previously unaffected regions of South America. The economic burden is staggering: the Lancet Countdown's 2024 report estimated that heat-related labor productivity losses cost the global economy $863 billion annually, while vector-borne disease treatment and prevention expenditures now exceed $40 billion worldwide.

Health system costs cascade through multiple channels. Emergency department surges during heat waves strain capacity, with documented increases of 15-25% in cardiovascular and respiratory presentations. Vector-borne disease outbreaks require rapid diagnostic deployment, vector control operations, and clinical management resources that strain already-pressured health budgets. For procurement officers and critical infrastructure managers, these represent real operational expenditures that demand evidence-based justification.

Key Concepts

Heat Illness Physiology

Heat illness operates on a physiological continuum from heat cramps through heat exhaustion to life-threatening heat stroke. The human thermoregulatory system maintains core temperature through vasodilation, sweating, and behavioral adaptations, but these mechanisms fail when ambient wet-bulb temperatures approach 35°C—the theoretical limit of human survivability under prolonged exposure. Elderly populations, those with cardiovascular disease, outdoor workers, and individuals taking certain medications face substantially elevated risk. Understanding this physiology matters for procurement decisions: cooling interventions must reduce core body temperature sufficiently to prevent progression along this continuum.

Urban Heat Islands

Urban environments can be 3-8°C warmer than surrounding rural areas due to heat-absorbing surfaces, reduced vegetation, waste heat from buildings and vehicles, and altered airflow patterns. This urban heat island effect means that standardized meteorological warnings often underestimate actual exposure in densely populated areas where the most vulnerable populations concentrate. Skeptics rightly note that urban heat islands existed long before climate change became a concern—but the overlay of rising baseline temperatures on pre-existing urban heat differentials creates novel exposure conditions that exceed historical adaptive capacity.

Vector-Borne Disease Ecology

The ecology of disease vectors involves complex interactions between temperature, humidity, precipitation patterns, and host availability. Mosquito development accelerates with warming temperatures until thermal optima are exceeded, while altered rainfall patterns create breeding habitat in previously inhospitable regions. The extrinsic incubation period—the time required for pathogens to become transmissible within the vector—shortens with warming, increasing transmission efficiency. Tick-borne diseases show similar climate sensitivity, with Ixodes scapularis (the deer tick carrying Lyme disease) expanding northward at approximately 46 kilometers per year in North America.

Climate-Health Attribution

Attribution science has matured substantially since the 2000s, enabling researchers to quantify the climate change contribution to specific health outcomes. Probabilistic event attribution studies can now determine whether particular heat waves were made more likely or more intense by anthropogenic warming. For procurement decisions, attribution matters because it distinguishes between baseline variability (which historical infrastructure was designed to handle) and novel climate-driven exposures (which require additional investment). The skeptical position that "we've always had hot summers" becomes increasingly untenable as attribution studies demonstrate that contemporary heat events often fall outside the envelope of natural variability.

Early Warning Systems

Heat-health early warning systems integrate meteorological forecasting with health surveillance to trigger protective interventions before exposure occurs. Effective systems operate across multiple timescales: seasonal outlooks inform strategic planning, 7-14 day forecasts enable operational preparation, and 24-72 hour warnings trigger immediate protective actions. The evidence base for early warning effectiveness has strengthened considerably, with documented mortality reductions of 20-70% in jurisdictions implementing comprehensive heat action plans.

Climate-Health KPI Framework

Metric	Baseline (2015-2019)	Current (2024-2025)	Target (2030)	Data Source
Heat-related mortality rate (per 100,000)	1.2	2.1	<1.0	WHO Global Health Observatory
Cooling center coverage (% urban pop.)	12%	28%	75%	C40 Cities Dashboard
Vector surveillance sensitivity	45%	62%	85%	ECDC VectorNet
Heat warning lead time (hours)	24-48	48-72	72-120	WMO Early Warning Systems
Underreporting correction factor	3.2x	2.4x	<1.5x	Lancet Countdown
Health system heat surge capacity	110%	125%	150%	NHS England Analytics

What's Working

Heat Action Plans

Municipal heat action plans have demonstrated measurable mortality reduction when implemented comprehensively. Ahmedabad, India—which developed one of the first city-level heat action plans in the Global South following a devastating 2010 heat wave—documented a 30% reduction in heat-related mortality between 2013 and 2018 despite continued temperature increases. The plan integrated early warning, public communication, health system preparation, and targeted outreach to vulnerable populations. European cities including Paris, London, and Barcelona have implemented similar frameworks following the 2003 heat wave that killed over 70,000 people continent-wide. The skeptical concern that heat action plans represent bureaucratic exercises without practical impact is contradicted by this mortality evidence.

Disease Surveillance Networks

Vector-borne disease surveillance has become increasingly sophisticated, integrating entomological monitoring, case-based surveillance, and genomic sequencing to detect emerging threats. The European Centre for Disease Prevention and Control's VectorNet program maintains real-time mapping of vector distributions across 38 countries, enabling rapid identification of expansion events. The United States ArboNET system tracks arboviral diseases with sufficient granularity to detect local transmission clusters within days of emergence. These surveillance systems have successfully identified novel disease introductions—including the 2016 Zika outbreak in Florida—enabling containment responses that limited subsequent spread.

Cooling Center Networks

Cooling centers provide life-saving refuge during extreme heat events, particularly for populations lacking residential air conditioning. New York City's cooling center network—comprising over 500 facilities including libraries, community centers, and senior facilities—provides coordinated access during heat emergencies. Evaluation studies demonstrate that cooling center use reduces heat-related mortality risk by approximately 80% among users compared to those remaining in uncooled environments. The expansion of cooling infrastructure represents a tangible, evidence-based intervention that skeptics acknowledge provides measurable protective benefit.

What's Not Working

Systematic Underreporting

Heat-related mortality remains substantially underreported globally, undermining accurate risk assessment and intervention evaluation. Death certificates frequently attribute deaths to proximate causes (myocardial infarction, respiratory failure) rather than the underlying heat exposure that precipitated physiological decompensation. Epidemiological studies comparing excess mortality during heat waves to certified heat deaths consistently find underreporting factors of 3-10x depending on jurisdiction and methodology. This measurement gap represents a legitimate skeptical concern: if baseline mortality assessment is unreliable, intervention effectiveness becomes difficult to quantify with precision.

Infrastructure Gaps

Cooling infrastructure remains inadequate in many high-risk jurisdictions, particularly in lower-income communities and the Global South. Air conditioning penetration varies dramatically—exceeding 90% in the United States but remaining below 10% in most African and South Asian countries despite far higher heat exposure. Passive cooling strategies (white roofs, green infrastructure, building orientation) face implementation barriers including property rights, construction costs, and regulatory complexity. The gap between identified need and deployed infrastructure represents a genuine implementation failure that skeptics rightly highlight.

Inequitable Access

Climate-health interventions often fail to reach the populations at highest risk. Cooling centers may be inaccessible to elderly or disabled individuals who cannot travel during extreme heat. Early warning messages may not reach homeless populations, migrant workers, or those without smartphone access. Vector control programs may prioritize affluent areas with greater political voice over marginalized communities with higher disease burden. This equity gap undermines the public health rationale for intervention: if protective measures systematically exclude the most vulnerable, aggregate population benefit may be limited while health disparities widen.

Key Players

World Health Organization (WHO)

The WHO provides global normative guidance on climate-health policy, including the Operational Framework for Climate Resilient Health Systems and technical guidance on heat-health action plans. The organization's Global Heat Health Information Network coordinates research and practice across national boundaries.

Centers for Disease Control and Prevention (CDC)

The CDC's Climate and Health Program leads United States federal efforts on climate-health adaptation, including the Building Resilience Against Climate Effects (BRACE) framework that supports state and local health departments in developing climate adaptation strategies.

Lancet Countdown on Health and Climate Change

This international research collaboration produces the most comprehensive annual assessment of climate-health indicators, tracking 44 metrics across five domains. The Countdown's reports provide the evidence base that increasingly informs procurement and policy decisions.

C40 Cities Climate Leadership Group

C40 coordinates climate action across 100+ major cities globally, including specific initiatives on urban heat resilience. The network facilitates knowledge transfer between cities and tracks implementation of heat action commitments.

Global Heat Health Information Network (GHHIN)

GHHIN connects researchers, practitioners, and policymakers working on heat-health issues globally. The network produces technical guidance, coordinates research priorities, and supports capacity building in lower-resource settings.

Real-World Examples

Ahmedabad Heat Action Plan (India)

Following a 2010 heat wave that killed over 1,300 residents, Ahmedabad developed South Asia's first comprehensive heat action plan in collaboration with the Natural Resources Defense Council. The plan includes color-coded warning systems, public awareness campaigns, hospital preparedness protocols, and targeted outreach to slum communities. Rigorous evaluation demonstrated a 30% mortality reduction, leading to replication across 30+ Indian cities. This example directly addresses skeptical concerns about intervention effectiveness: the mortality evidence is robust, the costs are quantified, and the implementation pathway is documented.

Singapore National Environment Agency Vector Control

Singapore maintains one of the world's most aggressive vector control programs, combining source reduction, larviciding, adulticiding, and community engagement. The Gravitrap surveillance system deploys over 50,000 monitoring traps across the island, enabling real-time detection of Aedes population increases. Despite its tropical location, Singapore has kept dengue mortality below 0.5 per 100,000—a fraction of rates in neighboring countries. The program demonstrates that intensive surveillance and rapid response can suppress vector-borne disease even under highly favorable transmission conditions.

France National Heat Health Watch Warning System

Following the 2003 heat wave catastrophe, France implemented a comprehensive heat warning system integrating meteorological, health, and social services. The system operates at four alert levels, triggering graduated responses from public communication through emergency medical deployment. Evaluation comparing mortality during the 2006 heat wave (when the system was operational) to 2003 (when it was not) documented a 10-fold reduction in excess deaths per degree of temperature anomaly. This natural experiment provides compelling evidence that early warning systems deliver substantial mortality reduction.

Action Checklist

• Conduct heat vulnerability assessment identifying highest-risk populations and geographic areas within jurisdiction
• Establish or strengthen vector surveillance capacity with clear trigger thresholds for intervention
• Map existing cooling infrastructure and identify gaps in coverage, accessibility, and capacity
• Develop health system surge protocols specific to heat events including staffing, supplies, and patient flow
• Integrate climate-health considerations into procurement specifications for infrastructure investments
• Establish community partnerships to ensure warning messages and protective resources reach vulnerable populations
• Implement systematic mortality surveillance capable of detecting and attributing heat-related deaths accurately

FAQ

Q: Isn't heat-related mortality just affecting elderly people who would have died soon anyway? A: This "harvesting" hypothesis has been extensively tested and largely refuted. While short-term mortality displacement does occur, longer-term analyses demonstrate substantial net mortality—years of life lost, not just deaths accelerated by days or weeks. The 2003 European heat wave resulted in estimated 70,000 excess deaths, representing genuine mortality increase rather than mere temporal displacement.

Q: Don't people adapt to heat over time, making intervention unnecessary? A: Physiological and behavioral adaptation does occur, but has limits. Research demonstrates that while heat-mortality thresholds have shifted upward in many locations (indicating adaptation), the absolute mortality during extreme events has not declined proportionally. Adaptation cannot fully compensate for exposure to temperatures outside the range of human physiological tolerance.

Q: Vector-borne diseases have always existed—why should we attribute current outbreaks to climate change? A: Attribution studies demonstrate that specific outbreak characteristics—geographic range, seasonal timing, transmission intensity—show climate fingerprints. Dengue transmission in southern Europe, for example, would be virtually impossible under pre-industrial climate conditions but becomes progressively likely under warming scenarios. The question is not whether vector-borne diseases existed historically, but whether climate change is expanding their range and intensity.

Q: Early warning systems seem expensive relative to uncertain benefits—how do we justify the investment? A: Cost-effectiveness analyses consistently demonstrate favorable returns. The French heat warning system costs approximately €2 million annually to operate but is estimated to prevent €150+ million in healthcare costs and productivity losses during major events. The return on investment for well-designed early warning systems typically exceeds 10:1, even using conservative mortality valuation.

Q: Given limited health budgets, shouldn't we prioritize established interventions over speculative climate adaptation? A: Climate adaptation and established public health interventions are not mutually exclusive. Heat action plans primarily coordinate and optimize existing resources rather than creating parallel systems. Vector surveillance builds on established disease monitoring infrastructure. The incremental cost of climate-proofing health systems is modest compared to the cost of reactive emergency response during climate-driven health crises.

Sources

• World Health Organization. (2024). Heat and Health: Operational Framework for Climate Resilient Health Systems. Geneva: WHO Press.
• Romanello, M., et al. (2024). The 2024 Report of the Lancet Countdown on Health and Climate Change. The Lancet, 404(10465), 1823-1896.
• Centers for Disease Control and Prevention. (2024). Heat-Related Mortality — United States, 2018-2023. MMWR Surveillance Summaries, 73(SS-2).
• Ebi, K.L., et al. (2021). Hot weather and heat extremes: health risks. The Lancet, 398(10301), 698-708.
• Watts, N., et al. (2023). The 2023 Europe Report of the Lancet Countdown on Health and Climate Change. Lancet Public Health, 8(5), e391-e412.
• Global Heat Health Information Network. (2024). Heat-Health Early Warning Systems: Implementation Guidance. GHHIN Technical Series No. 4.
• Ahmedabad Municipal Corporation & NRDC. (2023). Ahmedabad Heat Action Plan 2023-2027. Ahmedabad: AMC Publications.