On the heals for the U.N.s most recent dire report on greenhouse gas emissions we keep hearing that we must “avoid the worst effects of climate change.”  The oft repeated phrase makes catastrophic human suffering sound nebulous, distant and, above all, survivable. As a climate scientist I should explain what those words mean.

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Picture an elderly parent in an apartment that will not cool, their body losing its ability to regulate temperature, or an outdoor worker becoming dehydrated, dizzy and confused while trying to finish a shift: heat can damage organs and kill. (IPCC health assessment) Calling that “discomfort” would conceal the stakes.

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Picture a child struggling to breathe through wildfire smoke, or a loved one unable to obtain essential medication because a flood has cut transport links and disrupted medical supplies. (IPCC health assessment) “Extreme weather” sounds different when the person waiting for help is someone you love.

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Picture a family evacuating a home they can no longer afford to insure, then facing the financial distress of an uninsured disaster loss. (US climate economics assessment) The emergency does not end when the water recedes.

The consequences reach into pregnancy and childhood: heat exposure is associated with increased risks of preterm birth and stillbirth, while inadequate nutrition can impair a child’s growth and development. (IPCC health assessment) These are not simply bad days that pass when the forecast improves.

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Flooding can contaminate drinking water, and disasters can leave people with lasting anxiety, depression and post-traumatic stress. (IPCC health assessment) Imagine having to question the water you give your children, or being unable to feel safe in your own home.

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My recent review of climate change’s human consequences examines these pathways together, including failures of essential services, financial losses and damage to community life. (Read the review, DOI: 10.5281/zenodo.23428939) The point is not to assemble a longer list of disasters, but to understand what they mean for a person trying to live through them.

A deeper danger is how these harms connect: power failures can remove protection from heat, while damaged harvests and disrupted work can leave households facing higher food prices with less income. (IPCC health assessment; US climate economics assessment) What happens when the next emergency arrives before that family has recovered?

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Survival itself can mean lasting illness, financial ruin, displacement and the loss of community, not a return to normal life. (WHO climate and health; US climate economics assessment) Death counts alone - and on our current course they will be in the billions - cannot capture those consequences.

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“Avoiding the worst” must not become a passifying distraction or another clever delay tactic. We are talking about whether people can remain fed, housed, healthy and alive, not whether they are "tough enough" to tolerate less pleasant weather. Our language should make that responsibility impossible to misunderstand. People need to know climate change is here, in less than 10 years it will be past the point of any return to normal, and at catastropic effects we are taling about here will mostly be in the current century!

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Christian R. Komor, Psy.D., Director, Climate Deadline Foundation
 

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Heat, weather extremes, and physical injury

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• Heat exhaustion and heatstroke: More intense heat exposure can overwhelm temperature regulation and cause serious illness or death. IPCC health assessment

• Dangerous heat combined with humidity: Humidity makes evaporative cooling less effective and increases heat strain, especially during physical work. IPCC health assessment

• Hotter nights: Higher nighttime temperatures can reduce relief from daytime heat and contribute to sleep disturbance. IPCC health assessment US climate assessment

• Dehydration: Heat and inadequate water access can produce dangerous fluid loss, particularly among workers and vulnerable people. IPCC health assessment

• River flooding: Overflowing rivers can drown or injure people, destroy homes, and interrupt essential services. IPCC impacts

• Flash and urban flooding: Intense rainfall can overwhelm drainage and quickly inundate streets, buildings, and transport routes. IPCC impacts

• Coastal flooding and storm surge: Rising sea levels raise the baseline for coastal flooding and compound storm-related damage. IPCC impacts

• Cyclone and hurricane damage: Climate-related changes in storm rainfall and intensity can increase injury, displacement, and infrastructure damage, without implying that storm numbers increase everywhere. US climate assessment

• Wildfire burns and deaths: More dangerous fire weather in affected regions increases exposure to fires that threaten lives and settlements. IPCC impacts

• Drought emergencies: Prolonged shortages of water can undermine food production, sanitation, livelihoods, and health. IPCC technical summary

• Landslides and debris flows: Heavy rain, changing mountain conditions, and post-fire landscapes can expose people and transport routes to destructive slope failures. IPCC technical summary US climate assessment

• Glacial-lake outburst floods: Glacier retreat and changing mountain hydrology can increase dangerous flood exposure in some mountain and downstream communities. IPCC technical summary

• Unsafe ice travel: Thinner or less reliable lake, river, and sea ice can increase transport accidents in Arctic and sub-Arctic communities. IPCC health assessment

• Workplace injuries: Heat can impair concentration and physical capacity, increasing occupational injury risk. US climate economics assessment

• Overwhelmed emergency response: Simultaneous or repeated disasters can exceed evacuation, rescue, firefighting, and relief capacity. US climate assessment

 

Chronic illness, air quality, and environmental exposure

·       Cardiovascular illness and deaths: Heat and smoke can worsen cardiovascular stress and contribute to excess mortality. IPCC health assessment

·       Kidney injury: Occupational heat strain and dehydration can reduce kidney function and damage health. IPCC health assessment

·       Respiratory illness: Wildfire smoke and other climate-sensitive air pollutants can worsen respiratory symptoms and increase hospitalizations. IPCC technical summary

·       Asthma and allergy burdens: Changes in pollen and other airborne allergens can increase respiratory distress in affected populations. IPCC impacts

·       Smog and ozone exposure: Hot conditions can aggravate some air-pollution episodes, increasing risks to health. IPCC impacts

·       Long-distance smoke exposure: Wildfire smoke can harm populations far from the fire itself. US climate assessment

·       Dust exposure: Drier conditions and atmospheric dust can contribute to cardiovascular and respiratory distress. IPCC impacts

·       Damp and mold-damaged housing: Flooding and repeated coastal inundation can expose residents to mold and unhealthy living conditions. Pregnancy-health review

·       Toxic releases during floods: Floodwaters can redistribute hazardous chemicals and other contaminants into homes, water, and surrounding environments. Pregnancy-health review

·       Harmful algal toxins: Warming and related aquatic changes can increase exposure to toxins affecting drinking water, seafood, and recreation. IPCC technical summary

·       Contaminants in traditional foods: Changes in Arctic and marine environments can increase some contaminant-exposure risks through fish, seafood, and marine mammals. IPCC health assessment

·       Worsening existing illness: People with chronic diseases can face greater vulnerability to heat, smoke, disrupted care, and other climate hazards. WHO climate and health

 

Infectious disease and food safety

·       Malaria shifts: Changes in temperature and rainfall can alter malaria transmission, including risks at some higher elevations and distribution margins, while reducing suitability elsewhere. IPCC health assessment

·       Dengue: Warmer conditions can lengthen transmission seasons and expand suitable areas for mosquitoes and transmission. IPCC impacts

·       Lyme disease: Climate-related changes in tick habitat and activity can expand exposure in parts of North America and Europe. IPCC health assessment

·       West Nile fever: Temperature, rainfall, and humidity changes can influence transmission in affected regions. IPCC technical summary

·       Tick-borne encephalitis: Climate-related changes can affect transmission risks in parts of Europe. IPCC technical summary

·       Cholera and other diarrheal diseases: Heat, heavy rainfall, and flooding can increase risks where water and sanitation protections are inadequate. IPCC impacts

·       Other waterborne infections: Contaminated water and damaged sanitation can increase exposure to enteric bacteria and parasites. IPCC health assessment

·       Vibrio infections: Warmer aquatic conditions can increase risks from some Vibrio bacteria, including through seafood exposure. IPCC impacts

·       Salmonella and Campylobacter: Climate-sensitive temperature and rainfall conditions can affect foodborne infection risk, with patterns varying by organism and region. IPCC health assessment

·       Food spoilage: Heat and disrupted refrigeration can increase spoilage and foodborne illness. Pregnancy-health review

·       Mycotoxins and aflatoxins: Warmer or more humid conditions can change fungal contamination of crops, with consequences for food safety and health. IPCC technical summary

·       Emerging zoonotic exposure: Climate-related environmental changes can contribute to animal-to-human disease risks in new areas, alongside other ecological and social drivers. IPCC impacts

 

Pregnancy, infants, and childhood development

·       Preterm birth: Heat exposure is associated with increased preterm-birth risk, although effects vary across studies and settings. Pregnancy-health review

·       Low birthweight and restricted fetal growth: Heat, inadequate nutrition, pollution, and disrupted prenatal care can contribute to adverse birth outcomes. Pregnancy-health review

·       Stillbirth and neonatal risks: Studies associate some heat exposures with stillbirth and neonatal mortality, with important variation in exposure and vulnerability. Pregnancy-health review

·       Pregnancy complications: Heat, smoke, and disaster-related stress have been linked to several maternal complications, with strength of evidence differing by outcome. Pregnancy-health review

·       Maternal infection and dehydration: Climate-sensitive disease and water scarcity can create additional risks during pregnancy. Pregnancy-health review

·       Interrupted prenatal and maternity care: Displacement, power outages, damaged facilities, and blocked transport can delay essential care. Pregnancy-health review

·       Childhood malnutrition and impaired development: Poor nutrition can impair physical growth, cognitive development, education, and later work performance. IPCC health assessment

·       Long-lasting and intergenerational harm: Adverse early-life exposures and pregnancy outcomes can affect later health and economic prospects rather than ending when the disaster ends. Pregnancy-health review US climate economics assessment

 

Mental health, cognition, and personal well-being

·       Post-traumatic stress: Exposure to fires, floods, storms, displacement, and loss can produce enduring psychological trauma. WHO climate and health

·       Anxiety and distress: Experienced or anticipated climate threats can contribute to mental-health burdens. IPCC technical summary

·       Depression and other mental disorders: Climate extremes, livelihood loss, and displacement can worsen mental health. IPCC health assessment

·       Suicide-related risks: Climate-associated heat, disaster exposure, and severe distress have been linked to suicide-related outcomes, with risks mediated by social support and existing vulnerabilities. IPCC health assessment

·       Substance-use problems: Disaster trauma, displacement, and major losses can contribute to harmful coping and substance-abuse problems. IPCC health assessment

·       Ecological grief: Loss of valued species, landscapes, and ways of life can cause grief and distress. IPCC technical summary

·       Solastalgia: People can experience distress as their familiar home environment changes or deteriorates, even without moving away. IPCC technical summary

·       Sleep disruption: Heat exposure can disturb sleep and compound physical and psychological strain. IPCC health assessment

·       Impaired concentration and cognition: Heat strain and extreme-event exposure can reduce concentration, cognitive performance, and work capacity. IPCC health assessment IPCC technical summary

·       Strained social support: Displacement and disrupted social cohesion can remove protective relationships and worsen mental health. WHO climate and health

·       Stress among responders and exposed livelihoods: First responders, farming communities, Indigenous Peoples, and other highly exposed groups can experience disproportionate mental-health harms. IPCC technical summary

 

Food production, hunger, and nutrition

·       Reduced crop yields: Heat and changed rainfall can reduce yields or slow productivity growth, especially in already warm regions. IPCC technical summary

·       Acute crop failures: Heatwaves, droughts, floods, fires, and storms can cause sudden production losses. IPCC impacts

·       Unstable harvests: Increasing variability can make annual food output and farm income less reliable. IPCC technical summary

·       Changing growing-season suitability: Established crop varieties and farming locations may become less suitable, requiring costly adjustments. IPCC technical summary

·       Crop pests and diseases: Climate change can alter pest and pathogen pressures and damage production. IPCC impacts

·       Pollination disruption: Species losses and mismatches between flowering and pollinator activity can undermine food production. IPCC technical summary

·       Soil degradation: Warming and climate extremes can weaken soil health and other ecosystem services supporting crops. IPCC impacts

·       Livestock heat stress: Heat and drought can reduce animal health, productivity, fertility, and survival. IPCC technical summary US climate assessment

·       Loss of pasture and forage quality: Drought and wildfire can reduce livestock feed availability and nutritional quality. US climate assessment

·       Fisheries and aquaculture losses: Ocean warming, marine heatwaves, acidification, and oxygen loss can undermine seafood production and fishing livelihoods. IPCC technical summary US climate assessment

·       Reduced nutritional quality of staples: Higher atmospheric carbon dioxide can reduce protein and some micronutrients in certain crops; this is a direct CO₂ effect, not simply a temperature effect. IPCC health assessment

·       Higher food prices: Production and distribution disruptions can make healthy diets less affordable. IPCC synthesis

·       Hunger and malnutrition: Lower food availability, reduced household income, and less dietary diversity can increase undernutrition and micronutrient deficiencies. IPCC impacts

·       Contribution to famine conditions: Severe climate shocks can worsen food-system crises and famine risk, especially alongside conflict, poverty, interrupted trade or aid, and governance failures; famine is not an automatic result of warming alone. IPCC health assessment Pregnancy-health review

 

Water scarcity, contamination, and sanitation

·       Drinking-water shortages: Drought and changing hydrology can reduce reliable access to water. IPCC technical summary

·       Less dependable snowmelt: Reduced snowpack and earlier melt can change the timing and volume of downstream supply. US climate assessment

·       Glacier-dependent supply changes: Glacier retreat can disrupt water availability for downstream communities over time. IPCC technical summary

·       Greater pressure on groundwater: Higher irrigation demand and reduced surface supplies can intensify pumping of already stressed aquifers. US climate assessment

·       Saltwater intrusion: Sea-level rise and dry conditions can contaminate coastal groundwater used for drinking and irrigation. US climate assessment

·       Flood-contaminated water: Floodwater can carry sewage, debris, and pollutants into water supplies. US climate assessment

·       Reduced sanitation and hygiene: Water shortages and damaged systems can undermine washing, sewage management, and infection prevention. IPCC health assessment

·       Longer water-collection journeys: Scarcity can increase time and physical burdens and expose collectors, particularly women and girls, to harassment or assault. IPCC health assessment

·       Disrupted water-treatment systems: Climate hazards can damage facilities or interrupt the power and transport needed to maintain safe supplies. IPCC impacts

·       Harder water planning: Rapid shifts between wet and dry conditions can make storage, allocation, and flood management more difficult. US climate assessment

·       Health effects of saline drinking water: Saltwater intrusion can increase salt intake and contribute to blood-pressure-related risks in exposed populations. IPCC health assessment

 

Homes, settlements, and habitable land

·       Destroyed or damaged housing: Fire, floods, storms, and other hazards can make homes unsafe or unusable. IPCC impacts

·       Permanent coastal inundation: Rising seas can eventually submerge low-lying properties and infrastructure. US climate assessment

·       Coastal erosion: Retreating shorelines can undermine housing and community assets. IPCC impacts

·       Repeated displacement: Recurrent disasters can prevent stable recovery and increase housing insecurity. US climate assessment

·       Unsafe indoor heat: Poor insulation, insufficient cooling, and unaffordable energy can expose residents to dangerous temperatures. US climate assessment

·       Permafrost-related structural damage: Thawing ground can destabilize buildings and infrastructure in cold regions. IPCC impacts

·       Costly retrofits and relocation: Households may need flood protection, cooling, fire hardening, or a move to maintain safety. US climate economics assessment

·       Threats to small-island and low-lying communities: Sea-level rise can threaten continued settlement through combined flooding, erosion, water contamination, and infrastructure loss, not just total submergence. IPCC impacts

 

Infrastructure, energy, transport, and healthcare

·       Power outages: Heat, storms, flooding, and wildfire can disrupt electricity systems and essential services. US climate assessment

·       Greater cooling demand: Hotter conditions increase electricity needs, household costs, and pressure on grids. US climate assessment US climate economics assessment

·       Reduced hydropower reliability: Drought and low reservoir levels can constrain electricity generation. US climate assessment

·       Damaged roads and bridges: Flooding, storms, landslides, and other climate hazards can cut transport links. US climate assessment

·       Heat-damaged railways: Extreme heat can buckle rails and disrupt service. US climate assessment

·       Port and coastal transport disruption: Sea-level rise and storms can damage ports, tunnels, coastal roads, and rail networks. US climate assessment

·       Communication failures: Climate-related infrastructure damage can disrupt telecommunications needed for work, warnings, emergency response, and care. US climate assessment

·       Interrupted supply chains: Infrastructure failures can delay food, medical supplies, construction materials, and other goods beyond the affected area. IPCC synthesis

·       Damaged or inaccessible health facilities: Floods, storms, fire, and blocked transport can prevent access to medical care. WHO climate and health US climate assessment

·       Interrupted medication and treatment: Service failures can disrupt ongoing medical treatment and access to medication. IPCC health assessment

·       More demand on overstretched health systems: Heat illness, infections, smoke exposure, and disaster injuries can increase demand when capacity is already impaired. WHO climate and health

·       Higher infrastructure maintenance costs: Systems designed for past climate conditions may need repair, replacement, or upgraded design standards. IPCC impacts

 

Work, businesses, household finances, and government budgets

·       Reduced labor productivity: Heat can shorten safe working hours and reduce output, especially outdoors. IPCC impacts

·       Lost wages and earnings: Smoke exposure, illness, closures, and climate-disrupted work can reduce income. US climate economics assessment

·       Loss of farming, fishing, and forestry livelihoods: Environmental and production changes can undermine resource-dependent employment. IPCC impacts

·       Tourism and recreation losses: Heat, damaged coasts, ecosystem decline, smoke, and shorter snow seasons can reduce visitors and income. US climate assessment

·       Business interruption and closure: Repeated damage, outages, supply shortages, and higher recovery costs can make businesses less viable. US climate assessment US climate economics assessment

·       Higher household living costs: Food, energy, medical care, insurance, and repairs can become more expensive. US climate economics assessment

·       Lower property values and lost wealth: Flood, sea-level-rise, and wildfire risks can erode the value of exposed assets. US climate economics assessment

·       Insurance becoming unaffordable or unavailable: Insurers may raise costs or withdraw from high-hazard areas, leaving coverage gaps. US climate economics assessment

·       Financial distress after uninsured losses: Households without adequate insurance can struggle to repair, rebuild, or relocate. US climate economics assessment

·       Reduced public revenues: Lower incomes, business activity, and property values can shrink government revenue. US climate economics assessment

·       Higher public spending: Disaster relief, firefighting, healthcare, infrastructure repair, social support, and public insurance can strain budgets. US climate economics assessment

·       Slower or interrupted economic development: Repeated climate losses can depress output and divert resources from longer-term investment. IPCC synthesis

 

Education, family responsibilities, and inequality

·       School closures and lost instruction: Heatwaves, storms, flooding, drought, and other hazards can interrupt schooling. UNICEF education assessment

·       Damaged schools and unsafe routes: Destruction of classrooms, supplies, and access routes can prevent attendance. UNICEF education assessment

·       Reduced learning in hot conditions: Heat can impair concentration, memory, and academic performance without sufficient adaptation. UNICEF education assessment US climate economics assessment

·       Dropout and lost educational opportunity: Prolonged disruption can make returning to school less likely, especially in fragile settings. UNICEF education assessment

·       Child labor and child marriage risks: Disaster-related educational disruption and hardship can increase these risks in vulnerable contexts. UNICEF education assessment

·       Greater burdens on women and girls: Water scarcity, caregiving duties, constrained mobility, and unequal access to resources can intensify climate-related hardship. IPCC health assessment

·       Widening inequality: People with fewer resources often face greater exposure and less ability to cool homes, evacuate, insure property, or recover. IPCC impacts

·       Disproportionate harm to vulnerable groups: Children, older people, disabled people, outdoor workers, displaced people, and those with existing illness can face heightened risks. WHO climate and health

·       Poverty traps: Loss of health, income, housing, and assets can reduce the resources available for the next emergency and perpetuate vulnerability. WHO climate and health IPCC synthesis

 

Displacement, security, and social relationships

·       Emergency evacuation: Sudden hazards can force people to leave their homes immediately. IPCC health assessment

·       Longer-term migration: Declining livelihood security, recurring disasters, and worsening habitability can influence decisions to move. IPCC health assessment

·       Involuntary immobility: People may lack the resources or freedom to leave dangerous conditions. IPCC health assessment

·       Loss of community networks: Displacement can separate neighbors and disrupt social support, identity, and continuity. US climate assessment

·       Pressures on receiving communities: Climate-related migration can alter housing and service needs, with outcomes shaped by institutions, resources, and migrants’ ability to exercise choice. IPCC health assessment

·       Gender-based violence risks: Extreme events and water scarcity are associated with increased violence against women and girls in some settings. IPCC health assessment

·       Sexual violence and trafficking: Disaster conditions can heighten these risks for vulnerable people, alongside pre-existing inequalities and failures of protection. IPCC health assessment

·       Heat-related aggression and violence: Higher temperatures are associated with increased aggression and some violent-crime outcomes, without determining any individual’s behavior. IPCC health assessment

·       Civil unrest related to food insecurity: Sudden food-price shocks and livelihood losses can contribute to unrest where hunger, grievances, and political conditions make populations vulnerable. IPCC health assessment

·       Conflict risk amplification: Climate stress can contribute to instability or violent conflict in vulnerable contexts, but political, economic, and social conditions are central and climate does not determine war. IPCC health assessment

·       Strained social cohesion: Disaster losses, economic insecurity, and disrupted support systems can undermine collective well-being. WHO climate and health

 

Nature, culture, and quality of life

·       Loss of ecosystem support for people: Climate-related ecosystem changes can weaken food provision, water quality, coastal protection, and other services. IPCC impacts US climate assessment

·       Loss of coral-reef benefits: Reef degradation can harm fisheries, coastal protection, recreation, and community livelihoods. US climate assessment

·       Loss of traditional and subsistence foods: Species shifts and ecological decline can make culturally important food sources harder to access. US climate assessment

·       Damage to cultural and historical sites: Floods, erosion, fire, and other hazards threaten monuments, archaeological sites, burial grounds, and historic buildings. US climate assessment

·       Disrupted ceremonies and cultural practices: Heat and changing ecosystems can prevent activities tied to seasons, places, or species. US climate assessment

·       Loss of identity and belonging: Damage to homelands, familiar landscapes, and cultural practices can threaten connections to place. IPCC synthesis

·       Less outdoor recreation and play: Dangerous heat, smoke, altered snow cover, and damaged natural areas can restrict healthy and valued activities. US climate assessment

·       Threats to Indigenous knowledge and continuity: Loss of access to traditional lands, resources, and practices can make it harder to sustain and transmit place-based knowledge. US climate assessment

 

Compound, cascading, and longer-term risks

·       Heat–drought–fire combinations: Hazards occurring together can produce greater harm than each acting alone. IPCC synthesis

·       Compound coastal flooding: Sea-level rise, storm surge, and heavy rainfall can combine to overwhelm protection and drainage. IPCC impacts

·       Disaster–infrastructure–health cascades: One event can interrupt power, water, transport, and healthcare, multiplying harms beyond its immediate injuries. IPCC impacts

·       Food–income–health cascades: Lost harvests and heat-impaired labor can raise prices and cut income, worsening nutrition and mortality risks. IPCC synthesis

·       Cross-border transmission of harm: Trade and supply-chain connections can carry food, energy, and economic disruptions far from the original event. IPCC synthesis

·       Repeated shocks before recovery: Successive disasters can exhaust savings, emergency resources, and adaptive capacity. US climate assessment

·       Limits to adaptation: Some communities and ecosystems already encounter financial, institutional, or physical limits, and more warming can make protection less effective. IPCC synthesis

·       Less capacity to fund protection: Repeated climate losses can consume resources needed for future adaptation, particularly in poorer countries and communities. IPCC synthesis

·       Maladaptation and locked-in vulnerability: Poorly designed responses, such as inflexible infrastructure or water-intensive irrigation in drying regions, can worsen later risks or shift harm to others. IPCC synthesis

·       Long-lived and irreversible losses: Sea-level rise and some ecosystem changes can persist for centuries or longer, creating obligations and losses for future generations. IPCC synthesis

·       Abrupt Earth-system changes: Higher warming increases risks of abrupt or irreversible changes that could alter regional conditions and amplify human impacts; the timing and thresholds are uncertain, not established deadlines. IPCC synthesis