Table 1

Summary of findings from systematic reviews according to health outcome and climate impact

Climate impactnSummary of findings
Infectious diseases (n=41)
Vector-borne infectious diseases (n=25)
Meteorological22Systematic reviews suggest that meteorological factors, such as temperature, precipitation, humidity, and wind, are associated with diverse vector-borne infectious diseases, including malaria and dengue.9 12 26 29 31 47–63 This association was mostly proportional (eg, higher temperature and increased rainfall associated with vector-borne diseases), although findings were at times conflicting, with some suggesting an inversely proportional association12 (eg, decreased rainfall) or no association at all52 (eg, with the human puumala hantavirus Infection.) Geographical location, seasonality and potential interaction with other climate-related factors may partly explain these inconsistencies.12 29 Temperature, humidity and rainfall were the most common and important meteorological factors reported by reviews and factors such as wind, air pressure and sunshine were reported less often.
Extreme weather7There are limited and conflicting findings concerning the association of extreme weather events with vector-borne diseases. Some reviews suggest water-related extreme events64 and flooding6 31 65 are associated with an increased risk of vector-borne diseases, while drought is associated with a reduction of dengue incidence.12 Other reviews focused specifically on Puerto Rico56 and Australia66 did not find an association between hurricanes and/or floods and mosquito-borne disease transmission.
Food and water borne infectious diseases (n=19)
Meteorological14Reviews suggest that meteorological factors, such as temperature, precipitation and humidity, are associated with diverse food-borne and water-borne infectious diseases, in particular, cholera, schistosomiasis, salmonella and E. coli gastroenteritis.11 31 53 55 58 61 67–74 Overall, higher temperatures and humidity,11 53 67 71 along with lower precipitation55 74 was associated with these infectious diseases. Directionality and strength of the association seemed to vary according to disease and pathogens,72 seasons and geographical region.69
Extreme weather10Reviews suggest a proportional association between extreme water-related events,60 64 75 such as flooding6 53 65 and heavy rainfall,47 and food-borne and water-borne diseases, including diarrhoea, food contamination, cholera.6 31 47 53 58 60 64 65 70 75 Drought may also be proportionally associated with food-borne and water-borne disease,47 76 but these associations are less consistent than those with water-related extreme events.70
Other infectious diseases (n=8)
Meteorological8Reviews suggest an association of most meteorological factors, such as temperature and humidity, with various other infectious diseases, including meningitis,24 47 Ebola,24 influenza,31 and paediatric infectious diseases such as hand-foot-and-mouth disease.7 8 30 62 68 This association was mostly proportional for meteorological factors such as temperature,7 8 62 diurnal temperature range30 and humidity,7 8 31 although some meteorological factors, such as air pressure8 and lower temperatures31 62 were inversely proportional to these diseases. Some conflicting evidence is reported concerning the association with some meteorological factors, such as sunshine with hand-foot-and-mouth disease,7 8 and humidity and paediatric infectious diseases.68 No association was found between some meteorological factors, such as precipitation, wind speed and sunshine with hand-foot-and-mouth disease.7 8
Mortality (n=32)
Meteorological24Reviews suggest that temperature (high, low, or diurnal range) was consistently associated with all-cause and cause-specific mortality.24–26 30 33 34 55 58 60 62 77–89 A strong association was reported between heat (including heat waves) and mortality (all-cause),77 heat related,55 81 stroke related,24 82 cardiovascular related,33 60 and respiratory related,26 33 83 especially in rural,80 very young children62 and ageing populations.25 Mortality seems to be the most frequent health outcome studied in association with heatwaves.34 Inconsistent results are found concerning the association between heat and childhood mortality.87 Due to limited evidence, this association was weaker in some geographical regions.24 84 Also, heat wave intensity (compared with duration) was more strongly associated with heat-related mortality.88 Finally, although less studied, low temperature was also associated with mortality,62 89 specifically respiratory,77 stroke82 and cardiovascular mortality.60 79 83
Extreme weather5Reviews suggest an association between extreme weather events such as floods,6 droughts,76 cyclones90 and other water-related events,26 64 with direct (eg, drowning) and indirect long-term mortality (eg, due to malnutrition, environmental toxin exposure, armed conflict, etc).6 64 76 90
Air quality5Reviews suggest an association between exposure to air pollution26 91 or wildfire smoke92–94 and air pollution related-mortality, such as respiratory-specific mortality. There is currently limited evidence, but reviews suggest a potential association between wildfire smoke exposure and cardiovascular-specific mortality.92–94
Respiratory, neurological and cardiovascular (n=23)
General1A review suggests a proportional association between climate change, in general, and ragweed pollen allergies in Europe.95
Meteorological17Reviews suggest an association between meteorological factors, such as temperature and humidity, and cardiovascular, respiratory and neurological outcomes.24 26 30 33 35 49 58 62 68 77 79 81 82 86 87 96 97 Exposure to high temperatures and extreme heat are associated to cardiovascular and respiratory diseases,24 26 49 62 79 stroke,82 long-term neurological outcomes (due to heat strokes),81 myocardial infarction,33 35 and childhood asthma and paediatric respiratory diseases.87 97 A review also suggests a beneficial association between heat and the shortening of a respiratory virus season.58 Exposure to low temperature (cold), temperature drop, or diurnal temperature range was associated with cardiovascular and respiratory diseases,30 77 79 stroke,82 and myocardial infarctions.33 Humidity (most often high humidity, but also lower humidity) and low temperatures were also associated with respiratory diseases in children, including childhood asthma.68 96 97
Extreme weather1A previous review suggests an association between drought and respiratory and cardiovascular outcomes, most likely due to droughts leading to increased dust in the air.76
Air quality6Reviews suggest a proportional association between exposure to air pollution26 55 58 or wildfire smoke exposure92–94 and respiratory outcomes, including asthma, chronic obstructive pulmonary disease, coughing, wheezing and overall lung function. Although there is currently limited evidence,92 reviews also suggest a potential association between air pollution or wildfire smoke exposure and cardiovascular outcomes.58 93 94
Health systems (n=16)
General1A previous review suggests that climate change in general puts a strain on public health resources, via population health issues and shows that using an integrated surveillance system may guide future adaptation to climate change.98
Meteorological11Previous reviews suggest an association between temperature change30 extreme heat, aridity and cold temperatures and an increase in use of healthcare services (mostly linked to heat-related health impacts), such as an increase in emergency department visits, hospital admissions and use of ambulances.24 26 30 33–35 55 62 84 87 99
Extreme weather2Reviews suggest that extreme weather events32 and flooding6 may be associated with an increase in use of healthcare services (eg, increased hospitalisations) and a compromised quality of care as extreme weather events may lead to power outages.32
Air quality2Reviews suggest an association between wildfire smoke exposure and an increase in use of healthcare services, such as an increase in emergency department visits.92 94
Mental health (n=13)
Meteorological3Reviews suggest an association of most meteorological factors such as temperature increase, aridity, heat and heat waves with mental health outcomes, including hospital admissions for mental health reasons,55 suicide,100 and exacerbation of pre-existing mental health conditions, difficulty sleeping and fatigue.35 No association was found between sunlight duration and suicide incidence.100
Extreme weather9Most reviews reported a proportional association of extreme weather events,36 58 64 101 flooding6 26 102 and drought76 103 with diverse mental health issues, including, psychological distress, post-traumatic stress disorder, anxiety, depression, psychotropic medication use, alcohol consumption. There was conflicting evidence regarding the association of floods with suicide, tobacco, alcohol and substance abuse.102 No association was found between drought and suicide.76
Air quality1A previous review suggests no association between wildfire smoke exposure and mental health, as measured by physician visits and hospitalizations for mental health reasons during wildfires.93
Pregnancy and birth outcomes (n=11)
Meteorological5Reviews suggest that adverse birth outcomes may be higher among people exposed to meteorological factors such as high temperature, heat, sunlight intensity, cold and humidity.55 104–107 These outcomes include low birth weight, preterm birth, eclampsia and preeclampsia, hypertension and length of pregnancy.55 104–107 The association between heat and adverse birth outcomes seems to have stronger support than the association with cold temperatures.107
Extreme Weather2Reviews suggest a potential association of extreme weather events36 and flooding6 with adverse birth outcomes, such as low birth weight, preterm birth and preeclampsia. It is suggested that extreme weather events may indirectly affect birth outcomes via the pregnant person’s well-being (eg, stress and worry during pregnancy.)6 36
Air quality3There is limited and inconsistent evidence concerning the association between wildfire smoke exposure and adverse birth outcomes, but reviews suggest a potential proportional association between wildfire smoke exposure and lower birth weight.92–94
Other1The association between environmental pollutants and adverse birth outcomes (ie, preterm birth) remains unclear due to conflicting evidence.28
Nutritional (n=9)
General1A review suggests an association between climate change and obesity.108
Meteorological4Reviews suggest an association between meteorological factors, such as changes in temperature, heat and precipitation, with diverse nutritional outcomes, including undernutrition, malnutrition and child stunting.24 27 55 84 This association may be explained by the impact of meteorological factors, such as temperature increase and precipitation decrease, on crop production and food insecurity.55 84
Extreme Weather6Reviews suggest an association between extreme weather events, such as flooding and droughts,76 and diverse nutritional outcomes, including malnutrition and undernutrition in children and adults27 47 55 58 60 via, among others, crops production and food insecurity (eg, low food aid following flooding.55
Other1A review suggests a potential association between certain environmental risk factors (eg, sanitation, cooking fuels and food-borne mycotoxins), and childhood stunting, which could be aggravated by climate change.109
Skin diseases and allergies (n=8)
General1A review suggests a potential proportional association between climate change, in general, and skin and soft-tissue infections (eg, fatal vibrio vulnificus necrotising).110
Meteorological7Reviews suggest an association of meteorological factors, such as ultraviolet light exposure, temperature and humidity, with diverse skin diseases and allergies, including skin cancer, sunburn, acute urticaria, eczema and paediatric skin irritabilities.24 35 58 60 62 68 111 Higher temperature and ultraviolet light exposure is proportionally associated with sunburn35 and skin cancer,58 111 while low humidity and low temperatures were associated with eczema and skin irritabilities in children.62 68
Occupational health and injuries (n=6)
Meteorological6Reviews suggest that heat is associated with adverse occupational health outcomes, including injuries (eg, slips, trips, falls, wounds, lacerations and amputations), heat strain, dehydration and kidney diseases.103 112–117 This association was found in many occupational settings, including agriculture, construction, transport and fishing, and seems to affect both outdoor and indoor workers.112 This association may be explained by a combination of direct (eg, dehydration) and indirect factors (eg, impaired cognitive and physical performance.)116
Other1A review suggests a potential association between environmental pollution (eg, heavy metals, fertilisers, etc) and occupational diseases, such as chronic kidney disease.117 This association is suggested to be affected by increasing temperatures.
Other (n=17)
General1A review suggests a potential association between climate change in general and disability-adjusted life years, which is an indicator that quantifies ‘the burden of disease attributable to climate change’.118 Authors suggest that the cost of disability-adjusted life years could be high, especially in low-income to middle-income countries.
Meteorological10Reviews suggests an association between increasing temperatures and temperature changes,30 and other various health outcomes, including acute gouty arthritis,119 unintentional injuries,120 diabetes,77 genitourinary diseases,30 77 impaired sleep time and quality,121 cataracts (indirectly associated via people spending more time outside and therefore increased exposure to ultraviolet light),58 60 heat stress, heat exhaustion and kidney failure,35 and renal diseases, fever and electrolyte imbalance in children.62 87
Extreme weather6Reviews suggests an association between extreme weather events,101 such as flooding,6 cyclones,90 hurricanes121 and drought,76 and other various health outcomes including injuries (eg, debris, diving in water that is shallower than expected),6 76 90 101 impaired sleep,121 oesophageal cancer (likely linked to high salinity of water due to droughts),76 and exacerbation of chronic illnesses.6 36
Air quality1There is limited evidence, but a systematic review suggests a potential association between wildfire smoke exposure and ophthalmic outcomes, such as eye irritation and cataracts.92

  • Reviews that covered multiple climate impacts are listed in each relevant category.