Editing IPCC:AR6/WGII/Chapter-7 (section)

=== 7.2.3 Observed Impacts on Non-communicable Diseases ===

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NCDs are those that are not directly transmitted from one person to another person; they impose the largest disease burden globally. NCDs constitute approximately 80% of the burden of disease in high-income countries; the NCD burden is lower in low- and middle-income countries but are expected to rise ( [[#Bollyky--2017|Bollyky et al., 2017]] ). NCDs constitute a large group of diseases driven principally by environmental, lifestyle and other factors; those identified as being climate sensitive include non-infectious respiratory disease, cardiovascular disease (CVD), cancer and endocrine diseases including diabetes. Additionally, there are potential interactions between multiple climate-sensitive NCDs and food security, nutrition and mental health. The literature on climate change and NCDs continues to develop. More recently, scientists have identified key gaps in the calculation of the global burden of disease due to environmental health factors ( [[#Shaffer--2019|Shaffer et al., 2019]] ).

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==== 7.2.3.1 Cardiovascular Diseases ====

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CVDs are a group of disorders of the heart and blood vessels that include coronary heart disease, cerebrovascular disease, peripheral arterial disease, rheumatic heart disease, congenital heart disease, deep vein thrombosis and pulmonary embolism. CVDs are the leading cause of death globally and over three quarters of the world’s CVD deaths now occur in low- and middle-income countries ( [[#Roth--2020|Roth et al., 2020]] ).

''Climate change affects the risk of CVD through high temperatures and extreme heat (assessed in [[#7.2.4.1|Section 7.2.4.1]] ) and through other mechanisms (medium confidence), though the degree to which non-temperature risks may increase remains unclear.'' For example, exposure to air pollutants including PM, ozone (via its precursors), black carbon, oxides of nitrogen, oxides of sulphur, hydrocarbons and metals can invoke pro-inflammatory and prothrombotic states, endothelial dysfunction and hypertensive responses ( [[#Giorgini--2017|Giorgini et al., 2017]] ; [[#Stewart--2017|Stewart et al., 2017]] ). Winter peaks in CVD events, associated with greater concentrations of air pollutants, have been reported in a range of countries and climates ( [[#Claeys--2017|Claeys et al., 2017]] ; [[#Stewart--2017|Stewart et al., 2017]] ); however, the association between air pollution, weather and CVD events is complex and seems to differ between cold and warm months, particularly for gaseous pollutants such as ozone ( [[#Shi--2020|Shi et al., 2020]] ).

Climate change is projected to increase the number and severity of wildfires ( [[#Liu--2015b|Liu et al., 2015b]] ; [[#Youssouf--2014|Youssouf et al., 2014]] ) and the evidence for wildfire smoke-related CVD morbidity and mortality is suggestive of increased CVD morbidity and mortality risk ( [[#Chen--2021a|Chen et al., 2021a]] ) including significant increases in certain cardiovascular outcomes (e.g., cardiac arrests) ( [[#Dennekamp--2015|Dennekamp et al., 2015]] ). CVD risks to highly exposed populations, such as firefighters, are clearer ( [[#Navarro--2019|Navarro et al., 2019]] ) and could increase with additional exposure driven by climate change.

Other climate-related mechanisms that may increase CVD risk include reductions in physical activity related to hot weather ( [[#Obradovich--2017|Obradovich et al., 2017]] ), sleep disturbance ( [[#Obradovich--2017|Obradovich et al., 2017]] ) and dehydration ( [[#Lim--2015|Lim et al., 2015]] ; [[#Frumkin--2019|Frumkin and Haines, 2019]] ). There is little literature on how changes in winter weather may affect these risks. Saline intrusion of groundwater related to sea level rise ( [[#Taylor--2012|Taylor et al., 2012]] ) may increase the salt intake of affected populations, a risk factor for hypertension that has been observed to increase blood pressure in exposed populations ( [[#Talukder--2017|Talukder et al., 2017]] ; Al [[#Nahian--2018|Nahian et al., 2018]] ).

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==== 7.2.3.2 Non-communicable Respiratory Diseases ====

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Lung diseases, including asthma, COPD and lung cancer, comprise the largest subsets of non-communicable pulmonary disease ( [[#Ferkol--2014|Ferkol and Schraufnagel, 2014]] ). Overall, the global burden of non-communicable lung disease including all chronic lung disease and lung cancer is substantial, being responsible for 10.6% of deaths and 5.9% of DALYs globally in 2019 (Vos et al., 2020).

''Several non-communicable respiratory diseases are climate sensitive based on their exposure pathways (very high confidence).'' Multiple exposure pathways contribute to non-communicable respiratory disease ( [[#Deng--2020|Deng et al., 2020]] ), some of which are climate-related ( [[#Rice--2014|Rice et al., 2014]] ), including mobilisation and transport of dust ( [[#Schweitzer--2018|Schweitzer et al., 2018]] ); changes in concentrations of air pollutants such as small particulates (PM2.5) and ozone formed by photochemical reactions sensitive to temperature ( [[#Hansel--2016|Hansel et al., 2016]] ); increased wildland fires and related smoke exposure ( [[#Johnston--2002|Johnston et al., 2002]] ; [[#Reid--2016|Reid et al., 2016]] ); increased exposure to ambient heat driving reduced lung function and exacerbations of chronic lung disease ( [[#Collaco--2018|Collaco et al., 2018]] ; [[#Jehn--2013|Jehn et al., 2013]] ; [[#McCormack--2016|McCormack et al., 2016]] ; [[#Witt--2015|Witt et al., 2015]] ) and modification of aeroallergen production and duration of exposure ( [[#Ziska--2019|Ziska et al., 2019]] ).

''Burdens of allergic disease, particularly allergic rhinitis and allergic asthma may be changing in response to climate change (medium confidence)'' ( [[#D’Amato--2020|D’Amato et al., 2020]] ; [[#Eguiluz-Gracia--2020|Eguiluz-Gracia et al., 2020]] ; [[#Deng--2020|Deng et al., 2020]] ; [[#Demain--2018|Demain, 2018]] ). This is supported by evidence showing an increase in the length of the North American pollen season attributable to climate change ( [[#Ziska--2019|Ziska et al., 2019]] ), an association between timing of spring onset and higher asthma hospitalisations presumed to be due to higher pollen exposure ( [[#Sapkota--2020|Sapkota et al., 2020]] ) and other evidence linking aeroallergen exposure with a worsening burden of allergic disease ( [[#Demain--2018|Demain, 2018]] ; [[#Poole--2019|Poole et al., 2019]] ).

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==== 7.2.3.3 Cancer ====

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''Climate change is'' likely ''to increase the risk of several malignancies (high confidence), though the degree to which risks may increase remains unclear.'' Cancers, also known as malignant neoplasms, include a heterogeneous collection of diseases with various causal pathways, many with environmental influences. Malignant neoplasms impose a substantial burden of disease globally and are responsible for slightly more than 10 million deaths and 251 million DALYs globally in 2019 (Vos et al., 2020). Climatic hazards affect exposure pathways for several different chemical hazards associated with carcinogenesis ( [[#Portier--2010|Portier et al., 2010]] ). Most relevant literature has focused on elaborating potential pathways and producing qualitative or quantitative estimates of effect, though there is limited literature on current and projected impacts.

The vast majority of elaborated pathways point to increased risk; for example, there is concern that climate change may alter the fate and transport of carcinogenic polyaromatic hydrocarbons ( [[#Domínguez-Morueco--2019|Domínguez-Morueco et al., 2019]] ) and increase mobilisation of carcinogens such as bromide ( [[#Regli--2015|Regli et al., 2015]] ), persistent organic pollutants (POPs) including polychlorinated-biphenyls that have accumulated in areas contaminated by industrial runoff ( [[#Miner--2018|Miner et al., 2018]] ) and radioactive material ( [[#Evangeliou--2014|Evangeliou et al., 2014]] ). Exposure to these known carcinogens can occur through multiple environmental media and can be increased by climate change, for example through increased flooding related to extreme precipitation events and mobilisation of sediment where carcinogens have accumulated ( [[#León--2017|León et al., 2017]] ; [[#Santiago--2012|Santiago and Rivas, 2012]] ). In addition, there is concern that changes in ultraviolet light exposure related to shifts in precipitation may increase the incidence of malignant melanoma, particularly for outdoor workers ( [[#Modenese--2018|Modenese et al., 2018]] ). Other harmful pathways include migration of and increased exposure to liver flukes, which cause hepatobiliary cancer ( [[#Prueksapanich--2018|Prueksapanich et al., 2018]] ) and the introduction of infectious diseases such as schistosomiasis that increase cancer risk due to climate-related migration ( [[#Ahmed--2014|Ahmed et al., 2014]] ). Increased exposure to carcinogenic toxins via multiple pathways is also a concern. Aflatoxin exposure, for example, is expected to increase in Europe ( [[#Moretti--2019|Moretti et al., 2019]] ), India ( [[#Shekhar--2018|Shekhar et al., 2018]] ), Africa ( [[#Gnonlonfin--2013|Gnonlonfin et al., 2013]] ; [[#Bandyopadhyay--2016|Bandyopadhyay et al., 2016]] ) and North America ( [[#Wu--2011|Wu et al., 2011]] ). Other carcinogenic toxins originate from cyanobacteria blooms ( [[#Lee--2017a|Lee et al., 2017a]] ), which are projected to increase in frequency and distribution with climate change ( [[#Wells--2015|Wells et al., 2015]] ; [[#Paerl--2016|Paerl et al., 2016]] ; [[#Chapra--2017|Chapra et al., 2017]] ).

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==== 7.2.3.4 Diabetes ====

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''Individuals suffering from diabetes are at higher risk of heat-related illness and death (medium confidence).'' Extreme weather events and rising temperatures have been found to increase morbidity and mortality in patients living with diabetes, especially in those with cardiovascular complications ( [[#Méndez-Lázaro--2018|Méndez-Lázaro et al., 2018]] ; [[#Zilbermint--2020|Zilbermint, 2020]] ; [[#Hajat--2017|Hajat et al., 2017]] ). Evidence suggests that the local heat loss response of skin blood flow is affected by diabetes-related impairments, resulting in lower elevations in skin blood flow in response to a heat or pharmacological stimulus. Thermoregulatory sweating may also be diminished by type-2 diabetes, impairing the body’s ability to transfer heat from its core to the environment ( [[#Xu--2019b|Xu et al., 2019b]] ). Higher rates of doctor consultations by patients with type-2 diabetes and diabetics with cardiovascular comorbidities have been observed during hot days, but without evidence of heightened risk of renal failure or neuropathy comorbidities ( [[#Xu--2019b|Xu et al., 2019b]] ).

''People with chronic illnesses are at particular risk during and after extreme weather events due to treatment interruptions and lack of access to medication (medium confidence).'' The impacts of extreme weather events on the health of chronically ill people are due to a range of factors including disruption of transport, weakened health systems including drug supply chains, loss of power and evacuations of populations ( [[#Ryan--2015a|Ryan et al., 2015a]] ). Evacuations also pose specific health risks to older adults (especially those who are frail, medically incapacitated or residing in nursing or assisted living facilities) and may be complicated by the need for concurrent transfer of medical records, medications and medical equipment ( [[#Becquart--2018|Becquart et al., 2018]] ; [[#Quast--2019|Quast and Feng, 2019]] ; US Global Change Research Program, 2016). Emergency room visits after Hurricane Sandy rose among individuals with type-2 diabetes ( [[#Velez-Valle--2016|Velez-Valle et al., 2016]] ).

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