Discuss climate change and its effects on health.

Climate Change and Health

• The mechanism — carbon dioxide, methane, nitrous oxide and halocarbons trap outgoing infrared radiation, producing the greenhouse effect and a rise in global mean temperature
• The greenhouse effect itself is natural and necessary — without it the earth would be far too cold; the problem is its enhancement by human emissions, a distinction worth making precisely
• The health effects should be organised as direct, ecologically mediated and socially mediated, since a list alone conveys little:
• Direct effects — heat waves causing heat stroke, dehydration and excess mortality, particularly among the elderly, outdoor workers and those with chronic disease; increased floods, cyclones and storms with drowning, injury and displacement; drought; and forest fires and their smoke
• India’s exposure to heat is particularly severe, since a large part of the workforce is engaged in outdoor manual labour — agriculture and construction — where work cannot simply be moved indoors
• The combination of high temperature with high humidity is what kills, since sweat cannot evaporate and the body loses its principal means of cooling — which is why the wet-bulb temperature matters more than the dry-bulb reading
• Ecologically mediated effects — changes in vector distribution, with malaria and dengue extending to higher altitudes and latitudes and lengthening their transmission seasons; increased water-borne disease after floods and where water supplies fail; reduced crop yields and reduced nutritional content of staple grains under higher carbon dioxide; fisheries decline; and increased aeroallergens and longer pollen seasons
• Socially mediated effects — food and water insecurity and malnutrition; displacement and migration; conflict over resources; loss of livelihood, particularly for farmers; and mental health effects, including the distress following crop failure and displacement
• The equity dimension must be stated, because it is the moral centre of the topic — the countries and people who have contributed least to emissions suffer the greatest harm and have the least capacity to adapt
• Within India the same applies — the poor, outdoor workers, slum dwellers, coastal and drought-prone populations, women, children and the elderly bear the burden
• The response has two arms, and both are needed:
• Mitigation — reducing emissions, through renewable energy, energy efficiency, cleaner transport, reduced deforestation and changes in agriculture and diet
• Adaptation — reducing the harm from changes that are already unavoidable, through heat action plans with early warning and cool shelters; strengthened disease surveillance for vector-borne disease; climate-resilient water and sanitation; disaster preparedness; crop diversification and drought-resistant varieties; and climate-resilient health facilities
• The concept of CO-benefits is what makes this a persuasive public health argument rather than only an environmental one
• Many mitigation measures improve health immediately and locally, independent of any effect on the climate:
• Reducing fossil fuel use reduces air pollution and the cardiovascular and respiratory deaths it causes
• Active transport — walking and cycling — reduces obesity, diabetes and heart disease
• A diet with less red meat and more plants reduces colorectal cancer and cardiovascular disease
• Clean cooking fuel reduces indoor air pollution, COPD and childhood pneumonia
• Green space improves mental health and physical activity and reduces urban heat
• These benefits accrue now and to the same population that bears the cost, which answers the usual objection that mitigation means present sacrifice for distant and uncertain gain
• The frameworks — the PARIS agreement; India’s national action plan on climate change with its missions; and the national programme on climate change and human health, which builds health-sector capacity for surveillance, heat action plans and awareness
• The role of the health sector itself — surveillance and early warning; preparedness; advocacy, since health arguments are more persuasive than abstract environmental ones; and reducing its own considerable carbon footprint
• Co-benefits accrue now and locally, which answers the objection that mitigation trades present cost for distant gain
• Wet-bulb temperature is what kills, since humidity prevents sweat evaporating and removes the body cooling mechanism
• Indian outdoor workers cannot move inside, which makes heat a livelihood problem as well as a medical one
• Those least responsible suffer most, which is the equity dimension and the moral centre of the topic
• The greenhouse effect is natural and necessary; the problem is its enhancement by human emissions
• Vectors extend to higher altitudes and latitudes, lengthening transmission seasons for malaria and dengue
• Higher carbon dioxide lowers grain nutrient content, which is a less obvious route from climate to malnutrition
• Mitigation and adaptation are both required, since some change is already unavoidable whatever is done now
• Heat action plans use early warning and shelters, and are already implemented in several Indian cities
• Health arguments persuade where environmental ones do not, which is the specific role of the health sector in advocacy
• Crop failure causes mental illness and suicide, which is a socially mediated effect that mortality data attribute elsewhere