Strong action will save millions of lives, improve health of billions
“Climate change is the biggest global health threat of the 21st century.” So concluded a Lancet—UCL Commission earlier this year. Asystematic appraisal of available evidence showed that the risks from changing patterns of disease, food insecurity, unsafe water and sanitation, damage to human settlements, extreme events, and population growth and migration were far more severe for human health than most observers had understood. The message added an important new dimension to the political debate about how to respond to climate change. The threat was not only environmental and economic; it was directed at life itself.
So begins “The climate dividend,” a commentary on six new studies appearing in the Lancet medical journal (here). I had blogged on the earlier commission report here. Green Car Congress has a good story on the studies, noting that “a potential 150-million-stove program in India from 2010-2020 gives the largest co-benefit of any examined in the six papers.” By “providing low-emission stove technologies in poor countries that currently rely on solid fuel household stoves to cook and heat their homes,” the “10-year program could prevent 2 million premature deaths in India” while reducing greenhouse pollution by hundreds of millions of tons.
One of the papers “contains analysis of 18 years of data on the long-term health effects of black carbon—the first study of its kind ever conducted. The study followed 352,000 people in 66 US cities.” Black carbon is a major GHG pollutant. Kirk R. Smith, professor of global environmental health at UC Berkeley and lead author of the paper, said:
Combustion-related air pollution is estimated to be responsible for nearly 2.5 million premature deaths annually around the world and also for a significant portion of greenhouse warming. These studies provide the kind of concrete information needed to choose actions that efficiently reduce this health burden as well as reduce the threat of climate change.
The evidence is now in: The bipartisan climate and clean energy bill — and an international agreement coming out of Copenhagen — will save millions of lives and improve the health of billions of people over the course of this century.
Let’s look at the summaries of these six important studies:
1. Public health benefits of strategies to reduce greenhouse-gas emissions: household energy
Energy used in dwellings is an important target for actions to avert climate change. Properly designed and implemented, such actions could have major co-benefits for public health. To investigate, we examined the effect of hypothetical strategies to improve energy efficiency in UK housing stock and to introduce 150 million low-emission household cookstoves in India. Methods similar to those of WHO’s Comparative Risk Assessment exercise were applied to assess the effect on health that changes in the indoor environment could have. For UK housing, the magnitude and even direction of the changes in health depended on details of the intervention, but interventions were generally beneficial for health. For a strategy of combined fabric, ventilation, fuel switching, and behavioural changes, we estimated 850 fewer disability-adjusted life-years (DALYs), and a saving of 0·6 megatonnes of carbon dioxide (CO2), per million population in 1 year (on the basis of calculations comparing the health of the 2010 population with and without the specified outcome measures). The cookstove programme in India showed substantial benefits for acute lower respiratory infection in children, chronic obstructive pulmonary disease, and ischaemic heart disease. Calculated on a similar basis to the UK case study, the avoided burden of these outcomes was estimated to be 12 500 fewer DALYs and a saving of 0·1—0·2 megatonnes CO2-equivalent per million population in 1 year, mostly in short-lived greenhouse pollutants. Household energy interventions have potential for important co-benefits in pursuit of health and climate goals.
2. Public health benefits of strategies to reduce greenhouse-gas emissions: urban land transport
We used Comparative Risk Assessment methods to estimate the health effects of alternative urban land transport scenarios for two settings—London, UK, and Delhi, India. For each setting, we compared a business-as-usual 2030 projection (without policies for reduction of greenhouse gases) with alternative scenarios—lower-carbon-emission motor vehicles, increased active travel, and a combination of the two. We developed separate models that linked transport scenarios with physical activity, air pollution, and risk of road traffic injury. In both cities, we noted that reduction in carbon dioxide emissions through an increase in active travel and less use of motor vehicles had larger health benefits per million population (7332 disability-adjusted life-years [DALYs] in London, and 12 516 in Delhi in 1 year) than from the increased use of lower-emission motor vehicles (160 DALYs in London, and 1696 in Delhi). However, combination of active travel and lower-emission motor vehicles would give the largest benefits (7439 DALYs in London, 12 995 in Delhi), notably from a reduction in the number of years of life lost from ischaemic heart disease (10—19% in London, 11—25% in Delhi). Although uncertainties remain, climate change mitigation in transport should benefit public health substantially. Policies to increase the acceptability, appeal, and safety of active urban travel, and discourage travel in private motor vehicles would provide larger health benefits than would policies that focus solely on lower-emission motor vehicles.
3. Public health benefits of strategies to reduce greenhouse-gas emissions: low-carbon electricity generation
In this report, the third in this Series on health and climate change, we assess the changes in particle air pollution emissions and consequent effects on health that are likely to result from greenhouse-gas mitigation measures in the electricity generation sector in the European Union (EU), China, and India. We model the effect in 2030 of policies that aim to reduce total carbon dioxide (CO2) emissions by 50% by 2050 globally compared with the effect of emissions in 1990. We use three models: the POLES model, which identifies the distribution of production modes that give the desired CO2 reductions and associated costs; the GAINS model, which estimates fine particulate matter with aerodynamic diameter 2·5 μm or less (PM2·5) concentrations; and a model to estimate the effect of PM2·5 on mortality on the basis of the WHO’s Comparative Risk Assessment methods. Changes in modes of production of electricity to reduce CO2 emissions would, in all regions, reduce PM2·5 and deat
hs caused by it, with the greatest effect in India and the smallest in the EU. Health benefits greatly offset costs of greenhouse-gas mitigation, especially in India where pollution is high and costs of mitigation are low. Our estimates are approximations but suggest clear health gains (co-benefits) through decarbonising electricity production, and provide additional information about the extent of such gains.
4. Public health benefits of strategies to reduce greenhouse-gas emissions: food and agriculture
Agricultural food production and agriculturally-related change in land use substantially contribute to greenhouse-gas emissions worldwide. Four-fifths of agricultural emissions arise from the livestock sector. Although livestock products are a source of some essential nutrients, they provide large amounts of saturated fat, which is a known risk factor for cardiovascular disease. We considered potential strategies for the agricultural sector to meet the target recommended by the UK Committee on Climate Change to reduce UK emissions from the concentrations recorded in 1990 by 80% by 2050, which would require a 50% reduction by 2030. With use of the UK as a case study, we identified that a combination of agricultural technological improvements and a 30% reduction in livestock production would be needed to meet this target; in the absence of good emissions data from Brazil, we assumed for illustrative purposes that the required reductions would be the same for our second case study in São Paulo city. We then used these data to model the potential benefits of reduced consumption of livestock products on the burden of ischaemic heart disease: disease burden would decrease by about 15% in the UK (equivalent to 2850 disability-adjusted life-years [DALYs] per million population in 1 year) and 16% in São Paulo city (equivalent to 2180 DALYs per million population in 1 year). Although likely to yield benefits to health, such a strategy will probably encounter cultural, political, and commercial resistance, and face technical challenges. Coordinated intersectoral action is needed across agricultural, nutritional, public health, and climate change communities worldwide to provide affordable, healthy, low-emission diets for all societies.
5. Public health benefits of strategies to reduce greenhouse-gas emissions: health implications of short-lived greenhouse pollutants
In this report we review the health effects of three short-lived greenhouse pollutants—black carbon, ozone, and sulphates. We undertook new meta-analyses of existing time-series studies and an analysis of a cohort of 352 000 people in 66 US cities during 18 years of follow-up. This cohort study provides estimates of mortality effects from long-term exposure to elemental carbon, an indicator of black carbon mass, and evidence that ozone exerts an independent risk of mortality. Associations among these pollutants make drawing conclusions about their individual health effects difficult at present, but sulphate seems to have the most robust effects in multiple-pollutant models. Generally, the toxicology of the pure compounds and their epidemiology diverge because atmospheric black carbon, ozone, and sulphate are associated and could interact with related toxic species. Although sulphate is a cooling agent, black carbon and ozone could together exert nearly half as much global warming as carbon dioxide. The complexity of these health and climate effects needs to be recognised in mitigation policies.
6. Public health benefits of strategies to reduce greenhouse-gas emissions: overview and implications for policy makers
This Series has examined the health implications of policies aimed at tackling climate change. Assessments of mitigation strategies in four domains—household energy, transport, food and agriculture, and electricity generation—suggest an important message: that actions to reduce greenhouse-gas emissions often, although not always, entail net benefits for health. In some cases, the potential benefits seem to be substantial. This evidence provides an additional and immediate rationale for reductions in greenhouse-gas emissions beyond that of climate change mitigation alone. Climate change is an increasing and evolving threat to the health of populations worldwide. At the same time, major public health burdens remain in many regions. Climate change therefore adds further urgency to the task of addressing international health priorities, such as the UN Millennium Development Goals. Recognition that mitigation strategies can have substantial benefits for both health and climate protection offers the possibility of policy choices that are potentially both more cost effective and socially attractive than are those that address these priorities independently.
Kudos to The Lancet for this important work.
The time to act is now — the health and well-being of current and future generations depends on it.
The photo is of air pollution in Tehran, Hamid Najafi via flickr via Treehugger.
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