01 December, 2009

Climate change and global health security

Humans are today a major factor of global warming and climate change. Humans are also victims of radical environmental changes. Both statements are true and correlated. They mark the complex interactions between humans an the environment. The issue that most directly reflects these interactions is health.

Sergio Abranches

The world will have to manage an altered human health environment resulting from climate change, says an important report on the health effects of climate change issued by the medical journal The Lancet, and the University College of London Institute for Global Health Commission.

Effects of climate change on health will affect most populations in the next decades and put the lives and well-being of billions of people at increased risk.

Management of the health effects of climate change will require inputs from all sectors of government and civil society, collaboration between many academic disciplines, and new ways of international cooperation that have hitherto eluded us. Involvement of local communities in monitoring, discussing, advocating, and assisting with the process of adaptation will be crucial. An integrated and multidisciplinary approach to reduce the adverse health effects of climate change requires at least three levels of action. First, policies must be adopted to reduce carbon emissions and to increase carbon biosequestration, and thereby slow down global warming and eventually stabilize temperatures. Second, action should be taken on the events linking climate change to disease. Third, appropriate public health systems should be put into place to deal with adverse outcomes.

Many situations of high risk to human society also entail significant benefits from the endeavors to manage and prevent probable hazards. This is the case of health risks associated to climate change. Margaret Chan, director-general of the World Health Organization (WHO), tells how and why on her article for The Lancet commenting the results from the report “Managing the health effects of climate change”. Environmental events such as climate change are not quirks of nature, she argues.

Instead they are markers of massive failure in international systems that govern the way nations and their populations interact. The contagion of our mistakes shows no mercy and makes no exceptions on the basis of fair play. For example, countries that have contributed least to greenhouse-gas emissions will be the first and hardest hit by climate change.

Health consequences of climate change are no longer a matter of scientific uncertainty. They have been identified and their projections are anything but uncertain.

Several health consequences of a changing climate have been identified with a high degree of certainty. Malnutrition, and its devastating effects on child health, will increase. Worsening floods, droughts, and storms will cause more deaths and injuries. Heat waves will cause more deaths, largely among people who are elderly. Finally, climate change could alter the geographical distribution of disease vectors, including the insects that spread malaria and dengue. All these health problems are already huge, largely concentrated in the developing world, and difficult to control.

This correlation between climate change and collective health hazards calls for linking climate and health security goals globally.

Most of the mitigation measures for climate change investigated (including cleaner household-energy sources, less dependence on automobile transport, and reduced consumption of animal products in developed countries) would bring public health benefits. In many cases, these benefits are substantial, and would help to address some of the largest and fastest growing global health challenges and the greatest drains on health-sector resources, such as acute respiratory infections, cardiovascular disease, obesity, cancer, and diabetes. While the climatic effects of mitigation measures are long term and dispersed throughout the world, the health benefits are immediate and local, making them more attractive to politicians and the public.

Mitigation and its side benefits

As a political agreement on global climate policy seems now more likely to be reached in Copenhagen than it was a few weeks ago, we should start looking at the benefits of taking immediate action, and what to do to make it happen.

The issue now is not whether climate change is occurring, but how we can respond most effectively. The first steps are clear. In the short term, strengthening health systems, and widening coverage of proven and cheap public health interventions to control climate-sensitive diseases, would accelerate progress towards the health-related Millennium Development Goals and save millions of lives. In the long term, the same actions would also reduce vulnerability to climate change. Responding to climate change is not a distraction from the business of protecting health: it is part of the same agenda.

The Lancet has also published a series of articles dealing with the relationship between climate change and human health.

A group of academic and government health and energy specialists led by Paul Wilkinson of the London School of Hygiene and Tropical Medicine developed an interesting model to examine the possible health gains from reducing green-house gases emissions of household energy use. The model shows that mitigation strategies bring benefits to health for both high-income and low-income households.

The broad conclusion is clear—that in both high-income and low-income settings there is a set of abatement actions with appreciable potential overall benefits to health. In the contrasting examples we investigated, the health benefits seem especially great for the populations of India that rely on inefficient combustion of biomass fuels for household energy. Evidence from many studies shows that women, children, and men in such settings are exposed to very high concentrations of particles, gases, and other noxious pollutants that are often at least an order of magnitude higher than the health-protection values set by national and international agencies. Further, these populations might be especially vulnerable to the health consequences of breathing such pollution because of poor nutrition, poor access to health care, and other risk factors.

Climate change and urban transport

Health and transportation professionals used comparative risk assessment methods to estimate the health effects of alternative urban land transport scenarios for two settings—London, UK, and Delhi, India.

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.

Their conclusions are both far-reaching and clear. There are concrete advantages from linking policies addressing urban transportation hurdles to the reduction of GHG emissions. A climate change perspective enriches and strengthens urban policies. At the end of the day it yields direct health benefits to citizens and financial gains to households’ budgets and taxpayers.

Important health gains and reductions in CO2 emissions can be achieved through replacement of urban trips in private motor vehicles with active travel in high-income and middle-income countries. Technological measures to reduce vehicle pollutants might reduce emissions, but the health effect would be smaller. The combination of reduced reliance on motorized travel and substantial increases in active travel with vigorous implementation of low-emission technology offers the best outcomes in terms of climate change mitigation and public health. In many cities, the increase in use of cars, motorcycles, and HGVs, with the resulting increase in road danger has meant that many individuals who can afford to are changing to private motorized transport. An increase in the safety, convenience, and comfort of walking and cycling, and a reduction in the attractiveness of private motor vehicle use (speed, convenience, and cost) are essential to achieve the modal shifts envisaged here.

Low-carbon power

A study on low-carbon electricity and public health concludes that reduction of particle air pollution emissions from coal-fired power plants have highly positive effects on health in developed regions like the European Union, or emerging countries, such as China and India.

Changes in modes of production of electricity to reduce CO2 emissions would, in all regions, reduce PM2·5 and deaths 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 decarbonizing electricity production, and provide additional information about the extent of such gains.

The gains are greater, the more coal-intensive electricity generation is. But even “cleaner” fossil energy would have an incrementally positive effect on health.

This study indicates that some health benefits will result from changes in the means of electricity generation in response to a 50% CO2 reduction target by 2050. Estimates indicate savings in years of life that will be greatest in India, followed by China. If in 2030 changes were made that were consistent with the 2050 reduction targets, gains in India and China would be about 1500 and 500 life-years per million people, respectively. In the EU, the benefits are expected to be more modest, at around 100 life-years per million people in 2030. The modest improvement in Europe expected in a carbon-mitigated future compared with that in a business-as-usual future is mainly the result of the existence of already clean methods of electricity production from fossil fuels. These methods are projected to become cleaner in the business-as-usual setting. This is also the case, but to a lesser extent, in China.

The food system

What about land use change and agriculture? It is well known that the food system is a major contributor to global greenhouse-gas emissions, “from farming and its inputs through to food distribution, consumption, and the disposal of waste.” The major challenge would be to link improvements on agriculture with GHG emissions reductions and redirecting production to the provision of a balanced and healthier human diet.

We (…) 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. (…)

Inadequate policies, social inequality and a distorted structure of market incentives and disincentives lead to a pattern of food production and consumption that is unfit to human health. Correcting these factors would lead to both a cleaner food production system and greater supply of a more balanced diet.

[A] strategy to reduce production and consumption of foods from animal sources would help to prevent dangerous climate change from greenhouse-gas emissions and benefit the health of adults in countries consuming high amounts of animal products. (…) An important challenge in public health is to balance the need for adequate population intake of animal-source protein and essential nutrients with reduced consumption of saturated fat. Almost a billion people have protein-energy undernutrition, most of whom are also undernourished in micronutrients, especially iron and zinc. Adequate protein, energy, iron, and zinc can be obtained from a plant-based diet. However, the consumption of a small amount of animal-source foods per day in low-consumption populations could help to alleviate the burden of undernutrition. At present, agricultural production is mismatched with the provision of a diet that is balanced in terms of foods from plant and animal sources. Globally, production per head of energy, fats, proteins, and micronutrients has increased and is sufficient to meet global population needs, but the benefits have not been distributed evenly across countries and regions. A wide range of factors affect the supply and demand for animal-source foods; some policy levers offer potential approaches to change consumption patterns in populations.


Short-lived greenhouse pollutants emitted from fuel combustion account directly or indirectly for a large proportion of present global warming as well as for most of the direct damage to human health from energy use worldwide.

Short-lived greenhouse pollutants include gases such as the directly health-damaging carbon monoxide and non-methane volatile organic compounds, and others responsible for ozone creation in the lower atmosphere such as methane. Aerosols of short-lived greenhouse pollutants include sulphate, organic carbon, and black carbon particles, which have differing climate implications: the first two cooling, but the third strongly warming.

Short-lived greenhouse pollutants need to be controlled in addition to regulating carbon dioxide emissions because they collectively create a substantial proportion of all human-contributed global warming and directly damage health. Importantly, control of some short-lived greenhouse pollutants may lead to quick reductions in global warming.

An agenda for human advancement

This collection of papers together with the full report offer us a wealth of reasons to see cuts of carbon emissions as a developmental issue and not as a limiting factor to human well-being.

The finding of generally positive health effects of mitigation shows that strategies promoting a low greenhouse-gas emission economy can also have potential to improve public health. It also provides a rationale to reduce greenhouse-gas emissions that is not wholly confined to the achievement of climate change mitigation. Some commentators suggest that many features of climate change are now irreversible and that the most important objective is to try to adapt to it and other global environmental threats. However, the case for mitigation is greatly strengthened if it has direct collateral benefits in addition to restriction of climate change.

Mitigation strategies can be designed as development strategies. Investment in emissions reduction can also result in less expending in health and nutrition. Changing energy and transportation strategies should not be viewed as limits to growth, but rather as a contribution to better urban living, lower overall costs, and new opportunities for investment and employment.

If societies change their energy systems in ways that improve outdoor and indoor air quality, change their methods of transport in ways that encourage physical activity and social contact, and modify intensive food production practices and consumer choices in ways that reduce dietary risks to health, then many positive health consequences will result. Despite uncertainties about the magnitude and timescale, health co-benefits from mitigation can be anticipated. Therefore, commitment to mitigation actions producing many such benefits becomes very appealing, especially if (as is likely) the health gains entail substantial national cost savings as an offset to the costs of the mitigation actions. The strategic significance of this issue is potentially great. If the health co-benefits from mitigation activities in lower-income countries were sufficiently large, it would strengthen the rationale for achieving convergence of mitigation schedules between low-income and high-income countries.

These studies add strength to an argument I use to guide most of my writings on global warming: the climate change agenda is an agenda for real human progress. It should be, from now on, the guiding principle of every public and private policy-making agenda.

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