Managing the health effects of climate change. Lancet and University College London Institute for Global Health Commission

Climate change is the biggest global health threat of the 21st century: Effects of climate change on health will affect most populations in the next decades and put the lives and wellbeing of billions of people at increased risk. During this century, earth's average surface temperature rises are likely to exceed the safe threshold of 2°C above preindustrial average temperature. Rises will be greater at higher latitudes, with medium-risk scenarios predicting 2-3°C rises by 2090 and 4-5°C rises in northern Canada, Greenland, and Siberia. In this report, we have outlined the major threats-both direct and indirect-to global health from climate change through changing patterns of disease, water and food insecurity, vulnerable shelter and human settlements, extreme climatic events, and population growth and migration. Although vector-borne diseases will expand their reach and death tolls, especially among elderly people, will increase because of heatwaves, the indirect effects of climate change on water, food security, and extreme climatic events are likely to have the biggest effect on global health. A new advocacy and public health movement is needed urgently to bring together governments, international agencies, non-governmental organisations (NGOs), communities, and academics from all disciplines to adapt to the effects of climate change on health. Any adaptation should sit alongside the need for primary mitigation: reduction in greenhouse gas emissions, and the need to increase carbon biosequestration through reforestation and improved agricultural practices. The recognition by governments and electorates that climate change has enormous health implications should assist the advocacy and political change needed to tackle both mitigation and adaptation. 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 stabilise 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. While we must resolve the key issue of reliance on fossil fuels, we should acknowledge their contribution to huge improvements in global health and development over the past 100 years. In the industrialised world and richer parts of the developing world, fossil fuel energy has contributed to a doubled longevity, dramatically reduced poverty, and increased education and security for most populations. Climate change effects on health will exacerbate inequities between rich and poor: Climate change will have its greatest effect on those who have the least access to the world's resources and who have contributed least to its cause. Without mitigation and adaptation, it will increase health inequity especially through negative effects on the social determinants of health in the poorest communities. {A figure is presented}. Despite improvements in health with development, we are still faced with a global health crisis. 10 million children die each year; over 200 million children under 5 years of age are not fulfilling their developmental potential; 800 million people go to bed each night hungry; and 1500 million people do not have access to clean drinking water. Most developing countries will not reach the Millennium Development Goal health targets by 2015. In September, 2008, the WHO Commission on Social Determinants of Health reported that social inequalities are killing people on a grand scale, and noted that a girl born today can expect to live up to 80 years if she is born in some countries but less than 45 years if she is born in others. The commission concluded that health equity is achievable in a generation, it is the right thing to do, and now is the right time to do it. The effects of climate change on health are inextricably linked to global development policy and concerns for health equity. Climate change should catalyse the drive to achieve the Millennium Development Goals and to expedite development in the poorest countries. Climate change also raises the issue of intergenerational justice. The inequity of climate change-with the rich causing most of the problem and the poor initially suffering most of the consequences-will prove to be a source of historical shame to our generation if nothing is done to address it. Raising health status and reducing health inequity will only be reached by lifting billions out of poverty. Population growth associated with social and economic transition will initially increase carbon emissions in the poorest countries, in turn exacerbating climate change unless rich countries, the major contributors to global carbon production, massively reduce their output. {A figure is presented}. Luxury emissions are different from survival emissions, which emphasises the need for a strategy of contraction and convergence, whereby rich countries rapidly reduce emissions and poor countries can increase emissions to achieve health and development gain, both having the same sustainable emissions per person. Key challenges in managing health effects of climate change: The UCL Lancet Commission has considered what the main obstacles to effective adaptation might be. We have focused on six aspects that connect climate change to adverse health outcomes: changing patterns of disease and mortality, food, water and sanitation, shelter and human settlements, extreme events, and population and migration. Each has been considered in relation to five key challenges to form a policy response framework: informational, poverty and equity-related, technological, sociopolitical, and institutional. Our capacity to respond to the negative health effects of climate change relies on the generation of reliable, relevant, and up-to-date information. Strengthening informational, technological, and scientific capacity within developing countries is crucial for the success of a new public health movement. This capacity building will help to keep vulnerability to a minimum and build resilience in local, regional, and national infrastructures. Local and community voices are crucial in informing this process. Weak capacity for research to inform adaptation in poor countries is likely to deepen the social inequality in relation to health. Few comprehensive assessments on the effect of climate change on health have been completed in low-income and middle-income countries, and none in Africa. This report endorses the 2008 World Health Assembly recommendations for full documentation of the risks to health and differences in vulnerability within and between populations; development of health protection strategies; identification of health co-benefits of actions to reduce greenhouse gas emissions; development of ways to support decisions and systems to predict the effect of climate change; and estimation of the financial costs of action and inaction. Policy responses to the public health implications of climate change will have to be formulated in conditions of uncertainty, which will exist about the scale and timing of the effects, as well as their nature, location, and intensity. A key challenge is to improve surveillance and primary health information systems in the poorest countries, and to share the knowledge and adaptation strategies of local communities on a wide scale. Essential data need to include region-specific projections of changes in health-related exposures, projections of health outcomes under different future emissions and adaptation scenarios, crop yields, food prices, measures of household food security, local hydrological and climate data, estimates of the vulnerability of human settlements (eg, in urban slums or communities close to coastal areas), risk factors, and response options for extreme climatic events, vulnerability to migration as a result of sea-level changes or storms, and key health, nutrition, and demographic indicators by country and locality. We also urgently need to generate evidence and projections on health effects and adaptation for a more severe (3-4°C) rise in temperature, which will almost certainly have profound health and economic implications. Such data could increase advocacy for urgent and drastic action to reduce greenhouse gas emissions. {A figure is presented}. The reduction of poverty and inequities in health is essential to the management of health effects of climate change. Vulnerability of poor populations will be caused by greater exposure and sensitivity to climate changes and reduced adaptive capacity. Investment to achieve the Millennium Development Goals will not only reduce vulnerability but also release public expenditure for climate change currently consumed by basic prevention strategies (eg, malaria control). Health-oriented and climate-orientated investments in food security, safe water supply, improved buildings, reforestation, disaster risk assessments, community mobilisation, and essential maternal and child health and family planning services, will all produce dividends in adaptation to climate change. Poverty alleviation and climate adaptation measures will be crucial in reducing population growth in countries where demographic transition (to stable and low fertility and death rates) is delayed. Population growth will increase overall emissions in the long term and expand the number of vulnerable individuals.