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Vaccines: A Top Priority for Global Health

Vaccination Week in the Americas Goes Global

On the Brink of a Watershed Moment for HIV Vaccine R&D

Reflections of a Lifetime Dedicated to Public Health Advocacy - In Memory of Beth Waters

Climate Change: Skeptics Step Aside

Anthony Costello

Many of us have prior experience of scientific skepticism and denial about the health consequences of HIV infection and tobacco use. When scientists doubted the link between HIV and AIDS, and influenced policy-makers in South Africa to delay treatment rollout, there were at least 300,000 unnecessary deaths. The link between tobacco and lung cancer was denied for nearly 50 years by tobacco companies and apologists, despite huge loss of life.

Climate skeptics had a brief respite this winter. The media had a bonanza with the e-mails leaked from the UK University of East Anglia climate research group hinting at some kind of conspiracy to withhold climate data, followed by the admission by Dr. Rajendra Pachauri, director of the Intergovernmental Panel on Climate Change (IPCC) that there had been an error about the rate of Himalayan glacier melting in their last report.

But the summer is here and climate issues have not gone away. Skeptics and contrarians in the scientific community are a tiny minority - a recent Stanford University study shows they comprise at most 3 percent of the field. So we should spend little time debating climate change denial.

The science, in truth, is fairly simple. Global warming, whereby net heat gain exceeds heat losses, can only occur through three mechanisms: increased solar radiation (no evidence for major recent change), decreased albedo (reflection of radiation from the planet) and changes in atmospheric composition.

The hard evidence comes from increases in surface temperature (about 0.8 degrees since 1900), increasing differentials between surface and deep ocean temperatures, ocean acidity, sea level rise, and melting rates of the Greenland and Antarctic ice sheets. Coupled with the steady and relentless increase in atmospheric carbon dioxide levels from human burning of fossil fuels, this scientific evidence is why many members of the U.S. National Academy of Sciences signed a letter to Science in May 2010 stating, "There is compelling, comprehensive, and consistent objective evidence that humans are changing the climate in ways that threaten our societies and the ecosystems on which we depend."

Every doubling of CO2 levels is expected to raise temperature by 1.9 to 4.5 degrees. With business as usual, current midline estimates are for 3-4 degrees warming by 2100. If nothing is done to arrest greenhouse gas emissions, tipping points may kick in and accelerate the warming process.

Two major threats are from sudden displacement or increases in melting from ice sheets, and from release of methane hydrate gases, 23 times as powerful as C02 in their greenhouse effects, because of melting of the Siberian and north Canadian permafrost, a process that has already started.

If temperature rises are at the upper end of current climate model projections, there is a risk that we could warm by 7 degrees or more, which would exceed the limit of heat endurance for many human and mammalian populations, according to a recent paper by Sherwood and Huber in Nature. Effects on health will be expressed much earlier: changes in the distribution and transmission of communicable diseases, heat stress, the consequences of food and water insecurity, deaths from extreme climatic events, and population migration. The effects of climate change will exacerbate an already profoundly worrying deterioration in our ecosystem services as a result of the increase in human consumption, pollution and population footprint.

So what can be done? Last year the UCL Lancet Commission published a report on ‘Managing the Health Effects of Climate Change' and made clear that global warming was the biggest threat to health in the current century. There were three broad actions needed by the health community to address the problem: to help reduce emissions, to address the pathways linking climate change to health outcomes, and to strengthen health systems.

The health sector has a crucial role in helping to reduce greenhouse gas emissions and to bring about ‘contraction and convergence' across the world. High-emitting countries in the U.S., Europe and elsewhere must drastically reduce emissions by up to 90 percent by 2050 with an individual annual limit eventually capped at about 2 tons per head of CO2 equivalent (industrialized countries currently emit 10-20 tons per head). Low-emitting developing countries, who have contributed almost nothing to the problem, should be able to increase emissions up to the same level.

Until recently, I was deeply pessimistic about the ability of our global leaders to bring about such an enormous change in our industrial processes, and to police and effect such challenging policy changes. But two things have made me more optimistic.

First, we can afford it. The high costs for the U.S. economy of reducing emissions were a major reason for rejecting U.S. ratification of the Kyoto Protocol. Recent reviews by Barker and Ekins of the costs needed to bring about required reductions in greenhouse gases suggests that if policies are expected, gradual, and well designed, they should cost no more than 1-4 percent of world GDP. The amount, several trillion dollars, sounds like a lot, but actually represents no more than 6-12 months of world economic growth. This is equivalent to the recent bank bailouts, and the sooner such policies are planned and coordinated, the lower the bill.

Second, there are reasons to be optimistic about the development of renewable energy technology. The technology we need is either available or not too far from development. Solutions are needed to develop renewable energy sources. Protecting ideas through intellectual property rights is a key issue if eco-technology is to succeed.

Private companies are recognizing the economic potential of a green second industrial revolution. There is significant commercial gain through going green, and companies such as WalMart, Nike, O2, Unilever and Marks and Spencer have implemented ambitious eco-efficiency drives which reduce waste, use of fuel and packaging, thereby improving their profitability. Non-fossil fuel options are vying for the interest of major investors, from countries like China, from our pension funds, and from high net-worth individuals like Bill Gates and Warren Buffett.

The International Energy Agency says that $10,000bn of investment will be needed globally over the next 20 years, but estimates that $8600bn will be recouped in fuel savings and other benefits. Governments are devoting a large proportion of stimulus spending to environmental projects and emerging markets are recognizing the economic potential. The World Bank is financing a project called Lighting Africa using light-emitting diodes (LED) to provide an alternative to polluting kerosene lamps which is a surprisingly large market. In Brazil, the government has set deforestation reduction targets and, in India, government subsidies have supported the growth of a wind power industry.

The second strategy from the UCL Lancet Commission was to manage the complex pathways linking individual effects of warming on health. Each country must develop plans to reduce vulnerability to communicable diseases, heat stress, food and water insecurity, extreme climatic events, poor shelter and population migration.

Governments and international agencies must provide additional resources to poorer countries. The poorest billion people contribute just 3 percent of the global carbon footprint but may, according to climate epidemiologist Anthony McMichael, suffer up to 500 times the loss of life compared to the richer world. In addressing these pathways, the science and health communities face a great challenge. We need much more information about local climate risks and how to build resilience. Poverty and inequalities in all countries will increase vulnerability, and our efforts to bring populations out of poverty must be redoubled.

Technological advances and research are needed to improve crop varieties, irrigation techniques, pest control, cheaper ways of desalinating and conserving water, improvements in building materials and heat insulation, improvements in communications technology to obviate the need for so much aviation and travel, and the development of early warning systems for climate events and their local consequences. Social and cultural change to move toward a low-carbon lifestyle presents the biggest challenge. Incentives and legislation to change behavior will need to be effective and on a large scale, but must not alienate electorates. Advocacy about the health consequences is a high priority. The United Nations Convention on Climate Change was set up in 1992 to ensure nations worked together to minimize the adverse effects. But McMichael and Neira noted that in preparation for the Copenhagen conference in December 2009, only four of 47 nations mentioned human health as a consideration.

The third major strategy is to strengthen health systems. In many countries health systems are fragmented, with little in the way of coherent, population-based, and bottom-up health planning. They must not only deliver clinical services but also effective public health responses to climate-induced threats to health. Weak health governance and management structures require long-term investment in human capacity. As a colleague wryly observed, many countries have an airline but not a coherent research or health policy. This needs to change.

There is also much to be done in harnessing existing resources in the private sector to better serve the public interest. In brief, health systems need three specific climate actions. First, each country needs its own detailed risk assessment which is reviewed and updated at intervals. Second, they need to plan a program of specific interventions to reduce risks in key areas of vulnerability, for which many will need extra financial support from climate change aid funds. And third, countries need to promote the health benefits of reducing greenhouse gas emissions.

A Lancet series in December 2009 reviewed mitigation strategies for household energy, transport, food and agriculture, and electricity generation and showed that actions to reduce greenhouse-gas emissions often produce substantial benefits for health. Specific policies that reduce emissions and result in health benefits include increased active transport (walking and cycling) and reduced private-car use in urban settings, increased use of improved cook stoves in low-income countries, reduced consumption of animal products in high-consumption settings, and generation of electricity from renewable or other low-carbon sources rather than from fossil fuels. The health benefits include reductions in obesity and heart disease, in deaths from pneumonia and asthma, and in diabetes, stress and depression. Apart from the human benefits, there will be major cost-savings within the health sector.

Climate change remains an enormous challenge for national and international government. But the economic crisis has taught us that our global well-being is highly interconnected and that nations must work together to bring financial, trade and climate stability. Wealthier countries must be prepared to maintain aid support to the poorest, because achieving the Millennium Development Goals will assist countries to reduce poverty, mortality and fertility rates, which will stabilize population growth and increase the resilience of populations to cope with climate change adaptation. High-consumption countries must also recognize the central part they have played in creating the threat of climate change, but with strong leadership and informed electorates, there is still no reason why we should not create a second industrial revolution and bequeath a sustainable world to our children and grandchildren.

Anthony Costello is professor of international child health and director of the University College London (UCL) Institute of Global Health, chaired the UCL Lancet Commission on Managing the Health Effects of Climate Change, and directs research on maternal and child survival in Malawi, India, Nepal and Bangladesh.