Models of future climate scenarios have taken insufficient account of population patterns and trends, according to a UCL review to be published in the print edition of The Lancet in November 2013. The review, "Population, development, and climate change, links and effects on human health", examines the interconnections between population growth and climate change, from the perspective of global health.

The authors found that while population growth is an important factor, it is consumers, rather than people per se, who drive climate change. Reducing consumption thus represents the most effective way to reduce carbon emissions. This can have substantial health co-benefits, and consideration of human health should therefore be integral to future plans for tackling climate change.

Professor Judith Stephenson, UCL's Institute for Women's Health, says: "Disruption of the environment and climate system caused by unprecedented human activity since the industrial revolution confronts us with an urgent and complex problem that requires reduction in growth of both consumption and population for a sustainable world."

Population growth and health

The world's population is expected to be ten times larger by 2050 (roughly 10 billion) than it was for most of the 19th century (around 1 billion). Future population size in poor countries will have significant consequences for health and the environment, say the authors. Improved sanitation, nutrition and healthcare are allowing more children to survive into adulthood, whilst a reduction in fertility rates is leading to an aging population.

When implemented with other social and economic improvements, family planning is one of the most effective ways of managing increases in population growth and for delivering extensive health benefits, in both developed and poor countries. Access to family planning has significantly reduced maternal and infant deaths, although there remains a considerable unmet need for family planning, say the authors.

Population, health and climate change

Although population is an important factor, demographic trends are more significant for climate change than total population, says the review.

Consumption patterns, together with aging and urbanization in some countries, have bigger implications for health and the reduction of carbon emissions than the total number of people in the world.

The world's poor have contributed little to climate change and yet will experience the biggest effects. Although poor countries have some of the world's highest fertility rates, growth in consumption exceeds growth in population in developing and developed countries. According to the authors reducing consumption and achieving more sustainable lifestyles in rich countries thus represents the most effective way to reduce carbon emissions and ultimately deliver health benefits.

The authors say insufficient attention has been paid to the interconnections between population, development, climate change and human health. According to Professor Judith Stephenson: "Bringing together natural and social scientists with people from different organisations and communities in the global South and global North is essential to improve understanding of the interactions between consumption, demographic change and the climate, and to devise more scientifically and politically integrated solutions for global health."