Climate change, biodiversity loss, depletion of freshwater and many other unprecedented environmental changes are occurring on a global scale. These changes are driven by increasing demands for energy, food and raw materials to support unsustainable and inequitable patterns of consumption by growing human populations.
In recognition of these pervasive trends, last month a working group of scientists recommended that a new geological epoch called the Anthropocene should be officially recognised. Whilst some may question the exact definition and rationale, there can be no doubt that dramatic changes in the global environment have taken place, particularly since the middle of the last century, as a result of the dominance of human activities.
These changes have the potential to halt and undermine the marked progress in human health and development achieved in recent decades, with the onset of more dangerous extreme weather events and a reduced ability to work in tropical and sub-tropical regions due to increasing thermal stress. The Rockefeller Foundation/Lancet Commission on Planetary Health report also highlighted a range of other risks including increasing undernutrition as a result of declines in crop yields and fisheries, especially at low latitudes, and of emerging infectious diseases . Inevitably, many of these impacts will fall disproportionately on people who have contributed least to causing them, notably the poor.
There is much that can be done to help humanity address these burgeoning environmental threats. In particular, progress towards achieving the Sustainable Development Goals (SDGs) adopted by the 193 UN member states a year ago, is essential to safeguard health in the Anthropocene epoch. Whilst achieving Universal Access to effective health care is essential (SDG 3), progress towards many of the other SDGs can directly or indirectly improve the prospects for health, including SDG 2 on improved nutrition and sustainable agriculture and SDG 7 on access to modern energy sources.
The future of humanity will be shaped by urban development and thus the achievement of SDG 11 on sustainable cities is crucial for health. Population growth is concentrated in cities, more than one-half of the world's population is now urban and by 2050 the proportion is projected to reach two thirds. Cities generate around 85% of global GDP and 71-76% of energy related GHG emissions. Nearly all cities with more than 100 000 inhabitants in low- and middle income countries, and just over half of those in high income countries, do not meet WHO air quality guidelines. Pollution levels are increasing overall despite improvements in some regions.
Though the percentage of city dwellers living in slums declined over the last decade, more than 880 million people worldwide were still living in slums in 2014. Nearly half of the world's urban dwellers live in a growing number of relatively small cities with less than 500,000 inhabitants. It is in these smaller cities where the greatest rates of population growth are now seen and where there is consequently huge potential to improve environmental sustainability and address the drivers of ill health. In more established cities the challenge will be to achieve and sustain high levels of health and development at much lower levels of environmental impact than today.
Some clues about how to shape the cities of the future can be gleaned by comparing cities with a similar population and level of development but different environmental footprints. For example,the city of Atlanta has about 10 fold greater transport greenhouse gas emissions per head than Barcelona as a result of its much larger urban area of - 4280 Km 2 compared to 161 km 2 for Barcelona - and much lower connectivity to urban mass transit systems. The external costs of urban sprawl are about $400 billion annually in the USA alone due to the increased cost of providing public services, higher capital investment needed for infrastructure and the costs of increased traffic congestion, crashes and air pollution.
There is growing evidence that the built environment and urban transport can be powerful influences on health. More compact cities tend to have lower levels of obesity, diabetes and heart disease.
Case studies of bus rapid transit systems in Bogotá, Mexico City, Johannesburg and Istanbul suggest the potential to improve quality of life by reducing travel time, air pollution, GHG emissions, and traffic -related injuries. Low carbon transport (e.g. electric and plug-in hybrid vehicles) can also reduce air pollution. Increased active travel (walking and cycling) can help to reduce the risk of heart disease, stroke and diabetes related to physical inactivity which, on a global scale, is responsible for over three million deaths annually.
Research shows the benefits of physical activity generally outweigh the increased risk of road injury and air pollution exposure. Green spaces in cities can reduce the urban heat island effect and probably improve mental health, as well as fostering urban biodiversity.
The Earth's population is growing rapidly. Our towns and cities must be fit for purpose. New epoch or not, we must halt and where possible reverse the dramatic changes in the Earth's natural systems whilst adapting as far as possible to the changes we have caused.
Achieving the SDGs will help to reduce the risks to health in the near term and for generations to come.
This post is part of a series produced by The Huffington Post to mark the occasion of the one-year anniversary of the adoption of the Sustainable Development Goals (SDGs, or, officially, "Transforming Our World: the 2030 Agenda for Sustainable Development"). The SDGs represent an historic agreement -- a wide-ranging roadmap to sustainability covering 17 goals and 169 targets -- but stakeholders must also be held accountable for their commitments. To see all the posts in the series, visit here.