1. Chapter1: Introduction and Overview
Protecting our Health from Climate Change: a Training Course for Public Health Professionals
Chapter1: Introduction and Overview

2. Overview
This module provides an introduction to global environmental change and the issues that will be covered in the course “Protecting our Health from Climate Change”

3. Historical Perspective
Over past 10,000 years, humans have altered their environment
Leading to increased population size, improved living conditions, and increased life expectancy
Last 150+ years, gains in population health from increasing:
Access to safe water and sanitation
Food security
Access to simple medical care
Education and literacy
Humans have been altering their environment for 10,000 years, initially in ways that were beneficial to population health (e.g., agriculture, settlements). In the past 150 or so years, life expectancy and the quality of life increased dramatically for those with sustainable access to safe water and sanitation, food security, access to medical care, and education. The Millennium Development Goals aim to ensure access to these for everyone.
More on the Millennium Development Goals: 3

4. Epidemiology Since ~1850: Changes in Emphasis / Units of Analysis
Population
Germ theory
Micronutrients
Sub-groups
Occupational risks
Individuals
Non-infectious diseases
Individual risk factors
Genetics and epigenetics
1850s
1900s
1950s
The unit of interest in epidemiology has shifted since the 1850s, when it was realized that germs caused infectious diseases and that a lack of micronutrients was the reason for scurvy and other human afflictions. As basic public health infrastructure improved, and developed countries went through the epidemic transition from most deaths due to infectious diseases to most deaths due to chronic diseases, attention turned to non-communicable diseases and injuries and to sub-groups with higher rates of specific diseases, such as occupational groups. Further advances in scientific understanding of risk factors lead to the current focus on individuals and the risk factors, from exposures to behaviors to genetics, that increase rates of specific chronic diseases. 4

5. 21st Century
The risks populations are facing have become more complex, larger scale, and potentially more devastating
Global environmental changes mean that environmental epidemiology must now study current and future health risks due to changes in climate, food systems, water resources, and other factors
Focus on the individual level is not adequate for the risks that will face populations in the 21st century. New risks are arising that are more complex and wider in scale. Epidemiologists and public health practioners are beginning to study the global environmental changes that are affecting our air, water, food, and ecosystems in ways that are potentially devastating. 5

6. Main Global Environmental Changes
Atmospheric composition and chemistry
Food systems
Freshwater resources
Biodiversity
Changes to global cycles of major elements
Persistent organic pollutants
The phrase global environmental change includes changes to the systems listed. It is apparent that these changes could affect all aspects of our lives.
The focus of this course is on global climate change, primarily because more is known about the changes that are occurring and their potential consequences for human health. Information is rapidly emerging on the potential health consequences of changes in other systems. For example, an International Assessment of Agricultural Science and Technology for Development was completed in 2008 that detailed recent and projected changes in food systems, the consequences for health, and options available to address pressing risks. Other assessments have included consideration of changes in freshwater resources and biodiversity, including the Millennium Ecosystem Assessment and assessments conducted for the Intergovernmental Panel on Climate Change (e.g., IPCC, 2007a).
More on Millennium Ecosystem Assessment :
More on Intergovernmental Panel on Climate Change: 6

7. Pathways from Global Change to Human Health
Environmental degradation, ecosystem disturbances,
geophysical changes
Demographic change
Aging
family structures
urbanization
Economic activities
Trade
wealth creation and distribution
Social change
Institutions
governance
Global environmental changes are being caused by increasing population pressures and urbanization, changes in social structure and governance, and the economic activities needed to support a rapidly increasing global population. The result has been environmental degradation, ecosystem disturbances, and geophysical changes that threaten the gains made in population health. These interact with poverty, income inequalities, and other factors to increase the burden of a wide range of adverse health outcomes.
Human health 7

8. Ecosystem Services and Human Health
Regeneration of fertile land  food
Viable fisheries  food
Wetlands: flood storage, cleansing of surface water
Nutrient recycling (nitrogen, phosphorus, etc.)
Intact ecosystems: control of infectious disease vectors (mosquitoes, ticks, rodents)
Buffering against environmental stressors (protection by forests and reefs against cyclones, storm surges, and droughts)
Source of medicinals
Support/inspiration for aesthetic/spiritual values
The Millennium Ecosystem Assessment (2005) detailed how human health relies on a range of ecosystem services, nearly all of which are being degraded. The slide lists the basic services and their importance to health.
Ecosystem services are the benefits humans received from a multitude of resources and processes that are supplied by natural ecosystems, such as clean drinking water. Ecosystem services can be divided into provisioning, such as the production of food and water; regulating, such as the control of climate and disease; supporting, such as nutrient cycles and crop pollination; cultural, such as recreational benefits; and preserving, which includes guarding against uncertainty through maintenance of biodiversity. 8

9. What is Different About Studying the Health Impacts of Global Change?
Temporal and spatial scale issues
Not a discrete exposure
Everyone is exposed
Exposures will increase over coming decades
Risks will increase with increasing exposures
Impacts operate through a wide range of pathways
Studying global change is challenging how epidemiologists think about risks to human health. Global change is happening over large spatial scales, in some cases the scale is the planet (i.e., climate change). As discussed in the previous slides, the exposure is not discrete in the sense of smoking a packet of cigarettes or exposure to arsenic in drinking water. Global change is altering our air, water, food, and ecosystems. Everyone, to some degree, is exposed to these changes; there is no unexposed group. Inertia in these systems and increases in driving pressures mean that exposures will continue to increase, increasing risks of adverse consequences for human health. Studying the impacts is complex because of the nature of the exposures, the scales over which they operate, and the multiple pathways by which health can be affected. 9

10. Regional air pollution Environmental tobacco smoke
Scale and Type of Environmental Health Risks
Global change
Extremes of exposures; disruption of life/health-support systems
Regional air pollution
Acid rain,
Asian brown cloud
Local air pollution
The example of air pollution illustrates the range of scales and types of causal pathways that exist. At the very local level, many studies have shown an increased risk of lung cancer in relation to environmental tobacco smoke (passive smoking). At the whole-community level, ambient air pollution due to noxious gases and particulates released by power generation, industry and motorised traffic is a well-demonstrated cause of respiratory and cardiovascular disease risks. These two levels of exposure and research are very much part of the mainstream of environmental epidemiology.
Moving to larger scales, acid rain (due primarily to sulphur and nitrogen oxides) results from the trans-boundary spread (at higher altitude) of air pollution. In addition to any toxicological impacts of that transported air pollution, there have been studies of its impacts on the acidity and productivity of water-ways, on the acidification of soil with consequent mobilisation of various metals (detrimental to some plant and tree growth), and on the overall health of forests. These adverse impacts, in turn, can affect livelihoods and economic conditions and thereby indirectly affect wellbeing and health.
Finally, at the global scale, is global climate change, which will be covered in detail over the next few days.
Clearly, the study of both acid rain and climate change require a different, ecological, systems-based approach to the identification, characterization. and forecasting of health impacts.
Direct, toxic, hazard
Environmental tobacco smoke 10

11. Not Just Environment Changing
Worldwide emergence and re-emergence of infectious diseases since 1970s
Increase in obesity and diabetes
Trade and travel increasing transport of lifestyles, infectious people, hazardous materials, ….
Export of occupational hazards to low-income countries
Increasing income inequalities
These risks are emerging in the midst of other changes, some of which are listed on the slide. The health impacts of these other changes are also expected to increase in coming years, challenging the ability of public health systems to maintain and improved population health. 11

12. World Population: 1960 and 2050 1960 2050 Worldmapper, 2008b, e
These slides are cartograms that are generated by scaling country boundaries not by their geographic size, but by other factors. This shows world population in The colors are to differentiate countries.
Watch the population numbers in Africa, Europe, and Asia.
Population growth will strain public health and health care systems in some countries. Global environmental change will increase the pressure on the existing health systems. Significant support and development will be needed just to maintain current levels of health service.
2050
Worldmapper, 2008b, e 12

13. National Carbon Dioxide Emissions
This figure shows various countries and their levels of CO2 emissions per capita. Central to any study of climate change is the development of an emissions inventory that identifies and quantifies a country’s primary anthropogenic sources and sinks of greenhouse gas. Emissions are not usually monitored directly, but are generally estimated using models. Some emissions can be calculated with only limited accuracy. Emissions from energy and industrial processes are the most reliable (using energy consumption statistics and industrial point sources). Some agricultural emissions, such as methane and nitrous oxide, carry major uncertainties because they are generated through biological processes that can be quite variable.
Source: EastWestCenter (2009) 13

14. World Wildlife Fund Living Planet Report 2006
The World Wildlife Fund, among others, calculates the ecological footprint of human activities. The ecological footprint is a measure of human demand on the Earth's ecosystems. It compares human demand with the Earth’s ecological capacity to regenerate. It represents the amount of biologically productive land and sea area needed to regenerate the resources a human population consumes and to absorb and render harmless the corresponding waste. Using this approach, it is possible to estimate how much of the Earth (or how many planet Earths) it would take to support humanity if everyone lived a given lifestyle. Although the term ecological footprint is widely used, approaches to measure it vary.
An unfortunate milestone was passed early in this century – more than one Earth is now required to support human activities. That deficit is projected to grow at least through the next few decades. The path of current and future development will determine whether the world will shift to more sustainable ways of living. Continuing on a business-as-usual pathway is projected to lead to very significant adverse health impacts later in the century.
World Wildlife Fund, 2006 14

15. Millennium Ecosystem Assessment (2005): Ecosystems and Human Wellbeing
This statement, taken from the Millennium Ecosystem Assessment (2005), emphasizes the scale and rate of change. 15

16. Water Poverty Index
Some examples of global environmental changes follow. This map shows current levels of water poverty, showing that nearly all countries in Africa and may countries Asia experience some degree of water stress. Population growth and changes in the hydrologic cycle due to climate change will make this situation worse in most countries.
The Centre for Ecology & Hydrology of the United Kingdom, 2005 16

17. Projected Changes in Length of Growing Season, 2050
ECHam4, B1
ECHam4, B2
> 20% loss
5-20% loss
No change
5-20% gain
>20% gain
Agricultural models are generally pessimistic about the impacts of climate change on food availability in sub-Saharan Africa. These projections from 2050 suggest the growing season could be reduced by more than 20% along the edges of desert areas (red areas), and by 5-20% over much sub-Saharan Africa (pink areas). If the projections are borne out, then crops that currently need the entire growing season to mature will be adversely affected.
International Livestock Research Institute, 2006 17

18. Environmental tobacco smoke
Cereal Production under GCM Scenarios
Local air pollution
Under three different general circulation models, cereal production in 2060 is projected to decline in developing countries by up to 15%, depending on assumptions about the extent and speed of implementation of adaptation options (see text box in slide). The opposite is projected to occur in developed countries – climate change with adaptation is projected to increase crop yields by more than 10% under combinations of specific projections of climate change and implementation of adaptation options. The sum across world regions suggests a small decline. The degree to which these projections could exacerbate undernutrition depend on assumptions of trade and other factors.
Environmental tobacco smoke 18

19. Food Web and Future Productivity of Ocean Fisheries Affected by
Increasing ocean temperatures
Ocean acidification
Zooplankton, crustaceans, shellfish sensitive to pH
Over-fishing
An area of increasing research interest is the potential impact of climate change on the food productivity of ocean fisheries. Many fisheries are in dire straits because of over-harvesting. Increasing ocean temperatures and ocean acidification (due to dissolving of carbon dioxide into the ocean) are beginning to adversely affect ocean ecosystems, raising concerns that some ecosystems could collapse under these stresses.
25% of commercially exploited marine fish stocks are now seriously over-harvested
(Millennium Ecosystem Assessment, 2005) 19

20. Human Changes to Global Activated Nitrogen Cycle, 1900-2050
Human health risks include:
Decreased crop yields
Nitrogen oxides (air pollution)
Another large-scale change that is poorly studied is the increased use of fertilizers and other inputs to the activate nitrogen cycle. Human inputs are now in the range of total terrestrial input; i.e. doubling the amount of nitrogen. Within a few decades, more nitrogen is projected to be of human vs. bacterial origin. Human health risks include increases air pollution and decreases in crop yields. More impacts are likely to emerge as these changes are better understood. 20

21. Asian Brown Cloud
United Nations Environment Program (UNEP) estimates 1-2 million deaths in India annually from atmospheric pollution
Asia’s brown haze is also altering regional weather, creating acid rain, and (perhaps) affecting forest and crop yields
Another example of a large-scale change is the Asia Brown Cloud, which affects millions of people across multiple countries. Not only does the presence of the Asia Brown Cloud directly increase mortality (UNEP estimates 1-2 million deaths annually in India from atmospheric pollution), it also alters regional weather patterns, creates acid rain, can increase snow melt as black carbon increases heat absorption, and may be affecting forest and crop yields.
More on United Nations Environment Program (UNEP):
Photo source 21

22. Lyme Disease: Influence of Habitat Fragmentation and Biodiversity Loss
High Lyme Disease risk (humans)
Woodland suburban
housing (NE USA)
Complex life-
cycle of tick
High tick density
and high tick infection
prevalence  infected deer
Increase in “competent”
reservoir species – readily infected
Proliferation of mice
Reduced regulation between species
Loss of diversity of vertebrate
predators and microbial host species
This example shows how habitat fragmentation and habitat loss increase the risk of Lyme disease in humans. Forest fragmentation, hunting, and increasingly building housing in woodland areas, can reduce biodiversity, which provides an opportunity for the proliferation of the mice that carry the tick that carries Lyme disease. This increase in a readily-infected reservoir species then increases the risks of human exposure.
These interactions will be discussed further in the module on vectorborne diseases.
Forest fragmentation, hunting (wolves, passenger pigeons) 22

23. Whose Research Task?
Epidemiology is the study of the distribution and determinants of diseases in populations, and of ways to reduce the burden of disease
Some say that global environmental change is too big/too complex for epidemiologists to study
Then who will ensure that population health is protected from expected impacts?
Epidemiology has a responsibility to address societal needs
Epidemiologists have been slow to engage in the study of global change. This course is witness to the increasing interest. Your engagement will help ensure that public health addresses the major risks of our time.
Recommended reading: IPCC 2007 report, Summary Report, pages 1 to 22 23