Children are already bearing the brunt of the health impacts of climate change. The World Health Organization estimates that over 80% of the illnesses, injuries, and deaths occurring due to climate change are in children, particularly those living in poor and under-served areas. Climate change is altering weather patterns in ways that can affect the geographic range and incidence of health outcomes that are among the major killers of children: malnutrition, diarrheal diseases, and vector-borne diseases such as malaria. By the year 2000, climate change may have increased the numbers of cases of these diseases by roughly 3 to 10%.
These percentages translate into large numbers of children: diarrheal diseases claim the lives of nearly 2.5 million children annually, malaria causes an estimated 655,000 deaths, and malnutrition is an underlying cause of death of half of the just under 7 million deaths globally in children under age five. Based only on the climate influence on health risks, future impacts on children are projected to increase, assuming no additional interventions to avoid, prepare for, respond to, or recover from the impacts of climate variability and change.
Many other risks for children's health and well-being are expected or likely to occur with ongoing and future climate change, with additional data and understanding needed to quantify current and possible future adverse consequences. A few examples include:
- Contaminated water and inadequate sanitation and hygiene are the leading reasons for the high rates of diarrheal diseases. Rising temperatures that facilitate the replication of some pathogens, and more flooding events that damage water treatment and/or spread pathogens could increase significantly the burden of disease, depending on the effectiveness of control programs.
- Climate change is contributing to increases in pollen in some regions that may be exacerbating allergies and asthma. However, there is an incomplete understanding of the degree to which aeroallergens are contributing to the global increase in pediatric allergic disease, among other issues, to estimate the contribution of climate change.
- Increasing atmospheric concentrations of carbon dioxide are acidifying the ocean, with possible consequences for food security in some regions.
Providing more comprehensive estimates of current and projected impacts is complex because of the nature of climate change itself and because of the many factors that can increase or decrease the rates of climate-sensitive health outcomes. The science is clear on many aspects of climate change and its associated risks.
Climate change is caused by natural and man-made activities, particularly the burning of fossil fuels and deforestation that are adding significant quantities of greenhouse gases to the atmosphere. In 2007, the Intergovernmental Panel on Climate Change concluded the evidence is unequivocal that humans are changing the climate, based on observed increases in average air temperatures and other geophysical factors. Further, emitted greenhouse gases take decades to centuries to be absorbed in the soil and sequestered in the ocean, resulting in a "climate change commitment". Essentially, the greenhouse gases currently in the atmosphere will continue to drive climate change for at least 30-40 years. About as much climate change will occur over that time period as has already occurred since the Industrial Revolution; the rate of climate change is greater than it has been in at least 10,000 years.
We also know that shifts in the mean values of weather variables are also leading to very large observed percentage changes in the occurrence of extreme weather and climate events. The frequency and intensity of daily temperature extremes and heavy precipitation events in some regions are now different than they were before 1950, in part due to climate change. Estimating the extent to which these and other changes can be attributed to climate change is complex because of the difficulty in determining whether a single event would have occurred naturally. A simple analogy is athletic performance under the influence of performance enhancing drugs. An athlete might have achieved a particular outcome based on natural ability, but the use of drugs made it more likely. Further, it is easier to determine statistically by analyzing a series of past events to know if drugs influenced a series of outstanding performances than by looking at one particular achievement.
Similarly, the energy that greenhouse gases are adding to the atmosphere is being expressed through more and more severe extreme events, although it is not possible to attribute any one event to climate change alone.
Thus projections of future climate change and its impacts are, of course, inherently uncertain because it is not possible to fully predict how the climate system will respond to additional greenhouse gas emissions; what climate policies will be implemented (and how rapidly); how societies will develop in terms of demographics, economics, technology, etc.; and the effectiveness and timeliness of public health actions to address the health risks of climate change. However, we know that children are being affected by climate today, and these same risks are very likely to increase.
Children are being affected by recent increases in the frequency, intensity, spatial extent, and duration of extreme weather events. For example, in the Horn of Africa failed rains in the boreal winter of 2010/2011 and the boreal spring of 2011 played a critical role in the 2011 food crisis that lead to famine in parts of Ethiopia and Somalia; other important factors that were exacerbated by the lack of rainfall included high global food prices, political instability, and chronic poverty. This followed poor rainfall in 2008 and 2009. In addition to the immediate impacts of acute food shortage, chronic malnutrition affects a child's life course. Concern about achieving the MDG targets increases when combining the limited progress in reducing chronic childhood malnutrition in Africa with projections that climate change will increase the challenges to food security through changing crop yields under new temperature and precipitation patterns.
Climate change, then, can exacerbate current challenges for improving children's health and well-being and can create new risks. So how can we know by how much will risks to children increase? Although quantifying the risk to know exactly when, where, and by how much the risk will increase may not always be possible, other approaches to understanding how climate and other factors could interact to affect children's health in a particular region are available. When sufficient local data are lacking (which is common in the most vulnerable places), narrative scenarios based on expert judgment and local expertise can be helpful. Narratives of possible futures can be constructed to better understand how various risk factors can interact, including whether tipping points could be reached, to inform development of robust local policies and measures to avoid, prepare for, and respond to changing health burdens under a range of climate and socio-economic changes. Limited data and projections of the health impacts of climate change should not be a barrier to action, but a call to more research and to flexible and iterative approaches to decision-making, like the use of scenarios and adaptive management.
What can be done? Current policies and measures to prevent climate-sensitive health outcomes can and should be modified to address not only current impacts, but also consider the risks of future climate change, to ensure they are robust to warmer temperatures and changing precipitation patterns. The design, implementation, monitoring, and evaluation of new policies and measures should also explicitly incorporate consideration of the risks of climate change. Adaptive management approaches can be used to manage uncertainties about the magnitude and extent of climate change and its possible consequences, and about future development pathways. The absence of effective and timely actions to address climate change is expected to lead to preventable consequences for child growth and development, needlessly affecting current and future generations.