Swine flu, climate change, and the future of infectious diseases
Since the first cases of swine flu, or H1N1, were reported in April, public health organizations, governments, media and the general public have spent much time and energy trying to understand and contain the virus. Responses have ranged from the serious (like the WHO’s declaration of a phase 5 pandemic alert) to the ridiculous (like designer face masks). In the midst of all this hubbub, many of us have begun to wonder what causes outbreaks of infectious disease like this and how we can prevent outbreaks in the future. While answers to those questions are complex to say the least, mitigating climate change is one important piece of the equation. Here’s why.
Last weekend, epidemiologist and Google.org chief philanthropy activist Larry Brilliant published an alarming article in the Wall Street Journal about swine flu. Not only are we underprepared for a global influenza pandemic, he argues, we are also likely entering what he calls an “Age of Pandemics,” wherein outbreaks of infectious diseases will become increasingly common.
About two-thirds of the pathogenic viruses that affect humans, he continues, are zoonoses—viruses that jump from animals to humans. A study last year in the journal Nature (co-authored by Columbia Climate Center friend and CIESIN deputy director Marc Levy) agrees with Brilliant that the rate of new infectious diseases is increasing steadily.
Zoonoses in particular are on the rise because the rapidly increasing human population is converting huge amounts of forests, prairies, grasslands and wetlands to agricultural use, eroding “green belts,” or undeveloped areas of land that provide animal habitats. As a result, humans and animals live closer together and interact with each other more than ever before. And as we mingle, we also share our viruses.
Brilliant explains that climate change is the “Great Exacerbator” in this process. Changes in climate cause agricultural outputs to decrease due to increasingly severe droughts, floods and temperature changes, so humans are forced to move into previously uninhabited lands at a greater rate than they would if temperatures were stable. Animal habitats, too, are affected by changing climate and rainfall patterns, so some animal populations are also migrating to more habitable surroundings—and they carry their diseases to new areas as they do so. Says Brilliant, “all of these changes increase the potential for humans and animals to exchange new viruses.”
This climate-driven increase in infectious diseases is not inevitable, however. Some climate-related recommendations to help avoid future pandemics include are listed below, some adapted from this report.
- General climate change mitigation strategies like reducing greenhouse gas emissions, capturing and sequestering carbon dioxide, avoiding deforestation and reforestation.
- Integrating public health considerations into planning for land-use, water management, and strategies for adaptation to climate change.
- Preserving “green belts” and promoting conservation-oriented agricultural policies.
- Further research on deforestation, loss of biodiversity, and habitat fragmentation, especially with regard to effects on wildlife abundance and pathogen concentrations and transmission. This research could then be used to inform policy on land use and development.
Clearly, infectious diseases are a case where complex global challenges like climate, increasing population and urbanization, water management and land use converge and exacerbate the problem. So, Climate Matters readers, what do you think? Where should the global community focus its efforts if we are to reduce the spread of infectious diseases in the future?