Climate variability: refers to variations or deviations from the mean state of the climate or temporal variations of the atmosphere-ocean system around a mean state measure over a long period of time. Typically, this term is used for timescales longer than those associated with synoptic weather events (i.e., months to millennia and longer). The term “natural climate variability” is further used to identify climate variations that are not attributable to or influenced by any activity related to humans. However it is recognized that such “internal or natural variability” could be affected by external factors driving climate change such as changes in the atmospheric concentration of greenhouse gases. The El Niño-Southern Oscillation (ENSO) phenomena is a good example of the variability in the coupled oceanic and atmosphere system that is a central factor in short-term climate variability and the interannual timescale (http://www.cpc.noaa.gov/products/analysis_monitoring/ensostuff/prelude_to_ensofaq.shtml; http://www.ncdc.noaa.gov/paleo/outreach/coral/coralenso.html; http://www.sws.uiuc.edu/atmos/statecli/Climate_change/glossary.htm).
Ecosystem: Mutually interrelated communities of species and abiotic components, existing as a system with specific interactions and exchange of matter, energy, and information.
El Niño: A warming of the surface waters of the tropical Pacific that occurs every 3 to 5 years, temporarily affecting weather worldwide.
Emerging infection: Either a newly recognized, clinically distinct infectious disease or a known infectious disease whose reported incidence is increasing in a given place or among a specific population.
Endemic: Restricted or peculiar to a locality or region. Endemic infection refers to a sustained, relatively stable pattern of infection in a specified population.
Epidemic: Appearance of an abnormally high number of cases of infection in a given population.
Epidemiology: Study of the distribution and determinants of health-related states or events in specified populations. Epidemiology is the basic quantitative science of public health.
Extreme weather: refers to weather phenomena that are at the extremes of the historical distribution and are rare for a particular place and/or time, especially severe or unseasonal weather. Such extremes include severe thunderstorms; severe snowstorms, ice storms, blizzards, flooding, hurricanes, and high winds, and heat waves. For example, although flooding is common in the United