Australia: Climate-Ecosystem Variability and Impacts on Diseases

Photo of Kelly Gustafson encountering archives of research and equipment from ages past. Image Credit: URC.

Kelly Gustafson marvels at the advance of technology while encountering archives of research and equipment from ages past. Image Credit: URC.

Student: Kelly Cortney Gustafson
Florida International University

Major: Environmental Studies

Degree Level: Master of Science

Internship Site: NASA Goddard Space Flight Center, Greenbelt, Maryland

Mentor: Dr. Assaf Anyamba

Abstract: Climate variability in Australia is largely driven by an atmospheric phenomenon called the Southern Oscillation (SO), which involves a see-saw like behavior between low and high pressure systems within the equatorial Pacific regions. The interaction of SO with abnormally high sea surface temperatures (SSTs) – El Niño – and abnormally low SSTs – La Niña (“anti-El Niño”) – creates extreme drought or extreme flooding, respectively, throughout Australia. El Niño-Southern Oscillation (ENSO) events have significant impacts on Australia’s landscape, ecosystems, agriculture production, and, as this report shows, human health. During La Niña years, when ENSO events involve increased rainfall and consequential flooding, Australia’s tropical, warm climate and an associated increase in vegetation growth from the rainfall creates an ideal habitat for mosquito population increases. Certain species of mosquitoes (Culux annulirostris) are carriers of Murray Valley Encephalitis (MVE) virus, a rare but potentially fatal infection that attacks neurological and muscular functioning. We hypothesized that a widespread increase in vegetation indicates an expansion of ideal mosquito production habitats and will translate to an increased risk of MVE contraction. Our objective is to show if a correlation exists between the ENSO-driven climate and consequential ecosystem changes and MVE outbreaks throughout Australia. This study makes use of the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor operating on NASA’s Terra satellite to obtain monthly Normalized Difference Vegetation Index (NDVI) data. It is assumed in this research that an anomalous increase in NDVI values – indicative of vegetation growth – occurs due to increased rainfall, which, in tandem with Australia’s tropical climate, allows for NDVI to be an adequate proxy for the combined influence of rainfall and temperature on mosquito ecology. Our results showed a general temporal and spatial correlation between MVE outbreaks and a “greening” period, suggestive of ideal mosquito breeding habitats and assumed population increases. (This project was co-authored by K.Cortney Gustafson, Mouhamad Diabate, and Dr. Assaf Anyamba).

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