Energy, Environment and Water Research Center

Energy, Environment and Water Research Center

(1) Abstract: Cholera and climate - new perspectives

Dr. Shlomit Paz, University of Haifa
The relevance of climatic events as causative factors for cholera epidemics is well known. Over the years, several studies focused on the linkage between cholera outbreaks and climatic factors, such as air temperature, sea surface temperature and precipitation amounts. However, examinations of the involvement of climatic factors in the intra-continental disease distribution are still absent. The research suggests that the geographical diffusion of cholera epidemics is related to the dominant wind direction over lands. The possible influence of the wind direction on windborn dissemination by flying insects, which may serve as vectors, is discussed.

The geographical diffusion of three cholera outbreaks is examined through their linkage with the wind direction: (a) the Vibrio cholerae O1 biotype El Tor progress in Africa during 1970-1971; (b) and again in 2005-2006; (c) the Vibrio cholerae O139's mysteriously rapid spread over India during 1992-1993.

Analysis of pressure data at sea level and at several altitudes over Africa, India and Bangladesh show a correspondence between the dominant wind direction and the intra-continental spread of cholera.

The study explored the idea that winds have assisted the progress of cholera Vibrios throughout the continents. The analysis supports the hypothesis that aero-plankton (the tiny life forms which float in the air, and may be caught and carried upward by the wind, landing far from their origin) carry the cholera bacteria from one body of water to an adjacent one. This finding may improve the understanding of how climatic factors are involved in the rapid distribution of new strains throughout a vast continental area. Awareness of the aerial transfer of Vibrio cholerae may assist health authorities by improving the prediction of the disease's geographical dissemination.

(2) Abstract: The changing character of heat waves in Mediterranean climates

Dr. Alexander Gershunov, University of California
Most of the great California heat waves can be classified into primarily daytime or nighttime events depending on whether atmospheric conditions are dry or humid.  A rash of nighttime-accentuated events in the last decade was punctuated by an unusually intense case in July 2006, which was the largest heat wave on record (1948–2006). It’s astonishing magnitude was caused by a combination of factors, the most unusual of which was a very early and intense moisture anomaly advected into the region prior to the development of the main event. Generally, there is a positive trend in heat wave activity over the entire region that is expressed more strongly and clearly in nighttime rather than daytime temperature extremes. Daytime heat wave activity has been intensifying preferentially over the elevated interior compared to the lowland valleys. Nighttime heat wave activity shows a strong positive trend over the entire region and record. This trend has intensified markedly since 2000. Circulations associated with great regional heat waves advect hot air from the south. This air can be dry or moist, depending on whether an appropriately positioned moisture source is available, causing heat waves to be expressed preferentially during day or night. A particular source is a marine region west of Baja California that has been experiencing significant atmospheric moistening, which is intriguing because this moistening appears to be related to a global sea surface temperature warming pattern.

Time permitting, we will compare and contrast observed and model-projected changes in heat waves for California, the Mediterranean Basin, and possibly other regions with Mediterranean climates around the world.

For more information contact Eroulla Cadd 22208600 or email e [dot] cadd [at] cyi [dot] ac [dot] cy