Atmosphere and Climate
Atmosphere and Climate
There is a compelling need for environmental managers to consider atmospheric and climatic impacts upon the systems they manage. Pounds et al. (2006) linked dramatic losses of frog species in the neotropical genus Atelopus to regional climate effects on the temperature and relative humidity of highland forests. They related frog disappearances to tropical air temperatures, finding that ~80 percent of the missing species were lost after relatively warm years. The strength of association between warm years and disappearing frogs was independent of elevation, latitude, or range size. Such an association of extinctions with warmer years leads to a paradox: the believed cause of death of the Atelopine frogs is chytridiomycosis due to outbreaks of the fungus Batrachochytrium dendrobatidis, but Batrachochytrium becomes more pathogenic at lower rather than higher temperatures. Pounds et al. posited a resolution to this paradox by coupling higher temperatures to increased evaporation rates resulting in more water vapor in the atmosphere. Higher atmospheric water vapor drives increased cloud cover over Monteverde and other sites where scientists observed disappearances. In this case, more clouds led to cooler days, because they reflected more solar radiation, but also to warmer nights as they decreased heat loss to the atmosphere. The net result was that the range of daily maximum and minimum temperatures was not only less but less in a way that favored chytrid fungi (which grow best at 17–25 °C). Preventing it from getting too hot by day or too cold at night, the increased clouds during warmer years kept the temperature “just right” for Batrachochytrium to infect frogs. Conservation biologists recognize the significant impact that regional shifts in climate may have on populations of conservation concern (Hannah et al. 2005). However, much of the remote sensing work on the atmosphere and climate addresses global-scale phenomena, such as general circulation models (GCMs) of the atmosphere. Moving from these global scales to scales more appropriate to conservation work continues to be a significant challenge.
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