How the U S military tested its mettle and machinery in Alaska, from mundane surveys to a disgraceful medical study
adn.com - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from adn.com Daily Mail and Mail on Sunday newspapers.
The Costs of Sprawl Reconsidered: What the Data Really Show
heritage.org - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from heritage.org Daily Mail and Mail on Sunday newspapers.
The critical temperature beyond which photosynthetic machinery in tropical trees begins to fail averages approximately 46.7 °C (Tcrit)1. However, it remains unclear whether leaf temperatures experienced by tropical vegetation approach this threshold or soon will under climate change. Here we found that pantropical canopy temperatures independently triangulated from individual leaf thermocouples, pyrgeometers and remote sensing (ECOSTRESS) have midday peak temperatures of approximately 34 °C during dry periods, with a long high-temperature tail that can exceed 40 °C. Leaf thermocouple data from multiple sites across the tropics suggest that even within pixels of moderate temperatures, upper canopy leaves exceed Tcrit 0.01% of the time. Furthermore, upper canopy leaf warming experiments (+2, 3 and 4 °C in Brazil, Puerto Rico and Australia, respectively) increased leaf temperatures non-linearly, with peak leaf temperatures exceeding Tcrit 1.3% o