A study led by Princeton University researchers suggests that hotter nights may wield more influence than previously thought over the planet's atmosphere as global temperatures rise -- and could eventually lead to more carbon flooding the atmosphere. The researchers determined that warm nighttime temperatures, specifically in the tropics, lead plants to release more carbon through a process known as respiration. Average nighttime temperatures in tropical regions such as Manaus, Brazil, (above) have risen by 0.6 degrees Celsius since 1959. Further temperature increases risk turning Earth's land-based carbon-storage capacity, or sink, into a carbon source.
Just as warm nights make people more active, so too does it for plants. Although plants take up carbon dioxide from the atmosphere, they also internally consume sugars to stay alive. That process, known as respiration, produces carbon dioxide, which plants step up in warm weather. The researchers found that yearly variations in the carbon sink strongly correlated with variations in plant respiration.