Archives par mot-clé : Organisms

Abrupt summer sea ice decline has not affected polar bear numbers as predicted

by  Dr. Susan J. Crockford, July 14, 2017 in ClimateChangeDispatch

Yes, Arctic sea ice has declined since satellite records began in 1979 but polar bears have adjusted well to this change, especially to the abrupt decline to low summer sea ice levels that have been the norm since 2007. Some polar bear subpopulations have indeed spent more time on land in summer than in previous decades but this had little negative impact on health or survival and while polar bear attacks on humans appear to have increased in recent years (Wilder et al. 2017), the reasons for this are not clear: reduced summer sea ice is almost certainly not the causal factor (see previous post here).

Why there are so many species of tropical trees and other organisms

by Washington University in St-Louis, June 29, 2017 in ScienceDaily

If aliens sent an exploratory mission to Earth, one of the first things they’d notice — after the fluffy white clouds and blue oceans of our water world — would be the way vegetation grades from exuberance at the equator through moderation at mid-latitudes toward monotony at higher ones. We all learn about this biodiversity gradient in school, but why does it exist?