(2007) concluded, with very high confidence, that regional temperature trends had already affected species and ecosystems around the world (p. 792). With high confidence, they concluded that climate change would result in the extinction of many species and a reduction in the diversity of ecosystems (p.
Full Answer. Use of the Gregorian calendar keeps the arrival of spring on March 20 or March 21 for most years, though sometimes spring arrives on March 19. According to National Geographic, in addition to the astronomical start of spring, a biological spring begins each year, usually on a different date.
Spring starts about Mar 21 ( or Sept 21 - Southern H.) Summer, about June 21 (or Dec 21 - S.H.) Fall, about Sept 21 (or Mar 21 - S.H.) Winter about Dec. 21 (or Jun 21 - S.H.) The exact time varies slightly because the orbit is just slightly more than 4X3 months per season - 365 1/4 days all together.