(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 is the season when cold winter temperatures gradually rise to the warmth of summer. Spring begins on the vernal equinox, when the hours of daylight are equal to the hours of darkness. In the Northern Hemisphere this occurs on March 20 or 21. In the Southern Hemisphere it happens September 22 or 23.