(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.
The first climatological day of spring, as mandated by the World Meteorological Organization, is March 1 every year in the northern hemisphere and September 1 every year in the southern hemisphere. Canada, the USA, and some European countries customarily observe the astronomical date (ca. March 20-21/ca.