(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 spring, or vernal, equinox occurs around March 21 in the Northern Hemisphere and around September 21 in the Southern Hemisphere. In the Northern Hemisphere, the North Pole is tipped at its greatest angle toward the sun during the summer solstice, which occurs around June 21.