(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.
Washington's Birthday. Winter. In the United States and the rest of the northern hemisphere, the first day of the spring season is the day of the year when the Sun crosses the celestial equator moving northward (on March 20 th or 21 st). This day is known as the Vernal Equinox.