Why does spring happen?

What happens when winter begins to fade and spring brings the promise of regeneration?

Spring occurs as a result of the planet warming up after a plunge in the temperature during winter. There are several biological indicators that signal the season’s arrival. Plants start to bloom, hibernating animals resume their activities and soilborne microfauna (tiny organisms in the ground) begin to thrive. Snow-covered areas begin to see the light of day, and melted snow feeds into streams and rivers. In coastal areas, snowmelt trickles into the ocean after picking up nutrients during its journey. This enriched water causes enormous plankton blooms, which in turn support the rest of the sea’s ecosystem.

The timing of spring is affected by a number of factors. A region’s latitude and longitude determine when spring kicks in, along with the weather during that particular year. Countries in the southern hemisphere experience the opposite effects to the northern hemisphere. When flowers begin blossoming in Europe, leaves start to fall from the trees in Australia. Spring has no fixed arrival date – it happens when the conditions are right. Its arrival has a plethora of effects on Earth’s organisms. As plants shoot up from the ground, food availability increases. Herbivores get the opportunity to forage, while carnivores lie in wait for their prey. Sunlight hours extend, rain enriches the ground, and a huge number of species give birth to their young. The planet transforms before our very eyes every year, breathing new life into the Earth. Find out more about the science of springtime in issue 123 of How it Works out 21/03/19