Crocuses, lilacs, warmer days and bird song...all are lovely signs of spring. Spring arrives when the Earth tilts towards the sun. As the planet tilts, it gets warmer. The Earth tends to take about a month to heat up.
Spring is Coming Earlier
According to satellite reports, over the last fifty years spring has been arriving an average of eight hours earlier every year. What is eight hours? Not much, but add the time together over a period of decades and there is a distinct change in the beginning of the season. In Washington, DC, the city's cherry trees are blooming a week earlier than they did thirty years ago. The lilacs are blooming an average of two days earlier every decade. Brian Unwin's March 2008 Telegraph article entitled "Migrating Spring Birds Arriving Early" points to climate change as a possible culprit. Like a pot simmering on a stove, the Earth is getting a little too warm, too quickly.
Is It a Problem if Spring Comes too Early?
Early planting and harvest and shorter winters sound good. However, a problem arises because plants and animals are tied in complex ecological webs. When the timing goes off in part of the web, certain plants and animals pay the price. For example, if a crop begins to create flowers but the pollinators are not around to spread the pollen, the crop could fail. Also, while the season is shifting overall, surprise snowstorms and cold snaps could kill plants that have started to grow too early.
Some Species Are Changing Due to Temperature Shifts and Others Are Not
If spring is getting here earlier, why aren't all of the species shifting at the same time? This is because different animals and plants use different cues to decide when spring is coming. Some of them use temperature. Other plants or animals use day length to decide when to sprout or migrate.
In the new age of early spring, those who rely on day length will keep their old patterns. The days keep on gradually getting longer, just like they always have. However, those species who rely on temperature will wake up or begin growing a bit earlier every year. They may arrive at their breeding grounds only to discover that a key plant hasn't grown yet, and they will go hungry.
The change in the seasons is a wonderful event. It's something that people look forward to, as winter changes into the new life of spring. However, as the climate shifts, spring is becoming more challenging for some of the world's species.
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