During my time spent living in Japan, I was frequently asked by locals if, back in my country, we have four seasons. At first I thought this was a ridiculous question, as in my opinion, the world doesn’t stop rotating just for one country to avoid a season or two. But after experiencing weeks of lovely spring weather in the middle of what should have been a South African winter, I’m starting to wonder if the way we define our seasons isn’t a little outdated. Thanks to climate change, seasonal patterns are shifting, and it might be time to think about redefining the four seasons accordingly.
When I was a kid, I was taught that there were four seasons: winter, (which is cold and in my opinion terrible), spring (when the flowers bloom), summer (when you melt) and autumn ( when things turn orange). That was just the way things were. That is, until I moved to Japan, where they insist that only their country has all four of those seasons and make it sound like an achievement. Imagine my (and their) surprise then when my Indian colleague announced that India has five (including monsoon season)! Even in a country that so proudly demarcates its weather changes as Japan, though, the lines between the seasons are starting to blur, as rainy seasons get longer and winter snowfall dwindles.
So how do we actually define the four seasons anyway?
Well, actually there are two ways of doing that.
In the astronomical definition, the seasons are determined by how long each day is, which in turn is determined by the relative tilt of the Earth’s axis as it revolves around the Sun. According to that system, winter falls between the winter solstice, the shortest period of daylight in a year, and the vernal equinox, when day and night are about equal. Spring then lasts from the vernal equinox to the summer solstice, which marks the longest period of daylight. Summer then runs until the autumnal equinox, when light and darkness are equal again, and is followed by autumn, which continues until the winter solstice. The cycle then repeats again year after year.
The meteorological system is a lot less complicated, and probably the one most people subscribe to. The year is simply divided by four, meaning winter (in the Southern Hemisphere) falls over June, July, and August; spring is in September, October, and November, and so forth. Don’t ask me where India’s fifth season falls in there. I didn’t learn that one in South African primary school.
But human-induced climate change is redefining the four seasons
According to Patrick J. Kiger at How Stuff Works, recent discoveries show that as the planet warms up, the tropics have been expanding by 0.1 to 0.2 degrees of latitude every ten years. As a result, many of the places that once had four seasons are shifting to having only a measly two ( so the Japanese might be on to something when they interrogate foreigners about how many they have). Even in regions with four seasons, though, weather and temperature patterns are rapidly changing.
Kiger writes that across the USA, winters are becoming shorter as the shift from chilly winter temperatures to warmer spring weather starts earlier. In the last decade, some cities have even surprised by record breaking summer heat in the middle of their winter months.
This phenomenon is so prevalent all over the world, in fact, that it’s garnered the name “season creep”, and it’s led to a lot of observable changes in the natural world. Birds start laying their eggs earlier, and flowering trees start budding sooner. Even Japan is not exempt from the shifting seasons, as their much-loved cherry blossom trees have been blooming earlier than in previous decades.
It may seem like a lot of fun to have a longer summer and a shorter winter, but over the next few decades it may cause serious problems for agriculture and wildlife. Not to mention, we might need to rethink the ways with which we measure the seasons. In the future we may even begin to question whether we really need names for four distinct seasons, or whether having two would suffice. Perhaps, like India, we’ll even need five.
It sounds silly to even consider redefining the four seasons, and perhaps that’s because the shifting seasons are only the seemingly innocuous visible effects of a far more serious issue. The real problem here is not an extra week of summer, but how our behaviour is altering the world we know, and the one our parents and grandparents knew. Our future generations may not experience the world as we do, purely because we’ve allowed it to become a shadow of its former self.
That’s just some food for thought next time you’re admiring the lovely spring weather in the middle of what should be winter. It might also be a good answer to keep in mind for when you visit Japan and are asked about the seasons. Just in case.