Which are the implications of the changing length of the seasons as a warming world brings longer summers and shorter, hotter winters?
ADMITTEDLY,, the very idea of a ‘season’ is rather blurry. If you live near the Equator, you effectively have one season, with the same amount of daylight throughout the year – maybe two if you count the wet and dry periods. If you live not too far from the Arctic Circle, you basically experience two. But if you stand in the fortunate belts stretching somewhere between 30° and 60° – north of the Tropic of Cancer and south of the Tropic of Capricorn – you get the full treat of four discrete seasons.
For most of us, accustomed to living through this sequence of distinct climatic episodes every year, it makes a kind of arithmetical sense. Two equinoxes and two solstices split a year into four sets of three months with a similar length. Curiously, even each of Antonio Vivaldi’s Four Seasons has an analogous duration of 11 minutes (although some conductors make winter a little shorter).
We’re now in for a big change. According to a paper published some time ago by a group of researchers from three Chinese universities, ‘as global warming intensifies, the four seasons of a year no longer have equal months and their onsets are irregular’. The new normal is longer and hotter summers, shorter and warmer winters, and shorter springs and autumns. ‘This kind of trend,’ the authors write, ‘may be unavoidably amplified in the future.’
As we now approach the winter solstice, celebrated for millennia as a new beginning, a symbolic rebirth of the Sun, we’re about to say goodbye to a year that may go down in history as a climatic milestone. ‘We are now in an uncharted territory,’ warns the 2023 State of the Climate, a report compiled by a group of renowned climatologists that includes Sir David King, former chief scientific adviser to the UK government. ‘In 2023, we witnessed an extraordinary series of climate-related records being broken around the world,’ the report reads. In July, the planet reached the highest global daily average surface temperature ever measured, ‘possibly the warmest temperature on Earth over the past 100,000 years’.
No wonder the paper concluded that by the end of the century, summers could extend to nearly half the year. The meteorological definition of season would diverge more and more from the astronomical one. More prosaically, both the younger generations and future ones are going to experience a different type of life on Earth.
A shift in seasonal patterns could unsettle human and animal communities alike. Plants blooming sooner and birds migrating earlier could end up disrupting the balance of natural habitats. Warmer winters may cripple agricultural output as crops might not experience the cold dormant phase that’s essential for optimal growth, which could affect both the quality and quantity of produce. On the other hand, extended summers may increase the likelihood of intense heat spells and extreme weather events, presenting a string of new survival challenges for most species, including ours.
Phenologists – those who study the impact of periodic events on biological life cycles – are already talking about a ‘season creep’, a gradual yet unrelenting change in the rhythm of meteorological seasons. This is probably the climatic effect most acknowledged by the general public (‘The seasons aren’t what they used to be’) – at least by those living in the temperate belts. Yet, its innate slowness makes it appear like a normal, or maybe inescapable, problem. It isn’t.
It’s humanity’s common responsibility to stave off the worst outcomes of these trends – a responsibility as big as the survival of species whose destinies are interwoven with ours, and as big as the future of humanity itself. Because of the physical and chemical properties of the molecules we’ve been adding to
the atmosphere, climate change can’t be stopped, let alone rewound. The seasons will keep on changing and the lives of future generations will be different from ours. But we still have time and we absolutely must make sure that it won’t be too much different, come rain or shine. Or, in updated terms, come hail or drought.
Published on the December 2023 issue of Geographical Magazine
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