Seasons are not like they used to be.
People living in the middle latitudes of the world are accustomed to spring, summer, autumn and winter. If you’re in the northern hemisphere, you may have noticed that plants are blooming earlier than usual. It’s not your imagination: A 2022 study found that spring flowers coming a month early in the UK due to climate change.
For a new series We will be examining the consequences of these wrinkles in nature’s calendar in the coming months as we look at the seasons and how they are skewed by a warming climate.
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How do plants sense the seasons?
Other species cannot coordinate their activities to a specific date and time. Paul Ashton, chair of biology at Edge Hill University, says plants, the foundation of most ecosystems, stay current by paying close attention to changes in light and temperature.
Plants are among the first to learn when the days start getting shorter in the fall, as they use a pigment called phytochrome to detect changes in red light.
“While this subtle change eludes humans (our eyes are not sensitive to this part of the spectrum) a plant can detect this transition and begin to change.”
“Just as autumn causes a drop in the level of the hormone serotonin in our blood, a plant sensing the approach of winter will increase its production of a hormone called abscisic acid,” says Ashton. Abscisic acid allows deciduous trees to shed their leaves and grow hardy, frost-resistant winter buds.
Temperature tells many plants when to start growing in the spring. It’s not clear how plants sense this, Ashton says, but pigments in their cells likely play a role.
“[Plants] “It feels like the days are getting warmer, and it changes spring development in a way that’s similar to how people feel warmth on their skin and thus go out with less clothing.”
Read more: Plants are blooming earlier than ever – here’s how they sense the seasons
This is where climate change complicates matters: Rising temperatures have led to shorter, milder winters. Since 1986, plants in the UK have welcomed spring an average of 26 days earlier.
This relatively rapid change broke the agreement that plants and animals had agreed upon for thousands of years.
“Insects that are used to feasting on plants that bloom in April may find themselves a month late if warmer temperatures mean plants are now blooming in March,” say Chris Wyver and Laura Reeves, PhD candidates studying pollination and climate change at the university. Reading’s.
Read more: Plants are blooming a month early – here’s what this could mean for insect pollination
out of the loop
Hungry insects are bad enough. But if insects appear too late to visit waiting flowers, the entire ecosystem suffers.
“Take, for example, birds such as the blue tit, great tit and pied flycatcher that live in European oak forests,” says Charlie Gardner, lecturer in conservation biology at the University of Kent. Caterpillars are emerging earlier than in the past, and the birds that eat them can’t keep up.
“For every ten days of advance in caterpillar emergence, birds can only advance egg-laying by three to five days, depending on the species,” he says.
Read more: Climate collapse is throwing the natural world out of sync and we should all be worried
Strange weather patterns, a more common feature of our warm climate, can also confuse wildlife’s finely tuned senses, fooling some species into thinking the season has changed when they aren’t paying attention.
Stuart Thompson, a senior lecturer in plant biochemistry at the University of Westminster, highlights how the drought scorching Europe in 2022 has persuaded some trees to lose their leaves, giving the impression of autumn in mid-August.
Read more: Drought: Why do some UK trees lose their leaves in August?
Among the broader trends scientists have documented, at least one thing is consistent: Winter is being squeezed from both sides as the Earth warms.
“Climate researchers now have nearly fifty years of satellite observations,” says Jadu Dash, professor of remote sensing at the University of Southampton.
“Analysis of these data reveals that spring has advanced by approximately 15 days, while autumn has been delayed by a similar amount.”
Read more: How is climate change affecting the seasons?
But climate change won’t simply usher in seasons where everything will happen a month earlier or later. While some species will delay hibernation and emerge earlier in the spring, others will stick to their original schedule and take their cues from day length rather than temperature.
The result will be chaos, says Gardner:
“If we want to have a chance of protecting the living planet and preventing the extinction of a million species, we must do more than stop climate breakdown. We also need to invest in conservation to help wild plants and animals adapt to the changes we are currently locked into. “Not doing so would be bad news for all of us.”
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