Environment

It’s unsettling to imagine that in the near future, young people will have a very different understanding of the seasons

From Antarctica to the east coast of Ireland, plants worldwide are blooming at unexpected times

Group of blue butterflies (Lycaenidae)

Ella McSweeney's face
Ella McSweeney
Sat Feb 3 2024 - 05:00

I’ve spent decades getting used to our long, grey winters. It can feel as if the natural world has entered a lethargic holding pattern that seems never-ending until it’s broken by the energetic arrival of spring.

Liz Sheppard is an author whose farm and woodland near Raphoe, Co Donegal, stand as glorious havens for wildlife. In her book Donegal for All Seasons (1992), she writes about the day, usually in the middle of April, which marks the beginning of spring. She describes walking out into the morning sunshine, surrounded by birdsong, spotting great woodrush and patches of wood anemone in bloom, along with the dark, glossy leaves of celandine and the tips of bluebell that push up through the ground.

Sheppard observes a natural world finely tuned to Earth’s tilt relative to the sun. As the days lengthen and temperatures rise, species have evolved to emerge at a time that maximises their chance of survival and reproduction. So, in April, the lilac-tinged holly blue butterfly prepares to lay her white disc-shaped eggs along the base of an unopened bud on a holly tree. She times it perfectly; when her pale green caterpillars emerge, they’ll feed on the tiny flower buds.

The theme of the synchrony of nature also runs through Ronald Rood’s book Who Wakes the Groundhog? (1973), in which he observes and describes in detail the interdependence of different species for their reproductive success.

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Take the female damselfly. She waits until the water temperature rises before diving beneath the surface of a pond to lay her eggs on floating or submerged vegetation. Unbeknown to her, waiting nearby is a minuscule parasitoid wasp, the size of a grain of sand, which swoops in the second the damselfly has gone. This tiny, deadly hitchhiker enters the water, using her wings as oars, and lays her eggs inside the damselfly’s eggs. When these wasp eggs hatch, they have a ready-made meal to enjoy: the tissue of the damselfly nymph.

Timing is everything. Anything less than that is fatal, so nature follows synchronously. As Rood writes: “You seldom find the fierce nymphs of the assassin bug until there are newborn caterpillars to assassinate.”

One of the most exquisite examples of synchronicity is that of the early spider orchid (Ophrys sphegodes) and the solitary miner bee (Andrena nigroaenea). In early spring, triggered by an increase in temperature, the male miner bee emerges from hibernation a week before the female. During these seven days – an eternity to him, no doubt – he flies around, waiting for her to emerge.

The orchid, needing a pollinator for successful reproduction, has entered this celibate abyss by mimicking the female miner bee’s shape and scent, which entices the male into its flowers. As the bee puts all his focus and energy into mating with a petal, the orchid covers him in pollen.

This elegant entanglement has evolved over millions of years. But our rapidly warming climate means relations between the orchid and the bee are falling out of sync. Scientists in the UK examined historical records of bee flight, orchid flowering, and weather dating back three centuries. They discovered that rising temperatures have caused the orchids to bloom earlier and the bees to emerge earlier.

They are not, however, responding to the warming climate in the same way. Female bees are emerging up to two weeks earlier than usual – before the orchid has flowered. Since male miner bees prefer to copulate with females rather than with flowers, the orchid isn’t being pollinated and is falling into reproductive failure.

It’s unsettling to imagine that in the near future, young people will have a very different understanding of the seasons

From Antarctica to the east coast of Ireland, plants worldwide are blooming at unexpected times. This is evident from data collected during last year’s New Year Plant Hunt, organised by the Botanical Society of Britain and Ireland. It’s a yearly citizen-science survey that occurs for a few days on either side of January 1st. Participants are asked to walk for three hours and record every plant in bloom. The latest survey attracted a record number of participants in Ireland.

The results, published last week, were stark: half the species were flowering later than expected, a 30 per cent increase over the previous year. These “autumn stragglers” continue to flower because of the mild winters and lack of October frosts. Not only that, but spring flowers, such as celandine, are emerging earlier. It usually flowers in February and March but is now blooming in December.

Paul Green, a Wexford-based botanist who has participated in the New Year Plant Hunt since it began 13 years ago, is increasingly concerned about the climate-driven mismatch between when flowers bloom and when insects and birds emerge. He recorded snowdrops flowering for the first time in early December. Meadowsweet, a tall perennial with white fluffy flowers, typically blooms from summer until the first cold snaps in October. Green recorded it in late December.

[ From the Sargasso Sea to Lough Furnace, our eels face an increasingly perilous pilgrimage ]

It makes sense that seasons are going haywire. Last year was the planet’s warmest since 1850, and December was the warmest December ever. The consequences on the natural world are too immense to comprehend, and it’s unsettling to imagine that in the near future, young people will have a very different understanding of the seasons.

All we can do, as Liz Sheppard has done for the last 30 years in Donegal, is prioritise the restoration of nature wherever possible and advocate for rapid decarbonisation. It’s with these actions that we can stay hopeful.

As for our seemingly endless grey winters, I should just relax and enjoy them.

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