Never mind dreaming of a ‘White Christmas’ I’ve just lived through the balmiest festive season I can remember.
Temperatures may very well have reached record heights but such ‘unseasonal’ warmth is no longer an outlier, it’s the norm. Very quickly I’m also reminded of Baltic conditions in April, suggesting the seasons are increasingly out of kilter.
Evidence of the shift in climatic conditions is everywhere, whether it’s swallows overwintering in Co Down or a proliferation of men with tattooed legs wearing shorts in December and January.
You can also see it in the garden – pictures of daffodils in bloom on the local WhatsApp wildlife group and reports of snowdrops coming into flower weeks before they’re supposed to.
The Phenology Project at Cambridge University Botanic Garden has been tracking the effects of climate change on nature by monitoring 90 marked trees and woody plants in the gardens since 2020.
Through phenology, which is the study of seasonal changes in plants and animals from year-to-year, researchers hope to better understand how wildlife and plants respond to environmental change.
They’ve found that species such as oaks and cherry birch (Betula lenta) came into leaf and flowered earlier last year.
It would also appear that leaves are staying on the trees longer, meaning they’re having a longer active season and are dormant for a shorter period, potentially putting greater stress on the trees. Also, any blossom that appears early may be killed off by those increasingly harsh springs.
Climate change is expected to transform our gardens in ostensibly positive ways, such as increasing the range of tropical plants we can grow outdoors. Edibles like grapes, apricots and figs, that up until now have only prospered in gardens at the other end of Ireland, may become much more common in Ulster.
Rising winter temperatures have also seemingly extended the season for bulb planting, which was previously finished by mid-November but now includes up to early January.
The corollary of this, however, is that some bulbs, such as tulips and alliums, require a cold period – what’s knows as cold stratification – to develop their roots and ultimately their flowers to their full potential. So far this winter, it’s debatable whether the mercury has dropped far enough to trigger this important process.
Another downside is the year-on-year survival of pathogens that would previously been killed-off by frosts.
Over the past decade in southern Italy, a bacterial plant pathogen called Xylella fastidiosa – or the easier to pronounce ‘olive quick decline syndrome’ – has devastated hundreds of olive groves.
Whereas a process known as ‘winter curing’ would have previously restricted the spread of the spittlebug, which carry the bacteria from one olive tree to the next, the area in which the insects can survive throughout the year is steadily moving northwards.
The rapid spread of Phytophthora, the family of airborne fungi that includes potato blight, is also blamed on climate change, as is the endurance of insects such berberis sawfly and red spider mite, as well as new vine weevil species.
The absence of prolonged spells of sub-zero temperatures will also impact on soil structure, as freezing moisture helps break up the soil and make it more friable. Meanwhile, drier conditions combined with more regular strong winds will increase soil erosion and moisture loss.
Climate change for gardeners is very much a double-edged sword.
