Here’s a crazy aspect of climate change. On 25 July it was the UK’s hottest July day, and like one of those fairground hammer bells the mercury zipped up a thermometer in Cambridge, stopping just a fraction short of chiming 39C. Across Europe, though, all-time record temperatures were ringing out loud and clear – 45.9C in France, 40.5C in Germany. Yet on that searing hot day I saw my first almost-ripe blackberry of the year. Yes, at the height of this sweatiest of summer days there was a classic sign of autumn.
Actually, as far as nature is concerned it had been autumn since before the Wimbledon fortnight. I’m not talking about a Keats-like season of mists but we’re certainly witnessing the season of mellow fruitfulness way ahead of normal time. On 11 June I picked my first juicy bilberries on moorland to the west of Bradford, something which a couple of decades ago would have been unheard of until late July. And on 19 June, while birdwatching at the RSPB’s St Aidan’s nature reserve on the outskirts of Leeds I came across a hawthorn bush that positively blushed with red berries.
Since then I’ve seen other evidence of the seasons being out of whack: apples ripening in a North York Moors garden, a horse chestnut tree round the corner from my house laden with spiky green conkers two months ahead of time.
What’s going on is something called season creep. Basically, climate change is advancing the dates at which classic seasonal events in the countryside occur. The Woodland Trust’s Nature’s Calendar project, which is driven by a vast network of recorders around the UK, has concluded that rising global temperatures are confusing wildlife. Consequently, our summers and winters are shorter and the two main seasons are spring and autumn.
So although the Met Office still adheres to the yardstick that autumn runs from 1 September to 30 November, according to the Woodland Trust it now begins in June and December overlaps with springtime with events like blackbirds building their nests before Christmas.
Some people may rejoice at having autumn merge seamlessly with spring but I think it would be wrong to view season creep as a silver lining to all those climate change storm clouds. In fact, we should be worried.
Wildlife is already paying a high price. For example, hedgehogs are failing to hibernate from November to March, then starving because they go snuffling for their usual food of worms and beetles and can’t find any. As a result the UK hedgehog population is estimated to have fallen by one third since 2002.
But season creep spells bad news for all of us. Changes to nature’s clock are having an adverse effect on food production and the resulting imbalance in the ecosystem could wreak havoc. In recent years early crop growth due to season creep has been followed by late cold spells that have left frost-damaged harvests in fields. It is also causing a mismatch between crops and their pollinators, while harmful insects are emerging well before the arrival of the migratory birds that prey on them.
They are not as dramatic as floods and wildfires, but those early berries and conkers are a reminder that we have to work harder to stop climate change.