An unexpected visitor appeared in the back garden a couple of weeks ago, a foraging bumblebee. Is this a record, I thought to myself, given it was still only early February.
It meandered about for a bit before landing on a normally frost-sensitive window box plant that was brimming with blooms. Clearly there had been no frosts cold enough to kill off the plant and the bee cashed in on the free lunch before drifting off into someone else’s garden.
A few days later either that same bee or its nestmate made another visit, so it was no coincidence. I later learned that this was not one for the record books: bumblebees are willing to forage throughout the winter, weather permitting. There have been no further visits, at least that I have witnessed, but it seems as though there has been nothing but rain over the past weeks and that might have encouraged the bumblebees to stay under cover.
This little tale, absolutely true by the way, has climate warming written all over it, but without a heavy overlay of scientific evidence. Our neighbourhood hasn’t seen three days of frost all winter so far and that must be keeping the plant alive. And clearly the plant is expecting visitors, as it was well in bloom and ready for any bumblebees that might show up. There is no hard evidence embedded in this vignette that climate warming is under way in the Dublin suburbs, but where might one look for evidence?
You could look at the heavy, sometimes unprecedented rainfalls affecting the west and northwest and pushing the Shannon into damaging flood, with the waters rising as you read this. Maybe in the unprecedented wildfires in Australia that so far have killed 34 people and burned 18.6 million hectares of land. If this doesn't convince that climate warming is real then have a look at recent climate-related science; there is plenty of it about these days and in recent times the results often link to one of the more frightening consequences of climate warming – the presence of its evil twin, biodiversity loss.
Scientific study
Let's go back to our bees and look at a scientific study of bumblebee decline published earlier this month by the journal Science. Peter Soroye and colleagues from the University of Ottawa in Canada and University College London carried out a huge study, wading through 550,000 records of 66 bumblebee species, comparing two time blocks including from 1901 to 1974 and from 2000 to 2014. The team compared the bees' geographical and diversity distribution with local changes in temperature and precipitation.
They discovered the richness of bumblebee species declined rapidly between 2000 and 2014. The probability of a site being occupied by bees sank by 46 per cent in North America and 17 per cent in Europe compared with the earlier time window. The study showed that the bees were hardest hit in warming southern regions including Spain and Mexico, with just too much heat for them to be able to cope.
The bumblebees did expand into the northern fringe of their typical range, but to a smaller extent than the losses in the southern fringes. This could strain the bees’ ability to cope quickly enough with the changing climate, something which should not be dismissed as a minor inconvenience.
Bumblebees are top pollinators and many essential food crops are pollinated by them. Their loss or decline would have serious impacts on food production at a time when rising temperatures are stressing both pollinators and the food plants themselves. It is sobering when you consider that the current decline in bumblebee populations has occurred over a single generation, the researchers said.
Widespread threat
This threat to biodiversity, driven by human activity, is now widespread and being seen in many habitats, but the Earth can deal with this as it has five times before when mass extinctions have been triggered. During most of these mass deaths 75 per cent to 85 per cent of all land and marine species were wiped out. The worst of the five, known as the Permian-Triassic mass extinction, or more prosaically as the Great Dying, eliminated 96 per cent of all marine species and 75 per cent of land species.
After each extinction new life emerged from those creatures that survived to repopulate the seas and the land. But most of these mass extinctions, except for the asteroid impact that wiped out the dinosaurs, progressed over millions of years. We may now be watching the beginnings of the sixth great extinction, this time progressing very rapidly and impacting the Earth’s systems within a matter of a few human generations.
Up to 1 million species of all kinds are already under threat as a result of human activity, and without doubt more will be even if we discovered a way to undo the damage, given that warming will continue to rise on the basis of what we have already done. The Earth doesn’t mind, however, whether we are amongst the sixth mass extinction survivors or those creatures who disappeared. The planet will just sweep up the mess and dump it into the bin marked extinct.
