Every year that we fail to stem the tide, climate change gets closer to abruptly pushing species over tipping points as their geographic ranges reach higher and higher temperatures. That’s the big picture, and it’s some heavy stuff.
But suppose we zoom in from that wide view, for a moment, and focus on a much smaller scale, say, our own backyards. In the midst of all the big, bad biodiversity news out there, it turns out that just looking in those small patches surrounding our homes at all that creeps, crawls or flies proves the old adage that the everyday lives all around us are what’s truly extraordinary.
Nearing climate change tipping points
A tipping point is defined as the critical point in a process, situation or system beyond which a significant and often unstoppable change or effect takes place. In ecological terms, a tipping point is reached when an ecosystem can no longer cope with an environmental change, and the ecosystem suddenly shifts from one state to another. These shifts are almost always negative.
Now, a new study published in the journal Nature Ecology and Evolution predicts when and where climate change is likely to expose species across the globe to potentially dangerous temperatures—pushing them abruptly over tipping points.
For this study, a research team from the University of Connecticut, England’s University College London, New York’s University at Buffalo and South Africa’s University of Cape Town analyzed data from more than 35,000 species of animals (including amphibians, birds, cephalopods, corals, fish, mammals, plankton and reptiles) and seagrasses from every continent and ocean basin, alongside climate projections running up to 2100.
The scientists investigated when areas within each species’ geographical range will cross a threshold of thermal exposure, defined as the first five consecutive years when temperatures will consistently exceed the most extreme monthly temperature experienced by a species across its geographic range over recent history (1850–2014). Once that thermal exposure threshold is crossed, the animal is not necessarily going to die out; but there is also no evidence that it will be able to survive the higher temperatures. In other words, this research predicts that for many species, there could be an abrupt loss of habitat due to future climate change. Therefore, it is unlikely that climate change will gradually make environments more difficult for animals to survive in. Instead, for many, large swaths of their geographic ranges are likely to become unfamiliarly hot in a short span of time.
While some animals may be able to survive these higher temperatures, many others will need to move to cooler regions or evolve to adapt, which they likely cannot do in such abbreviated time frames. The researchers found that the extent of global warming will make a big difference: if the planet warms by 1.5 degrees Centigrade, 15% of the species they studied will be at risk of experiencing unfamiliarly hot temperatures across at least 30% of their existing geographic ranges in a single decade; but this doubles to 30% of species at 2.5 degrees Centigrade of warming.
In addition, another consistent trend was found: for many animals, the thermal exposure threshold will be crossed for much of their geographic ranges within the same decade. That means that many species facing unfamiliar temperatures will be living alongside other animals experiencing similar temperature shocks, which could pose grave risks to the functioning of local ecosystems.
The researchers state that while in the past, while we’ve had “snapshots” showing the impacts of climate change, this new data is more like a film, where you can see the changes unfold over time. It demonstrates that for many species, the risk is a bit like “everything, everywhere, all at once.” By animating the process, they hope to help target conservation efforts before it’s too late, while also showing the potentially catastrophic consequences of letting climate change continue unchecked. They conclude that once we start to notice that a species is suffering under unfamiliar conditions, there may be very little time before most of its range becomes inhospitable. So, it’s extremely important to identify in advance which species may be at risk in the coming decades.
Previously, a study by the same lead authors found that even if we stop climate change so that global temperatures peak and start to decline, the risks to biodiversity could persist for decades after.
Bordering big numbers of small beings
That’s the big picture at this point in time. But there’s another perspective I’d like you now to consider. That’s because it helps to temper the new Nature Ecology and Evolution analysis.
This outlook begins with a challenge among three housemates—University of Queensland mathematician Dr. Matt Holden, ecologist Dr. Andrew Rogers and taxonomist Dr. Russell Yong—to identify species around their inner-Brisbane, Australia, home during the COVID-19 lockdowns in 2020. What resulted was an astounding and upbeat academic research paper, showcasing the rich biodiversity to be found in urban landscapes.
The idea for the species count was born when Dr. Rogers went to vacuum cobwebs in his room and wondered how many spiders were on the property. The three soon envisioned a plan to comb through the house and backyard in search of the other critters that resided alongside them. Astonishingly, they discovered 1,150 unique species of animals, fungi and plants over a 12-month period.
Before their survey, the three asked a large number of conservation scientists and ecologists how many species they thought the housemates could be expected to find in this setting. The scientists predicted only 200. But after 60 days of surveying, the three had already discovered 777 species.
Included in those species were 436 butterflies and moths, 56 different spiders, 56 birds and eight reptiles. The bird species included blue-faced honeyeaters, laughing kookaburras, rainbow lorikeets, spotted doves, tawny frogmouths and a Brisbane favorite, the Australian white ibis. The housemates reported that blue-tongued skinks hibernated under the garage; and at night, blue-banded and teddy bear bees slept in the hedges under the front window.
Drs. Holden, Rogers and Yong stumbled upon the moth Scatochresis innumera, which, as a caterpillar, spends its whole time feeding inside the dung of a brushtail possum before emerging as an adult. The Parilyrgis concolor was another moth species whose caterpillar lives in spider webs and devours spider poop to survive. In fact, the house was a complex ecosystem of species interacting.
The three housemates were also surprised to discover three species not previously recorded in Australia’s leading biodiversity database, Atlas of Living Australia: a mosquito, a sand fly and an invasive flatworm, Platydemus manokwari, which is responsible for native snail population declines around the world.
The paper’s authors say that houses in all urban areas could play host to a similar array of biodiversity. It depends on how people tend to their homes and gardens; keeping low-maintenance shrubs and trees and eliminating manicured lawns and pesticides, they say, will significantly boost the number of beings found.
Verging on variety
Despite the warnings about climate change and their forecasted impact on biodiversity that have been sounding for decades, we have continued to stride ever closer to a precipice. I’m not sure, anymore, if we’ll be able to inch back from the edge. That doesn’t mean we shouldn’t try with a renewed commitment in 2024.
And, when we do take a brief break from that struggle, perhaps, we can comb through our own homes and backyards, find some unexpected creatures and delight in the diversity we discover.
Here’s to finding your true places and natural habitats,