Brandon Keim writes: In the Great Basin desert of the western United States, not far from the Great Salt Lake, is a kind of time machine. Homestead Cave has been inhabited for the past 13,000 years by successive generations of owls, beneath whose roosts accumulated millennia-deep piles of undigested fur and bone. By examining these piles, researchers have been able to reconstruct the region’s ecological history. It contains a very timely lesson.
Those 13,000 years spanned some profound environmental upheavals. Indeed, the cave opened when Lake Bonneville, a vast prehistoric water body that covered much of the region, receded at the last ice age’s end, and the Great Basin shifted from rainfall-rich coolness to its present hot, dry state. Yet despite these changes, life was pretty stable. Different species flourished at different times, but the total amount of biological energy – a metric used by ecologists to describe all the metabolic activity in an ecosystem – remained steady.
About a century ago, though, all that changed. There’s now about 20 per cent less biological energy flowing through the Great Basin than at the 20th century’s beginning. To put it another way: life’s richness contracted by one-fifth in an eyeblink of geological time. The culprit? Not climate change, as one might expect, but human activity, in particular the spread of invasive non-native grasses that flourish in disturbed areas and have little nutritional value, sustaining less life than would the native plants they’ve displaced.
I find myself thinking often of the parable of Homestead Cave, as I’ve come to call it. It underscores how resilient nature can be, and also the enormity of human impacts, which in this case dwarfed the transition to an entirely new climate state. The latter point, I fear, is too often overlooked these days, obscured by a fixation on climate change as Earth’s great ecological problem.
Make no mistake: climate change is a huge, desperately important issue. And it feels strange, if not downright traitorous, to raise concerns about the attention it receives. The parable of Homestead Cave is no licence to shirk climate duties on the assumption that nature will adapt, or to imagine that a rapidly warming, weather-extremed Earth won’t be calamitous for non‑human life. It will be. But so is a great deal else that we do. Paying attention to climate change and to other human impacts shouldn’t be a zero-sum game, but it too often seems that way. [Continue reading…]
