Global warming is already causing serious problems all around the planet, from stronger storms and longer droughts to rising seas and expanding diseases. But at the same time, it's also spurring lots of less serious, even innocuous phenomena — trumpeter swans are thriving in Alaska, for example, while Rocky Mountain marmots are feeling friskier.
And according to a new study published in the ecology journal Oikos, feral goats may also flourish on this thin, ephemeral silver lining of climate change. Whether that would be good news for anyone but goats, however, remains to be seen.
Researchers from the University of Oxford arrived at this forecast by studying a database of feral goat populations to map where they lived. It turns out anywhere north of 60 degrees latitude has traditionally been a no-goat zone, thanks to a mix of cold weather, scant daylight and low-quality vegetation. The problem isn't that goats simply freeze to death, but that the cold climate requires them to eat more food — and the same climate also makes plants less nutritious, requiring them to eat even more food. On top of that, the sun spends less time above the horizon at high latitudes, so northern goats face the unenviable task of eating more food in less time than their southern cousins.
"The further north they go, the more the goats are trapped by a combination of the costs of thermoregulation and declining vegetation quality, both of which require them to spend more time feeding," explains lead author Robin Dunbar. "But winter day lengths get shorter as you go further north. There comes a point where those two opposing forces crash together and they run out of time. That's the point north of which goats can't live."
But that's also where global warming comes in. By examining a specific goat population that lives on Scotland's Isle of Rum, Dunbar and co-author Jianbin Shi found that climate change is making day length and food quality less of an issue. "As temperatures have started to climb by bits of a degree over the last half century, we've been seeing the numbers of goats on the Isle of Rum increasing," Dunbar says. "As the climate warms, goats will be able to live further north. It's about one degree latitude further north for every one degree warmer in mean annual temperature."
Of course, climate change is never that simple. Dunbar adds that in the British Isles, goats' population boom could be offset by changes to the Gulf Stream, which normally keeps Western Europe warm for its high latitude by pumping in heat from the Gulf of Mexico. As global warming tinkers with the oceans' thermohaline circulation, the Gulf Stream could weaken or even vanish, leaving Europe — and its goats — out in the cold.
For now, though, rising temperatures seem to be helping goats thrive on the Isle of Rum, a trend Dunbar expects to apply elsewhere, too. And that may not be welcome in some parts of the world, since goats aren't always good ecological citizens. Their relentless grazing has wreaked havoc in the Galapagos Islands, for example, where balmy weather and a lack of predators have let them devour swaths of native plants. But that probably won't happen in the U.K., Dunbar notes. "Even under the worst climate change scenarios, we're not going to be basking in tropical palm trees in Britain," he says, "so it's very unlikely we're going to get the ecological disasters seen in the Galapagos."
And even if goats do run amok in other places, Dunbar says we shouldn't blame them. Not only is global warming largely fueled by our carbon emissions, but we're also responsible for bringing goats into habitats where they didn't evolve, so it's our job to manage the ecological consequences. "In some respects, goats have got a bad reputation," he says. "They're often not themselves the cause of habitat degradation; it's just that they're very good survivors. When well managed, they can be good landscape managers."
Nonetheless, with global temperatures projected to rise by up to 10.8 degrees Fahrenheit in the next 88 years, it's worth considering what a goat-friendlier world might be like. Despite potential benefits like goats mowing our lawns and eating our garbage, for instance, we'd also have to tolerate more of this:
Related goat stories on MNN:
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- Mountain goats are nature's finest high-elevation critters
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