Surviving the Big Freeze

Prof russell coope low res

I meet Professor Russell Coope on the front step of his house, overlooking the wilds of Loch Tummel in Highland Perthshire. His home immediately strikes me as an apt setting for a paleontologist who has dedicated much of his life to studying the natural history of ice ages. This highland landscape was once carved out of ice by a glacier several kilometers deep.

Prof. Coope shows me into a small study crammed with the remains of animals that have roamed the area. The skull of a saber toothed tiger gathers dust next to a set of woolly mammoth teeth and the pelts of otters, fox and wildcat. At 81 years old his passion for the natural world remains undimmed. After a long career lecturing paleontology at Birmingham University he still studies fossils for academic institutions around the country.

I explain that I had come in search of the answer to a perplexing question: how would wildlife adapt if we were to be thrown into an ice age?  Core ice samples from the arctic shelf and analysis of ocean sediments provide detailed records of how the climate has shaped the Earth’s distant past. These data, together with the fossil record, might help tell the story of how life on our planet has learnt to adapt to periods of extreme cold in the past.

The world has actually enjoyed a remarkably benign climate for several thousand years. Europe experienced a prolonged period of cold, severe winters between the 16th and 19th centuries when the River Thames would famously freeze over and frost fares were held on the ice. But as hard as these winters were they are unlikely to have caused big changes in the density and distribution of plants and animals. I spoke to Dr. Mark Spencer, a botanist at the Natural History Museum in London, who confirmed that: “From a botanical point of view, within the UK, there is no evidence of large scale species extinction during this cold period.”

The last truly big freeze in the Northern Hemisphere was the Younger Dryas Ice Age 10,000 years ago, when the polar ice cap stretched right down the west coast of Scotland into Loch Lomond. With average winter temperatures constantly well below freezing, the landscape would have resembled the sparse, treeless tundra of northern Scandinavia. It was so cold during this period that even the last of the woolly mammoths in the British Isles are thought be to have perished.

Prof. Coope’s main interest for the past fifty years has been in much less exotic creatures. He was overseeing the excavation of the remains of a woolly mammoth back in January 1955 when he noticed what looked like tiny black shells surrounding the bones. On closer inspection the shells turned out to be the fossilized remains of tens of thousands of beetles. “ Beetles are important climate indicators because they have such robust skeletons…they make great fossils,” Coope tells me.

Prof. Coope has been studying them ever since. The table in his study is covered with Petri dishes filled with black soil from different core samples. He invites me to peer into his microscope to see a whole new world of 100,000 year old beetle parts come into view. There is a strange beauty to these abstract shapes suspended in water. Some of their wing covers still glitter like brilliant, emerald jewels.
Prof. Coope’s conclusions from his study of these beetles mirrors research by climate scientists. He found that the Northern hemisphere appears to be have oscillated wildly between hot and cold over the past three million years. He found warm weather beetle species that would have lived in Britain alongside hippopotamus 120,000 years ago. Flash forward to 40,000 years ago (the blink of an eye in geological time) and these beetles have been replaced by high arctic species that are only found today in northern Russia.

This pattern of dramatic shifts between glacial and interglacial periods is repeated again and again in the fossil record. “Climate change is not gradual as we have been led to believe but happens suddenly, intensely and frequently,” comments Coope. “The Younger Dryas Ice Age is though to have replaced the previously temperate period in the space of a few decades.” 

This climactic instability has only given wildlife one survival strategy: movement. To avoid extinction species have had to make dramatic shifts in their geographical range to stay within their environmental limits. More mobile species such as winged insects, birds and plants that disperse their seeds widely in the wind have found it relatively easy to adapt. For the more pedestrian species, including many of the beetles that Coope has studied, these sorts of movements are much harder.

Prof. Coope pulls up a large, wooden drawer neatly lined with hundreds of tiny beetles mounted on needles. He picks one species, Donacia semicuprea, and shows me how it is identical to some of the 100,000 year old beetles that I have been looking at under the microscope. “I have no evidence that these beetles have evolved at all in the northern hemisphere in the last million years,” Coope explains. “To me the stability amongst my animals is due to the instability of the climate…it is as though evolution keeps getting set back to zero”

By the time step back outside Prof. Coope’s house the possibility of another glacier stretching through the Tummel Valley seems much more real than I had previously imagined. The debate rages over whether these dramatic shifts in temperature are caused by atmospheric changes, sunspot activity, or even the Gulf Stream switching off. The only certainty is that burning fossil fuels adds a whole new area of uncertainty into the mix. Coope puts it bluntly: “We are messing around with the trigger that causes climate change. We don’t know what the consequences will be but they are likely to be fairly ferocious.”

Looking back at the remote past shows that animals and plants are far more adapted to extreme changes in our climate than we give them credit for. But if there was another big chill or episode of sudden warming in the Northern Hemisphere the option of massive shifts in range is no longer open to many species. Many of the land routes for wildlife to move through have been fragmented by development, non-native forestry and, in the lowlands, intensive agriculture.

“Not only are we changing the environment, we are also making the solution to that change impossible for much of our wildlife,” says Prof. Coope. “We have to devise a system of wildlife corridors to allow plants and animals to move on a huge scale.”

Scottish Wildlife Trust Magazine, Winter 2011

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