Learning from the past could save biodiversity

Palaeo-archives are giving scientists new insights into how warming climates affected different species and biodiversity in the past, which they hope will inform future conservation strategies.

They have found that during ancient warming events species and biomes shifted their ranges hundreds to thousands of kilometres, altering the composition of communities and impacting critical ecosystem functions that humans rely on.

The hippopotamus (Hippopotamus amphibius), for example, relocated as far north as the UK during the last interglacial, when global temperatures were as least as warm as today, and giant tortoises (Hesperotestudo crassiscutata) used to roam the US Midwest, which now experiences severe frosts.

“Climate change has the potential to disrupt all facets of biodiversity, ranging from the gene to the ecosystem,” says Damien Fordham from Australia’s University of Adelaide, lead author of the study published in the journal Science.

With new tools to explore late Quaternary paleo-records, periodic rapidly warming climates over the past 130,000 years provide a “natural laboratory” that can give us an idea of what to expect, he adds.

“These abrupt warming events caused massive alternations in species distributions, abundances and genetic erosion, radically changing the structure and function of ecosystems, affecting services such as nutrient cycling, primary productivity and fire regimes.

“This provides the clearest picture yet of the wide-scale disruption that forecast rates of human-induced warming will have on biodiversity and the goods and services it provides to humanity.”

Their research shows how some species can become extinct if they can’t move fast enough to keep up with rapid climate changes.

In Eurasia, for example, the saiga antelope (Saiga tatarica) moved its range to a cooler refuge and survived a warming event 14,700 years ago. But the Arctic fox (Alopex lagopus) failed to shift its habitat after the last deglaciation 20,000 to 10,000 years ago in mid-latitude Europe and became extinct in that region.

Vegetation shifts include the tundra forest in Central Siberia, which moved around 200 kilometres northward 12,000 to 5000 years ago, while the prairie forest boundary on the North American Great Plains shifted about 200 to 250 kilometres eastward as conditions became drier.

The polar desert in high latitudes of Antarctica used to be home to tundra species of southern beech shrubs (Nothofagus beardmorensis) and during the last interglacial the Sahara Desert was a green savannah habitat.

To reveal these impacts, the team from across Australia, the US, Europe, Canada and New Zealand used advanced computational approaches to analyse integrated palaeontological research covering fossils, genetics, climate and macroecology, helped by the International Union for the Conservation of Nature (IUCN).

While biodiversity is suffering from major human drivers such as habitat destruction and invasive species, they say global warming will become increasingly important over the coming decades.

Palaeo-archives can help determine biotic responses and provide a much-needed evidence base to help to set conservation targets, says Fordham, as predicting changes from 20^th century observations is limited to observations of responses to lower temperatures than are being forecast in the future.

Future greenhouse warming from rising CO2 levels does differ from these past events, he notes, but historical insights “do offer rare and important opportunities to visualise and anticipate the ecological consequences of future climate change”.