When it comes to climate change, the writing's on the toilet.
A team of researchers is tracing the climate history of South Africa by looking at the midden heaps -- the animal equivalent of a latrine -- of the rock hyrax, a furry creature about the size of a guinea pig. Hyraxes urinate in the same place every day, and their urine is thick, viscous and quick-drying. It also contains lots of traces from the environment: leaves, grasses, gas bubbles and pollen. Once sealed in the solidified urine, the deposits of pollen and other components are protected from the elements.
By analyzing the stratified layers of ancient hyrax urine and feces, researchers can look at how the climate and local vegetation have changed over time. One urine layer could even be traced back to 50,000 years ago.
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"We are taking the piss, quite literally—and it is proving to be a highly effective way to study how climate changes have affected local environments," Montpelier University scientist Brian Chase told the Guardian.
That history is useful, because despite Southern Africa's sensitivity to climate change and its location at a key juncture between global circulation systems, not much is known about the environmental history of the region, researchers say.
The HYRAX project is trying to answer a number of questions about how climate changed in Southern Africa over the past tens of thousands of years, particularly what conditions were like in the region as the glaciers retreated.
Evidence from the hyrax middens suggests that Southern Africa experienced a period of significant cooling in the midst of that transition, thanks to the injection of massive amounts of fresh water into the North Atlantic as glaciers in Europe and North America melted. That sudden infusion of fresh water destabilized the gradient of salinity and temperature that controls the Gulf Stream, the powerful Atlantic Ocean current that brings warm water to the coasts of Western Europe.
Other scientists have peered into animal waste, hoping to get a glimpse of climate change. In 1995, University of New Mexico researchers published a paper in Science detailing how the fossil poop of the bushy-tailed woodrat could be used to trace fluctuations in body sizes over time. All of the woodrat populations that they examined, by way of collecting ancient fecal pellets from Colorado sites, got smaller when the climate got warmer.
“The precision with which the body size of woodrats tracked changes in environmental temperature is striking,” the UNM scientists wrote.
Chase presented his research at the AAAS Annual Meeting in Boston, along with Swansea University's Siwan Davies, who is creating a more precise history of climate change in the Arctic region by looking at the volcanic dust in ice cores taken from Greenland.
"The aim of these studies—including our work on hyraxes—is to create a very accurate timeline of past climate events so we can understand what is causing them," said Chase. "Some researchers use ice cores. We just happen to use urine."