Does industrial soot play a role in the meltdown of Alpine glaciers?
By Summit Voice
FRISCO — With temperatures in the European Alps rising twice as fast as the global average, there’s little hope of saving some of the world’s most famous glaciers without immediate and significant cuts in greenhouse gas emissions.
And there’s little doubt that the warming is caused by those emissions. Findings from a new study show the sudden onset of warming about 30 years ago. The study, led by researchers with the Byrd Polar Research Center at Ohio State, offers new and compelling evidence that the Italian Alps are warming at an unprecedented rate.
Based on the discovery of a leaf from a larch tree buried deep in the ice, the scientists concluded that the Alto dell’Ortles glacier, which did not show signs of melting for thousands of years, now appears to be shifting away from a constantly below-freezing state to one where its upper layers are at the melting point throughout the year, according to project leader Paolo Gabrielli.
“Our first results indicate that the current atmospheric warming at high elevation in the Alps is outside the normal cold range held for millennia,” he said. “This is consistent with the rapid, ongoing shrinking of glaciers at high elevation in this area.”
As they drilled into the glacier in 2011, Gabrielli and his team discovered that the first 100 feet (about 30 meters) of the glacier was composed of “firn” — grainy, compacted snow that had partly melted. Below that, they found nothing but solid and colder ice all the way down to the frozen bedrock.
That suggests that snow was accumulating on the mountaintop and was compacted into ice for thousands of years without ever melting—until about 30 years ago, which is when each year’s new deposit of snow began melting.
The researchers know that the glacier had previously remained unchanged for a very long time—in part because of the preserved larch leaf, which they found wedged into the ice well beyond the firn layer, around 240 feet beneath the surface and encased in solid ice. They identified the leaf as belonging to Larix decidua, or the European larch.
Carbon dating determined it to be around 2,600 years old. That means that Ötzi had already been dead for more than two millennia when this particular larch tree grew, though it was not far from his resting place.
“The leaf supports the idea that prehistoric ice is still present at the highest elevations of the region,” Gabrielli said.
The researchers are just beginning to chemically analyze the ice cores they retrieved. Trace metals and dust sealed in the ice will give more detailed clues to the climatic conditions when the ice was formed.
Gabrielli added that the cores are unique in the European Alps, because the winter and summer layers of ice accumulation are easily identifiable, offering the promise of a high-resolution climate record.
Of particular interest to the researchers is why temperatures in the Alps are increasing at twice the global rate. As the highest glacier in the eastern Alps (2.4 miles, or 3.9 km, above sea level), Alto dell’Ortles is located in the heart of Europe—one of the most industrialized and populated areas of the world. The team will investigate whether soot emitted by human activities in central and southern Europe plays a role—perhaps by darkening the surface of the glacier, absorbing the sun’s heat and melting ice.
“Ortles offers us the unique possibility to closely verify if and how regional environmental changes can interact with climatic changes of global significance,” Gabrielli said.