The Industrial Revolution May Be What Abruptly Melted the Glaciers in the Alps

It's now pretty well established that black carbon pollution is a serious component of climate change. In fact, all the soot from open-air cookstoves, old diesel engines, and dirty industrial processes is the second-most powerful form of global warming pollution out there, after carbon dioxide. Black carbon also has a serious impact on the world's glaciers, even beyond its influence on increasing temperatures, because it accelerates melting by changing their reflectivity.

Now, interesting new research published in the latest issue of Proceedings of the National Academy of Sciences shows that black carbon has been doing a number on glaciers going back to the start of the Industrial Revolution. The effect of soot falling on ice in the Alps may have been so strong that it effectively brought to an end to the Little Ice Age in the region.

As the report explains, what caused the glaciers of the Alps to abruptly stop advancing in the 19th century has long been a paradox for climatic and glaciological researchers.

The conventional glaciological wisdom has been that it's due to a combination of increasing temperatures and decreasing precipitation halting glacial advance at the time, temperature records in the Alps (remember this is the time when the modern scientific record starts), and climate proxies (ice cores and the like). But in fact, temperatures in the Alps by the mid-19th century were cooler than in the late 18th and early 19th centuries, and precipitation levels unchanged.

If some other factor wasn't at play, the glaciers in the Alps should have continued growing until roughly 1910. The major factor that changed at the time was a marked increase of black carbon pollution, specifically after 1850, when industrialization spread to Europe and then pretty much surrounded the Alps. The pollution continued increasing as the extent of industrialization increased, not decreasing until the 1970s when stronger pollution control began.

As it does today, the pollution increased the amount of solar radiation that the snow and ice absorb, in turn increasing the amount of snow and ice that melt. The new research quantifies the effect this pollution would have on glacier mass balance (Is it gaining or losing mass, advancing or retreating, getting thicker or thinner?) using different scenarios of radiative forcing. The report concludes that, "even the conservatively low forcing scenario … indicates negative mass balance occurring with realistic timing."

In the broader context of climate change over the past century and a half, the research is particularly poignant. Before increasing carbon dioxide concentrations in the atmosphere, invisible to the naked eye, began raising global temperatures, the very much visible pollution of the Industrial Revolution—that coated buildings in layers of grime thick enough to change their color—was already dramatically changing the alpine landscape.