Grand Aletsch Glacier, Switzerland [Image credit: Wikipedia]
It’s not the conclusion some might be expecting…
Analysis of ice cores delivers continuous data for the first time on industrial soot from 1740 to today, reports HeritageDaily.
In the first half of the 19th century, a series of large volcanic eruptions in the tropics led to a temporary global cooling of Earth’s climate.
It was a natural process that caused Alpine glaciers to grow and subsequently recede again during the final phase of the so-called Little Ice Age.
This has now been proven by PSI researchers, on the basis of ice cores.
Up to now, it was hypothesised that industrial soot in the second half of the 19th century had triggered the rapid melting of glaciers occurring at that time. The first-ever analysis of the amount of soot (also called black carbon) locked in the ice and thus historically archived now contradicts this assumption.
The resulting continuous timeseries of soot concentrations will, in addition, help researchers in the future to improve climate model simulations by enabling them to use experimental data. The results were published today in the scientific journal The Cryosphere.
Images of Alpine glaciers from the 1850s compared to the present day are often used in order to visualise anthropogenic climate change. This is wrong, however, as researchers have now proven on the basis of data from ice cores.
Scientists associated with Michael Sigl of PSI analysed atmospheric pollutants archived in the ice at different depths, with a focus on the amounts of industrial soot. Thus they created the first continuous data series for central Europe for the period from the 1740s to today on the amount of industrial soot in the atmosphere.
These data clearly show that industrial soot can hardly be responsible for the melting of the Alpine glaciers at the time, taking place mainly between 1850 and 1875.
“By 1875, the glacier retreat under way then was already around 80 percent complete”, Sigl says. But it was not until 1875 that the amount of industrial soot in central Europe exceeded the levels of black carbon naturally present in the atmosphere.
Sigl clarifies: “It’s only in the last 20 percent of that episode of glacier retreat in the 19th century that the soot could have had an influence.”
Continued here.
via Tallbloke’s Talkshop
October 18, 2018 at 04:33PM
Iowa Climate Science Education 