By Dr. Sebastian Lüning and Prof. Fritz Vahrenholt
(German text translated/edited by P. Gosselin)

A few days ago here at our blog we presented a study criticizing climate models and false soot data:

These data clearly show that industrial soot could hardly have been responsible for the melting of the Alpine glaciers at the time mainly between 1850 and 1875. ‘By 1875, about 80 percent of the glacier retreat had already been completed,’ said Sigl. Indeed it was not until 1875 that the amount of industrial soot in Central Europe exceeded the amount naturally present in the atmosphere.”

The study was even presented in October, 2018, in the Swiss SRF news. Click on the 13:22 mark of the broadcast. The report lasts about 3 minutes. One day later also a separate text accompanied the video release at the SRF website:

160 years ago – Industrialization not the cause of the end of the Little Ice Age

Is man, and his industrialization, responsible for the so-called Little Ice Age coming to an end in the middle of the 19th century? So far historians and climatologists have assumed that the melting of the Alpine glaciers began with industrialization after 1860 — because of the increased output of soot. This assumption is not correct – that’s what researchers from the Paul Scherrer Institute (PSI), link opens a new window. On the basis of evidence that is found deep in the ice: The analysis of the amount of soot that is trapped in the glacier ice refutes this previous assumption.”

Read more (German) at SRF. You can read the English language article at swissinfo.ch.

What was the driving force of the early glacier melt? Sigl and colleagues surmise that volcanoes and a weak sun in the Maunder Minimum caused the glaciers to grow excessively and, after few snowfalls and (natural) warming caused by the AMO, then to recede.

Here is the abstract of the study by Sigl et al. 2018:

19th century glacier retreat in the Alps preceded the emergence of industrial black carbon deposition on high-alpine glaciers
Light absorbing aerosols in the atmosphere and cryosphere play an important role in the climate system. Their presence in ambient air and snow changes the radiative properties of these systems, thus contributing to increased atmospheric warming and snowmelt. High spatio-temporal variability of aerosol concentrations and a shortage of long-term observations contribute to large uncertainties in properly assigning the climate effects of aerosols through time. Starting around AD1860, many glaciers in the European Alps began to retreat from their maximum mid-19th century terminus positions, thereby visualizing the end of the Little Ice Age in Europe. Radiative forcing by increasing deposition of industrial black carbon to snow has been suggested as the main driver of the abrupt glacier retreats in the Alps. The basis for this hypothesis was model simulations using elemental carbon concentrations at low temporal resolution from two ice cores in the Alps. Here we present sub-annually resolved concentration records of refractory black carbon (rBC; using soot photometry) as well as distinctive tracers for mineral dust, biomass burning and industrial pollution from the Colle Gnifetti ice core in the Alps from AD1741 to 2015. These records allow precise assessment of a potential relation between the timing of observed acceleration of glacier melt in the mid-19th century with an increase of rBC deposition on the glacier caused by the industrialization of Western Europe. Our study reveals that in AD1875, the time when rBC ice-core concentrations started to significantly increase, the majority of Alpine glaciers had already experienced more than 80% of their total 19th century length reduction, casting doubt on a leading role for soot in terminating of the Little Ice Age. Attribution of glacial retreat requires expansion of the spatial network and sampling density of high alpine ice cores to balance potential biasing effects arising from transport, deposition, and snow conservation in individual ice-core records.”

Already on September 17, 2018, in the New York Times there was an article about a Swiss ice core study on the Little Ice Age:

Europe’s Triumphs and Troubles Are Written in Swiss Ice
Pollen frozen in ice in the Alps traces Europe’s calamities, since the time Macbeth ruled Scotland. As plague swept through Europe in the mid-1300s, wiping out more than a third of the region’s population, a glacier in the Alps was recording the upheaval of medieval society. While tens of millions of people were dying, pollen from the plants, trees and crops growing in Western Europe were being swept up by the winds and carried toward the Alps. They became trapped in snowflakes and fell onto the region’s highest mountain, the Monte Rosa massif. Over time, the snow flattened into ever-growing layers of ice, storing a blow-by-blow record of regional environmental change. Centuries later, the crop pollens trapped in the ice reveal the collapse of agriculture associated with the pandemic, as bad weather led to poor harvests and fields lay fallow because there was no one left to work them.”

The study related here: Brugger et al. 2018 (A quantitative comparison of microfossil extraction methods from ice cores).