Swiss ETH: Glaciers melted in the 1940’s faster than today
January 3, 2010
Solar radiation as the decisive factor
In its work, the research team took into account the solar radiation measured on the Earth’s surface in Davos since 1934. Studies over the past two decades have shown that solar radiation varies substantially due to aerosols and clouds, and this is assumed to influence climate fluctuations. Recent years have seen the emergence of the terms ‘global dimming’ and ‘global brightening’ to describe these phenomena of reduced and increased solar radiation respectively. These two effects are currently the subject of more and more scientific research, in particular by ETH Zurich, as experts feel that they should be taken into account in the climate models (see ETH Life dated
July 9, 2009)
The new study, published in the journal ‘Geophysical Research Letters’, confirms this requirement. This is because, taking into account the data recorded for the level of solar radiation, the scientists made a surprising discovery: in the 1940s and in the summer of 1947 especially, the glaciers lost the most ice since measurements commenced in 1914. This is in spite of the fact that temperatures were lower than in the past two decades. “The surprising thing is that this paradox can be explained relatively easily with radiation”, says Huss, who was recently appointed to the post of senior lecturer at the Department of Geosciences at the University of Fribourg in Switzerland.
On the basis of their calculations, the researchers have concluded that the high level of short-wave radiation in the summer months is responsible for the fast pace of glacier melt. In the 1940s, the level was 8% higher than the long-term average and 18 Watts per square metres above the levels of the past ten years. Calculated over the entire decade of the 1940s, this resulted in 4% more snow and ice melt compared with the past ten years.
Solar radiation as the decisive factor
In its work, the research team took into account the solar radiation measured on the Earth’s surface in Davos since 1934. Studies over the past two decades have shown that solar radiation varies substantially due to aerosols and clouds, and this is assumed to influence climate fluctuations. Recent years have seen the emergence of the terms ‘global dimming’ and ‘global brightening’ to describe these phenomena of reduced and increased solar radiation respectively. These two effects are currently the subject of more and more scientific research, in particular by ETH Zurich, as experts feel that they should be taken into account in the climate models (see ETH Life dated
July 9, 2009)
The new study, published in the journal ‘Geophysical Research Letters’, confirms this requirement. This is because, taking into account the data recorded for the level of solar radiation, the scientists made a surprising discovery: in the 1940s and in the summer of 1947 especially, the glaciers lost the most ice since measurements commenced in 1914. This is in spite of the fact that temperatures were lower than in the past two decades. “The surprising thing is that this paradox can be explained relatively easily with radiation”, says Huss, who was recently appointed to the post of senior lecturer at the Department of Geosciences at the University of Fribourg in Switzerland.
On the basis of their calculations, the researchers have concluded that the high level of short-wave radiation in the summer months is responsible for the fast pace of glacier melt. In the 1940s, the level was 8% higher than the long-term average and 18 Watts per square metres above the levels of the past ten years. Calculated over the entire decade of the 1940s, this resulted in 4% more snow and ice melt compared with the past ten years.
Furthermore, the below-average melt rates at the measurement points during periods in which the glacier snouts were even advancing correlate with a phase of global dimming, between the 1950s and the 1980s.
All of it:
https://wattsupwiththat.com/2010/01/03/swiss-eth-glaciers-melted-in-the-1940s-faster-than-today/