The Register has an interesting article from Lewis Page about photos taken by the seventh Thule Expedition to Greenland led by Dr Knud Rasmussen in 1932:
There's much scientific interest in the Greenland ice sheet, as unlike most of the Arctic ice cap it sits on land: thus if it were to melt, serious sea level rises could occur (though the latest research says that this doesn't appear to be on the cards).While sulphur emissions in North America and Europe have been reduced in recent decades, due to concerns about acid rain, it's possible that catastrophic warming of the Earth by evil CO2-belching Westerners has been mitigated by evil sulphite-spewing Chinese. Some scientists speculate that "rapid coal- and diesel-fuelled industrialisation in China is serving to prevent further warming right now".
It's difficult to know exactly what's happening to the Greenland ice in total and very different estimates have been produced in recent times. However Professor Box says that many glaciers along the coasts have started retreating in the past decade.
It now appears that the glaciers were retreating even faster eighty years ago: but nobody worried about it, and the ice subsequently came back again. Box theorises that this is likely to be because of sulphur pollution released into the atmosphere by humans, especially by burning coal and fuel oils. This is known to have a cooling effect.
Still other scientists, differing with Prof Box, offer another picture altogether of Arctic temperatures, in which there were peaks both in the 1930s and 1950s and cooling until the 1990s: and in which the warming trend which resulted in the melting seen by Rasmussen's expedition actually started as early as 1840, before the industrial revolution and human-driven carbon emission had even got rolling. In that scenario, variations in the Sun seem to have much more weight than is generally accepted by today's climatologists.The truth is that we don't understand the mechanisms behind glacial melting, in Greenland or in the Himalayas. The story isn't nearly as simple as the global warming propagandists would have you believe.