Articles | Volume 10, issue 6
https://doi.org/10.5194/tc-10-2721-2016
https://doi.org/10.5194/tc-10-2721-2016
Research article
 | 
21 Nov 2016
Research article |  | 21 Nov 2016

Estimating the extent of Antarctic summer sea ice during the Heroic Age of Antarctic Exploration

Tom Edinburgh and Jonathan J. Day

Abstract. In stark contrast to the sharp decline in Arctic sea ice, there has been a steady increase in ice extent around Antarctica during the last three decades, especially in the Weddell and Ross seas. In general, climate models do not to capture this trend and a lack of information about sea ice coverage in the pre-satellite period limits our ability to quantify the sensitivity of sea ice to climate change and robustly validate climate models. However, evidence of the presence and nature of sea ice was often recorded during early Antarctic exploration, though these sources have not previously been explored or exploited until now. We have analysed observations of the summer sea ice edge from the ship logbooks of explorers such as Robert Falcon Scott, Ernest Shackleton and their contemporaries during the Heroic Age of Antarctic Exploration (1897–1917), and in this study we compare these to satellite observations from the period 1989–2014, offering insight into the ice conditions of this period, from direct observations, for the first time. This comparison shows that the summer sea ice edge was between 1.0 and 1.7° further north in the Weddell Sea during this period but that ice conditions were surprisingly comparable to the present day in other sectors.

Download
Short summary
Contrary to expectations, Antarctic sea ice cover has been increasing in area during the last three decades. In order to put these trends into a wider context this paper analyses direct observations of sea ice, recorded in ships' logbooks during the Heroic Age of Antarctic Exploration (1887–1917) for the first time. It shows that the sea ice was significantly further north in the Weddell Sea during the period but comparable to the present day in other sectors.