Paper describing the glacier length data set has been published in the Cryosphere!
Started a new postdoc position in Oslo on March 1st 2014, joining the Icemass project.
Donderdag 28 Februari 2013 geef ik een lezing over gletsjers voor de Skikring Alkmaar.
10 Februari 2013 gaf ik een lezing in de Leidse Winterlezingen serie in Museum Naturalis. Naar aanleiding daarvan verscheen er een stuk in de NRC en was ik te gast bij het radioprogramma Vroege Vogels
Defended my thesis on Feb. 8! 2012 PDF of thesis can be downloaded from the UU library by clicking on the image above.
Naar aanleiding van mijn promotie ben ik geinterviewed voor de Volkskrant en Trouw.
Glacier length fluctuations data set can be downloaded from Data downloads
Paper on the reconstruction of global temperature change has just been published! See Publications for a link.
I work on a compilation of worldwide glacier length fluctuations over the last centuries. The main purpose of the data set is the reconstruction of past climate from glacier fluctuations, but the data set is also used to estimate the glacier contribution to sea-level rise. Glacier length is the only geometric glacier parameter for which information is available far back in time on a world-wide scale. As much as possible, the world-wide available data on glacier length changes are collected and merged into one uniform data set. This data set can also be downloaded
Fig 1 Examples of glacier length records.
The Figure above shows examples of glacier length records in the data set. Each dot represents an observation, gaps are filled with Stineman interpolation (Stineman 1980). Sources of the record are given on the right.The examples show that there is a wide variaty in available length data. Some are long, others are short. The one is very detailed while the other has only a few observations. There is also a large difference in the type of observation. It varies from field measurements via satellite imagery to reconstructions from historical sources and dating of moraines. Recent data points are often derived from satellite images like Landsat. The detailed records are mostly obtained from regular field measurements (often done by volunteers). Specific information of the original sources used in the data set can be found in the list in the data download section.
The global distribution of the available records is given in the next Figure. Each dot represents a record, but often glaciers are so close together that the dots overlap. The records are distributed over 16 regions, indicated by black squares. The number inside the region represents the number of glaciers in the region, the number outside the boxgives the region number. As you can see there are glaciers on all continents, and virtual all latitudes. Also the gaps in our collection are easily picked out: although the Canadian Arctic and the Antarctic peninsula contain a large part of the glacier volume on earth (outside the ice sheets), we have no records in these regions.
Fig 2 Global distribution of glacier length records.
As shown by the examples (Fig 1), there is a large variety in the length of the different time series. Consequently, the number of available records changes strongly in time, as shown in the figure below (Fig 3). For the majority of the glaciers in the data set, the first available information is from the 19th century. From 1962 the number of available records decreases again to 293 in 2000 and 231 in 2005. A few times, a time series ends because of the (virtual) disappearance of the glacier, but mostly more recent data are not available because measurements are not continued or not reported.
Fig 3 Number of available records in time.