Climate reconstructions derived from global glacier length records

As glacier length fluctuations provide useful information about past climate, we derived historic fluctuations in the equilibrium-line altitude (ELA) on the basis of 19 glacier length records from different parts of the world. We used a model that takes into account the geometry of the glacier, the length response time and the mass balance-surface height feedback. The results show that all glaciers of the data set experienced an increase in the ELA between 1900 and 1960. Between 1910 and 1959, the average increase was 33 ± 8 m. This implies that during the first half of the 20th century, the climate was warmer or drier than before. The ELAs decreased to lower elevations after around 1960 up to 1980, when most of the ELA reconstructions end. These results can be translated into an average temperature increase of 0.8 ± 0.2 K and a global sea-level rise of about 0.3 mm a-1 for the period 19/0-/959