<p>Palaeo-glaciological studies of former ice thickness and extent within the tropical Andes have tended to focus on locations where glaciers are currently present, or in high elevation locations where evidence exists of recently deglaciated cirques. Few studies have focussed on low elevation regions due to the presumption that glaciers could not have existed at such low altitudes within the tropics. A latitudinal ‘data gap’ exists between Ecuador and more central and southern Peru where evidence for former glaciation is abundant. To fill this gap we present rare evidence of past glaciation from the Las Huaringas region, northern Peru, located in a relatively low elevation massif (<3900 m).</p><p>Within Las Huaringas a large valley glacier existed, extending N-S ~12 km down valley to ~2900 m in elevation while glacial cirques existed exhibiting an E-W orientation on the western facing hillslope of the massif with pronounced moraine complexes and bedrock erosion. We used high-resolution remotely sensed imagery, a 30 m ALOS DEM, and preliminary field observations to identify and map an abundance of geomorphic evidence of glaciation. These include moraines at different stages of preservation and predominance, eroded bedrock surfaces, cirque landforms and overdeepened valleys to develop the first glacial geomorphological map of the region. We performed morphometric analysis (e.g. width, length, altitude, azimuth) of the mapped glacial landforms and cirques along with hypsometric analysis of the main valley of Laguna Shimbe, yielding a hypsometric maxima of 3250 m. Using the geomorphological map, we determine the former extent and thickness of palaeoglaciers in the area and use delineated glacial outlines of their furthest extent to reconstruct Equilibrium Line Altitudes (ELAs) of these ice masses using a combination of ELA estimation techniques.</p><p>Ongoing research aims to determine whether the palaeoglacial evidence is consistent with formation by valley glaciers or an icecap and whether the timing of the local Last Glacial Maximum (LGM) was synchronous with the global timing. A set of hypotheses for the timing and drivers of the reconstructed extent of former glaciers in the area will be presented. Our analysis confirms the presence of former glaciers in a low elevation and low latitude region of the tropical Andes. Our ongoing work aims to unveil the timing of the glacial events and the drivers of the glacial and climate history seen within this important region.</p>

Characterising glaciological change within the tropical Andes is important because tropical glaciers are sensitive to climate change. Our understanding of glacier dynamics and how tropical glaciers respond to global climate perturbations is poorly constrained. Studies of past glaciation in the tropical Andes have focused on locations where glaciers are still present or recently vacated cirques at high elevations. Few studies focused on lower elevation localities because it was assumed glaciers did not exist or were not as extensive. We present the first geomorphological evidence for past glaciations of the Lagunas de Las Huaringas, northern Peru, at elevations of 3,900–2,600 m a.s.l. Mapping was conducted using remotely-sensed optical imagery and a newly created high-resolution (∼2.5 m) digital elevation model (DEM). The area has abundant evidence for glaciation, including moraines, glacial cirques, hummocky terrain, glacial lineations and ice-sculpted bedrock. Two potential models for glaciation are hypothesised: 1) plateau-fed ice cap, or 2) valley glaciation. Assuming glaciers reached their maximum extent during the Local Last Glacial Maximum (LLGM), between 23.5 ± 0.5 and 21.2 ± 0.8 ka, the maximum reconstructed glacial area was 75.6 km2. A mean equilibrium line altitude (ELA) of 3,422 ± 30 m was calculated, indicating an ELA change of −1,178 ± 10 m compared to modern snowline elevation. There is an east to west ELA elevation gradient, lower in the east and higher in the west, in-line with modern day transfer of moisture. Applying lapse rates between 5.5 and 7.5°C/km provides a LLGM temperature cooling of between 6.5–8.8°C compared to present. These values are comparable to upper estimates from other studies within the northern tropical Andes and from ice-core reconstructions. The mapping of glacial geomorphology within the Lagunas de las Huaringas, evidences, for the first time, extensive glaciation in a low elevation region of northern Peru, with implications for our understanding of past climate in the sub-tropics. Observations and reconstructions support a valley, rather than ice cap glaciation. Further work is required to constrain the timing of glaciations, with evidence of moraines younger than the LLGM up-valley of maximum glacier extents. Numerical modelling will also enable an understanding of the controls of glaciation within the region.

<p>Mountain glaciers and ice caps are undergoing rapid mass loss but rates of contemporary change lack long-term (centennial-scale) context. Future projections of glacier changes require spin up to present day conditions and thus baseline ice extents and ice volumes are a prerequisite for model validation.<strong> </strong>Here, we reconstruct the Little Ice Age maximum glacier extent and ice surface of Jostedalsbreen, which is the largest ice mass in mainland Europe. Jostedalsbreen had its largest Little Ice Age (LIA) maximum about 1740 to 1860. The LIA ice-covered area was 568 km<sup>2</sup> and the LIA ice volume was between 61 km<sup>3</sup> and 91 km<sup>3</sup>. We show that the major outlet glaciers have lost at least 110 km<sup>2</sup> or 19 % of their LIA area and 14 km<sup>3</sup> or 18 % of their LIA volume until 2006. The largest proportional changes are associated with the loss of ice falls and consequent disconnection of tributaries. Glacier-specific hypsometry changes suggest a mean rise in ELA of 135 m but there is wide inter-glacier variability. A median date for the LIA of 1755 suggests that the long-term rate of ice mass loss has been 0.05 m w.e. a<sup>-1</sup>. Comparison of that long-term rate of mass loss with our other published analyses of changes to mountain glaciers and ice caps since the LIA shows that Jostedalsbreen is unusual in not exhibiting an acceleration in mass loss since the LIA. Indeed, we have reported a 23 % acceleration of glacier mass loss in NE Greenland and a doubling for the Southern Alps of New Zealand. Others have reported a doubling of the rate of mass loss for the Vatnajökull ice cap and for Patagonia since the LIA. We have very recently reported a ten-fold increase for ~ 15,000 glaciers across the Himalaya. A synthesis of these long-term analyses reveals a latitudinal effect, regional climate effects and local controls on long-term glacier mass balance. For example, local rates of loss across the Himalaya were enhanced with the presence of surface debris cover (by 2 times vs clean-ice) and/or a proglacial lake (by 2.5 times vs land-terminating). Overall, we highlight the utility of geomorphological-based reconstructions of glaciers for understanding and quantifying long-term (centennial-scale) responses of mountain glaciers and ice caps to climate and hence for understanding of meltwater production and proglacial landscape evolution.</p>