Shrinking Patagonian Glaciers

This webpage is a shortened and simplified version of the Davies and Glasser 2012 paper published in Journal of Glaciology.

Introduction | Results | Glacier Change | Conclusions | References | Comments |

Introduction

OK, I know that this isn’t about Antarctic Glaciers, but Patagonia isn’t desperately far away… and it’s still relevant to glaciers and climate.

The Little Ice Age

Figure 1. Map of the glaciers of the Patagonian Andes. Note the precipitation gradient west and east across the mountain range.

The Little Ice Age (LIA) is widely recognised in places like the Alps in the northern hemisphere, where glaciers expanded and formed prominent moraines around 150 years ago. During this period of cooler temperatures, there were Frost Fairs on the Thames, which regularly froze over. This period of cooler temperatures also resulted in widespread glacier advances across the Andes in Patagonia, with many glaciers forming prominent moraines. Inside the moraines, the ground remains ice-scoured and relatively bare of vegetation. These geomorphological features can be seen by satellite, which means that it is possible to map the extent of the glaciers during the Little Ice Age across Patagonia. In combination with trimlines, which show the vertical extent and thickness of the glaciers during the Little Ice Age, it has been possible to map changes in glacier volume from the LIA to the present day (see Glasser and others, 2011, Nature Geoscience1). The LIA has also been recorded in the Antarctic Peninsula (with large moraines formed on James Ross Island, for example).

Measuring change by satellite

Figure 2. Mapping the glaciers of the Northern Patagonian Icefield.

Satellite measurements of the Patagonian icefields suggest that they are currently rapidly receding and thinning, with a measureable contribution to eustatic sea level rise2. Many workers argue that the glaciers of the Patagonian Andes are now shrinking at an increased rate as a result of recent climate change3-5. However, these assessments of change are restricted by the availability of maps (last 60 years) and satellite images (last 40 years). In this study (from 40° to 56° South), we used geomorphological evidence of glacier extent during the LIA (~AD 1870) and satellite images to map glacier extent across the Andes over the last 140 years, in 1870, 1975, 1986, 2001 and 2011.

 

Results

Figure 3. Glacier inventory data from the Patagonian inventory from the year 2011.

We mapped 626 glaciers across the Patagonian Andes, of which 386 drained the major icefields (North Patagonian Icefield, South Patagonian Icefield, Gran Campo Nevado, Cordillera Darwin). A few large glaciers made up the majority of the glacierised area. The remainder were smaller icefields and glaciers in the Chilean Lake District and on volcanoes and mountains. 100 of these glaciers ended in lakes or in the sea. 640 glaciers were mapped during the LIA (the remainder having entirely disappeared).

This data is available to download from the GLIMS database. The full inventory and analysis is available in Davies and Glasser 2012 (Journal of Glaciology).

Glacier change

Figure 4. Graphs illustrating glacier change across Patagonia.

Overall, 90.2% of glaciers shrank between the end of the LIA (approx. 1870) and 2011, 0.3% advanced and no change was observed in 9.5^ of the glaciers.  These small advances were generally short term, and limited to tidewater glaciers. All regions have suffered extensive glacier loss. The greatest annual rates of shrinkage were observed in the small (less than 5 km2 in size) land-terminating glaciers.

Annual rates of shrinkage across the Patagonian Andes increased in each time segment analysed (1870-1986, 1986-2001, 2001-2011), with annual rates of shrinkage twice as rapid from 2001-2011 as from 1870-1986 (0.10% a-1 from 1870-1986, 0.14% a-1 from 1986-2001, and 0.22% a-1 from 2001-2011).

 

Figure 5. These scatter plots show how glaciers are behaving differently at different latitudes, and that land-terminating glaciers are shrinking fastest. Circles represent calving glaciers, and squares represent land-terminating glaciers.

In general, rates of change were fastest from 2001-2011 in more northerly glaciers, with the glaciers in the Chilean Lake District and the Northern Patagonian Icefield shrinking particularly rapidly. The more southerly glaciers, in the Cordillera Darwin, Monte Sarmiento, Isla Riesco and Tierra Del Fuego, shrank fastest from  1986-2001.

This data suggests that the Patagonian glaciers are indeed shrinking faster now than they did in the last century. For example, our calculated rates of area loss from the Northern Patagonian Icefield suggest that there was an increase in annual area loss rates from 0.09% a–1 in the 116 years between AD 1870 and 1986, to 0.12% a–1 in the 15 years between 1986 and 2001, to 0.23% a–1 from 2001 to 2011.

 

 

Conclusions

Figure 7. Annual overall rates of shrinkage for glaciers across Patagonia.

The figures opposite and above show that latitude, terminal environment (calving or ending on land) and size exert the strongest controls on glacier shrinkage, with the more northerly, land-terminating, smaller (less than 5 km2) glaciers shrinking fastest. Calving glaciers have been observed to be thinning6-8, but their recession is strongly controlled by calving dynamics. Worldwide, small ice caps and glaciers have reacted particularly dynamically to worldwide increases in temperatures9-11, and it has been proposed that the volume loss from mountain glaciers and ice caps like these is the main contributor to recent global sea-level rise12.

On a regional scale, the large icefields and small icecaps and glaciers north of 56°S suffered particularly rapid shrinkage from 2001-2011, presumably as a result of the decreased precipitation and warmer tropospheric  air temperatures observed in this region2,13-16. The glacierised summits lie in this altitudinal zone, so warming is likely to have a significant control on the mass balance of the glaciers.

There is considerable inter-catchment variability in the behaviour of the glaciers across the Andes, with calving dynamics, latitude and size resulting in glaciers shrinking at different rates. However, overall, annual rates of shrinkage were far faster from 2001-2011 than from 1870-1986 or 1986-2001.

Figure 8. Period of fastest recession for Patagonian glaciers.

Go to top or jump to Ice Shelf Collapse.

 

Citation

Davies, B.J. and Glasser, N.F. 2012. Accelerating shrinkage of Patagonian glaciers from the Little Ice Age (~AD 1870) to the present day. Journal of Glaciology, 58 (212), 1063-1084. Please use this reference if citing.

References


1.            Glasser, N.F., Harrison, S., Jansson, K.N., Anderson, K. & Cowley, A. Global sea-level contribution from the Patagonian Icefields since the Little Ice Age maximum. Nature Geoscience 4, 303-307 (2011).

2.            Bown, F. & Rivera, A.s. Climate changes and recent glacier behaviour in the Chilean Lake District. Global and Planetary Change 59, 79-86 (2007).

3.            Rignot, E., Rivera, A. & Casassa, G. Contribution of the Patagonia Icefields of South America to sea level rise. Science 302, 434-437 (2003).

4.            Chen, J.L., Wilson, C.R., Tapley, B.D., Blankenship, D.D. & Ivins, E.R. Patagonia Icefield melting observed by Gravity Recovery and Climate Experiment (GRACE). Geophys. Res. Lett. 34, L22501 (2007).

5.            Ivins, E.R. et al. On-land ice loss and glacial isostatic adjustment at the Drake Passage: 2003-2009. J. Geophys. Res. 116, B02403 (2011).

6.            Aniya, M. Recent glacier variations of the Hielos Patagonicos, South America, and their contribution to sea-level change. Arctic Antarctic and Alpine Research 31, 165-173 (1999).

7.            Aniya, M., Sato, H., Naruse, R., Skvarca, P. & Casassa, G. Recent glacier variations in the Southern Patagonia Icefield, South America. Arctic and Alpine Research 29, 1-12 (1997).

8.            Willis, M.J., Melkonian, A.K., Pritchard, M.E. & Ramage, J.M. Ice loss rates at the Northern Patagonian Icefield derived using a decade of satellite remote sensing. Remote Sensing of Environment 117, 184-198 (2011).

9.            Oerlemans, J. & Fortuin, J.P.F. Sensitivity of Glaciers and Small Ice Caps to Greenhouse Warming. Science 258, 115-117 (1992).

10.          Hock, R., de Woul, M., Radic, V. & Dyurgerov, M. Mountain glaciers and ice caps around Antarctica make a large sea-level rise contribution. Geophysical Research Letters 36, L07501 (2009).

11.          Meier, M.F. et al. Glaciers Dominate Eustatic Sea-Level Rise in the 21st Century. Science 317, 1064-1067 (2007).

12.          Braithwaite, R.J. & Raper, S.C.B. Glaciers and their contribution to sea level change. Physics and Chemistry of the Earth, Parts A/B/C 27, 1445-1454 (2002).

13.          Giese, B.S., Urizar, S.C., Fu & kar, N.S. Southern Hemisphere Origins of the 1976 Climate Shift. Geophys. Res. Lett. 29, 1014 (2002).

14.          Villalba, R. et al. Large-scale temperature changes across the southern Andes: 20th-century variations in the context of the past 400 years. Climatic Change 59, 177-232 (2003).

15.          Rivera, A., Bown, F., Carriòn, D. & Zenteno, P. Glacier responses to recent volcanic activity in Southern Chile. Environmental Research Letters 7, 1-10 (2012).

16.          Aravena, J.C. & Luckman, B.H. Spatio-temporal rainfall patterns in Southern South America. International Journal of Climatology 29, 2106-2120 (2009).

Go to top or jump to Ice Shelf Collapse

Share this

If you enjoyed this post, please consider subscribing to the RSS feed to have future articles delivered to your feed reader.

8 thoughts on “Shrinking Patagonian Glaciers

  1. Pingback: Glaciar Steffen, Chile Retreat and Lake Expansion « From a Glaciers Perspective

  2. Pingback: Glaciar Chico Retreat, Patagonia, Chile | From a Glaciers Perspective

  3. Pingback: Reichert Glacier Rapid Retreat, Northern Patagonia Icefield, Chile | From a Glaciers Perspective

    • It is certainly true that glaciers and volcanoes interact. Geothermal heat flux is an important factor in controlling basal ice temperatures, and subglacial volcanoes regularly cause localised melting in ice sheets. However, the widespread changes in surface mass balance in Antarctica, thinning ice shelves and retreating grounding lines cannot be explained by volcanism. Rather, warm water melting the ice at the ice/ocean interface is causing rapid changes, including ice-shelf collapse, and acceleration and recession of Pine Island Glacier.

      In Patagonia, analysis of glacier area and length changes shows that recession is widespread (90.2% have retreated since 1870), is more rapid in smaller land-terminating glaciers, and that rates of recession are accelerating. Analysis of mass balance in Patagonia, using a combination of numerical modelling supported and validated by field measurements, shows that increased calving is an important part of accelerating mass loss in Patagonia. Schaefer et al. state that there are four active volcanoes within the Southern Patagonian Icefield, which may be accounting for some additional basal melt, but that changes to mass balance from a high geothermal heat flux can only account for a very small additional mass loss. Peripheral small, land-terminating glaciers have a strongly negative surface mass balance, which accounts for their rapid recession.

  4. Pingback: 14 photos of glaciers that reveal Patagonia's disappearing beauty | Immune Fashion

  5. Pingback: 14 photos of glaciers that reveal Patagonia's disappearing beauty | Immune Apps

Leave a Reply

Your email address will not be published.