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The quick rate of retreat of the Triglav Glacier, which began in the second half of the 20thcentury, further accelerated till the beginning of the 21st century. Due to increasing intensity of ice thinning, outcropping rocks began to emerge in the middle of the glacier, which disintegrated into two parts in 1992. In the last part of the first decade of the 21st century, the glacier has been retreating at a slower rate. The last major recession of the glacier was registered after the above average hot summer of 2003. The process stalled in years with above-average snow cover height in late spring, but just in the case of constant snow accumulation during the whole snow season.


This indicator shows changes in the surface area and volume of the Triglav glacier in the period 1992–2018 (volume measurements are periodical) and the average decade temperature of the melting season (May–October) at Kredarica in the period 1961–2018. The cumulative specific mass balance of selected European glaciers in the period 1946 – 2018 and in 2015 is presented as well. The measured surface area of the Triglav glacier includes glacier ice as well as snow directly above or adjacent to the glacier unless indicated otherwise. Glacier ice is entirely exposed only on rare occasions and only exceptionally for the period of several consecutive years.

Mass balance is the difference between accumulation and ablation of ice or snow covering the glacier. Due to variable density of snow and ice, it is expressed in millimeters of water equivalent. Specific mass balance means an average value per unit of surface area.

A glacier is a perennial mass of ice on the Earth’s surface that moves downslope under its own weight in response to gravitational force. A glacier forms above the snow line in locations where the mass accumulation of snow and ice exceeds ablation over many years. The snow is gradually transformed into glacier ice, which moves downslope reaching below the snow line until the glacier ice disappears due to prevailing ablation. The Triglav glacier because of his smallness doesnʹt have any more all the characteristics of the glacier; for this kind of very small glaciers (smaller than 25 ha) enforce the term glacieret (Cogley and the others, 2011). The key factors of ablation are: sun radiation (intensity, duration), air temperature, precipitation and wind (Gabrovec, Zakšek, 2007).

Changes in glacier volume and extent are an illustrative indicator of climate change. During the last decade, the trend of rapid glacier retreat has been characteristic of all Alpine glaciers. In Slovenia, there are two glaciers: the Triglav glacier and the Skuta glacier. Due to their extreme south-eastern position within the Alps and low altitude, both are exceptionally sensitive to climate change. Due to the small size of Slovenian glaciers, their relative retreat in respect to their present extent and volume is even greater than in other Alpine glaciers.


Charts

Figure PS05-1: Changes in the Triglav glacier surface area, 1992-2018
Sources: 

Anton Melik Geographical Institute, ZRC SAZU, 2018

Show data

surface [ha]

1992

4.30

1995

3

1999

1.10

2003

0.70

2005

1.10

2007

0.60

2008

1.10

2009

2.90

2010

2.50

2011

2.40

2012

0.60

2013

2.50

2014

3.60

2015

1.70

2016

1

2017

0.70

2018

0.80

Figure PS05-2: Changes in the Triglav glacier volume, 1992-2013
Sources: 

Anton Melik Geographical Institute, ZRC SAZU, 2019

Show data

Volume (1000m3)

1992

400

1999

60

2005

20

2008

10

2013

7.40

Figure PS05-3: Extent of the Triglav glacier, 1850-2012
Sources: 

Gabrovec, M., Hrvatin, M., Komac, B., Ortar, J., Pavšek, M., Topole, M., Triglav Čekada, M. in Zorn, M., 2014: Triglav glacier, page. 234

Show data
Figure PS05-4: Average temperature of the melting season (May–October) at Kredarica, 1955-2018
Sources: 

Slovenian Environment Agency, 2019

Show data

Average temperature of the melting season [°C]

1961-1970

3.30

1971-1980

2.70

1981-1990

3.70

1991-2000

3.80

2001-2010

4.20

2011-2018

4.70

Figure PS05-5: Cumulative specific net mass balance of selected glaciers, Europe, 1946-2018
Sources: 

World Glacier Monitoring Service, 2019

Show data

Careser (IT) [mm w.e.]

Gries (CH) [mm w.e.]

Hintereis (AT) [mm w.e.]

Saint Sorlin (FR) [mm w.e.]

Sarennes (FR) [mm w.e.]

Vernagtferner (AT) [mm w.e.]

Storglaciaeren (SE) [mm w.e.]

Nigardsbreen (NO) [mm w.e.]

Austre Broeggerbreen (NO) [mm w.e.]

Aalfotbreen (NO) [mm w.e.]

Hofsjokull N (IS) [mm w.e.]

Maladeta (ES) [mm w.e.]

1946

-1130

1947

-3190

1948

0

-3190

1949

-2990

-2290

1950

-4610

-3580

1951

-4410

-4230

1952

0

-6030

-4390

1953

-540

-6670

-5200

1954

-826

-7220

-6170

1955

-750

-6560

-6330

1956

-1025

0

-7160

-6810

1957

-1214

-360

-7680

-7130

1958

-2195

-330

-8350

-7780

1959

-2958

-1540

-9610

-8750

1960

-3020

-1870

-9490

-10360

1961

0

-3225

-1760

-9880

-11460

0

1962

-984

-3921

-2860

-10790

-11140

2250

0

1963

-1164

-4524

-2590

-10600

-11330

2030

-1100

1964

-1852

-5768

-4240

-12430

0

-10840

2980

-820

1965

-1407

-4843

-3780

-12400

751

-10410

3890

-340

1966

0

-1764

-4499

-3080

-11980

1383

-10940

2970

0

-1950

1967

-390

-1735

-4479

-3540

-12390

1466

-11170

5130

-650

-670

1968

-130

-1356

-4141

-2730

-12050

1767

-11270

5350

-750

280

1969

-130

-623

-4572

-2290

-12410

1460

-12310

4040

-1680

-1890

1970

-760

-1381

-5124

-2160

-12820

1236

-13830

3480

-2220

-3120

1971

-1410

-1908

-5724

-3010

-13920

812

-14020

4300

-2800

-2180

1972

-1010

-1500

-5798

-3250

-14290

949

-15070

4160

-3110

-2290

1973

-2290

-2595

-7027

-4010

-15160

489

-15020

5260

-3190

-110

1974

-2610

-2773

-6972

-4830

-16760

719

-15360

5740

-4110

920

1975

-2440

-2395

-6907

-4550

-16650

890

-14190

6010

-4420

2130

1976

-2710

-3416

-7221

-5960

-18720

940

-13920

6410

-4870

3660

1977

-1720

-2250

-6461

-4630

-17730

1292

-13720

5640

-4980

3100

1978

-1640

-1194

-6050

-3770

-17180

1580

-13800

5510

-5540

2590

1979

-1820

-2079

-6269

-3540

-17290

1624

-14010

6220

-6250

2460

1980

-1810

-1509

-6319

-2630

-16970

1764

-15280

5000

-6770

1850

1981

-2650

-1833

-6492

-2430

-16930

1709

-15470

5310

-7320

2070

1982

-4330

-3137

-7732

-2890

-17030

864

-15210

4890

-7360

1940

1983

-5120

-3916

-8312

-3030

-17100

327

-14930

5980

-7630

3540

1984

-5710

-3920

-8280

-2650

-17140

347

-14810

6320

-8360

4860

1985

-6470

-4446

-8854

-3120

-18350

235

-15530

6100

-8910

4300

1986

-7610

-5393

-9586

-4690

-20140

-573

-15590

6000

-9230

3890

1987

-9250

-6126

-10303

-5080

-21060

-863

-15110

7480

-9010

5960

0

1988

-10260

-7050

-11248

-4920

-21750

-1360

-15950

6590

-9530

3480

-740

1989

-11080

-8121

-11885

-7350

-24340

-1672

-14710

10060

-9980

6410

-160

1990

-12660

-10109

-12880

-8510

-26480

-2240

-14120

11830

-10640

8200

-760

1991

-14390

-11453

-14205

-9570

-27840

-3319

-13950

12030

-10510

8990

-2170

0

1992

-15590

-12578

-15325

-11310

-29150

-4177

-13070

13630

-10610

11280

-1110

-327

1993

-15890

-13630

-15895

-12280

-30350

-4649

-12070

15480

-11640

13460

-200

-359

1994

-17630

-13839

-17005

-12610

-30980

-5677

-12440

16040

-11800

14240

-120

-8

1995

-18710

-14117

-17465

-11940

-30220

-6075

-11740

17230

-12580

15440

-800

-651

1996

-20030

-14634

-18292

-12450

-30220

-6488

-12130

16820

-12750

13560

-1580

-444

1997

-20960

-15702

-18883

-12610

-30650

-6975

-12760

17290

-13460

13640

-2630

68

1998

-23200

-17755

-20115

-14830

-32990

-7978

-13280

18260

-14320

13750

-3310

-887

1999

-25000

-18319

-20976

-15870

-34050

-8086

-13460

18430

-14680

13810

-3560

-1651

2000

-26610

-19304

-21609

-17110

-35584

-8373

-12880

20150

-14700

15800

-4900

-2551

2001

-26860

-19533

-21782

-16950

-35194

-8597

-13580

19931

-15180

13707

-5480

-2049

2002

-28009

-20523

-22429

-18640

-37514

-8863

-14410

19043

-15760

12177

-6480

-2860

2003

-31326

-23234

-24243

-21590

-40654

-10996

-15450

17884

-16660

9675

-7460

-3962

2004

-32888

-24380

-24910

-24040

-43474

-11403

-15570

17841

-17780

9575

-8820

-5478

2005

-34893

-25892

-25971

-26540

-46754

-11926

-15640

18939

-18780

10243

-9250

-6957

2006

-36986

-27887

-27487

-27980

-49134

-12808

-17360

17540

-19510

7053

-9760

-8744

2007

-39731

-29360

-29285

-30230

-51654

-13774

-16950

18587

-19967

8323

-10150

-9691

2008

-41582

-30961

-30519

-32040

-53994

-14617

-16370

19687

-20097

9003

-10720

-9729

2009

-42919

-31844

-31701

-34690

-57894

-15576

-16900

19917

-20350

8853

-11070

-11143

2010

-43858

-33151

-32521

-35690

-59424

-16256

-17590

19117

-20790

7013

-13470

-10884

2011

-45780

-35301

-33940

-38710

-63577

-17211

-18650

18286

-21794

6168

-13790

-12388

2012

-45780

-35301

-33940

-38710

-63577

-17211

-18650

18286

-21794

6168

-13790

-12388

2013

-48240

-37341

-35501

-40840

-66267

-18366

-17970

19560

-21969

7529

-14250

-14859

2014

-49279

-37883

-36011

-41796

-67637

-18791

-19380

19328

-23019

6625

-14610

-14469

2015

-49410

-40113

-36133

-43136

-69547

-18935

-20270

18985

-23009

4972

-15560

-14391

2016

-1748

-1191

-1263

-1140

-1510

-781

-240

486

-1450

-635

-1130

-843

2017

-2747

-2437

-1826

-2640

-3001

-1335

470

587

-790

-750

-610

-1672

2018

-1981

-2045

-1963

0

-1960

-1550

-1570

-840

-880

-2040

0

257


Goals

  • to adapt to climate change and to reduce potential negative impacts
  • to adopt urgent measures to combat climate change and its consequences
  • to promote adaptation to climate change in key vulnerable sectors
  • to encourage Member States to adopt measures for protection against climate change

Similar oscillations within the last 400 years are typical of all Alpine glaciers. Following their peak at the beginning of the 17th century, glaciers remained at their maximum extent for the next 250 years, undergoing relatively insignificant changes. Most glaciers in the eastern Alps reached their second peak between 1770 and 1780, and in the mid-19th century. However, the post-1920 period records a continuous retreat of glaciers; the only variations occurring between individual years and decades were those concerning the rate of glacier retreat.

The melting of the Triglav glacier intensified during the 1990’s. The increasingly rapid thinning of the glacier ice caused individual rock formations to appear in the middle of the glacier, finally cutting it into two completely separate parts in 1992. The melting and disintegration of the Triglav glacier is still continuing, with occasional halts in the process occurring in years with exceptionally high snow cover during late spring. This occurred e.g. in 2004, when, at the beginning of July, snow measurement rods below the glacier revealed more than 2 m of snow. The snow cover remained in place until the end of the ablation season, so the glacier remained covered by snow and the measurements made no sense. The snow remained at the bottom of the glacier until the end of summer 2005, which is why the glacier’s surface area in this year was greater than in 2003. The smallest glacier area before 2018 was recorded in 2007, when it measured 0.6 ha. At the end of the melting season in 2008, the glacier was still mainly covered with snow from the previous winter season, and its measured surface area therefore amounted to 1,1 ha. The most significant glacier recovery occurred in 2009 and 2014, mostly thanks to above-average snow cover during two consecutive winters of 2008/09–2009/10 and 2012/13–2013/14, during which numerous avalanches were triggered as well. They are also among the important factors that make a glacier or its existence possible. At the end of the melting season in 2010, when most of the glacier was covered with thick layers of old snow, the glacier’s surface area was 2.5 hectares. It was similar at the end of the melting season in 2014, when it measured 3,6 hectares.

It should be borne in mind that the increase at that time was the result of several months of glacial firing or the well-reclaimed old snow of the last snow season. Due to the specific geographic location of the Triglav glacier, the latter has been only at the beginning of the years or even decades long process of the formation of the greenish firn ice, which gave the glacier the almost forgotten name "Green snow".

In September 2013, georadar measurements were carried out (13 cross sections with a length of 40–82 m in the NNE–SSW direction). They revealed that the surface area of glacier ice was 0.38 hectares (2.5 hectares including the snow on top of and adjacent to the glacier), while its volume amounted to 7,400 m3. The greatest thickness in some places was 5 m and the average thickness was 1.95 m. Including the snow on top of and adjacent to the glacier, the greatest thickness was 8 metres, while the average thickness was no more than 3 metres.

The trend of ice build-up stopped during the melting season in 2015, when the glacier's surface area was reduced by more than 50 %, to 1.7 hectares. Its thickness, and consequently its volume, was reduced even more (several metres in places). All of the firm that accumulated at previous years (more exactly from the beginning of the snow season 2005/06 with some spaces until the end of snow season 2013/14) disappeared due to intensive melting. Two seasons with snow volumes below average which were followed by very warm summers, caused further intense melting of the firn originating from previous winters, leading to contraction and thinning of the glacier. Even the snow season of 2017/18, which was pretty above average and which largely coincides with "the growing age" of the glacier (November-April) didn't stop this trend, as we subsequently recorded the warmest average melting season temperature since 1955, i.e. since the Krearica data are available. All of the 10 hottest melting seasons fall in the period after 2000. Out of 5 hottest, 4 happened after the year 2012.

Since 2017, the surface of the glacier is again smaller than one hectare. The maximal thickness of the glacial layer nowhere exceeds 5 meters at the end of the melting period. Only a patch of glacial ice caught in a karst depression remains, which is by the specific volume density increasingly similar to water ice.

The precise time determination of disappearance the glacier is impossible, because it isn't possible to be accurate enough in the prediction of the local climate change on  the Triglav glacier area. The latter is a result of the global climate change. With the continued occurrence of unfavourable climatic conditions in the coming years, there is a strong likelihood that the glacier will disintegrate into several smaller parts and disappear gradually.

When measurements began in the mid-1950s, the melting period was slightly shorter than the accumulation period, while in recent decades it has usually been the opposite. The glacier balance is very fragile, as current temperature conditions and other factors threaten the preservation of the Triglav glacier (table Average temperature (° C) melting season at Kredarica in decades). If atmosphere warming continues at the rate witnessed in the last two decades, the glacier will eventually disappear. More snowfall in the area of the glacier, which is a possible result of global climate change, will only temporarily delay the glacier's gradual disappearance.

Data from a nearby meteorological station in Kredarica show that the average melting season temperature has a rather large year-on-year variability, with a marked upward trend, which is consistent with observed patterns of temperature change at other stations in the Alps. After a fairly stable average in the 1950s and 1960s, the minimum was in the 1970s. At the beginning of the 1980s temperatures began to rise during the melting season and this trend continued into this millennium. A comparison of 10-year series of average melting season temperatures (May-October) shows the first two major temperature jumps in the second half of the 70's and the second half of the 80's of the 20th century (0.3 and 0.4 respectively) and a remarkable temperature jump (0.7 ° C) at the turn of the 20th to the 21st century. The average melting temperature of the next, that is, the last ten-year series (2007-2016), hasnʹt increased further than the previous one.

The highest average melting season temperatures between 1955 and 2016 were recorded at 5.5 ° C in 2018 (0.3 ° C higher than in the extremely warm year and the summer of 2003) and the lowest (1.7 ° C) in years 1972 and 1974. The average temperature of the last melting season (May-October 2016) was with 4.0 ° C almost equal to the long-term average (3.9 ° C) of the last climatological period (1981-2010). The rather cold October or the last month of the melting season stands out. The melting season in 2015 was also outstandingly warm (for a whole degree of Celsius too hot) relative to the comparative data for the climatological period. Compared to the reference period 1961-1990, the average temperature of the last melting season (2016) was 0.8 ° C above the average. A possible turnaround for glacier growth would require a sequence of sub-average melting seasons or a series of very snowy winters. However, it canʹt be overlooked, that since the beginning of the yearlong measurements at Kredarica (1955), as many as 9 warmest melting seasons fall in the period after 2000. In the first half of this 62-year observation series, almost all the melting seasons are from 2000 onwards, with the exception of 2010 and 2014. In the last period the glacier initially increased significantly-in 2013 and 2014. But in the next two years it reduced again and reached the surface decades ago. A significant decrease in glacier thickness or volume in 2016 was aided by relatively late (March) snowfall in the accumulation period and the above-average warming period, since four (June-September) of all six months were well above long-term average.

If the favorable conditions observed in the period 1992-2007 and in 2011, 2012, 2015 and 2016-2018 recur in coming years the glacier will continue to shrink. In this case the glacier may again disappear completely, which almost already happened at the beginning of this millennium. This is why the Triglav glacier will continue to be extremely important and one of the direct indicators of climate change in the region. Similar movements are typical of all Alpine glaciers. The largest mass losses were also recorded in the Sarennes (France), Careser (Italy) and the Hintereis (Austria) glaciers in 1946-2014 and 2015. Simultaneously mass increased in some Norwegian glaciers, also on one of the glaciers in the Pyrenees of Spain. Variations in the rate of change are caused by varying altitude, location and the size of glaciers in addition to the variable annual weather factors.

From 1900 until today, according to the European Environment Agency data, the Alps have lost about 50 % of their ice mass, mainly due to elevated  summer temperatures. The continued retreat of glaciers is predicted during the 21st century. According to the moderately optimistic scenario of RCP4.5 releases, the extent of European glaciers will decrease from 20 to 84 % until the year 2100 (compared to the year 2006). The pessimistic PCP 8.5 emission scenario forecasts the reduction of 38-89 %. The largest relative volume loss is expected in central Europe, while in Norway the glacier areas are expected to decrease by about third till the end of the century, according to the SRES B2 greenhouse gas emissions scenario.

 

 

 



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