Extensive melting in West Antarctica and the Peninsula

As the peak of Antarctica’s melt season approaches, surface snow melting has been widespread over coastal West Antarctica, with much of the low-lying areas of the Peninsula and northern West Antarctic coastline showing 5 to 10 days more melting than average. However, much of the East Antarctic coast is near average. Snowfall in Antarctica for the past year has been exceptionally high as a result of an above average warm and wet winter and spring.

Overview of conditions

Figure 1. The upper Antarctic ice sheet daily melt extent as a percentage of ice sheet area for November 1st 2022 through January 10th 2023 (red line) with 1990-2020 median line (blue dashed line) and the interquartile and interdecile ranges shown for the reference period (grey bands). Upper right, map of total melt days for the Antarctic Ice Sheet for November 1st to January 10th 2023; lower left, close-up of the Antarctic Peninsula showing total melt days for the period. Lower right, map of the difference from average melt days for November 1st to January 10th relative to 1990-2020 reference period. ||Credit: Credit: M. MacFerrin, CIRES and T. Mote, University of Georgia High-resolution image

Figure 1a. The upper maps of the Antarctic Ice Sheet (left) and the Antarctic Peninsula (right) show the total melt days for the areas from November 1, 2022 to January 10, 2023. The graph on the bottom shows daily melt extent for the Antarctic Ice Sheet as a percentage of ice sheet area for the same time period in red and the 1990 to 2020 average in blue. The interquartile and interdecile ranges appear in grey bands. 

Credit: E. Cassano and M. MacFerrin, CIRES and T. Mote, University of Georgia
High-resolution image

Figure 1b. This map shows , map of the difference from average melt days for November 1st to January 10th relative to 1990-2020 reference period. ||Credit: Credit: M. MacFerrin, CIRES and T. Mote, University of Georgia High-resolution image

Figure 1b. This map shows the number of melt days from November 1, 2022 to January 10, 2023, as a difference from average relative to the 1990 to 2020 reference period. Reds indicate more melt; blues indicate less melt.

Credit: E. Cassano and M. MacFerrin, CIRES and T. Mote, University of Georgia
High-resolution image

Antarctic surface snow melting through January 10 is above average and reached near-record extent in late December. A significant melt event spread over the Peninsula and across much of the West Antarctic Ice Sheet northern coast and into the Ross Ice Shelf area (Figure 1a). Melting has been moderately above average for the Peninsula areas, but unusually high in the Getz Ice Shelf area, where melting is less frequent. The Larsen Ice Shelf area has seen up to 25 days of melting, about 5 more than average, and the Wilkins region up to 30 days, again about 5 more than average (Figure 1b). The Getz and Sulzberger Ice Shelves (to the lower left of the Antarctic maps) have seen 10 melt days this season, about double the average for this time of year. East Antarctic Ice Shelves—Fimbul, Roi Baudouin, and Amery—have had near-average to slightly above-average melting of 5 to 10 days each.

Conditions in context

Figure 2. Weather conditions for Antarctica and the surrounding coastal areas for December 1st to January 10th 2023. Both charts show the air temperature (top) and air pressure (bottom) difference from average relative to a 1991-2020 reference period. ||Credit: National Centers for Environmental Prediction (NCEP) Reanalysis data, National Center for Atmospheric Research |High-resolution image

Figure 2. These plots show weather conditions as a difference from average relative to the 1991 to 2020 reference period for Antarctica and the surrounding coastal areas. The top plot shows air temperature at the 925 millibar level, in degrees Celsius, for December 1, 2022 to January 10, 2023. Yellows and reds indicate higher-than-average temperatures; blues and purples indicate lower-than-average temperatures. The bottom plot shows sea level pressure for the same period. Yellows and reds indicate higher-than-average air pressure; blues and purples indicate lower-than-average pressure.


Credit: National Centers for Environmental Prediction (NCEP) Reanalysis data, National Center for Atmospheric Research
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Antarctica’s weather for December through January 10, 2023, was warm in a broad area from the northern Ross Sea and along the northern West Antarctic coast to the northern tip of the Peninsula. Central West Antarctica had temperatures up to 2.5 degrees Celsius (4.5 degrees Fahrenheit) above average. Temperature differences from average were generally 1.5 degrees Celsius (3 degrees Fahrenheit) above average over parts of the Ross Sea and about 1 to 1.5 degrees Celsius (2 to 3 degrees Fahrenheit) above average through the northern West Antarctic coastal and Peninsula areas.

Air pressure was below average throughout most of the continent and adjacent Southern Ocean, with above-average pressures generally near 50 degrees South latitude. This creates stronger than average eastward-flowing winds around the continent, creating warm conditions in areas where the direction is southeastwards (i.e. the Peninsula), and in particular, causing strong foehn winds on the lee side (east side) of the Peninsula. Cool conditions in the high-altitude parts of East Antarctic are a result of strong circumpolar winds generally isolating this region from warmer air to the north.

Snow globe Antarctica

Figure 3. Top, accumulated surface mass balance (that is, total snowfall minus minor melt run-off and snow evaporation) in billions of tons (Gtons) for the Antarctic continent from March 1st 2022 to January 10th 2023 (red line), along with several recent years, presented as a difference from the average amount for 1981-2010. The grey band is the standard deviation (66% of all years in 1981-2010 fall within the grey band). Bottom, maps of total surface mass balance for the period, and difference from average, shown as millimeters of water equivalent for the accumulated snow. . These estimates are from the MARv3.12 model forced by the ERA5 reanalysis till Dec 2022 and by GFS afterwards. || Credit: Xavier Fettweis, University of Liège, Belgium| High-resolution image

Figure 3. The top graph shows accumulated surface mass balance (total snowfall minus minor melt run off and snow evaporation) in billions of tons (Gtons) for the Antarctic continent from March 1, 2022, to January 10, 2023 (red line), along with several recent years, presented as a difference from the 1981 to 2010 average. The grey band is the standard deviation (66 percent of all years in 1981 to 2010 fall within the grey band). The bottom left map shows the total surface mass balance for the period. The bottom right map show SMB as a difference from average, shown in millimeters of water equivalent for the accumulated snow. These estimates are from the MARv3.12 model forced by the ERA5 reanalysis until December 2022 and by Global Forecast System (GFS) afterwards.

Credit: X. Fettweis, University of Liège, Belgium
High-resolution image

Snowfall over Antarctica has been significantly above average over these last weeks, continuing a trend that began in November 2021. Several recent hydrological years (March 1 to February 28) for Antarctica have had up to 200 billion tons more snow than average, but the 2022 to 2023 year has reached nearly 300 billion tons as of January 10, 2023. This is in line with some future projections that suggest larger accumulation with a warmer climate until warming reaches above 7.5 degrees Celsius (13.5 degrees Fahrenheit). This very high deviation from average snow input suggests that the Antarctic Ice Sheet could gain mass this year. Snowfall amounts have been especially high along the western edge of the Peninsula and the Bellingshausen coast, where persistent southeastward-flowing winds push marine air against a series of mountain ranges and the ice ridge along the spine of the Peninsula. However, the biggest contribution to the above average total snow input occurs in East Antarctica, and specifically Wilkes Land and the interior of Antarctica. Overall, high snowfall in Antarctica may completely offset recent net ice losses from faster ice flow off the ice sheet for this assessment period. Most of the past decade has seen annual net losses of 50 to 150 billion tons.

Melt ponds and glacier retreat in the Peninsula

Figure 4. True color image from the Moderate-resolution Imaging Spectroradiometer (MODIS) sensor aboard the Aqua satellite acquired on January 10th 2023. The area shown is a part of the northern Peninsula and its eastern flank (see inset map). North is towards the upper right, and the image is 312.5 by 187.5 km in size (~180 x 120 miles). Credit: NASA WorldView|High-resolution image

Figure 4. This true color image shows several melt ponds on the northern part of the Antarctic Peninsula (see inset map) on January 10, 2023. The image is from the Moderate-resolution Imaging Spectroradiometer (MODIS) sensor aboard the NASA Aqua satellite. For reference, North is towards the upper right, and the image is 312.5 by 187.5 kilometers in size (about 180 x 120 miles).

Credit: NASA Worldview
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Above average surface melting over the northern Peninsula is evident in the accumulation of surface meltwater in several areas of the eastern side of the Peninsula. The Larsen C Ice Shelf, and the SCAR Inlet Ice Shelf, a remnant of the former Larsen B shelf, are all showing significant areas of accumulated meltwater on their surfaces. Meltwater on ice shelves can pose a threat to ice shelf stability through a process called hydrofracture, where water fills pre-existing cracks in the shelf and forces the crack to open further as water pressure increases inside the crack.

The warm conditions have also triggered several rapid tidewater-style retreats in the area this season, most noticeably for Hektoria/Green/Evans glacier system in the northwestern Larsen B embayment. The glacial ice front of Hektoria has retreated roughly 5 kilometers (3 miles) in the past two months. A similar outflow can be seen in the Moderate Resolution Imaging Spectroradiometer (MODIS) data to the north near the Sobral Peninsula from the Bombadier/Edgeworth/Dinsmore glacier system (not shown). The Seal Nunataks Ice Shelf remnant, which is between the Larsen A and Larsen B Ice Shelves, is also degrading since the sea ice minimum of early 2022.

Further reading

Kittel, C., C. Amory, C. Agosta, N. C. Jourdain, S. Hofer, A. Delhasse, S. Doutreloup, P.-V. Huot, C. Lang, T. Fichefet, T., and X. Fettweis. 2021. Diverging future surface mass balance between the Antarctic ice shelves and grounded ice sheetThe Cryosphere, 15, 1215–1236, https://doi.org/10.5194/tc-15-1215-2021

NASA Earth Observatory Article: Clear days for iceberg spotting

Record September

While most of the 2022 Greenland melt season was near average, September set records for high temperatures, melt extent, and ice loss. A persistent high air pressure pattern off the southeastern tip of the island, and low air pressure over the Canadian Archipelago—and remnants from Hurricane Fiona—drove the unusual conditions.

Overview of conditions

Figure 1a. The top left map illustrates cumulative melt days on the Greenland Ice Sheet for the 2022 melt season. The top right map illustrates the difference from the 1981 to 2010 average melt days for the same period. The bottom graph illustrates daily melt area for Greenland from April 1st through October 31st, 2022, with daily melt area for the preceding five years. The gray lines and bands depict the average daily melt area for 1981 to 2010, the interquartile range, and the interdecile range. ||Credit: National Snow and Ice Data Center/T. Mote, University of Georgia|High-resolution image

Figure 1a. The top left map illustrates cumulative melt days on the Greenland Ice Sheet for the 2022 melt season. The top right map illustrates the difference from the 1981 to 2010 average melt days for the same period. The bottom graph illustrates daily melt area for Greenland from April 1 through October 31, 2022, with daily melt area for the preceding five years. The gray lines and bands depict the average daily melt area for 1981 to 2010, the interquartile range, and the interdecile range.

Credit: National Snow and Ice Data Center/T. Mote, University of Georgia
High-resolution image

Cumulative daily melt area for the summer seasons over the 43-year satellite record. Average totals for the 1981-2010 30-year reference period, and for the most recent 21 years, 2001-2022 are shown as horizontal blue lines. ||Credit: National Snow and Ice Data Center/T. Mote, University of Georgia|High-resolution image

Figure 1b. This bar graph shows the daily cumulative melt area for the summer seasons over the 43-year satellite record. Average totals for the 1981 to 2010 30-year reference period, and for the most recent 21 years, 2001 to 2022 are shown as horizontal blue lines.

Credit: National Snow and Ice Data Center/T. Mote, University of Georgia
High-resolution image

For the melt season as a whole, ice sheet melting was well above average across the southwest and northeast while slightly below average in the northwest and southeast (Figure 1a). However, much of the above average seasonal melting resulted from an unusually warm September, particularly for the southwestern ice sheet. A major melting event took place at the beginning of September, with another significant melt spike in late September resulting from the remnants of Hurricane Fiona as an extra-tropical cyclone. Another period of above-average melt extent occurred in mid-July.

The 2022 melt season in Greenland overall (April 1 to October 31) had a cumulative total of 22.1 million square kilometers (8.53 million square miles) of melt, placing it at nineteenth highest in the 43-year satellite record (Figure 1b). While this is 18.1 million square kilometers (6.99 million square miles) above the 1981 to 2010 average, it is below the average for the twenty-first century years of 2001 to 2022 by 26.3 million square kilometers (10.2 million square miles). Though recent years have not reached or exceeded the extreme melting totals of 2010, 2012, or 2016, the past two decades continue to have consistently more melting than earlier years.

Conditions in context

Average Temperature and Height at 700 millibars

Figure 2. The top plot illustrates surface air temperatures as a difference from the 1990 to 2020 average for June 1 to to August 31, 2022, for Greenland and surrounding areas. The bottom plot shows the air pressure as indicated by the height difference from average of the 700 millibar level (about 10,000 feet above sea level) for Greenland and the surrounding region for the same period.

Credit: National Centers for Environmental Prediction (NCEP) Reanalysis data, National Center for Atmospheric Research
High-resolution image

Conditions for the core of the melt season from June to August, were not far from the long-term average, with slightly above average temperatures in the northern part of the ice sheet and its southern tip, but below average temperatures in its central area, especially the east-central coast (Figure 2). Low atmospheric pressure between Iceland and the eastern Greenland coast—a pattern termed the Icelandic Low—brought mostly westward-flowing winds in the north and cool winds from the northwest for the western and southern areas.

Record September

Figure 3. The map in the upper left shows the difference from average for melt days on the Greenland Ice Sheet for September in 2022, and shows the location of the Swiss Camp research station. At top right, automatic weather station air temperatures at Swiss Camp were above melting for much of September, 2022. The bottom plot illustrates the air pressure as indicated by the height difference from average of the 700 millibar level (about 10,000 feet above sea level) for Greenland and the surrounding region for the same period. Credits : National Centers for Environmental Prediction (NCEP) Reanalysis data, National Center for Atmospheric Research) and Swiss Camp data are from the GEUS GC-Net station, graphic by Jason Box, GEUS. High-resolution image

Figure 3a. The map in the upper left shows melt days as a difference from average on the Greenland Ice Sheet for September 2022, and shows the location of the Swiss Camp research station. The top right graph shows automatic weather station air temperatures at Swiss Camp, which were above melting for much of the month. The bottom plot illustrates the air pressure as indicated by the height difference from average of the 700 millibar level (about 10,000 feet above sea level) for Greenland and the surrounding region for the same period.

Credit: National Centers for Environmental Prediction (NCEP) Reanalysis data, National Center for Atmospheric Research; Swiss Camp data are from the Geological Survey of Denmark and Greenland (GEUS) Greenland Climate Network (GC-Net) station, graph by Jason Box, GEUS
High-resolution image

Figure 4. Meltwater runoff and total melt production per day for the Greenland Ice Sheet, June – September 2022, also showing 2020 and 2012 for comparison. Blue dashed line is the maximum daily value for any year between 1981 and 2010; in gray are the average amount and the typical range of values (standard deviation). These estimates are from the MAR 3.12 reanalysis model. Re Credit, Xavier Fettweis, University of Liége. Credits : National Centers for Environmental Prediction (NCEP) Reanalysis data, National Center for Atmospheric Research) and Jason Box, GEUS. High-resolution image

Figure 3b. These graphs show meltwater runoff at the top and total melt production at the bottom per day for the Greenland Ice Sheet from June to September 2022, along with 2020 and 2012. The blue dashed line represents the maximum daily value for any year between 1981 and 2010; in gray line and area depict the average amount and the typical range of values (standard deviation). These estimates are from the MAR 3.12 reanalysis model.

Credit: Xavier Fettweis, University of Liège
High-resolution image

September 2022 conditions were very different from earlier months, notably the June to August period (Figure 3a). A strong and persistent high air pressure pattern was present off of Greenland’s southeastern coast coupled with low air pressure in the Canadian Archipelago, resulting in a transfer of warm air from the southeast onto the ice sheet. This set record warm conditions and unprecedented surface melt extents through the month relative to the 40+ year satellite record. In most years, the September cumulative melt area totals do not exceed 1 million square kilometers (386,000 square miles). The 1981 to 2010 average is 486,000 square kilometers (188,000 square miles). By contrast, the 2022 cumulative melt area total was 3.9 million square kilometers (1.51 million square miles), more than doubling the previous record September melt. The record September prior to 2022 was 2010, with 1.6 million square kilometers (618,000 square miles).

Air temperatures for Greenland overall were 6 degrees Celsius (11 degrees Fahrenheit) above average at the 700 millibar level, roughly 10,000 feet above sea level. This is more than 3 standard deviations above the typical range, making it the warmest September on record since 1950 in the MAR 3.12 reanalysis record. Conditions at a weather station near Swiss Camp in Greenland show near-continuous melting conditions through the month, much warmer than the previous two years.

September 2022 had an unusual amount of melt and meltwater runoff (Figure 3b). The total amount of meltwater produced during the month was 57 billion tons, a record for September, compared to the 1981 to 2010 average September total of 9 billion tons—according to MARv3.12 forced by the ERA5 reanalysis. Runoff total was also a record at 55 billion tons. Total runoff in September was a high fraction of the total produced melt because warm events and rainfall occurred during the period of maximum bare ice exposure at the end of summer. Overall, the estimated total change in surface mass of the ice sheet surface (not considering the outflow of glaciers) was only -8 billion tons, a smaller number than melt and runoff because of the high amounts of rainfall that fell on the ice sheet (again a record for September since 1950), some of which freezes onto the snow or firn surface.

Exposed

Figure 5. Extent of exposed bare ice on the Greenland Ice sheet for 2022 and the preceding 5 years from Sentinel 3 data. Credit, Jason Box, GEUS, Adrien Wehrlé, Univ. of Zurich, and ESA EO Science For Society, ESA CCN 4000125043/18/I-NB.

Figure 4. This graph shows the extent of exposed bare ice on the Greenland Ice sheet for 2022 and the preceding five years from Sentinel 3 data.

Credit: Jason Box, Geological Survey of Denmark and Greenland (GEUS); Adrien Wehrlé, University of Zurich; and European Space Agency Earth Observation (ESA EO) Science For Society, ESA Contract Change Notice (CCN) 4000125043/18/I-NB
High-resolution image

The unusual timing of warm and rainy conditions throughout the month of September led to a jump in the amount of exposed bare ice on the ice sheet. In most years, snowfall begins to cover the icy edges of the ice sheet in September, but this year exposed bare ice increased to typical mid-summer levels. This has an effect on both melt, since darker bare ice absorbs more solar energy, and run-off, as the ice surface cannot absorb water.

Break-up of the last large ice shelf in Greenland

Figure 6. Landsat images spanning 22 years showing the retreat and breakup of the Zachariae Isstrøm ice shelf. Upper right, location of the ice shelf in northeastern Greenland. Christopher Shuman, NASA JCET/GSFC, and US Geological Survey.

Figure 5. These Landsat images span 22 years, showing the retreat and breakup of the Zachariae Isstrøm Ice Shelf. The upper right inset map shows the location of the ice shelf in northeastern Greenland. An animation by Christopher Shuman shows a longer series of images.

Credit: Christopher Shuman, University of Maryland, Baltimore Campus (UMBC) at NASA Goddard Space Flight Center (GSFC); data are from US Geological Survey
High-resolution image

Recently published research on the Zachariae Isstrøm (ZI) outlet glacier describes how this glacier’s floating ice shelf began to break apart early this century and is continuing to retreat under warming ocean and air conditions. As a result of the loss of the floating shelf, the grounded area of the glacier has accelerated and thinned, and it is now contributing more ice to the ocean.

Landsat data collected over the past 50 years indicates the floating ice in front of this outlet was relatively stable until late 2002. However, the loss of contact between the adjacent islands east of the ice shelf front initiated a break up in August 2002. This has proceeded with rapid ice front collapse events for the past several years.

References

Satellite Image Atlas of Glaciers of the World: Greenland