Dr Andrew Klekociuk
Dr Barbara Wienecke
State and trends of the Antarctic cryosphere
Antarctic environment (2016, 2011)
State and trends of the Antarctic cryosphere
Component
Summary
Grade
Very poor
Poor
Good
Very good
Confidence
In Grade
In Trend
Comparability
To previous years
From November 1978 to December 2012 across the Antarctic, overall, a 1.5 ± 0.3% increase per decade is seen, but there are regionally varying trends (both positive and negative) that are season-dependent
More certainty exists about the observations than about the environmental consequences. However, proxy information from ice-core and historical whaling records suggests that sea ice coverage declined significantly in the decades before the late 1950s to early 1960s
Year(s):
20163
Unclear
Confidence (in grade):
Adequate
Confidence (in trend):
Adequate
Comparability (to previous reports):
Comparable
Antarctica-wide since 1960 (the start of the modern satellite era): 1.2 ± 0.2% increase per decade with regionally opposite trends; 7.1 ± 0.9% decrease per decade in Amundsen-Bellingshausen seas, 4.9 ± 0.6% increase per decade in Ross Sea There is more certainty about the observations than about the environmental consequences; however, proxy information from ice core and historical whaling records suggests that a major decline in sea ice coverage occurred in the decades before the the late 1950s to early 1960s
Year(s):
20113
Unclear
Confidence (in grade):
Adequate
Confidence (in trend):
Adequate
Comparability (to previous reports):
Not assessed
Major and opposing trends are seen in different areas. In the western Antarctic Peninsula and north-western Weddell Sea, later annual advancing of sea ice edge and earlier retreat mean that the sea ice season is shortening, with deleterious effects on ecosystems. Sea ice advance appears more sensitive to climate variability than sea ice retreat. Conversely, the season is longer in the western Ross Sea. The trend patterns across East Antarctica are more complex
Year(s):
20162
Deteriorating
Confidence (in grade):
Adequate
Confidence (in trend):
Adequate
Comparability (to previous reports):
Comparable
There are major and opposing trends in different areas. In the West Antarctic Peninsula and north-west Weddell Sea, later annual advancing of sea ice edge and earlier retreat means the sea ice season is shortening, with deleterious effects on ecosystems; sea ice advance appears more sensitive to climate variability than sea ice retreat. Conversely, there is a longer season in the western Ross Sea. There is no clear trend in seasonality for East Antarctica, where the pattern of change is complex
Year(s):
20112
Deteriorating
Confidence (in grade):
Adequate
Confidence (in trend):
Adequate
Comparability (to previous reports):
Not assessed
Insufficient information exists to determine whether the extent or seasonality of fast ice is changing (current satellite-derived timeseries is too short, and limited to East Antarctica for 2000–08). From 2000 to 2008, there were different responses in the Indian Ocean and West Pacific sectors
Year(s):
20160
Unclear
Confidence (in grade):
Low
Confidence (in trend):
Low
Comparability (to previous reports):
Comparable
There is insufficient information about the seasonality of fast ice (current satellite-derived timeseries is too short and limited to East Antarctica for 2000–08). From 2000–08, there were different responses in the Indian Ocean and West Pacific sectors
Year(s):
20110
Unclear
Confidence (in grade):
Low
Confidence (in trend):
Low
Comparability (to previous reports):
Not assessed
Changes to the characteristics of pack ice are likely to have a cascading impact through the ecosystem. At present, there is great uncertainty in large-scale estimates of the thickness distributions of sea ice and its snow cover. Research continues to derive these key quantities from satellite data
Year(s):
20162
Deteriorating
Confidence (in grade):
Limited
Confidence (in trend):
Limited
Comparability (to previous reports):
Comparable
Changes to the characteristics of pack ice are likely to have a cascading impact through the ecosystem. At present, there is great uncertainty in large-scale estimates of the thickness distributions of sea ice and its snow cover. Research is under way to derive these key quantities from satellite data
Year(s):
20112
Deteriorating
Confidence (in grade):
Limited
Confidence (in trend):
Limited
Comparability (to previous reports):
Not assessed
Overall, mass balance for the East Antarctic Ice Sheet is neutral to positive, unlike the West Antarctic Ice Sheet, which is clearly losing mass. Ice changes at some locations on the coastal margin show significant variability in response to changes in ocean heat and potential vulnerability to irreversible retreat in the long term. The present state of knowledge does not allow us to fully assess state and trend
Year(s):
20160
Unclear
Confidence (in grade):
Low
Confidence (in trend):
Low
Comparability (to previous reports):
Not comparable
There is mounting evidence that the EAIS is losing mass, although by how much is uncertain. Continent-wide, there are also signs of acceleration in the loss rates, although the timespan of comprehensive observations is short. Lack of in situ data on glacial isostatic adjustment (uplift) limits interpretation of observations of ice sheet mass and elevation change. Net mass loss contributes to global sea level, and changes the freshwater budget of the Southern Ocean
Year(s):
20112
Deteriorating
Confidence (in grade):
Limited
Confidence (in trend):
Adequate
Comparability (to previous reports):
Not assessed
Most Heard Island and McDonald Islands glaciers have retreated since 1947: total glacier area decreased from 288 km2 in 1947 to 231 km2 in 2008
Rising temperatures and newly exposed terrain led to changes in the distribution of flora
Year(s):
20162
Deteriorating
Confidence (in grade):
Limited
Confidence (in trend):
Adequate
Comparability (to previous reports):
Comparable
Most Heard Island glaciers have retreated since 1947: total glacier area decreased (from 288 km2 in 1947 to 231 km2 in 1988); for 2000-03, ice loss of Brown Glacier is estimated at around 8.0 x 106 m3/year, more than double the average of the last 57 years. Rising temperatures and newly exposed terrain led to changes in distribution of flora
Year(s):
20112
Deteriorating
Confidence (in grade):
Limited
Confidence (in trend):
Limited
Comparability (to previous reports):
Not assessed
km2 = square kilometre; m3 = cubic metre
Assessment Summary Key
Grades
Very good
There are no significant changes in physical or chemical processes
Good
There are some significant changes in physical or chemical processes in some areas, but these are not to the extent that they are significantly affecting ecosystem functions
Poor
There are substantial changes in physical or chemical processes, and these are significantly affecting ecosystem functions in some areas
Very poor
There are substantial changes in physical or chemical processes across a wide area of the region as a result of human activities, and ecosystem functions are seriously affected in much of the region
Recent Trends
-
Improving
-
Stable
-
Deteriorating
-
Unclear
Confidence
-
Adequate: Adequate high-quality evidence and high level of consensus
-
Somewhat adequate: Adequate high-quality evidence or high level of consensus
-
Limited: Limited evidence or limited consensus
-
Very limited: Limited evidence and limited consensus
-
Low: Evidence and consensus too low to make an assessment
Comparability
-
Comparable: Grade and trend are comparable to the previous assessment
-
Somewhat comparable: Grade and trend are somewhat comparable to the previous assessment
-
Not comparable: Grade and trend are not comparable to the previous assessment
-
Not previously assessed
Klekociuk A, Wienecke B (2016). Antarctic environment: State and trends of the Antarctic cryosphere. In: Australia state of the environment 2016, Australian Government Department of the Environment and Energy, Canberra, https://soe.environment.gov.au/assessment-summary-72-state-and-trends-antarctic-cryosphere, DOI 10.4226/94/58b65b2b307c0
Comments
Assessment remains the same as in 2011.