An undated handout photo from the Australian Antarctic Division last September, 2017 as reported in one of the major dailies, shows a rough compacted Sea Ice in the Antarctic. Sea Ice cover in Antarctica dropped to a record low this year and scientists have warned the frozen continent’s unpredictable nature poses growing risks to shipping including tourist cruises.
Scientists from around the world are meeting in the Tasmanian capital Hobart this week to discuss sea ice fluctuations and improved navigation and forecasting, as tourists flock to the ocean in greater numbers. Satellite images confirm the continent’s sea ice fell to its lowest maximum and minimum levels this year since satellite observations began in 1979, they said.
“It appears that both the summer time minimum and the wintertime maximum sea ice extent around Antarctica have set new record lows”, said Jan Lieser from the Antartic Climate and Ecosystems Cooperative Research Centre, which is hosting the conference.
While climate change may have played a part, he said it was still too early to draw any clear link, “simply because the variability in the Antarctic sea i8ce system is so high.” “We still have a lot more work to do to understand the fundamental oceanic and atmospheric processes driving sea ice variability in Antarctica,” added Lieser.
The data showed the lowest recorded minimum sea ice cover on March 1 at 2.075 million square kilometers, with the lowest maximum on September 12 at 18.013 million square kilometers. But only three years ago,
ice levels hit a record high of more than 20 million square kilometers, illustrating the huge challenges sea traffic must deal with.
Lieser further said that the extreme swings made it vitally important to better understand ocean conditions to make credible forecasts for polar shipping. As well as resupply ships, some 50 cruise vessels carried almost 35,000 tourists to the Antarctic last year to witness its ice shelves, soaring glaciers and wildlife.
“We have seen a number of private and commercial ships becoming stuck in the Antarctic sea ice in recent years, which have led to costly rescue operations that can delay scientific work,” said Lieser.
In late 2013, a Russian ship carrying 74 scientists, passengers and crew became trapped in Antarctica. It triggered two weeks of rescue operation coordinated by Australian authorities which included French, Chinese, American and German agencies, during which a Chinese icebreaker also became stuck.
The diversion of several government’s Antarctic program resources drew criticism, with an Australian resupply ship running two weeks behind schedule and French scientists having to scrap an oceanographic campaign. The International Ice Charting Group, with 60 representative from 12 countries, wants to ensure such a situation does not happen again.
WHAT CAUSES THIS ICE VARIABILITY in ANTARCTICA?
Possible mechanisms of Antarctica Sea Ice variability, according to top scientists may be atmospheric warming, hydrology, sea ice formation and oceanology as follows:
- Atmospheric warming : accelerated melting of Antarctic melting of Antarctic ice shelves… increased freshwater input… more strongly stratified mixed layer…reduced ocean flux from deep ocean to ocean waters… cooler, fresher sea surface conditions…enhanced sea ice formation (Bintaja et al, 2013)
- Increased sea ice cover: increased melt of sea ice…increased freshwater input…more strongly stratified mixed layer… reduced ocean flux from deep ocean to surface waters…cooler, fresher sea surface conditions… enhanced sea ice formation (Goose and Zunz, 2014)
- Increases in precipitation: freshening of surface waters…cooler, fresher sea surface conditions…enhanced sea ice formation (Liu and Curry, 2010)
The sea ice surrounding Antarctica has increased in extent and concentration from the late 1970’s, when satellite based measurements began, until 2015. Although this increasing trend is modest, it is surprising given the overall warming of the global climate and the region, generally simulate a decrease in sea ice. Moreover, sea ice has presented a conundrum for global climate change science.
The National Academies of Sciences, Engineering and medicine held a workshop on January 11 to 12, 2016, in Boulder, Colorado, to bring together scientists with different sets of expertise of and perspectives to further explore potential mechanisms driving the evolution of recent Antarctic sea ice and its relationship to the broader ocean climate system.
The significant distinctions between the Southern and Arctic Oceans, which are dif ferent dynamic systems, was a common theme of the workshop discussions. In particular, the Southern Ocean surface is relatively insensitive to recent human caused greenhouse gas (GHG) forcing, so surface waters have experienced less warming than has been observe d in other areas. However, changes in the deep ocean can have an outsized effect on the Southern Ocean because it is a region of significant upswelling. Therefore, it is expected that as the global deep water continues to warm, it will continue to melt Antarctica ice for many decades, even if carbon dioxide levels are reduced.
There are many local, regional and global processes that influence sea ice growth and melt, but it is not clear what mechanisms best explain the observed variability and the slight increase in overall Antarctic sea ice extent. Some have highlighted how negative feedbacks between the ocean and sea keep Antarctica sea ice thin. Other studies suggest that there may be a modest decrease in Antarctic sea ice extent from anthropogenic warming, but that the trend is overwhelmed by a recent increase associated with internal variability, resulting in the recent slight expansion of Antarctic sea ice extent. Other factors that may be play include tropical Pacific and Atlantic teleconnections, variability in the winds and ocean currents that circumnavigate Antarctica and changes in surface conditions resulting from stratospheric ozone depletion.
Understanding the mechanisms and processes driving sea ice variability and trends is limited by the lack of a long, homogeneous record of sea ice extent and concentration. Furthermore, observations of the surrounding ocean are geographically sparse and short. Accordingly, more effort should go into extending the observational record using proxies, historical records and data assimilation. At this time, the data that have been captured to extend the historical record indicate a larger sea ice extent prior to the satellite period. However, questions were raised as to whether there is enough evidence in the diverse set of proxies to make such a definitive statement. In addition, some scientists highlighted the need for more validation of the passive microwave observations of sea ice concentrations taken from space based platforms. Reanalysis data also remain problematic and it is not clear which analysis is best suited for Antarctic studies.
Some say that there is little confidence in the models that are used for attribution of Antarctic sea ice variability. Furthermore, model biases such as stratification, mixed layer depth impact how the models respond to forcing, but there is uncertainty on how large an impact the biases have.
By and large, despite these shortcomings, various type of models are useful for understanding processes that may be affecting sea ice.
Breaking news! Breaking news!…as of this writing, another ice breaks in Antarctica and two (2) research ships cruising that area reportedly got stuck. OMG!