![]() ![]() Antarctica is surrounded by ocean, not a land surface that is losing its reflective snow and ice cover in the spring and summer. No such polar amplificationeffect has occurred on a large scale in the Southern Hemisphere, however. The melt-warmth-melt feedback cycle means that the Arctic is warming faster than the rest of the globe. Warmer conditions on land affect the nearby ocean, and more sea ice melts as a result. As Northern Hemisphere spring and summer snow cover declines, the underlying land surface absorbs more energy and warms. Ice and (especially) snow are highly reflective, bouncing much of the Sun’s energy back into space. In the Arctic, landmasses surround and influence the sea ice in the Arctic Ocean. Land-sea configurations affect sea ice extents not only by limiting where ice can form, but also by introducing their own effects. None of the trends are statistically significant. NOAA graph, based on Charctic data from the National Snow and Ice Data Center.Īccording to the National Snow and Ice Data Center’s Sea Ice Index, from the start of the satellite record in November 1978 through February 2022, Antarctic sea ice showed a slightly positive long-term trend in most months, with the exceptions of January, February, and November, which showed slightly negative trends. The summer minimum has been below-average for the past 7 years, but the long-term trend remains statistically insignificant thanks to the region's history of big swings in ice extent from year to year. February 2022 (dark blue) replaced 2017 (pink) as the smallest summer minimum on record. The dark gray dashed line shows the average, while the light gray area shows the range of variability (95% of values). But the overall trend, as of early 2022, is nearly zero.ĭaily ice extent in the Southern Hemisphere from 1979 through February 2022. ![]() Since the year 2013, Antarctic sea ice has exhibited its highest and lowest extents on record-highest-ever winter maximum in September 2014, and lowest-ever summer minimum in February 2022. Year-to-year variability has dominated, especially over the last decade. The satellite record spans over four decades, and although the ice has shown increasing and decreasing trends over portions of that record, few of those trends have been statistically significant. Overall, the long-term trend in Antarctic sea ice is nearly flat. ![]() The eastern Ross Sea region has shown a modest increase in ice extent over the same period. Another region near the northern tip of the Peninsula, in the Weddell Sea, showed strong sea ice declines until 2006, but the ice in that region has rebounded in recent years. The region south and west of the Antarctic Peninsula has shown a persistent decline, but this downward trend is small compared to the high variability of Antarctic sea ice overall. Those exceptions have occurred around the Antarctic Peninsula. From 1979–2017, Antarctic-wide sea ice extent showed a slightly positive trend overall, although some regions experienced declines. Unlike the Arctic, where sea ice extent is declining in all areas in all seasons, Antarctic trends are less apparent. The sea ice satellite record dates back to October 25, 1978. Weather exerts a greater influence on the Arctic minimum, and the Antarctic maximum. Weather events often drive variability, but have different effects in the Northern and Southern Hemispheres. These changes largely result from the geographic differences mentioned above, namely Antarctic sea ice’s distance from the pole (sea ice can melt back all the way to the coast in summer, making for less year-to-year variability) and unconstrained growth potential in winter. Compared to the Arctic, Antarctic sea ice shows lower variability in summer, and higher variability in winter. Sea ice waxes and wanes with the seasons, but minimum and maximum summer and winter extents vary. Although this can occur in the north as well, it is less common. The heavy snow burden can depress ice floes, and seawater can subsequently flood those floes. This saturated snow can freeze, forming “snow ice,” an important component of southern sea ice. However, snowfall often thickens Antarctic sea ice. So overall, average Antarctic ice thickness is much lower than Arctic sea ice. Photo captured by the DMS camera on the first flight of NASA’s Operation Ice Bridge Campaign. The brighter the ice, the more it has been compacted by wind and waves. Young, thin ice floats in the Amundsen Sea on October 16, 2009.
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