Polar climate
Polar climate is defined by its persistently cold temperatures, characterized by tundra or ice cap environments and the presence of permafrost. This climate exists at both poles of the Earth, with Antarctica at the south, where temperatures can plummet to -70° Celsius, and the Arctic tundra in the north, which experiences short, cool summers and long, harsh winters. In the Arctic, temperatures can range from 0° Celsius in some areas to as low as -28.1° Celsius at high elevations in Greenland. The region's unique permafrost, a layer of permanently frozen soil, supports limited vegetation during its active melting season.
Climate change significantly impacts polar regions, with Antarctica warming at a rate ten times faster than the global average. This warming leads to the melting of ice sheets, shrinking glaciers, and declining sea ice extent, threatening local wildlife and ecosystems. For instance, Adelie penguin populations are struggling to adapt to the changing environment, while other species, such as seals and certain penguin species, are migrating further south. The Arctic is also experiencing dramatic changes, including predictions of an ice-free summer in the Arctic Ocean by 2027. These shifts disrupt traditional lifestyles for indigenous communities reliant on the land and waterways, highlighting the urgent need for understanding and addressing the implications of climate change in polar climates.
Subject Terms
Polar climate
Definition
Polar climate is characterized by year-round cold conditions, tundra or ice cap, and permafrost. At Earth’s south pole is Antarctica, 95 percent of which is covered in ice. Temperatures on the continent range from 0° Celsius to -70° Celsius. At Earth’s north pole is the Arctic tundra, as well as treeless vegetation zones. The tundra is bordered on the south by forests and on the north by the Arctic lands and has a layer of permafrost. The Arctic is characterized by short, cool summers and long, cold winters. Arctic high temperatures range from 0° Celsius in Russia to 12.2° Celsius in Alaska; lows range from -16.3° Celsius in Canada to -28.1° Celsius at the highest point of Greenland’s ice sheet.
Permafrost is a permanently frozen soil layer under the topsoil. The top layer, or active layer, melts and refreezes each year, while the lower level stays frozen year-round. The active layer provides water and a place for plants to grow. The temperature in the lower levels is at or below 0° Celsius, and usually ranges from -6° to -9° Celsius. One-fourth of the land in the Northern Hemisphere is in permafrost zones, and almost all the permafrost areas in the Southern Hemisphere are in Antarctica.
Significance for Climate Change
Although the ice sheet is not expected to melt completely in the near future, the Antarctic is warming ten times faster than the average anywhere else in the world. Since the mid-1940’s, the average temperature is -16° Celsius warmer year-round and -13° to -14° Celsius warmer in early winter. The far western edges and ground are becoming warmer, and the ice sheet edge is rapidly eroding. The amount of sea ice was stable from 1840 to 1950, but has decreased since then by roughly 20 percent.
The icebergs are shrinking, glaciers are receding, and the immense Larsen ice shelf began disintegrating in 1995. Nearly 2,590 square kilometers of the ice shelf collapsed between 1998 and 2000. The breakups of ice chunks lead to the faster flow of ice from the glaciers upstream, which in turn can increase the sea level over time. With the edges of the ice sheet melting, the wildlife populations are fluctuating. Adelie penguins are dying off, because they cannot adjust to the changes in their environment. Meanwhile, other species are migrating south and establishing colonies. Scientists have observed the southern migration of elephant and fur seals, as well as other species of penguins. Additionally, low grasses, mosses, and tiny shrubs are thickening in several areas.
Climate changes are more dramatic in the Arctic. The Arctic is ringed by the lands of Canada, Denmark (through Greenland), Finland, Iceland, Norway, Russia, Sweden, and the United States. Sea ice covers the entire Arctic Ocean and nearby waters every winter. This sea ice provides a home for polar bears and transportation routes for people, and shields coastal towns and underwater creatures. Normally, the ice melts on land in the summer and breaks up some in the Arctic Ocean, but there was 80 percent less ice in 2005 than in the 1970s, with more rapid melting since 2003. According to the US National Oceanic and Atmospheric Administration, in the summer of 2016 Arctic sea ice reached its second minimum extent on record—the minimum extent recorded was in 2012—and was 29 percent smaller than the average minimum between 1981 and 2010. The Arctic sea ice shrunk to 1.65 million square miles (4.28 million square kilometers) in 2024. While this was not as low as 2016's 1.31 million square miles (3.39 million square kilometers), it was the seventh-lowest on record. In 2024, the National Snow and Ice Data Center (NSIDC) estimated that the loss of sea ice has been about 30,000 square miles (77,800 square kilometers) per year. Scientific data suggested that the Arctic Ocean may be ice-free in the summer as early as 2027, which has not happened in at least 800,000 years. A rise in ice sheet melting raises the sea level, and even a 1-2 millimeter rise increases flooding at the coastlines.
Summertime temperatures in parts of the Arctic are warmer than those recorded in the last four hundred years, and winter temperatures have increased by 2° to 4° Celsius since 1976. The Arctic cools the Earth, because it reflects more solar radiation than it absorbs, with ice and snow the most reflective, followed by tundra vegetation. The warmer temperatures have led to unpredictable weather patterns that threaten the delicate natural balance of the environment and endangered the plants and animals, as well as the humans who depend on them. The ice sheets near the coastline are smaller or nonexistent, which greatly affects subsistence whalers and seal hunters and subjects the coastline to damaging waves. Several coastal Alaskan villages have had to relocate inland and others are threatened because of coastal erosion.
When the lower layers of permafrost thaw, they can create an underground lake which may drain off, leaving a cavity. The surface will then slump inward, creating a sinkhole into which trees, roads, and buildings slowly fall. This melting has already happened in Siberia and Fairbanks, Alaska, where the permafrost is at the warmest levels since the last ice age. The sinkholes are patchy so far and usually occur where digging and construction opened up the landscape. Thawing permafrost can also cause the sea levels to rise slowly and, because it traps large amounts of carbon, melting permafrost releases the carbon back into the atmosphere as methane, a greenhouse gas.
Bibliography
"Arctic Report Card: Update for 2016." Artic Program, National Oceanic and Atmospheric Administration, http://www.arctic.noaa.gov/Report-Card/Report-Card-2016. Accessed 12 Dec. 2024.
Flannery, Tim. We Are the Weather Makers: The Story of Global Warming. Rev. ed. London: Penguin, 2007.
Henson, Robert. The Rough Guide to Climate Change: The Symptoms, the Science, the Solutions. New York: Penguin Putnam, 2006.
Wohlforth, Charles. The Whale and the Supercomputer: On the Northern Front of Climate Change. New York: North Point Press, 2004.
Younger, Sally. "Arctic Sea Ice Near Historic Low; Antarctica Ice Continues to Decline." NASA, 24 Sept. 2024, www.nasa.gov/earth/arctic-sea-ice-near-historic-low-antarctic-ice-continues-decline/. Accessed 12 Dec. 2024.