Climate Matters•September 15, 2021
Arctic sea ice minimum
KEY CONCEPTS
As the yearly Arctic sea ice melt season comes to an end, it looks like this year will be among the 12 lowest ice minimums on record. This means the 15 lowest sea ice extents (ice coverage) in the 42-year satellite record have all occurred in the last 15 years.
Climate change is melting the Arctic, and fast. Both the average September (minimum) and March (maximum) sea ice coverage have been decreasing since records began in 1979 and will only accelerate as global temperatures rise. The amount of multi-year sea ice (ice that survives multiple melt seasons) has also plummeted to its lowest level over the past four decades. In addition, warming conditions on the Greenland ice sheet have led to massive, unprecedented melting events in 2021.
So why does this matter? Declining sea ice can accelerate global temperatures, impact local weather patterns, as well as affect global commerce and the livelihood of local indigenous communities.
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As the Arctic sea ice melt season comes to an end, it looks like this year will likely be among the 12 lowest ice minimums on record. Sea ice coverage naturally fluctuates throughout the year, but over many years, there has been a decreasing trend. Climate change is warming the Arctic three times as fast as the global average, and as a result, we are seeing a rapid decline of ice.
Declining sea ice coverage: Both the average September (ice minimum) and March (ice maximum) sea ice coverage have been decreasing since records began in 1979. In fact, the 15 lowest sea ice extents (ice coverage) in the 42-year satellite record have all occurred in the last 15 years. This rapid decline will only accelerate as global temperatures rise. According to the Intergovernmental Panel on Climate Change (IPCC) sixth assessment report, the Arctic sea ice is projected to be effectively ice-free during its summer minimum at least once before 2050.
Melting multiyear ice: Arctic sea ice can have different ages. There is first-year ice that forms in the winter and melts within the year (and is usually thin) and then there is multiyear ice that survives one or more melt seasons (and is usually thicker). However, as the Arctic continues to warm, multiyear ice drastically decreases.
This year has the lowest extent of multiyear ice on record.
The proportion of the oldest multiyear sea ice (older than four years) has decreased by more than 86% since 1985. In March 2020, during the ice coverage maximum, the oldest sea ice only made up 2% of sea ice cover, while the thinner, first-year ice made up about 70%.
Greenland ice sheet: We also see ice loss in Greenland as warming air and ocean temperatures melt its glaciers. Unlike melting sea ice, melting glacial ice contributes to sea-level rise.
There have been several massive melting events in 2021 so far. One melt event in July had the seventh-largest melt area and fourth-highest runoff in the satellite record.
On August 14th, rain fell on the highest point of the Greenland Ice Sheet for nine hours. According to the National Snow and Ice Data Center, this was the third time in less than a decade that this area had above-freezing temperatures.
Why does this matter? What happens in the Arctic, doesn’t stay in the Arctic. Everything is connected in the climate system, and warming in the Arctic region can have significant effects on:
Global climate: Snow and ice reflect sunlight and help cool the planet. Loss of ice cover in the summer decreases this natural cooling and exposes darker surfaces that absorb even more heat. In addition, a warmer Arctic region can thaw permafrost, releasing more heat-trapping greenhouse gases into the atmosphere.
Local climate: A growing body of research is connecting the warming Arctic to changes in the jetstream that drive our weather patterns. Some studies have linked this to summer heatwaves and winter cold waves, like the Texas winter storm that killed over 100 people this February. Melting in Greenland has been linked to changes in the North Atlantic ocean currents, impacting ecosystems, fisheries, and weather patterns in the Northeast and Europe.
Global security & economy: The loss of Arctic sea ice can allow new stretches of ocean to open up for shipping. This can create routes for commerce, exploration, and potential geopolitical conflict.
Indigenous Communities: Climate change threatens the livelihoods of Indigenous communities within the Arctic region. Thinning and slow-forming sea ice makes it difficult for the Inuit community to access traditional hunting grounds and travel for healthcare while thawing permafrost near Alaskan communities has led to soil erosion that floods their homes and roads.
Additional resources on the Arctic:
Closely follow on the NASA OMG mission to Greenland with coverage from these accounts:
Follow OMG (Oceans Melting Greenland) on Twitter at: #omgnasa
POTENTIAL LOCAL STORY ANGLE
How are coastal areas affected by melting glacial ice?
When glaciers melt, the water that was once frozen on land pours into the ocean, contributing to sea level rise. To learn more about glacial ice loss and how this can impact coastal communities, take a look at Chapter 4: Sea Level Rise and Implications for Low-Lying Islands, Coasts and Communities in the IPCC Special Report On The Ocean And Cryosphere In A Changing Climate. You can also use our Climate Central sea level rise tools to visualize the future flooding in your area.
NATIONAL EXPERTS
Josh Willis, Ph.D. Principal Investigator for Oceans Melting Greenland
Project Scientist for Sentinel-6 and Jason-3
NASA's Jet Propulsion Laboratory (JPL)
Contact: joshua.k.willis@jpl.nasa.govJoel Clement, Senior Fellow, Arctic Initiative
Harvard Kennedy School’s Belfer Center for Science and International Affairs, Harvard University
Contact: joel_clement@hks.harvard.eduJennifer Francis, Ph.D, Acting Deputy Director and Senior Scientist
Woodwell Climate Research Center
Expertise: Link between Arctic and North American weather patterns
Contact: jfrancis@woodwellclimate.org
METHODOLOGY
Arctic sea ice extent is defined as the area of ocean with at least 15% sea ice concentration. Multiyear Arctic sea ice extent and Greenland surface melt extent data were obtained from the National Snow and Ice Data Center.
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